Introduction to the Pulmonary Reading Material Introduction to the Pulmonary Reading

Respirology Primer 2006 University of Alberta Chapter One

The reading material on this CD consists of a series of Of course, few algorithms can take into account all possibilities and chapters specifically written to help you manage common there will certainly be times when the algorithms cannot or should problems seen in respirology while on your rotation. Note not be followed rigorously. However, for the majority of cases, they some important points: will likely apply to a large degree. As well, the handouts often take into account local practice (i.e. Edmonton, specifically the University of Alberta Hospital), which is usually influenced by local resources, The Primer is not meant to substitute for textbook reading. It disease epidemiology, and local expertise. Thus, in areas where is assumed that, at the postgraduate level, you will already these factors may differ, what we do locally may not strictly be the know the basic facts of common respiratory diseases and that pattern of practice followed elsewhere (although it will likely be you have access to reference material to supplement your quite similar). learning. The purpose of the Primer is to provide you with a practical guide to help you manage the clinical pulmonary issues that you may encounter. Most of the topics intentionally deal with diagnosis rather than treatment, since the latter tends to be more individualized and can

evolve relatively rapidly. Many of the sections utilize an algorithmic approach to problems. Unless otherwise specified, the algorithms have not necessarily been prospectively evaluated. However, they Feel free to direct feedback or suggestions for new topics in the represent a reasonable approach to problems seen by reading material to me. (email: [email protected] or practicing Respirologists and are based on clinical experience, 2E4.34 WMC) supplemented by the literature whenever possible. Chapter Two

Basics on Non-Invasive Ventilation THE BASICS ON NON-INVASIVE POSI- TIVE PRESSURE VENTILATION by Dr. L. Cheung

Figure 1: CPAP applies a continuous set pressure on 1. Introduction inspiration and expiration Case 1: A 68 year old male presents to the ER with an acute COPD exacerbation and has an ABG on 5 lpm which shows a PO2 of 68, PCO2 76, pH 7.26, HCO3 33. He is inspiration CPAP tachypneic and in moderate respiratory distress but is reasonably alert and awake. Is he a good candidate for continuous set non-invasive mechanical ventilation (NIMV)? presure Case 2: A 45 year old male presents with a 5 day history of increasing dyspnea due to community acquired pneumonia and is now in the ER requiring 15 lpm of oxygen to maintain his Oxygen saturation at just over expiration 89%. He is tachypneic and tachycardiac, and has CPAP increased work of breathing. Is he a good candidate for NIMV? continuous set Case 3: presure A 65 year old female is on the surgical ward post-op day 2 for a right hemicolectomy for colon cancer. She is now hypoxemic due to bilateral lower lobe atelectasis, requiring about 15 lpm of oxygen to maintain oxygen saturations of over 90%. However, she seems to be in Although one might think that this applied pressure would minimal respiratory distress, is speaking full sentences, help inspiratory effort, the effect is actually quite and is hemodynamically stable. Is she a good candidate negligible at the low levels previously mentioned (5 to 10 for NIMV? cm H2O). Thus, the main effect during inspiration is to Case 4: help “stent” the upper airway open in people with sleep A 70 year old male with end stage pulmonary fibrosis is apnea, but it provides little help for the inspiratory admitted due to severe hypoxemia requiring flush (> 15 muscles. lpm) oxygen by mask. He and his family know that he is going to die soon from his underlying disease. He has During expiration, however, the applied pressure acts as a increased work of breathing. Is he a good candidate for “back pressure”, and helps open collapsed alveoli by “palliative” NIMV? increasing functional residual capacity (FRC), the volume of gas remaining in the lungs after a normal tidal (The answers to these cases are described at the end of exhalation. This may improve oxygenation through this chapter) improved V/Q matching. The alveoli are the most vulnerable to collapse at end-exhalation since this is when This chapter will enable you to answer the following the lung volume is at it’s lowest. clinically important questions regarding NIMV 1. What is the difference between CPAP and BiPAP? Note, however, that if the pressure is set too high, it 2. What are the indications and contraindications for becomes uncomfortable during expiration – the patient each? feels like he can’t exhale – and it may actually impair 3. What are the typical settings that should be ordered? exhalation to the point where the patient is using energy trying to actively exhale against the high back pressure.

2. What is the Difference Between Thus, based on the above discussion, the indications for CPAP and BIPAP? CPAP would include either sleep apnea or hypoxemia due to atelectasis and low lung volumes resulting in very high A. CPAP O2 requirements in a patient who is otherwise stable. CPAP provides continuous positive airway pressure at low Although some would start CPAP for hypoxemia from levels, usually starting at 5 to 10 cm H2O. Because the other causes (eg. pneumonia with severe hypoxemia), pressure is applied continuously throughout the there are conflicting studies as to whether this improves ventilatory cycle, it occurs at a constant level throughout inspiration and expiration, as illustrated in Figure 1. THE BASICS ON NON-INVASIVE POSI-

TIVE PRESSURE VENTILATION outcome. Part of the problem is that these patients can EPAP, which is lower than the inspiratory pressure. This is deteriorate quickly – if CPAP is applied, it should be done illustrated in Figure 2. in a monitored setting. Typical initial settings would be an EPAP of 4 cm H2O and Although CPAP starting pressures are usually 5 to 10 cm a starting IPAP of 8 cm H2O for an individual with an H20, higher pressures of up to 15 cm H20 may be required average sized body habitus and chest wall compliance. if a patient is obese (with low chest wall compliance, These settings are usually set low at first to get the higher back pressures are needed to open up the alveoli). patient used to the pressure and then titrated upwards as necessary. If a patient requires assistance with inspiration (eg. due to increased work of breathing, respiratory muscle fatigue, The IPAP is titrated by 2 cm H20 upward as necessary to a and hypercapnea from COPD), we need to increase the maximum of 20 cm H2O. Typical final settings for IPAP applied inspiratory pressure. But, as mentioned, if the would be about 12 to 18 cm H2O. same continuous positive airway pressure is simply increased, it may help inspiration but actually be Since the goal of the IPAP is to help inspiration, it is intolerable during expiration. For these instances, we titrated to improve the patient’s work of breathing and need to have bi-level positive airway pressure or BiPAP – sense of dyspnea, as well as to improve the PCO2 (by a higher pressure during the inspiratory phase to augment improving the tidal volumes during inspiration). inhalation and assist fatigued or weak inspiratory muscles, but a lower pressure during the expiratory Since the goal of the EPAP is to prevent alveolar collapse phase. at end-expiration (thus improving V / Q matching), it is titrated to improve the oxygenation. Final EPAP settings B. BIPAP are usually 4 to 8 cm H2O. BIPAP consists of an inspiratory positive airway pressure or IPAP and an expiratory positive airway pressure or Monitoring the effectiveness of BIPAP consists of clinical assessment and ABG’s, typically done just before the onset of BIPAP and then 1 hr, 6 hrs, and 24 hrs post- intiation of BIPAP (or more if necessary). Figure 2: BiPAP applies an inspiratory positive airway pressure to help fatigued or weak inspiratory muscles In general, indications for BiPAP would include during inspiration. However, BiPAP applies a lower expi- hypercapneic respiratory failure due to a number of ratory positive airway pressure during expiration - reasons including an acute exacerbation of COPD, enough to help keep the alveoli open but not so much as asthma, or cystic fibrosis, or acute, potentially reversible to impair exhalation. neuromuscular weakness in a patient who is still able to protect his airway. In general, hypoxemic respiratory failure is not really an indication for BiPAP.

inspiration IPAP 3. Contraindications to Mask

IPAP > EPAP Ventilation There are certainly situations where it is not safe to administer NIMV. These contraindications are listed below: • Cardiac or respiratory arrest • Severe encephalopathy - (eg. GCS < 10) Note, expiration EPAP however, that decreased LOC due to hypercapnea from acute COPD exacerbation might improve with NIMV. Thus, whether NIMV should be applied in this IPAP > EPAP setting should be decided on a case by case basis. As well, it is important to be reasonably sure that the hypercapnea is causing the decreased LOC and not THE BASICS ON NON-INVASIVE POSI-

TIVE PRESSURE VENTILATION

the other way around (ie. that decreased LOC is causing hypoventilation which, in turn, is causing 4.Answers to the Introductory hypercapnea - NIMV will not reverse the cause of the decreased LOC itself in these circumstances). Cases Case 1: • inability to protect the airway / high risk for aspiration This patient presents with hypercapneic respiratory failure • severe hemodynamic instability or unstable cardiac due to an acute COPD exacerbation and meets rhythm physiologic and clinical criteria for NIMV (hypercapnea, • active GI bleeding with hematemesis (vomiting blood respiratory acidosis, increased work of breathing, no into the mask would be bad) obvious contraindications). NIMV has been shown to • multiple organ failure improve outcomes in this setting. • acute facial surgery or trauma • immediately post-op after esophagectomy (where air Case 2: blowing into esophagus could disrupt the This patient presents with severe hypoxemic respiratory anastamosis) failure due to pneumonia alone (ie. let’s assume there is no concomitant COPD). There are conflicting reports Table 1 reviews the indications and typical settings for about whether outcome is improved with NIMV in this CPAP and BiPAP. setting and, in fact, some studies suggest a worse outcome. Thus, at this time, NIMV in this setting is not generally recommended. If it is attempted, it should be

Table 1 MODE INDICATIONS and TYPICAL SETTINGS

CPAP • sleep apnea – helps stent the upper airway open • severe hypoxemia due to atelectasis, refractory to other measures such as chest physio or incentive spirometry – helps expand the alveoli or at least decreases collapse at end-expiration. The best example of this would be a post-op patient with bilateral atelectasis and low lung volumes who requires high flow oxygen but doesn’t appear to be in much respiratory distress (i.e. does not seem to have a high work of breathing) • usually set at 5 to 10 cm H2O

BIPAP • COPD exacerbation along with physiologic criteria • other causes of hypercapneic (ventilatory) respiratory failure where help for the inspiratory muscles is needed to improve ventilation, such as exacerbations of CF, asthma, decompensation of an acute, reversible neuromuscular disease • hypoxemic respiratory failure (eg. pneumonia) – this indication is controversial as studies provide conflicting results as to whether BIPAP in this setting actually improves outcome • start EPAP at 4 cm H2O, start IPAP at 8 cm H2O and titrate IPAP as necessary to max 20 cm H2O (most patients will require 12 to 16 cm H2O). Titrate EPAP 4 to 8 cm H2O as tolerated. THE BASICS ON NON-INVASIVE POSI-

TIVE PRESSURE VENTILATION done in a monitored setting, such as ICU.

Case 3: This patient has hypoxemia due to atelectasis and is otherwise stable. She might improve with CPAP (to help open up the alveoli and prevent their collapse on end-expiration). Thus, it is reasonable to try CPAP on her, as long as she is in a monitored setting.

Case 4: This patient has end stage fibrosis and hypoxemic respiratory failure. He should be palliated with medications (eg. narcotics), not BiPAP, since the latter would simply prolong the dying process. I can think of very few circumstances where I would even contemplate a trial of BiPAP on this person.

References: 1. Liesching T. Kwok H. Hill N. Acute Applications of Noninvasive Positive Pressure Ventilation. CHEST 2003;124:699-713. 2. Squadrone V et al. Continuous Positive Airway Pressure for Treatment of Post-operative Hypoxemia. JAMA 2005;293 (5):589-595. Chapter Three

Mechanical Ventilation MECHANICAL VENTILATION By Dr. L. Cheung 1. Introduction Figure 1 This chapter will enable you to answer the following clinically important questions regarding mechanical ventila- Volume Preset Pressure Preset tion: Ventilation Ventilation 1. What are the two main categories of invasive ventilation that most modes fall under and how do they differ? 2. What are the commonest modes of ventilation seen on the Pulmonary ward and what are the features of each? Partial Partial 3. What are the clinical scenarios for which each mode Control Control Support Support Mode Mode of ventilation is best suited? Mode Mode 4. What are some common initial settings for each mode of ventilation?

When we put a patient on invasive mechanical ventilation, we have control over his inspiration. Thus, the key •SIMV •A/C • PSV •PCV to knowing the differences between the various modes of ventilation is in distinguishing how each mode differs in its delivery of the inspiratory breath.

(Exhalation is passive and beyond our direct control. We As well, some modes of ventilation combine these two can influence the volume of the lungs at end-expiration features and would fall under a third category called by using PEEP - more on this later) “dual control modes”, but for simplification, we’ll just

focus on the two main categories of ventilation so we can Inspiration has 3 components: understand the basic concepts. 1. initiating the inspiration, which is called “triggering”

2. delivering the breath, which is either via a preset However, before we distinguish volume vs pressure pre- pressure or preset tidal volume set ventilation, let’s discuss the difference between pa- 3. terminating the inspiration, which is called tient and machine triggered breaths. “cycling” (the details of which you do not need to

know) 2. Triggering As shown in Figure 1, many modes of mechanical ventila- Breaths can either be patient triggered or machine trig- tion can be distinguished based on how the ventilator gered. In patient triggered breaths, the patient initiates delivers the breath - either via a preset pressure vs a pre- inspiration by contracting his diaphragm, thus lowering set tidal volume - during patient triggered or machine intrathoracic pressure slightly. The ventilator senses this triggered breaths. and delivers a breath, as shown in Figure 2.

Figure 2: an illustration of patient triggered breaths 3. Ventilator detects the slight movement of air flow towards the patient and delivers a breath 1. Patient initiates inspiration

2. Intrathoracic pressure drops MECHANICAL VENTILATION

Figure 4 All modes of ventilation deliver a breath when the patient initiates it. In fact, there are one or two modes of venti- Volume lation which will only deliver a breath when the patient Preset initiates it. In other words, for these modes of ventilation, Mode if the patient is apneic and making no attempts at triggering, the ventilator will not deliver any breaths and the apnea alarm will ring.

In addition to patient triggered breaths, most modes of Airway pressure ventilation also deliver machine triggered breaths (also needed to inflate the called “controlled” breaths) if the patient does not make lung may vary if any attempt at inspiration. An example of this is illus- there are changes to the resistance to Figure 3 airflow or compliance of the lungs Machine triggered breaths every 4 seconds

Time changes in the airflow resistance or respiratory system compliance. Also note that, if the patient tries to take a Patient triggered breath deeper breath, he will still get the set tidal volume - it will still not change.

In pressure preset modes of ventilation, the breath is delivered at a constant airway inflating pressure that we trated in Figure 3. set. Thus, the airway pressure does not change (unless we change it). If changes in airflow resistance or lung In this example, the ventilator is set at a respiratory rate compliance occur, this will cause a change in tidal vol- of 15 - the first 3 breaths occur every 4 seconds (60 / 15) umes. As well, the tidal volume can vary somewhat because the patient is not making any attempt at inspira- based on the patient’s own inspiratory effort - greater tion. The fourth breath, however, is patient triggered. effort from the patient will result in a higher tidal volume, After this breath, the ventilator “resets the timer” so that all other factors being equal. the next breath will be delivered 4 seconds after the patient triggered breath if he makes no further attempt at triggering on his own. If he does trigger the ventilator 4. Commonest Modes of Ventila- again before the 4 seconds are up, the timer will be reset tion on the Pulmonary Ward again, and so on. Now that we have reviewed some basic concepts, I will list some of the commonest modes of ventilation 3. Volume Preset vs Pressure Pre- (summarized in Table 1) on the Pulmonary ward and describe the following for each ventilatory mode: set Ventilation • the manner in which the breath is delivered As previously mentioned, one of the keys to understand- • the differences between the various modes ing the differences between the modes of ventilation is in • the advantages and disadvantages of each knowing which modes deliver the breath at a preset vol- • the clinical scenarios in which each is commonly ume vs a preset pressure. used • the initial settings that are commonly prescribed As shown in Figure 4, in volume preset modes, we set the tidal volume that will be delivered during the breath. In- spiration continues until this set tidal volume is achieved. This set tidal volume does not change (unless we change it) - as a result, the airway pressure that the ventilator needs to deliver this breath will vary if there are any MECHANICAL VENTILATION

Usual Clinical Settings Decreased LOC with (but ventilation for surgery lungs) normal weak- severe neuromuscular ventilation on the ness (chronic a using ward or at home ventilator) “simple” to but starting LOC Decreased up (eg. emerging from wake for a routine post-op anesthetic patient) breathing pa- Spontaneously tient ARDS or Severe pneumonia lung reduced with markedly compliance Similar to A/C but in the ICU setting • • • • • • • stant flow rates) variable flow rates) variable flow Triggered Breaths Only Type of Breath Delivery of Breath Delivery Type Set Pressure with Each Breath Set Pressure with Each Breath Set Volume with Machine Set Volume with Each Breath (but Set Volume with Each Breath (at con- Type of Triggering Type Patient Triggered Only Only Patient Triggered Patient and Machine Triggered Triggered Patient and Machine Triggered Patient and Machine Triggered Patient and Machine Triggered Patient and Machine Mode A/C SIMV PSV PCV PRVC Table 1 MECHANICAL VENTILATION

A. Assist Control Mode (A/C) • Advantages include a guaranteed tidal volume and 1. Features: respiratory rate in patients who are not able to • This mode allows for both patient triggered and ma- achieve this on their own, but more control of tidal chine triggered breaths. Thus, we set the respiratory volume (at least more than A/C) in able patients. rate (which will be the minimum rate the patient will The classic use for SIMV is in the post operative pa- receive) but the patient can trigger the ventilator and tient who is just emerging from anesthesia and is breathe faster than this set rate. starting to awaken but easily drifts off to sleep when not stimulated. • This is a volume preset mode. We set the tidal volume and every single breath, whether it is patient • Disadvantages include the same risk of barotrauma triggered or machine triggered, is delivered at this for the machine triggered breaths as seen in A/C. set tidal volume. 3. General initial settings: 2. Advantages, disadvantages, and clinical settings: • respiratory rate 16, tidal volume 8 to 10 mL / kg (for • Advantages include a guaranteed tidal volume and the machine triggered breaths). respiratory rate in a patient who is not able to do this on his own (eg. a patient with a low respiratory rate, C. Pressure Support Ventilation (PSV) tidal volume, or both due to drug overdose, anesthe- 1. Features: sia, severe neuromuscular weakness or paralysis, • In contrast to A/C and SIMV, PSV is a pressure tar- etc). As well, the patient triggered breaths allow for geted mode of ventilation. In other words, each some patient control over ventilation. breath is delivered at a preset pressure and tidal vol- • Another advantage is that A/C, being a relatively sim- ume will vary depending on patient effort and any ple mode of ventilation, can be done by the simple changes in airflow resistance or lung compliance. ventilators that we use for home or ward ventilation. • Also in contrast to A/C and SIMV, note the word • Disadvantages include lack of full control over venti- “support” in the name of PSV. This means that this lation in an awake, spontaneously breathing patient, mode of ventilation only delivers patient triggered which may lead to poor ventilator tolerance. In other breaths, no machine (or controlled) triggered breaths. words, the patient cannot vary his tidal volume up or Thus, if the patient makes no effort to trigger the down from breath to breath like most of us do spon- ventilator, he will not receive any breaths. taneously. If the patient wants a higher tidal volume, 2. Advantages, disadvantages, and clinical settings. the only way he can get “more air” is to breathe • Advantages include more control by the patient over faster. Another disadvantage is the risk of baro- his ventilation and the ability to vary the tidal volume trauma if you try to overdistend the lungs with a set and respiratory rate. As well, since it is a pressure tidal volume that is too high, leading to high airway preset mode, the airway pressures will be constant, inflation pressures. reducing the risk of barotrauma. We often use this 3. General initial settings: mode of ventilation when we are trying to wean pa- • respiratory rate 16, tidal volume 8 to 10 mL / kg (in tients off of the ventilator (ie. they have to do an in- a patient with normal lungs), FiO2 to keep > 90%, creasing amount of work as we lower the amount of adjust ventilation to maintain a pH of 7.35 to 7.45. PS over time) or in patients who too awake and alert and not tolerating other modes of ventilation like A/ B. Synchronized Intermittent Mandatory C. • Disadvantages include fatigue and tachypnea if the Ventilation (SIMV) pressure support level is set to low and the risk of 1. Features: apnea in a patient who is not fully awake, alert, etc. • This mode allows for both patient triggered and ma- 3. General initial settings: chine triggered breaths. • the PS can be set anywhere between 6 to 30 cmH20, • SIMV is a volume preset mode of ventilation. Every with a PS of around 18 a reasonable starting point machine triggered breath is delivered at a set tidal and then adjusted up or down based on the patient’s volume. However, in contrast to A/C, the patient tidal volumes. triggered breaths are not delivered at the set tidal volume. Rather, the patient triggered breaths are either unsupported, or supported with pressure sup- D. Pressure Control Ventilation (PCV) port (see later). Thus, the tidal volume for the patient 1. Features: triggered breaths will vary based on patient effort. • Like PSV, and in contrast to A/C and SIMV, PCV is a 2. Advantages, disadvantages, and clinical settings: pressure preset mode of ventilation where we set the inflation airway pressure that the ventilator will use MECHANICAL VENTILATION

to deliver each breath. Unlike PSV, this mode is capa- breaths). ble of delivering both patient triggered and machine • We preset the tidal volume and the ventilator will triggered breaths. Thus, we are able to set a mini- deliver this tidal volume with each breath, like in A/C. mum respiratory rate (hence the use of the word However, unlike A/C, in which each breath is deliv- “control” in the name of the mode). ered at a fixed inspiratory flow rate over a fixed 2. Advantages, disadvantages, and clinical settings: amount of time (thus delivering a preset tidal volume • Advantages include a reduced risk of barotrauma in each time), in PRVC the inspiratory flow rates will patients with “stiff”, poorly compliant lungs, from vary to try to minimize the airway pressure for each diseases like ARDS or severe pneumonia. As well, in breath. As well, as a safety feature, if the airway contrast to PSV, we can deliver a minimum set rate, pressure becomes too high, the set tidal volume will ideal for the above patients who also require a lot of not be delivered and the breath will switch to exhala- sedation. tion. • Disadvantages include tidal volumes which may be • However, in the end, I would say that PRVC is more quite low if the lungs are very stiff, potentially leading like a volume preset mode of ventilation rather than to severe hypoventilation and worsening hypercap- a pressure preset mode since the ventilator will try to nea. deliver the preset tidal volume per breath. 3. General initial settings: 2. Advantages, disadvantages, and clinical settings: • respiratory rate 20 to 24 (usually higher because, in • PRVC has many of the advantages of A/C but, be- settings like ARDS or severe pneumonia, where we cause the ventilator will vary the inspiratory flow usually use PCV, the tidal volumes are lower and the rates to minimize the airway pressures and baro- patient needs a higher rate to try to minimize the trauma, PRVC has less of the disadvantages of A/C. hypoventilation.), PC ~ 16 to 20 cmH20. Thus, you can use PRVC in all of the settings that you would use A/C - patients who would hypoventilate E. Pressure Regulated Volume Control because of decreased LOC, neuromuscular weakness or paralysis, etc. The disadvantage is that PRVC, be- (PRVC) ing a more complex mode than A/C, is not found on As mentioned near the beginning of this chapter, some the simple ventilators that we use for home venitila- modes don’t fall fully into either the volume preset or tion. Thus, we use A/C mode on simple ventilators pressure preset category but, rather, combine some ele- for these long-stay patients or as a prelude to going ments of each. PRVC is a mode of ventilation which falls home or to a long term care facility. into this “dual control” mode, as illustrated in Figure 5, which expands the classification scheme presented in Table 1 lists the modes of ventilation that we have dis- Figure 1. cussed and compares their features.

1. Features: • With the word “control” in the name, you’ve probably guessed that this mode can deliver machine triggered as well as patient triggered breaths (as opposed to PSV which only delivers patient triggered

Figure 5 Volume Preset Dual Control Pressure Preset Ventilation Modes Ventilation

Partial Partial Control Control Support Support Mode Mode Mode Mode •PRVC

•SIMV •A/C •PSV •PCV MECHANICAL VENTILATION

space, chest wall, and upper airway. 5. PEEP As previously mentioned, exhalation is passive and beyond our direct control. One of the things about exhala- Figure 6 Upper Airway tion that we can influence is the end-expiratory lung volume via PEEP (positive end expiratory pressure).

PEEP helps improve oxygenation by preventing alveolar Chest Wall collapse at end expiration, a time when the alveoli are most prone to collapse because the lung is at its lowest Small Airway volume.

However, adjusting the PEEP can also be useful in inspiration. Sometimes, a patient with airflow obstruction Alveolus from COPD may have autoPEEP, leading to difficulty triggering the ventilator. This in turn leads to an increase in Pleural Space the work of breathing. The components that are involved include Adjusting the applied PEEP may help the patient, specifi- • the upper airway (either the endotracheal or tra- cally by helping him trigger the ventilator. In this section, cheostomy tube) we will: • the patient’s chest wall which expands when the • define autoPEEP diaphragm contracts • explain how it can cause a patient who is on a venti- • the small airways leading to the alveoli lator to have difficulty triggering a breath • the pleural space, which is a reflection of the intra- • describe how applied PEEP can alleviate this prob- thoracic pressure. lem • list ways that we can detect the presence of autoPEEP. At the end of expiration, a patient with normal lungs on a ventilator will have an alveolar pressure equal to the upper airway pressure. 1. What is AutoPEEP?

Normally, at the end of expiration, alveolar pressure With the next inspiration, this patient can trigger the equals atmospheric pressure – in other words, there is no ventilator by initiating a breath via diaphragmatic con- pressure gradient between the alveoli and mouth, there- traction. This causes slight expansion of the chest wall, fore there is no airflow. By convention, we think of pres- which leads to a slight drop in pleural pressure that is sure at the mouth (atmospheric pressure) as a reference transmitted to the alveoli. value of zero.

The slight drop in alveolar pressure results in a pres- If someone has airflow obstruction, as in COPD, it will sure gradient from the upper airway (which is at a ref- take longer to exhale the air. If the next inspiration starts erence pressure of zero) to the alveoli which results in a before the previous exhalation is complete, there will be slight amount of airflow into the patient’s lungs. This is air trapped in the alveoli leading to a positive pressure at shown in the Figure 7 below. end expiration. This is called autoPEEP or intrinsic PEEP.

This will be compounded if the patient is tachypneic – the Figure 7 00 faster he breathes, the harder it will be for him to exhale the air out of his lungs prior to the next inspiration and the worse the air trapping and autoPEEP will be.

The classic clinical scenario where autoPEEP occurs is in the patient with a COPD exacerbation, who has airflow obstruction and tachypnea.

2. How Does AutoPEEP Lead to Difficulty Triggering the -2 Ventilator? 0 First, let’s look at a diagram of the respiratory system of -2 a patient on a ventilator. In Figure 6, I’ve drawn a sche- matic of the relationship between the lungs, pleural End-expiration Onset of inspiration MECHANICAL VENTILATION

The ventilator senses this airflow and determines that autoPEEP. In the example shown in Figure 9, the applied the patient is initiating a breath – thus triggering the ven- PEEP is +10 cm H2O, which matches the autoPEEP. Thus, tilator which subsequently delivers a positive pressure with the next inspiration, the patient only has to drop the breath. The numbers shown for the alveolar and pleural intrathoracic pressure by 2 cm H2O (rather than by 12 pressures are arbitrary and for the purpose of example cm H2O), resulting in an alveolar pressure of +8 cm H2O, only. which is less than the pressure at the upper airway. This leads to triggering of the ventilator with less effort. However, if a patient has airflow obstruction of the small airways, as in COPD, they will have air trapping and autoPEEP at the end of expiration due to inability to exhale all of the air out of the lungs prior to the next inpsira- tion. Thus, they will have positive alveolar pressure at +10 Figure 9 +10 end-expiration.

With the next inspiration, in order to achieve a pressure gradient from the upper airway to the alveoli and thus trigger the ventilator, the pleural pressure has to drop a fair bit to overcome the autoPEEP.

This means that the inspiratory muscles (e.g. diaphragm and accessory muscles) have to work harder to generate +10 +8 this negative intrathoracic pressure. This is illustrated in Figure 8. -2 End-expiration – Onset of Inspiration – 0 Figure 8 0 autoPEEP as well a pressure gradient is as applied PEEP achieved with less effort

Interestingly, although one might think that the applied PEEP would actually add to the autoPEEP, this doesn’t seem to happen in the presence of airflow obstruction as long as the applied PEEP doesn’t exceed the level of autoPEEP. Although the reason for +10 -2 this is not entirely clear, it is thought that the airflow obstruction makes transmission of the applied PEEP -12 to the alveoli more difficult).

End-expiration in a Onset of inspiration – Note – in practice, the amount of applied PEEP that is patient with harder effort to required to overcome the increased work of breathing autoPEEP overcome autoPEEP associated with autoPEEP is actually about 80% of the amount of autoPEEP. This is to ensure that the ap- In this example, because of an autoPEEP of 10 cm H2O, plied PEEP doesn’t equal the autoPEEP, which would the intrathoracic pressure has to drop to -12 cm H2O in lead to the applied PEEP adding to and worsening the order for the alveolar pressure to drop to -2 cm H2O. Only autoPEEP. This is contrary to the diagrams above then will a pressure gradient result from the upper airway where the external PEEP matches the autoPEEP – I to the alveoli, leading to triggering of the ventilator. did it this way simply to illustrate the concepts first.

3. How does applied PEEP (which we set on the ventila- It is important to note the following regarding applied tor) help the patient with autoPEEP trigger the ventilator? PEEP: If we apply enough PEEP to the patient via the ventilator, • it helps the patient with autoPEEP trigger the venti- the upper airway pressure at end-expiration will approxi- lator. mate the autoPEEP. Thus, at end-expiration, no pressure • it does not help a patient trigger the ventilator if gradient between alveoli and upper airway will exist. Thus, autoPEEP is not present. with the next inspiration, it will the patient won’t have to • it does not help reverse the airflow obstruction – in generate as much effort to overcome the effects of the other words, it doesn’t treat the COPD itself, it simply MECHANICAL VENTILATION makes it easier to trigger the ventilator. Figure 10 • if the applied PEEP is greater than the autoPEEP, it can actually add to the autoPEEP already present, making it worse.

The main treatment of autoPEEP is to treat the cause of the autoPEEP. In the case of COPD or asthma, this would include bronchodilators, etc. As well, since a fast respiratory rate will shorten the amount of time available for expiration and make it more difficult to exhale the air out The dotted line represents normal expiratory flow of the lungs fast enough, slowing down the patient’s res- (remember, the waveform above the x-axis repre- piratory rate goes a long way in reducing the amount of sents inspiration and the waveform below the x-axis autoPEEP. represents exhalation). The solid expiratory flow line

is prolonged, signifying airflow obstruction, and the This is often easier said than done, however. If the pa- flow does not reach zero prior to the next inspiration, tient is able to breathe spontaneously, you can’t simply implying the presence of airtrapping and autoPEEP turn down the respiratory rate on the ventilator because he’ll be able to breathe over this set rate. Sometimes, in a patient with severe COPD on a ventilator who has • Based on the above assessments, external PEEP can tachypnea and a lot of autoPEEP, we often have to use a be applied on the ventilator and gradually titrated lot of sedation to slow his respiratory rate down. In ex- upward until the patient no longer visibly seems to treme cases, we also need to add pharmacologic paraly- have difficulty triggering the vent. This is an empiric sis so that we have total control over the patient’s respi- way of titrating the amount of applied PEEP to ratory rate. roughly match the amount of autoPEEP.

4. How can we determine whether or not autoPEEP is References present? 1. Oakes D. Shortall S. Ventilator Management: a bed- There are several ways to determine if autoPEEP is pre- side reference guide. Health Educator Publications, sent and to measure the actual amount autoPEEP. Inc. 2002. • Clinically, at the bedside, autoPEEP is suspected if a 2. Pilbeam S. Mechanical Ventilation: physiology and patient visibly has difficulty triggering the vent. While clinical applications. 3rd Ed. Mosby. 1998. looking at the patient, one may notice that the patient exerts inspiratory effort, using his diaphragm and even accessory muscles of inspiration, but no breath is delivered by the ventilator. The patient may try several times, exerting harder inspiratory effort until a breath is finally triggered and delivered. Note that, although we might infer the presence of autoPEEP this way, we obviously don’t know for sure if it is present or what the actual amount is. • If the ventilator has a screen which provides graphi- cal displays of the variables of inspiration, one can look at the graph which displays airflow over time. In the presence of airflow obstruction, the expiratory limb of the graph will show a prolonged expiratory phase. As well, if autoPEEP is present, the next inspiration will occur before the expiratory flow has reached zero – this indicates that expiration was not finished prior to the next inspiration, leading to air trapping and autoPEEP. An example of this is shown in Figure 10 Chapter Four

Approach to PFT Interpretation APPROACH TO PULMONARY FUNCTION TEST INTERPRETATION By Dr. L. Cheung, with excerpts on basic physiology from Dr. R. Jones and suggestions by Dr. N. Skjodt.

The flow chart shown in Figure 2 provides a step-by-step 1. Introduction approach to PFT interpretation. Although it is somewhat While you are doing rounds, Dr. Damant puts you on the simplified, this approach will help you deal with most of spot and asks you to interpret a patient’s PFT. (The con- the PFT’s you will encounter. The rest of the handout clusion to this scenario is given at the end of this chapter) explains the steps in the flow chart.

This chapter will enable you to answer the following clinically important questions regarding PFT interpretation : Figure 2: Flowchart showing the overall approach to PFT 1. What is the overall approach to PFT interpretation? interpretation 2. What are the components of the flow volume loop and spirogram? Read the • Information on 3. How do you define an obstructive defect and what Patient’s height, weight, etc else do you need to determine if an obstructive de- Demographic fect is present? Information 4. How do you define a restrictive defect? 5. How does the DLCO and / or DLCO adjusted for VA help you generate a differential diagnosis if an obstructive or restrictive defect is present? Analyze Flow • Is an obstructive or Volume Loop restrictive defect PFT interpretation involves analyzing the following four and obvious? main components seen in virtually all PFT’s, shown below Spirogram in Figure 1: 1. Flow volume loop and spirogram 2. Spirometry 3. Lung volumes • Obstructive defect present? 4. Diffusion capacity Analyze • Reversibility? Spirometry •Severity?

Figure 1: the components of a PFT

• Restrictive defect present? Analyze Lung •Severity? Volumes

Analyze • May narrow differential diagnosis DLCO and if an obstructive or restrictive DLCO defect is present adjusted for • May indicate disease even if VA spirometry and lung volumes are normal

Put It All • Provide and overall interpretation Together and Provide an Interpretation APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

The large airways have relatively little change in resis- 2. Patient Demographics tance with different lung volumes. At high lung volumes, The demographics section of the Pulmonary Function the large airways contribute most to Raw while at low Test provides useful information on the patient’s height, lung volumes (less than FRC) the peripheral airways con- weight, and BMI, all of which can affect the test results. tribute most to Raw.

Therefore, in normal individuals, measurements like 3. Analyze the Flow Volume Loop PEFR and FEV1 are most affected by the resistance of large airways while FEF75 is most affected by resistance and Spirogram of the peripheral airways. (Note: FEF75 is the forced expi- In this section, we will do the following: ratory flow after 75% of the forced vital capacity has • review some basic physiologic concepts been exhaled. - LC). In patients with airway disease (such as COPD), the high peripheral airway resistance • explain the features of a normal flow volume loop can also affect PEFR and FEV1. and spirogram

• illustrate the differences seen in an obstructive de- Figure 4 shows how the relative cross sectional area of fect (of the small airways) and restrictive defect. the large and peripheral airways changes during a forced expiration from TLC (total lung capacity) to RV (residual A. Basic Physiologic Concepts (the following volume). (Note: normally, the total cross sectional area excerpt is by Dr. Jones, pulmonary physiolo- of all of the small airways exceeds that of the large airways – LC). gist) During a forced expiration, the Ppl (pleural pressure) is positive relative to atmospheric pressure and it, along with Pst (lung static recoil pressure), create the positive Palv (alveolar pressure) required to push air out of the lungs (see Figure 3 below). The higher the Palv, the higher will be forced expired flow.

Figure 4

Figure 3 For normals, PEFR is affected mainly by the resistance in the large upper airways. However, later in the expiration the decreased lung volume causes reduced cross sectional area in the small airways which now becomes the Airway resistance (Raw) changes with lung volume. High limiting resistance. At the end of expiration, at or near lung volumes = low Raw and low lung volumes = high RV, many of the peripheral airways become so narrow Raw. These changes in Raw are caused primarily by the that they actually close. (Note: this may cause the curve peripheral airways which are tethered by the surrounding to become slightly concave upward near RV in a normal lung parenchyma. person, as shown in Section II “The Normal Flow Volume Loop (FVL) and Spirogram” – LC). APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

Figure 5 illustrates that similar changes occur in the Note the following points labelled on the Flow Volume lungs of patients with airway obstruction but the periph- Loop: eral airways in these patients are narrow due to inflammation and/or bronchospasm. “A” represents Peak Expiratory Flow. It is up to 8 L/sec in a normal individual, which corresponds to 480 L/min if measured by a Wright’s peak flow meter.

“B” represents Peak Inspiratory Flow.

“C” represents Residual Volume.

“D” represents Functional Residual Capacity.

Length “D” to “E” represents inhaled Tidal Volume

“F” represents Total Lung Capacity

Figure 5 Length “F” to “C” represents exhaled Vital Capacity. Note that there is a slightly concave upward appearance near end-exhalation due to the normal slowing of expiratory flow as RV is reached.

Therefore, at large lung volume, near TLC, the peripheral Forced expiratory flows depend on effort, chest wall mus- airways may contribute significantly to overall airway cle strength, lung elastic recoil, and total airway resis- resistance and limit PEFR (peak expiratory flow rate). As tance. Forced inspiratory flows depend on effort, chest the lung loses volume during the expiration, the periph- wall muscle strength, and total airway resistance. eral airway resistance increases dramatically, causing low forced expired flows. RV occurs at a higher than nor- Common pattern of abnormalities in the FVL include ei- mal lung volume because the airways close prematurely ther an obstructive or restrictive defect which are shown due to their small size. later.

B. The Normal Flow Volume Loop (FVL) and Spirogram a. The normal flow volume loop (flow on the y axis, volume on the x axis) is shown in Figure 6:

Figure 6: The components of the FVL

A 8 slightly concave Flow exhalation upward (L/sec) 4

F DE C 0

inhalation - 4 B Volume (L) APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

Before going on, let us briefly review the physiologic determinants of the volumes and capacities that we described in the previous flow volume loop diagram. These physiologic determinants are illustrated in Figure 7.

Vital Capacity (VC): this is the volume of air exhaled from the lungs starting from maximal inspiration to maximal expiration. Note that this represents what we often refer to as the FVC, or forced vital capacity. Sometimes, when following a patient’s respiratory muscle strength on the ward (for example, in a patient with acute neuromuscular weakness such as Guillain Barre syndrome), we can follow the inspiratory VC – the volume of air inhaled into the lungs starting from maximal expiration to maximal inspiration. This is useful in this clinical setting because a decreasing VC suggests worsening respiratory muscle weakness in the absence of expiratory airflow obstruction, which will eventually lead to atelectasis, a decreased ability to cough and clear secretions, and eventual respira- Figure 7 tory failure.

Tidal Volume (VT): this is the volume of air entering the lungs per Total Lung Capacity (TLC): breath. It is deter- this is the volume of air mined by the activity in the lungs after maxi- of the respiratory con- mal inspiration. It is trol centers of the determined by the in- brain and the me- ward elastic recoil of chanics of the lungs the lungs, the outward and chest wall. elastic recoil of the chest wall, and the strength of the inspiratory muscles.

Residual Volume (RV): this is the gas left in the lungs after a full, forced expira- Functional Residual Capacity (FRC): this tion. The RV is determined by the bal- is the gas left in the lungs after a nor- ance between the inward elastic recoil mal tidal expiration. Since no muscles of the lungs, the outward elastic recoil are contracting to achieve this, the of the chest wall, the strength of the FRC is determined by the balance be- expiratory muscles, and the presence tween the inward elastic recoil of the of any dynamic compression of the lungs and the outward elastic recoil of airways during forced expiration (for the chest wall. example, in COPD) leading to air trapping in the alveoli. APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION b. The normal spirogram is shown in Figure 8. Note the following ways that an obstructive defect alters the normal Flow Volume loop: Figure 8 • Lung volumes are shifted to higher than normal - note that this is not evident on this flow volume loop because only relative volumes were measured; Spirometry hence, the volume at total lung capacity (far left) is at “zero”, but, in reality, TLC would not really be zero! Volume If the measured lung volumes were actual lung volumes, as they are in some PFT labs, you would see FVC the flow volume loop shifted to the higher lung volumes. FEV 1 • Expiratory flow rate (peak of the loop) is reduced • Forced Vital Capacity (distance from TLC to RV) is reduced slightly due to an increased RV • the descending part of the exhalation curve is mark- 1 2345678 Time (sec.) edly concave upward

An example of a spirogram of the same patient is shown Volume is on the y axis and time is on the x axis. The in Figure 10. technique involves the patient inhaling to TLC, then exhaling forcefully all the way to RV. Figure 10

The volume exhaled after 1 sec is the FEV1. Normally, Because the FVC took so long to FEV1 is ≥ 75% of the FVC, giving an FEV1/FVC ratio of complete (due to expiratory airflow ≥0.75. However, keep in mind that the FEV1/FVC ratio obstruction), the curve doubles back on itself twice! declines slightly with age because FEV1 and FVC both decrease with age but FEV1 decreases slightly out of proportion to FVC. Thus, be sure to look at the reference value on the PFT, which is based on the patient’s age.

C. Obstructive Defect: Effects on the FVL and Spirogram. An example of an FVL with an obstructive defect is shown in Figure 9.

Figure 9 Note the following ways that an obstructive defect alters the normal spirogram: • Both FEV1 and FVC are lower than normal, but the Predicted flow FEV1 is lower relative to FVC rates and • Forced exhalation is prolonged – after 8 seconds, the volumes tracing doubles back on itself and continues for a total of about 19 seconds

exhalation • During exhalation, the curve takes a long time to plateau until the FVC is finally reached inhalation APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

D. Restrictive Defect: Effects on the FVL Note the following features: • exhaled volume rises very quickly at the beginning of and Spirogram exhalation, indicating relatively fast airflow An example of an FVL with a restrictive defect is in Figure • both FEV1 and FVC are lower than normal, but the 11. (this FVL is from ACCP Pulmonary Board Review FEV1 is high relative to FVC 2003, p. 308) • as explained later, a restrictive defect is ideally defined as a low Total Lung Capacity measured in the Figure 11 “Lung Volumes” section of the PFT. Spirometry may suggest but should not be used to diagnose a restrictive defect.

4. Analyze the Spirometry When analyzing the spirometry, determine the following 3 things: • does an obstructive defect exist? • if an obstructive defect does exist, is it reversible (either partially or completely) with bronchodilator? • how severe is the obstructive defect?

A. Does an obstructive defect exist? Conceptually, an obstructive defect is characterized by a disproportionate decrease in maximal exhaled airflow Note the following ways that a restrictive defect alters from the lung compared to the whole volume that can be the normal Flow Volume loop: exhaled from the lung (VC). • lung volumes are shifted to lower than normal (note that absolute, not relative, lung volumes are shown In PFT terms, small airways obstruction is present when on the “x” axis in this flow volume loop). there is a decrease in the FEV1 / FVC ratio (i.e. a decrease • absolute peak expiratory flow rate is either normal or in FEV1 alone or a decrease in FEV1 out of proportion to a slightly reduced decrease in FVC). • FVC is quite reduced However, the exact definition of what constitutes a de- • the shape of the exhalation curve is a bit more up- creased FEV1 / FVC ratio depends on the information right –the exhaled flow rates may be high relative to source. FVC (this is reflected in a FEV1/FVC ratio that may be

higher than normal) For example, the GOLD criteria (Global Initiative for

Chronic Obstructive Lung Disease dealing specifically An example of a spirogram (different patient from above) with COPD) define it as a ratio < 70%, yet the ATS with a restrictive defect is shown in Figure 12. (American Thoracic Society) discourages the use of a fixed ratio because it tends to decrease with age. Figure 12 Thus, ATS defines a low FEV1 / FVC ratio as < 90% of the predicted ratio, taking into account that person’s height, race, and gender. (For example, if a person’s predicted FEV1 / FVC ratio is 72%, then a measured FEV1 / FVC ratio of < 65% would be required to label him as having an obstructive defect).

As well, the clinical context is important as extremely fit athletes may have a slightly decreased FEV1 / FVC ratio yet have an FEV1 and an FVC which are both above normal.

APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

B. If an obstructive defect exists, is it re- 5. Analyze the Lung Volumes versible with bronchodilator? As a clinician, the main thing to look at when analyzing To answer this question, we do not look at the FEV1 / FVC the lung volumes is to determine if a restrictive defect is ratio. Instead, an increase of 12% and 200 mL in either present, defined as a TLC < 80% predicted. the FEV1 or the FVC are reasonable criteria in concluding that reversibility exists (according to ATS). If a restrictive defect is present, stratify the severity based on the TLC: C. If an obstructive defect exists, how severe TLC 70 to 79% predicted: mild restrictive defect is it? To answer this question, we look at the decrease in FEV1 TLC 60 to 69% predicted: moderate restrictive only. Again, the exact definitions of severity using FEV1 defect will differ depending on the information source but a reasonable stratification is given in the GOLD document, TLC < 60% predicted: severe restrictive defect which quantifies the severity of COPD specifically: For the PFT “connoisseur”, other information, such as Mild COPD FEV1 > 80% predicted abnormalities in the RV (residual volume), FRC (functional residual capacity), IC (inspiratory capacity), Moderate COPD FEV1 30 to 80% predicted and ERV (expiratory reserve volume), can be helpful in distinguishing between the many causes of a restrictive Severe COPD FEV1 < 30% predicted or FEV1 < 50% defect, such as interstitial lung disease, chest wall de- predicted plus respiratory fail- formity, obesity, and neuromuscular weakness. ure or clinical signs of right heart failure Measuring lung volumes can also help ascertain whether hyperinflation from obstructive lung disease is present, Note that if a combined obstructive and restrictive defect but, generally, the diagnosis of an obstructive defect exists, both can cause a decrease in FEV1 and it can be should be made by analyzing the spirometry. hard to quantitate the contribution by each defect. The following excerpt by Dr. Jones covers three topics: • a review of some basic physiologic concepts • an explanation of how lung volumes are actually measured • clinical pearls on the patterns of abnormality in RV, VC and FRC seen in certain restrictive and obstructive diseases.

A. Basic Physiologic Concepts Two important descriptors of lung size — RESTRICTION and HYPERINFLATION — are obtained from lung volume measurements.

A restrictive defect is defined as a decrease in total lung capacity (TLC) and hyperinflation is defined as an increase in TLC. APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

The volume time tracing in Figure 13 shows that it is im- However, in patients with airway obstruction, the residual possible to obtain TLC without measuring the residual volume is usually increased and this, too, can cause a volume (RV). In practice, the functional residual capacity low vital capacity even though TLC might be normal or (FRC) is measured and then inspiratory capacity is added increased (hyperinflation). to get the TLC. Therefore, the presence of airway obstruction prevents Figure 13 interpretation of the cause for a low vital capacity on simple spirometry, since you do not know if it is caused by a low TLC (restrictive defect), a high residual volume secondary to the airway disease, or a combination of high residual volume and low total lung capacity (as illustrated in Figure 14).

Figure 14

It is important to remember that simple spirometry cannot provide the TLC since there is no measure of RV.

While it is true that nearly all patients who have a restric- In summary, a low VC from simple spirometry can give tive defect (low TLC) also have a low vital capacity (VC) or some indication about a restrictive defect when there is low forced vital capacity (FVC), VC and FVC are not always no airway obstruction or when airway obstruction is mini- reliable in estimating whether a restrictive defect exists. mal and where an increase in RV would not be expected.

Patients with stiff lungs or abnormal chest walls will of- All bets are off about a low VC being indicative of a re- ten have restrictive defects without airway obstruction. strictive defect when there is moderate or severe airway In these patients, the low vital capacity measured with obstruction, since the expected high RV would be at least simple spirometry is highly suggestive of a restrictive partially responsible for the low VC. Lung hyperinflation defect. can never be estimated from spirometry. Therefore, there is a need to measure lung volumes to describe true lung size. APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

B. Measuring Lung Volumes The example of helium-dilution in Figure 15 shows that As mentioned above, a measure of residual volume must the FRC had to be 3.33 L in order to dilute the 10% He be obtained before TLC can be determined. This is com- down to 6% after rebreathing. With the measured FRC, monly done by measuring functional residual capacity we can then add the inspiratory capacity (IC) to get TLC (FRC) using a gas dilution method or a body plethys- and we could also subtract the expiratory reserve volume mograph. (ERV) to get the RV.

1. Gas Dilution: b. Nitrogen-washout method There are two common gas dilution methods used: He- The nitrogen-washout test of lung volume relies on the lium-dilution and Nitrogen-washout. fact that 80% of the gas in the lungs is N2, as shown in Figure 16. By having the patient breathe 100% O2 from a. Helium-dilution method an open circuit system, it is possible to measure the volume of N2 washed from the lungs by collecting the ex- The helium dilution method uses a closed circuit breath- haled gas in a bag. ing system where CO2 is scrubbed out of the exhaled gas and O2 is added to compensate for the oxygen consumption. Figure 16

By having a known concentration of helium in the breathing circuit prior to starting rebreathing and by knowing the volume of the breathing circuit, one can determine the volume of the FRC after rebreathing the He- containing gas, since the FRC dilutes the He concentration in the breathing circuit and the concentration of gas equilibrates between circuit and patient. This is illustrated in Figure 15.

Figure 15

Since the volume of N2 collected in the bag above represents 80% of the FRC, FRC can be calculated.

APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

2. Body Plethysmograph Therefore, FRC can be measured in the body box and by Another way to measure lung volume is to use a body adding IC, TLC can be obtained and by subtracting ERV, plethysmograph or body box. RV can be obtained. The FRC measured in the body box consists of ALL air in the lung at FRC. The body box measures lung volume by utilizing Boyle’s Law. Essentially, the lung is compressed and decom- Since the shutter prevents air flow into the lung, all gas- pressed by breathing against a closed airway and the containing regions will expand with the attempted inspi- pressure in the lung is measured along with the change ration and contribute to the DV. Therefore, the body box in volume caused by the breathing efforts. FRC consists of the volume of normally ventilated gas spaces as well as any trapped gas spaces. If you know the change in volume caused by compressing a sealed bag of air and you also know the pressure inside In summary, gas dilution methods of measuring lung the bag, then you can calculate the volume of the bag: volume provide the volume of the spaces that can receive the helium or eliminate the nitrogen. Therefore, gas dilution volume is that of the ventilated spaces and P1V1 = P2V2 these methods will not measure any trapped gas volume.

P1V1 = P2 (V1 + delta V) The body box lung volume measurement includes the normally ventilated gas plus any trapped gas. Therefore, V1 = (P2 delta V) / (P1-P2) the body box TLC measurement will more closely resem- ble what is seen on a chest X-ray, which shows all air in the lungs. The trapped gas volume can be obtained by

If V1 is FRC and at FRC there is no air flow, P1 in the lung subtracting the dilution TLC from the body box TLC. will be atmospheric pressure. C. Interpreting Lung Volumes (Clinical If the patient’s mouth is occluded and he attempts to inhale against the mouthpiece, the pressure in the lung Pearls) There is clinical significance to several lung volume pat- will decrease and the volume of the lung will expand terns. However, in order to determine if a particular vol- slightly due to decompression of the gas inside. ume is higher or lower than the predicted value, you have

to know the normal ranges. We can measure the pressure in the lung by measuring it at the mouth (no flow, so mouth pressure = alveolar pres- The predicted values depend on gender, age, and height. sure) and the change in volume of the chest is measured The graphs in Figure 18 show the 95% confidence inter- by the box pressure change, as shown in Figure 17. vals for the clinically important lung volumes.

Figure 17 The normal range for VC and TLC is about 76-78% to 122-124% of the predicted value while, for RV, a high value would have to be greater than 150% of predicted for a young person and greater than about 130% of predicted for a person who is 80 years old. A low value for FRC would be in the range of about 60% of predicted. APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

Figure 18 • If a restrictive defect was identified on lung volume measurement, the DLCO adjusted for VA (to be explained later) can help distinguish between interstitial lung disease (DLCO adj for VA is low) from other causes of a restrictive defect such as neuromuscular weakness, a chest wall abnormality, or obesity (DLCO adj for VA is normal). The caveat to this is these latter patients may develop atelectasis which may also decreased DLCO adjusted for VA.

• If an isolated reduction in DLCO is seen with an otherwise normal PFT (i.e. no obvious obstructive defect on spirometry or restrictive defect on lung volume measurement), possible causes include anemia, car- boxyhemoglobinemia, pulmonary vascular disease (e.g. chronic pulmonary emboli, pulmonary hypertension, pulmonary vasculitis), very early interstitial lung disease or early emphysema.

For a more thorough discussion regarding DLCO, the fol- Typical patterns seen for lung volumes and DLCO are lowing excerpt by Dr. Jones reviews the basic physiology shown in the table 1 below: behind DLCO measurement, explains the concept of “DLCO adjusted for VA”, and briefly reviews the interpre- Table 1 tation of the DLCO. (I’d recommend reading these sec- Condition TLC VC FRC RV DLCO tions to grasp the concepts; the mathematical equations are not necessary to remember. – LC) Asthma / ↑ ↔ ↔↓ ↑↔ ↑↑ ↔ Bronchitis A. Basic Physiologic Concepts (by Dr. Jones) Emphysema ↑ ↓ ↑↑ ↑↑ ↓ Diffusing capacity is a measure of the uptake of carbon monoxide from the alveolar spaces into the pulmonary capillary blood. The choice to use carbon monoxide for Pulmonary ↓ ↓ ↓ ↔ ↓ this measurement was dictated by the need to have a Fibrosis gas which had an uptake into blood that was diffusion- limited rather than blood flow-limited. Chest Wall ↓ ↓ ↓↔ ↑↓↔ ↔ Shape Defect Only two common gases have this property, oxygen and carbon monoxide. These two gases chemically combine Weak Chest ↓ ↓↓ ↔ ↑ ↔ Wall with hemoglobin and therefore have a nearly unlimited sink into which they can be absorbed. Obesity ↓↔ ↓↔ ↓ ↔ ↔ The rate of blood flow is not important but the thickness of the alveolar-capillary membrane and the surface area available for diffusion are very important. The latter, the 6. Analyze the Diffusing Capacity surface area, is determined primarily by the number of capillaries in the lung which are recruited (open) and (DLCO) have blood in them. For that reason, we say that pulmo- Lastly, PFT interpretation involves analysis of the DLCO. nary capillary blood volume is an important factor in de- As a clinician, you can use this information in one of sev- termining diffusing capacity. eral ways: • If an obstructive defect was identified on spirometry, Of course, the other important factor is thickness of the the DLCO can help distinguish chronic bronchitis alveolar-capillary membrane. Since carbon monoxide (DLCO often normal) from emphysema (DLCO often uptake is intimately tied to the hemoglobin sink, hemo- decreased). globin concentration is also important as is the carboxy- APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION hemoglobin concentration, since it impedes the further The single breath measurement of DLCO actually allows uptake of carbon monoxide from the alveolar spaces. measurement of DLCO during a 10 second breath-hold at full lung inflation. During the process of obtaining DLCO, Fortunately, we can use a simple mathematical correc- we also obtain a measurement of the lung volume at tion for the effects of hemoglobin and carboxyhemoglo- which the breath was held - the VA seen in the first equa- bin (if known) on diffusing capacity (see below) and when tion. The VA should be close to TLC, but sometimes a full this correction is done, a low value for diffusing capacity inspiration of the CO-containing gas is not accomplished means that either the diffusion membrane is thick or and VA is less than TLC in those patients. Actually, the that the number of blood-containing pulmonary capillar- inhaled gas contains more than CO. It also contains a ies is small. Another complicating factor affecting diffus- non-diffusible gas, such as helium, for measurement of ing capacity is the size of the lungs themselves, the al- the VA. veolar volume (VA). Since VA affects DLCO, it is common practice to “correct” (VA) (Pulmonary Cap Blood Vol) ([Hgb]) for the effect of alveolar volume on diffusing capacity. This is done by expressing DLCO as DLCO/VA. This, how- DLCO ∝ ever, does not “correct” diffusing capacity and, in fact, it (Alveolar capillary thickness) ([CO Hgb]) can cause a marked overestimation of the diffusion results when lung volume is small. This is illustrated in Figure 19. The driving force for flow of CO across the alveolar- Figure 19 capillary membrane is the difference in partial pressure for CO between the alveolar spaces and the capillary blood (DPCO). The resistance to CO gas flow offered by the alveolar-capillary membrane and the hemoglobin is represented by (DPCO / flow):

ΔPCO Resistance to CO Flow = CO Flow

However, a better way to think about diffusion is to think of it as a conductance, or ease with which CO can flow into the blood for a given driving pressure for CO across the alveolar-capillary membrane. A conductance is the reciprocal of resistance:

CO Flow The graph above shows that if a normal person breath- holds at only 40% of TLC, the measured DLCO will be CO Conductance = about 70% of the predicted value. Most people believe Δ PCO that the DLCO/VA will correct for this, but you can see that the DLCO results in over-correction (DLCO/VA = 180% predicted). CO Uptake (ml / min) DLCO = This same pattern of effect of VA on DLCO and DLCO/VA is seen in patients with lung disease, and it is very com- Δ PCO (mm Hg) mon for patients with severe restrictive lung disease from pulmonary fibrosis to have low DLCO and normal or high DLCO/VA, just as in the graph. Results such as these are typically misinterpreted to indicate normal diffusing capacity. APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION

Clearly, in interstitial lung disease, the DLCO should be B. Interpretation of Diffusing Capacity decreased to reflect the altered alveolar-capillary mem- Interpretation of the DLCO results is sometimes difficult. brane and the abnormal pulmonary vasculature. There- You must remember that the DLCO result represents dif- fore, the DLCO/VA is not a good way to “correct” the fusion properties only in the parts of the lungs that re- DLCO results for the effects of VA. ceived the test gas.

A better way, in my opinion, to do the correction for VA is For instance, one whole lung might be consolidated and to use the straight-line regression equation shown in the unventilated and DLCO is low, but DLCO adjusted for VA graph for DLCO and correct the measured DLCO for VA might be normal. All this tells you is that the ventilated using the following formula: parts of the patient’s lungs have normal diffusion properties and it does not mean that all lung regions have nor- Measured DLCO mal diffusion.

DLCO adjusted for VA = Generally though, if Hb is normal and there is no cause to Measured VA 0.42 + 0.58 believe that a high COHb exists, a low DLCO and low Predicted TLC DLCO adjusted for VA tells you that either the pulmonary capillary blood volume is decreased and/or that the alveolar-capillary membrane is thicker than normal. The diffusion results can then be presented as both

“DLCO” and “DLCO adjusted for VA”. It is suggested that In heavy smokers though, you are never quite sure if the measured DLCO always be shown since it is possible COHb is a confounding factor when you have no measure for the DLCO adjusted for VA to misrepresent the clinical of carboxyhemoglobin. In patients with normal lung me- situation (see section II “Interpretation of Diffusing Ca- chanics and low DLCO, it is wise to investigate whether pacity” below). hemoglobin concentration is low or whether COHb is high

before going off on a tangent thinking about the lung As mentioned above, it is possible to correct the DLCO parenchyma and the pulmonary microcirculation. results for the effects of [Hb] and [COHb]. The following equations show how this is done: One classic example was seen at the U of lab where a

patient had a low DLCO but was otherwise normal. A 1. DLCO correction for Hb (g/dL) venous blood sample revealed normal [Hb] but a COHb of 36%! The problem was a leaky furnace flue that was poisoning a whole high-rise apartment building with CO. As always, clinical correlation of the DLCO results is critical.

2. DLCO correction for COHb (%) High values for DLCO are also clinically significant. Look at the first equation in “Basic Physiologic Concepts” and you will see that an increased [Hb] or a high pulmonary capillary blood volume (pulmonary vascular congestion) can increase DLCO and DLCO adjusted for VA. Since the pulmonary membrane cannot be thinner than normal and there cannot be a negative COHb, these factors are not involved in high diffusing capacity.

The lower and upper limits of normal DLCO depend on the reference equations used, but generally these are 75% and 130% of predicted, respectively. These can be used for DLCO or DLCO adjusted for VA. APPROACH TO PULMONARY

FUNCTION TEST INTERPRETATION 7. Put It All Together and Provide An Interpretation After reviewing the PFT, your final interpretation should include your analysis of the spirometry, lung volumes, and diffusing capacity and the main potential clinical causes of any abnormalities present.

8. Conclusion to the Introductory Scenario Fortunately, you already read this chapter covering the approach to PFT interpretation and were totally prepared for Dr. Damant’s inquisition. After you expertly interpret the patient’s PFT, Dr. Damant bows to your greatness and lies prostrate before you in homage to your skill.

References 1. Dr. Richard Jones! (pulmonary physiologist) 2. American Thoracic Society. Lung Function Testing: Selection of Reference Values and Interpretative Strategies. Am Rev Respir Dis 1991;144:1202-1218 Chapter Five

Approach to Hemoptysis APPROACH TO HEMOPTYSIS By Dr. L. Cheung

This chapter will enable you to answer the following clini- 1. Introduction cally important questions regarding patients with hemop- A 45 year old male who has smoked 1 pack per day for tysis: 25 years presents with a 2 day history of worsening 1. What is the overall diagnostic approach to a patient hemoptysis and has coughed up about a half a cup of with hemoptysis? blood in the past 24 hrs. He has had a new cough pro- 2. How can you use the CXR to narrow down the differ- ductive of yellow sputum for a week preceding the ential diagnosis? hemoptysis but otherwise had previously been feeling 3. What other tests, besides the CXR, can help you de- quite well. He denies any fever, chills, or chest pain. He termine the cause of hemoptysis? has mild exertional dyspnea. His vital signs are stable and routine bloodwork is unremarkable. A CXR does not The overall diagnostic approach to hemoptysis is illus- reveal any abnormalities. (The workup of this case is de- trated in the flowchart in Figure 1. The flowchart is ex- scribed at the end of this chapter) plained in the rest of this chapter.

Figure 1. Flowchart illustrating ENT / GI History / Physical Exam a diagnostic approach to Source hemoptysis. Quantity of Blood?

ENT / GI Evaluation Non-Massive Massive

Stabilize patient first - V/Q Scan or YES Clinically ensure airway patency, CT angio Suspect PE? stabilize hemodynamics, consult appropriate NO services such as ICU, thoracic surgery, CXR respirology

Normal Mass Diffuse Process Focal, obvious abnormality (eg. bronchiectasis, lung cavity, AVM)

HRCT, other Risk Factors for Malignancy? tests Specific • age > 35 Diagnosis? Consider • smoking history bronchoscopy to verify that bleeding • hemoptysis > 1 week YES NO is localized, then YES control bleeding NO Bronchoscopy with angiography Treat with bronchial History consistent artery embolization with bronchitis? Specific Diagnosis? YES YES NO NO Consider further Consider Consider tests such as CT or bronchoscopy or bronchoscopy, Treat as HRCT bronchoscopy Bronchitis other tests such further as a biopsy evaluation with CT Observe

NO Further YES Bleeding?

No Further Consider Evaluation Bronchoscopy APPROACH TO HEMOPTYSIS

• some patients are only able to expectorate a small 2. History / Physical Exam amount of blood (due to impaired cough mecha- Direct the history and physical exam to determine the nisms) but have pulmonary bleeding significant following: enough to cause severe hypoxemia. • distinguish hemoptysis from GI or nasal sources of bleeding Thus, a clinical definition of massive hemoptysis would • determine the severity of the hemoptysis be hemoptysis sufficient to cause significant hypoxemia • determine the etiology of the hemoptysis or hemodynamic instability. While the patient’s estimate of the expectorated blood is very important to note, it has Distinguishing hemoptysis from GI or nasal sources of to be taken within the clinical context. bleeding can sometimes be difficult if the patient is unable to give an accurate description of his symptoms. Massive hemoptysis requires emergency therapy in paral- Figure 2 summarizes some of the distinguishing features. lel with diagnostic workup. If in doubt, one thing to try is to simply ask the patient to cough and see what comes out! Non-massive hemoptysis Patients with non-massive hemoptysis are clinically stable. Figure 2 ENT: may have other nasal or throat symptoms (eg. Minor bleeding (some flecks of blood mixed in with spu- pain, sensation of blood tum) can usually be worked up as an outpatient. trickling down throat, etc) Moderate bleeding (> several teaspoons of blood for more than several days) may require hospital admission Hemoptysis: blood with or, at the very least, an expedited, urgent outpatient coughing, alkaline pH, workup. may see sputum mixed with blood 4. Pulmonary Embolism Sus- GI: may have other GI pected symptoms (dyspepsia, etc), Note that PE usually doesn’t cause massive hemoptysis. acidic pH, may have posi- However if, for whatever reason, there is a high clinical tive fecal occult blood or suspicion for PE, appropriate investigations should be frank blood on rectal exam done, such as a V / Q scan or a CT angio chest.

5. Determine the Cause of 3. Estimate the Quantity of Bleed- Hemoptysis, Starting with the ing to Determine the Severity of Clinical Findings and the CXR Hemoptysis Causes of hemoptysis can be arbitrarily grouped according to the site of bleeding origin. These sites include: Massive hemoptysis • the tracheobronchial airways, where bleeding occurs Traditionally, massive hemoptysis has been defined us- from mucosal vessels, with or without inflammation. ing volume - ie. expectorating > 200 mL of blood in 24 • the lung parenchyma, where bleeding occurs from hrs. the capillaries in the alveoli, with or without inflammation Problems with this definition include the following: • vascular abnormalities, such as arterio-venous mal- • patients may misperceive the volume of blood actu- formations or pulmonary emboli. ally expectorated. For example, some patients com- plain of expectorating “enough blood to fill up a bath- Typical causes of hemoptysis based on the site of bleed- room sink” – this would be several liters of blood and ing are illustrated in Figure 3. unlikely in someone who is hemodynamically stable

APPROACH TO HEMOPTYSIS

Vascular Abnormalities • arteriovenous malformation Figure 3: Causes of pulmo- • pulmonary embolus nary bleeding by site of ori- • high pulmonary venous pres- gin: lung parenchyma, tra- sures (eg. mitral stenosis) cheobronchial airways, vas- • pulmonary artery rupture from a cular PA catheter balloon tip • primary pulmonary artery hypertension

Lung Parenchyma / Alveoli (a) “vasculitic” • Wegener’s granulomatosis • Goodpasture’s disease • lupus pneumonitis Tracheobronchial Airways (b) non-vasculitic (a) with inflammation • pneumonia • acute bronchitis • tuberculosis • chronic bronchitis • lung abscess • bronchiectasis • lung contusion • neoplasm • neoplasm • anticoagulants or bleeding (b) without inflammation diathesis • airway trauma • foreign body

Direct the history and physical exam to distinguish the chronic. However, it is still usually prudent to rule out possible causes of hemoptysis listed in Figure 3. As well, malignancy. If a CT chest can be obtained quickly, it the CXR findings can help narrow the differential diagno- would also be reasonable to do this first to look for a sis, as described next. mass or adenopathy not obvious on the CXR, and then to procede to bronchoscopy. A. Clear or Normal CXR This often indicates that the bleeding is from the tracheo- Occasionally, there are patients who have “sudden” bronchial airways and the patient is able to expectorate hemoptysis without preceding symptoms to suggest the blood out of the airways before it sinks down into the bronchitis (such as a preceding productive cough) yet, on alveoli and accumulates. bronchoscopy, are found to have inflamed and bleeding airways not related to malignancy. These patients are If the patient is young, has no risk factors for malignancy, often presumed to have had bronchitis which was not has a history compatible with acute bronchitis, and has clinically obvious. minor hemoptysis, then giving antibiotics and following the patient is a reasonable course, reserving further tests B. Obvious Mass on CXR (such as bronchoscopy) if the patient’s hemoptysis per- This suggests malignancy as the cause of hemoptysis sists. and bronchoscopy plus CT should be considered.

If risk factors for malignancy are present, a bronchoscopy is a reasonable initial test. Admittedly, even in this set- C. Diffuse Process, Such As Nonspecific ting, bronchoscopy will often reveal diffuse or local air- Consolidation, on CXR way bleeding from bronchitis, either chronic or acute on In these settings, the blood is often coming from the lung APPROACH TO HEMOPTYSIS

parenchyma and the airspace disease represents either diffuse bronchitis) can usually not be treated in this man- blood in the alveoli or the etiologic process (e.g. pneumo- ner due to the shear number of blood vessels that would nia) causing the hemoptysis. need to be embolized.

If symptoms suggest a “vasculitic” cause, do the appro- In bronchial artery embolization, the femoral artery and priate tests (such as c – and p – ANCA, anti-GBM anti- aorta are cannulated, and the bronchial arteries are iden- body, urinalysis or urine for cytodiagnostics, ANA, etc). tified. Often, they will be tortuous in the area of inflammation, and this is usually the only indication that they If pneumonia is suspected and the hemoptysis is minor, may be causing the bleeding. It is uncommon to actually treat with appropriate antibiotics and obtain cultures. see extravasation of contrast out of the bleeding vessel. Also, rule out a co-existing bleeding diathesis (platelet count, PT, PTT). Because the anterior spinal arteries originate off of the bronchial arteries instead of the aorta in 5% of the popu- Consider a CT chest to look for subtle abnormalities that lation, there is a risk (< 1% in experienced hands) that might suggest a particular diagnosis (e.g. many small paraplegia may result if the bronchial arteries are em- areas of microcavitation – Wegener’s Granulomatosis, bolized proximal to the takeoff of these anterior spinal etc) or bronchoscopy to confirm the alveolar nature of the arteries. bleeding.

If evidence of a systemic vasculitis is present clinically, 7. Conclusion of the Introductory biopsy is ideally needed to confirm the diagnosis. If the patient is too unstable to undergo lung biopsy, consider Case biopsy of another affected organ, such as a renal biopsy. Based on his history and clear CXR, the patient’s physician made a clinical diagnosis of acute bronchitis and placed him on antibiotics. However, because of his smok- D. Other Obvious Abnormality on CXR ing history, he also arranged a bronchoscopy to rule out Focal abnormalities such as a pulmonary arteriovenous an endobronchial lesion. On bronchscopy, no active malformation, or other abnormalities such as bronchiec- bleeding or lesions were seen. The airways were dif- tasis or a lung cavity may be seen on CXR. fusely inflamed, confirming the clinical suspicion of acute bronchitis. The patient’s hemoptysis subsided and For bronchiectasis, inflammation is usually present (even ceased after antibiotic therapy. in the absence of new / acute symptoms) and antibiotics are a reasonable treatment. References: A lung cavity could represent TB, a bacterial abscess, or 1. Lenner R, Schilero GJ, Lesser M. Hemoptysis: diagno- even a cavitating lung cancer depending on the clinical sis and management. Compr Ther 2002; 28(1):7-14. context, and appropriate tests and treatment should be 2. Dweik RA, Stoller JK. Role of bronchoscopy in mas- started, including respiratory isolation if TB is clinically sive hemoptysis. Clin Chest Med. 1999. 20(1):89-105. likely.

An AVM will often look like a mass on CXR. CT with contrast will often be able to locate “feeding vessels” into the mass, revealing its nature as an AVM.

6. Consider Bronchial Artery Em- bolization for Persistent or Signifi- cant Focal Bleeding Generally, focal etiologies of bleeding cause local inflammation of the surrounding bronchial arteries, causing them to bleed. Bronchial artery angiogram (not pulmonary angiogram) tries to embolize these affected arteries.

Only focal causes of bleeding (e.g. a focal area of bronchiectasis, a lung cavity, etc) are amenable to bronchial artery embolization. Diffuse bleeding (e.g. vasculitis or Chapter Six

Approach to Pleural Effusion APPROACH TO PLEURAL EFFUSION By Dr. L. Cheung ment and thoracentesis fail to discern the cause of 1. Introduction the pleural effusion? An 88 year old male who has smoked 1 ppd for the last 70 years presents to the ER with a several week history The overall diagnostic approach to pleural effusion is il- of increasing dyspnea, especially with exertion and when lustrated in the flowchart in Figure 2. The flowchart is lying on his left side. He denies any other symptoms explained in the rest of this chapter. such as chest pain, cough, although he does admit to having lost about 10 kg over the past 2 months due to a decrease in appetite. On physical exam, his vital signs Figure 2 are stable. Significant findings include decreased breath sounds, dullness to percussion, and decreased fremitus, Pleural Effusion all at the left base up to the left mid-lung zone. A CXR reveals a left pleural effusion (black arrow) and a 3 cm Significant Amount of left lung mass (white arrow), as shown in Figure 1. Pleural Fluid Present? Yes No Figure 1 Clinical Evidence Follow of Volume Overload? Yes No

Clinical signs Yes Consider thoracentesis suggesting and send off tests to inflammation? differentiate transudate from exudate No

Treat the volume Transudate? Exudate? overload

Treat the Establish cause of the cause of the transudate, exudative including effusion diuresis

Cause Found?

Yes No

Treat the Consider (The workup of this case is described at the end of this cause of the observation chapter) exudative or pleural effusion biopsy This chapter will enable you to answer the following clinically important questions regarding patients with a pleural effusion: 1. What is the overall approach to a patient with a pleural effusion? 2. When should you perform a diagnostic thoracentesis and when can you be satisfied with a clinical diagnosis alone? 3. How do you distinguish a transudate from an exudate and when can a transudate be misclassified as an exudate? 4. When is chest tube drainage needed in the setting of a parapneumonic effusion? 5. What are the diagnostic options when clinical assess- APPROACH TO PLEURAL EFFUSION

2. Pleural Effusion of Unknown Figure 3a Figure 3b Cause is Detected When a pleural effusion of unknown cause is detected, clinical assessment, including a focused history and physical exam, can help you distinguish amongst the various possibilities.

Clinical assessment should focus on differentiating between the following common causes of effusions: • Congestive heart failure, chronic liver failure, or chronic renal failure characterized by volume overload, pedal edema, etc. • Acute infection (eg. Parapneumonic effusion) • Subacute infection, such as tuberculosis or fungal B. Is a pleural effusion truly present? infections • Sometimes, what seems like a pleural effusion on • Malignancy, such as cancers of the lung or breast, CXR is actually not a pleural effusion. An example of mesothelioma, lymphoma this is shown in Figure 3 (a—b). • Pulmonary embolism • In Figure 3a, there appears to be a right pleural effusion on this PA view, in addition to nodular opacities Other less common causes of effusion may also be seen in both lung fields. However, the mediastinum is not in conditions with characteristic clinical findings such as shifted to the contralateral side, suggesting that an the following: effusion may not be truly present. Figure 3b, a right • Esophageal rupture lateral decubitus view, shows that the supposed • Collagen vascular diseases, such as rheumatoid arthritis or lupus erythematous Figure 3c • Pancreatitis • Hemothorax due to trauma • Post– CABG effusion • Asbestos related pleural disease, either due to mesothelioma or a benign asbestos related pleural effusion.

3. Is There a Significant Amount of Pleural Fluid Present? In order to determine whether bedside thoracentesis can be safely performed, a few things need to be determined.

A. Is there enough fluid present? • Generally, if the effusion is more than a quarter of the hemithorax, enough fluid is likely to be present “pleural effusion” does not layer out, even though the for thoracentesis. fluid in the stomach does! A subsequent CT chest • If the amount of fluid is hard to estimate on the PA (Figure 3c) revealed pleural thickening (ultimately and lateral view, a decubitus view should be done. If found to be due to cancer with pleural metastases), the fluid layers out and is > 10 mm thick on the not a pleural effusion. decubitus view, a bedside thoracentesis is probably • The bottom line is that it is important to be sure that safe. Of course, an ultrasound guided thoracentesis a pleural effusion is present, either by finding classic could be requested as well. signs on the initial CXR, clinical exam, or a decubitus • If only a small amount of fluid is present (eg. < 10 CXR, or performing an ultrasound or CT chest if really mm thick on the decubitus view), a reasonable ap- necessary. proach is to follow the effusion without performing invasive testing if clinically appropriate.

APPROACH TO PLEURAL EFFUSION

C. Is a coagulopathy present? B. Differentiate Between Exudate vs Transu- Prior to thoracentesis, it is obviously important to rule out date any untreated coagulopathy. The fluid is considered an exudate if one of the following of Light’s criteria are met (sensitivity and specificity for 4. Is There Clinical Evidence of exudate are listed in parentheses after each criteria): • Pleural fluid to serum protein level > 0.5 (sens 86%, Volume Overload? spec 84%) If the patient has obvious clinical evidence of a volume • Pleural fluid to serum LDH level > 0.6 (sens 90%, overloaded state, such as congestive heart failure or spec 82%) chronic liver failure, further diagnostic workup is usually • Pleural fluid level > two-thirds the upper limit of nor- not necessary to determine the cause of the effusion(s). mal for serum LDH level (sens 82%, spec 89%).

In the above setting, further testing with thoracentesis C. Situations Where a Transudate Can Be might be appropriate in the following situations: • Clinical signs of pleural inflammation, such as pleu- Misclassified as an Exudate ritic chest pain or fever. Sometimes, when a transudative effusion is treated with • A large unilateral effusion or significantly asymmetri- aggressive diuresis for several days prior to thoracente- cal bilateral effusions sis, the fluid can develop the chemical characteristics of • An obvious chest xray abnormality suggesting a an exudate. cause other than volume overload for the effusion, such as a lung mass, consolidation, etc. If, in this setting, clinical assessment strongly suggests a transudative effusion, one can measure (or have the lab add on these tests to the fluid already drawn) the serum 5. Consider Thoracentesis minus pleural fluid albumin level. If the difference is < 12 If there is no clinical evidence of a volume overloaded g / L, then the fluid is likely an exudate (sensitivity for state to explain the pleural effusion, one should consider exudate 87%, specificity 92%). performing diagnostic thoracentesis. D. Management of Transudate A. Tests to Order Management of a transudate consists of managing the At the time of thoracentesis, the four following groups of cause of the transudate, such as optimizing control of tests should be ordered: congestive heart failure, etc. • Chemistry, including total protein, LDH. Other tests include glucose, amylase, and pH if clinically indicated. Serum protein and LDH should also be drawn. Pleural and serum albumin may also be necessary 6. Determine the Cause of the as explained later. Exudate • Hematology, including cell count and differential If the fluid is classified as an exudate, the next step is to • Microbiology, including gram stain, AFB stain, bacte- determine its cause. It is beyond the scope of this hand- rial, TB, and fungal cultures. out to cover this topic comprehensively. Rather, some • Cytology. It is important to send as much fluid as clinical pearls will be discussed. possible when requesting cytologic analysis. A. Appearance of the Fluid It is also important to note the appearance of the fluid • Empyemas may appear obviously purulent. (purulent, bloody, etc) as this also provides important diagnostic information. • Malignant effusions may appear bloody (hemothorax is described in more detail later). In theory, one would first classify the fluid as an exudate • Sometimes, chronic rheumatoid effusions can be or a transudate, and then only order further testing for thick, yellow, and viscous, almost appearing exudates in a stepwise fashion. However, in practice, it is “purulent”. simpler to order these other tests at the time the fluid is • Milky fluid suggests a chylothorax or chyliform effu- drawn. sion.

APPROACH TO PLEURAL EFFUSION

B. Significance of the Cell Count and Dif- tube due to loculations and if the patient can tolerate surgery. ferential i. White Blood Cell Count If the patient cannot tolerate surgery, then streptokinase, The total pleural fluid white blood cell count is of limited via a single or multiple chest tubes, may be required. use in distinguishing the cause of an exudative effusion. Although high white blood cell counts (> 10,000 per uL) are usually associated with parapneumonic effusions, B. Malignant Effusion they can be seen in other inflammatory disorders like Treatment of a malignant effusion involves the following pancreatitis, etc. steps: 1. Determine the cause of the malignancy. Common The differential white count is somewhat more helpful causes of malignant pleural effusions include lung than the total white cell count as listed below: and breast cancer and lymphoma. Other causes include mesothelioma, ovarian cancer, or cancer of • > 50% lymphocytes are often seen in malignancy unknown primary. (eg. Lymphoma), tuberculous pleuritis, or post CABG 2. Treat the underlying malignancy if possible. effusion. Chronic, longstanding effusions in general 3. Treat the effusion related to the malignancy. can also have high numbers of lymphocytes • Generally, effusions due to malignancies that re- • > 10% eosinophils are usually due to air or blood (the spond to chemotherapy, such as lymphoma or small latter present for usually more than several days) in cell carcinoma, may not need pleurodesis. In other the pleural space. Other causes of pleural fluid eosi- words, the pleural effusion might be controlled with nophilia include benign asbestos related pleural effu- chemotherapy alone. (note that “respond” does not sions, drug reactions (eg. Dantrolene, bromocriptine, necessary mean “cure”). If the effusion is large and nitrofurantoin, etc), parasitic diseases, Churg-Strauss causing dyspnea, an initial therapeutic thoracentesis syndrome. In 25% of cases, the origin of the pleural may be needed. fluid eosinophilia is not established. • If the malignancy is one that is not responsive to che- ii. Red Blood Cell Count motherapy, chest tube drainage and pleurodesis may If the hematocrit of the pleural fluid is > 50% of the he- be required. Prior to this, keep in mind a few points. matocrit of the serum, a hemothorax exists. This can be • Chest tube drainage and pleurodesis is only indi- seen in malignancy, pulmonary embolism with lung in- cated if the effusion is causing symptoms, spe- farction, trauma (including iatrogenic trauma due to the cifically dyspnea. thoracentesis itself if an intercostals blood vessel is punc- • Make sure you know what you are treating. For tured) example, a unilateral whiteout on CXR, assumed to be due to pleural effusion, may actually represent tumor infiltration of the lung or a combina- 7. Treat the Cause of the Exudate tion of effusion and lung collapse secondary to If a cause of the exudative effusion is found, it should be endobronchial obstruction by tumor. If the latter, treated. Two common causes will be discussed here. the lung may not re-expand after drainage of the effusion, a situation referred to as a “trapped A. Parapneumonic Effusion lung”. In this case, pleurodesis will likely be un- According to the 2000 ACCP Consensus Statement enti- successful because the visceral and parietal sur- tled “Medical and Surgical Treatment of Parapneumonic faces are not in contact and will not form adhe- Effusions”, there are 4 categories of effusions associated sions after inflammation is induced by the scle- with bacterial pneumonia. With regards to treatment, rosing agent (eg. Talc). the main decision is whether or not chest tube drainage is needed in addition to antibiotics. 8. What to do If the Cause of the Indications for chest tube drainage, in the setting of a parapneumonic effusion, include the following: Exudate Cannot be Determined. • Large, free-flowing effusion > half the hemithorax If no definitive cause for the exudate is found after his- • Positive gram stain or culture (ie. Empyema) tory, physical exam (including lymph node assessment), • Frank pus (ie. Empyema) and initial thoracentesis, a CT angio should be done. This • pH < 7.20 will help rule out a pulmonary embolism as well as look for intrathoracic abnormalities that may be causing the Surgical decortication is indicated if the parapneumonic effusion (such as a mass, adenopathy, pleural lesions, effusion or empyema cannot be fully drained with a chest etc). If abnormalities are found on CT, then they could be APPROACH TO PLEURAL EFFUSION further investigated with biopsies, etc. weight loss, and the presence of the left lung mass), a diagnostic thoracentesis was performed which showed a Bronchoscopy may help determine the cause of the effu- biochemical exudate. The cytology revealed adenocarci- sion if a lung mass or infiltrate is present, or if an endo- noma. The patient was subsequently referred to the bronchial lesion is clinically suspected because of Cross Cancer Institute. hemoptysis or mediastinal shift towards the side of an effusion, implying the presence of an obstructing lesion. References If malignancy is clinically suspected and initial investiga- 1. Light R. Pleural Effusion. NEJM 2002;346(25):1971- tions are negative, a repeat thoracentesis could be per- 1977 formed. Overall, three separate pleural fluid samples 2. Light R. Pleural Diseases. 4th Ed. Lippincott Williams obtained from a patient with malignant pleural disease and Wilkins. Philadelphia. 2001. will yield a positive result about 80% of the time, and 3. Colice et al. Medical and Surgical Treatment of most of these will be metastatic adenocarcinoma. The Parapneumonic Effusions. CHEST 2000;18(4):1161- approximate yield of thoracentesis in detecting other malignancies, such as squamous cell cancer, Hodgkin’s lymphoma, and non-Hodgkin’s lymphoma, is lower.

Closed (bedside) needle biopsy of the pleura may help make the diagnosis of tuberculosis if it is clinically suspected. There are times when thoracentesis, sputum, and bronchoscopy with bronchial wash for AFB and TB culture are all negative, despite a strong clinical suspicion of TB. In these cases, if a pleural effusion is still present, closed pleural biopsy sent for AFB, culture, and histology may make the diagnosis, either by identifying the organism or by identifying granulomas compatible with the disease.

At this point, if still no diagnosis is established, the two options include observation of the pleural effusion versus surgical pleural biopsy.

If the patient is a good surgical candidate, it is reasonable to consider surgical pleural biopsy. It is important to realize (and warn the patient) that a diagnosis might still not be obtained, even after biopsy. In other words, the pleural biopsy may simply show chronic, nonspecific inflammation without an obvious cause. However, in these circumstances, the patient can at least be assured that all reasonable tests have been done to rule out malignancy.

If the patient would tolerate surgery poorly or refuses surgery, then it is reasonable to observe the effusion with serial CXR’s. It is also important to realize that, in up to 15% of pleural effusions, a diagnosis is never established.

9. Conclusion of the Introductory Case Given the high clinical suspicion of a malignant pleural effusion (based on his extensive smoking history, the Chapter Seven

Approach to Interstitial Lung Disease APPROACH TO INTERSTITIAL LUNG DISEASE by Drs. L. Cheung & B. Chiam

cally important questions regarding patients with sus- 1. Introduction pected interstitial lung disease: A 54 year old male is referred to the Pulmonary Clinic 1. What is the overall diagnostic approach to patients with an 8 month history of gradually increasing dyspnea with suspected interstitial lung disease? and decreasing exercise tolerance. Aside from a dry 2. When is a lung biopsy necessary and when is it not cough, he denies any other symptoms. Physical exam necessary? reveals stable vital signs, bibasilar crackles, a non- 3. How do the history, CXR, high resolution CT, and elevated JVP, and bilateral finger clubbing. CXR reveals other non-invasive tests help to narrow the differen- reticular fibrosis with a basal and peripheral predomi- tial diagnosis? nance. (The workup of this case is described at the end of this chapter) The overall diagnostic approach to interstitial lung disease is illustrated in the flowchart in Figure 1. The flow- This chapter will enable you to answer the following clini- chart is explained in the rest of this chapter.

Figure 1: Flowchart illustrating Suspect ILD Perform further non-invasive workup. Tests include PFT’s, the approach to a patient with after history, ABG, high resolution CT chest. If clinically indicated, suspected interstitial lung dis- physical exam, consider rheumatoid factor, ANA, ANCA, anti-Jo1 Ab, CK, ease CXR, +/- review urinalysis. Also consider bronchoscopy (see text for details) of old radiographs Clinical and radiographic features classic for IPF / UIP pattern?

no yes Clinically suspect Other causes for ILD granulomatous include medications, inhalational disease, infection, or exposures, known malignancy? connective tissue disease, etc no yes

Other cause Consider for ILD readily bronchoscopy + evident? transbronchial lung biopsy yes no

Consider Diagnosis empiric obtained? treatment

no yes Can patient tolerate open Start lung biopsy? treatment

no yes

Use HRCT to Consider determine if empiric open lung treatment might be biopsy helpful Supportive care, Mainly ground Mainly end stage consider referral glass fibrosis for lung transplant Consider workup if empiric therapy appropriate APPROACH TO INTERSTITIAL LUNG DISEASE

In total, the physiologic function of the alveoli (and some- 2. What is Interstitial Lung Dis- times also the very small airways leading to the alveoli) is altered, hence the symptoms. ease? More often than not, interstitial lung disease (ILD) comes to the attention of the physician when a CXR demon- 3. Classifying ILD to Focus Your strates a pattern compatible with ILD. History and Physical Exam As illustrated in Figure 2, the interstitium refers to the The differential for ILD is long, and recalling potential alveolar walls which includes capillaries, cells such as diagnoses can be a painful and inelegant exercise. The macrophages, and proteins such as fibronectin and patient’s history, perhaps the most important element in laminin. determining the etiology of ILD, can shorten the differential list, and many people find it useful to frame their his- Figure 2 tory-taking in the context of the clinical classification alveolar cells and scheme in Figure 3. macrophages The respiratory symptoms usually consist of dyspnea or cough, and are not particularly specific for ILD. However, information regarding acuity, and extra-pulmonary mani- interstitium festations of a systemic disease may provide important clues. fibroblast For example, determining that the patient was exposed to asbestosis twenty years ago could help diagnose a CXR finding of increased reticular markings in the base capillary of the lungs. Similarly, a history of coal mining could suggest coal miner’s lung or silicosis.

Any process that impacts on the alveolar walls, or more Smoking is an uncommon habit in people with hypersen- specifically on its components, results in interstitial lung sitivity pneumonitis, while it is a common feature in eosi- disease. For example, a vasculitic process impacting on nophilic granuloma. the capillaries could present as ILD, or an inflammatory disease process that increases the amount of cells in the Also, assessing whether the disease process is acute, interstitium will present as ILD. subacute, or chronic can further narrow your differential. For example, an acute injury or disease (days-weeks) In each possible situation, the process results in damage: may be caused by trauma, drugs, toxins, connective tis- vascular permeability can be altered, fibroblastic prolif- sue diseases, infections, etc. An example of a subacute eration and excessive collagen deposition may occur. disease is hypersensitivity pneumonitis.

Figure 3: Focusing the history and physical exam Suspected- Radiologic Confusers Pulmonary Idiopathic • infection, hemorrhage, Fibrosis • no obvious pulmonary edema, aspira- clinical cause tion Unclassified • granulomatous disease, lymphatic Drug or Toxin diease,etc Related Job Related Connective Tissue • amiodarone, • pneumoconiosis, Disease nitrofurantoin, hypersensitivity • rheumatoid arthritis, chemotherapy, pneumonitis SLE, polymyositis, radiation etc APPROACH TO INTERSTITIAL LUNG DISEASE

Figure 4: CXR features of the various causes of ILD - using the CXR to help narrow the differential diagnosis

Lymphadenopathy + ILD Upper Lobe Predominance sarcoid, berylliosis, lymphangitic car- chronic sarcoid, eosinophilic granuloma, cinomatosis silicosis, talcosis, radiation pneumonitis, chronic hypersensitivity pneumonitis, certain connective tissue diseases like ankylosing spondylitis Recurrent Pneumothorax + ILD IPF, eosinophilic granuloma, lymphan- Pleural Disease + ILD gioleiomyomatosis, tuberous sclerosis, pleural plaques (asbestosis), chylothorax neurofibromatosis (lymphangioleiomyomatosis), pleural thickening (rheumatoid arthritis, lupus)

Kerley’s B lines + ILD lymphangitic carcinomatosis, pulmonary veno-occlusive disease Lower Lobe Predominance IPF, asbestosis, drug induced, certain connective tissue diseases like rheumatoid arthritis ILD+ Increased Lung Volumes eosinophilic granuloma, lymphangioleiomyomatosis, tuberous sclerosis, neurofibromatosis

Physical examination is aimed toward both confirming ity of progression. Chronic, endstage fibrosis often the presence of abnormal lung parenchyma, and deter- has a characteristic “honeycomb” appearance – its mining any extra-pulmonary signs, which may identify a presence suggests that the process has occurred systemic process (for example, a helioptrope rash, hand over a relatively long period of time. skin lesions, and weakness would be compatible with 2. How would you characterize the abnormality? In dermatomyositis). other words, does it look like reticular fibrosis vs airspace disease? Most of the chronic interstitial lung Particular note should be made of clubbing, as it is a diseases look like the former. common finding in patients with idiopathic pulmonary 3. What is the distribution of the abnormality? Certain fibrosis, and not common in other diseases that cause interstitial lung diseases tend to have either a lower interstitial lung disease. zone or upper zone predominance. As well, note whether the distribution is mainly central vs peripheral. 4. Are there other ancillary abnormalities, like pleural 4. Analyzing the CXR in a Patient disease, lymphadenopathy, etc? with Suspected ILD 5. Are the lung volumes increased in the setting of ILD? Certain CXR features can help narrow the differential Although most causes of ILD lead to decreased lung diagnosis and are illustrated in Figure 4. When looking volumes due to the scarring and fibrosis, increased at a CXR of a patient with suspected interstitial lung dis- lung volumes may be seen in some ILD’s or may be ease, ask yourself the following questions: seen in ILD + emphysema in a heavy smoker.

1. Is the abnormality acute, subacute, or chronic? Inter- stitial lung disease generally progresses slowly - in either a chronic or subacute fashion - and reviewing old CXR’s (if available) may help determine the rapid- APPROACH TO INTERSTITIAL LUNG DISEASE

At this point, after the history, physical exam, CXR, HRCT, 5. Perform Other Non-Invasive and other non-invasive tests, we often do bronchoscopy to rule out infection or malignancy. Tests Other noninvasive tests to perform in a patient with sus- If we clinically suspect a granulomatous process (such as pected ILD include pulmonary function tests (to verify the sarcoid or hypersensitivity pneumonitis), we may often do presence of a restrictive defect and determine the DLCO), transbronchial biopsies at the time of bronchoscopy as ABG, and a “vasculitis workup” if a connective tissue dis- well. ease is suspected for other reasons, such as rheumatoid factor, ANA, etc. Examples of some lab test results and If we do not clinically suspect a granulomatous process, their significance in the context of an ILD are shown in we may forgo the transbronchial biopsies since the table 1. chance of obtaining a tissue diagnosis with this biopsy method is quite low for other diseases.

Table 1 Laboratory 6. Is the Clinical - Radiographic Examples of Diseases Findings Picture “Classic” for IPF / Pre- Eosinophilic pneumonia, sarcoi- Eosinophilia dosis, systemic vasculitis, drug sumed UIP - pattern? induced If, based on clinical assessment and non-invasive tests, a classic picture of IPF / presumed UIP-pattern emerges, Urinary sediment Connective tissue disease, sys- then this is usually all that is required to make a diagno- abnormalities temic vasculitis, drug induced sis. (See the chapter entitled “Interstitial Lung Disease - making sense of the acronyms” for more details on the Connective tissue disease, sys- significance of lung tissue histology, such as “UIP- Serum temic vasculitis, sarcoidosis, IPF, pattern”). In other words, this clinical pattern has been autoantibodies silicosis, asbestosis, lymphocytic shown to have a high specificity for yielding a histologic interstitial pneumonia UIP-pattern on subsequent open lung biopsy. Hypogamma- Lymphocytic interstitial pneumo- globulinemia nia Unfortunately, no therapy has been conclusively shown to improve outcome in patients with IPF / presumed UIP- Antibasement Goodpasture’s syndrome pattern. Thus, consider referral to a lung transplant cen- membrane antibody tre if clinically appropriate. Antineutrophil cyto- Systemic vasculitis plasmic antibody 7. What if the Clinical - Radio- graphic Picture Suggests a Disease A CT scan usually follows CXR. High-resolution CT scans may be useful to help create a differential diagnosis; Other than IPF? however, the potential differential diagnosis can still be If clinical assessment and non-invasive testing suggest a wide. disease other than IPF, then you need to decide if further invasive testing (ie. lung biopsy) is needed. A high resolution CT chest can also help ascertain the nature of the lung involvement (interstitial vs. alveolar As mentioned previously, if you clinically suspect a granu- disease), detect any coexisting pleural effusions or ade- lomatous process (such as sarcoid or hypersensitivity nopathy, and determine how much of the disease repre- pneumonitis), a bronchoscopy plus transbronchial biopsy sents active inflammation (usually seen as ground glass will have a reasonably high yield for diagnosis. opacification) vs. permanent, endstage fibrosis (usually seen as honeycombing). The latter findings can help de- Any finding other than infection, granulomas, or malig- termine whether or not treatment may be beneficial nancy on a transbronchial lung biopsy is generally consid- (active inflammation is more likely to respond to treat- ered non-specific or inconclusive. ment than endstage fibrosis). For example, finding some nonspecific fibrosis on trans- Other imaging techniques, such as gallium scanning, bronchial lung biopsy (TBBx) does not automatically indi- have no well documented role in the workup or manage- cate the presence of idiopathic pulmonary fibrosis. Most ment of patients with ILD. inflammatory lung diseases will have nonspecific fibrosis APPROACH TO INTERSTITIAL LUNG DISEASE

as the final common pathway whereas idiopathic pulmo- fects and should not be used unless they have a reason- nary fibrosis has characteristic pathologic findings which able chance of working, and a lung biopsy is necessary to usually cannot be seen on the small biopsies taken dur- determine if a steroid responsive disease is present. In ing a transbronchial lung biopsy. addition, some diseases require more than just steroids (e.g. cyclophosphamide), so it may be important to estab- As well, finding some “organizing pneumonia” on TBBx lish whether or not these are present via open lung bi- does not automatically indicate the presence of crypto- opsy. genic organizing pneumonia (formerly known as BOOP) because many inflammatory conditions can give rise to If an open lung biopsy is performed, the clinician must “organizing pneumonia”, whereas cryptogenic organizing then incorporate the biopsy findings with the clinical pic- pneumonia has characteristic findings that usually re- ture to generate a diagnosis. quire the larger biopsies obtained through open lung biopsy. 9. Using the High Resolution CT Thus, some would even argue that if a granulomatous disease, infection, or malignancy are unlikely based on Chest To Determine if Empiric history and clinical assessment, one should proceed Treatment Might Be Helpful straight to open lung biopsy (and not bother with bron- Unfortunately, many patients will not likely tolerate an choscopy or transbronchial lung biopsy) because the find- open lung biopsy due to co-morbid medical illness or ings on bronchoscopy will likely be nonspecific. Of course, frailty. For these patients, the findings on CT chest may others argue that bronchoscopy is far less invasive than help determine whether empiric therapy (usually steroids open lung biopsy and should be done first. and / or cyclophosphamide) should be attempted.

Sometimes, the cause of ILD may be clinically evident on In the context of an ILD, predominantly ground glass clinical assessment and non-invasive testing. Examples opacification suggests active alveolitis and inflammation of this include ILD in a patient with known connective which is more likely to respond to steroids (an example is tissue disease, ILD in a patient on a medication known to shown in Figure 5 - compare with the normal CT shown in cause ILD (such as nitrofurantoin or amiodarone), or ILD Figure 6, the CT showing consolidation in Figure 7, and in a patient with a clear occupational exposure, such as the CT showing fibrosis in Figure 8) asbestos or silica. In these cases, some would treat empirically with steroids and / or withdraw the offending Ground glass opacification on CT has increased attenua- agent. tion but is not opaque enough to appear as frank consoli-

8. When Should You Consider an Figure 5: Ground Glass Open Lung Biopsy? If the patient’s clinical features are not “classic” for IPF, and there are no clinical features to suggest a granulomatous disease, and no other cause for the ILD is readily evident on clinical assessment, then many respirologists would recommend that the patient undergo an open lung biopsy. However, this is not universal thinking by any means, and, unfortunately, the question of whether open lung biopsy actually helps us manage these patients is very controversial.

The “anti- open lung biopsy” camp has many arguments. Although open lung biopsy is the “gold standard” for diagnosis, it is invasive and many patients are not likely to tolerate it due to frailty or co-morbid illness. As well, many of the interstitial lung diseases are treated with steroids anyway, so why not just put everyone on steroids without doing a lung biopsy?

The “pro- open lung biopsy” camp has their counterargu- ments. Steroids have significant long term adverse ef- APPROACH TO INTERSTITIAL LUNG DISEASE

Figure 6: Normal CT as infection, pulmonary edema, hemorrhage, etc. How- ever, hopefully, at this stage in the clinical assessment, these other entities have already been empirically treated or “ruled out” as best as possible.

A finding of mainly end-stage fibrosis suggests that the disease will likely not respond to empiric steroids – ie. the damage has already been done. In this case, the side effects of empiric therapy may outweigh any potential benefits. Supportive care is important including oxygen, home care support, and, possibly, a discussion of end of life issues.

Figure 8: CT showing fibrosis

dation. In other words, the vasculature can still be seen. In contrast, consolidation is very opaque, and the vasculature in the consolidated area cannot be seen.

Of course, in general, ground glass opacification is non- specific – it could be due to diseases other than ILD, such

Figure 7: CT showing Consolidation

10 . Conclusion of the Introduc- tory Case PFT’s on the patient revealed a restrictive defect and low DLCO when adjusted for VA (see the chapter on the Ap- proach to PFT Interpretation for more details on what this means). ABG’s revealed mild hypoxemia on room air. A high resolution CT chest revealed fibrosis and honeycombing in a peripheral and basal distribution. Blood- work and urinalysis were unremarkable.

Based on the clinical and radiographic features, the patient’s presentation was classic for IPF / presumed UIP pattern. No other causes for his ILD was apparent on history (eg. occupational exposures, medications, etc). Thus, the patient was referred for lung transplant assessment. APPROACH TO INTERSTITIAL LUNG DISEASE

References 1. Fishbein MC. Diagnosis: To Biopsy or Not to Biopsy. CHEST 2005;128:520S-525S. 2. Lynch et al. Idiopathic Interstitial Pneumonias: CT Features. Radiology 2005;236:10-21. 3. American Thoracic Society / European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumo- nias. AJRCCM 2002;165:277-304. Chapter Eight

Interstitial Lung Disease Interstitial Lung Disease—Making Sense of the Acronyms By Dr. L. Cheung

tures of each pattern in “plain language” or “Cheung- 1. Introduction speak” (for those wanting more formal, accurate descrip- 1. This handout is meant to accompany the handout tions and pictures of the pathology, feel free to read the entitled “Approach to Interstitial Lung Disease”. references). 2. Although there are many times when a lung biopsy cannot be done (eg. patient wouldn’t tolerate it or The rest of the handout will describe the contents of Ta- refuses, etc), in an ideal world, the diagnosis of inter- ble 1 in more detail. stitial lung disease (or ILD) is made after integrating the clinical, radiologic, and pathologic / histologic information. This handout is meant to help you make 2. Usual Interstitial Pneumonitis sense of the information obtained from lung biopsy when it is performed. (UIP) 3. The commonest histologic patterns are UIP (usual A. Histologic Appearance: interstitial pneumonitis), NSIP (non-specific intersti- The histologic features include the following: tial pneumonitis), and OP (organizing pneumonia). • lots of endstage fibrosis with distortion of the lung 4. Note that it is best to describe these entities as architecture “patterns” when referring to the pathology since each • little active inflammation pattern can have many clinical causes. For example, • predominantly a basal and subpleural distribution the UIP-pattern can be seen in idiopathic pulmonary fibrosis (IPF) where no clinical cause can be identified, but it can also be seen in pulmonary fibrosis B. Radiologic Appearance secondary to collagen vascular disease, drug toxicity, Because of the pathologic features of the UIP pattern, asbestosis, and sometimes chronic hypersensitivity radiographically you will see the following: pneumonitis. Thus, after receiving the report of UIP- • linear, reticular opacities (as opposed to fluffy air- pattern from the pathologist, the clinician must de- space disease) cide if any of the latter four entities are the cause or • possible honeycombing and distortion of the lung whether it is idiopathic pulmonary fibrosis. architecture 5. If a lung biopsy cannot be done, how well does the • little ground glass opacification on CT due to the pau- appearance on high resolution CT (HRCT) chest corre- city of active inflammation late with the histologic patterns? HRCT is best for • a predominantly basal and peripheral distribution of diagnosing UIP-pattern. In other words, the classic the fibrosis appearance of reticular opacities, honeycombing, • Figure 1 shows the classic UIP-pattern on CT. The and architectural distortion due to fibrosis with a black arrow points out the fibrosis. basal and peripheral predominance is often “diagnostic” of a UIP histologic pattern and a lung biopsy is usually not needed to confirm this. C. Clinical Features 6. Findings on HRCT other than those classic for UIP- Because of the pathologic features of the disease pattern are usually non-specific. For example, a HRCT (endstage, usually irreversible fibrosis with little active with a lot of ground glass opacification is non-specific inflammation), no medications have been conclusively and can be seen in NSIP, DIP, RB-ILD, and LIP. The proven to be of benefit for IPF secondary to the UIP pat- “classic”features of OP include subpleural or peri- tern. bronchovascular consolidation, but these can also be seen in infection, malignancy, and eosinophilic pneu- Causes of the UIP - pattern include the following: monia. • connective tissue disease • drug toxicity (eg. nitrofurantoin, amiodarone, etc) In Table 1, I’ve shown an overview of the 4 commonest • asbestosis (often see pleural plaques on CT) pathologic patterns (UIP, NSIP, OP, and DAD) that you • chronic hypersensitivity pneumonitis (uncommon) might see on your clinical rotations. • in the above clinical settings, the diagnosis would be “UIP pattern due to connective tissue disease” or Although as clinicians, you will never need to be able to “UIP pattern due to drug toxicity”, etc, based on what identify the pathology on your own, I think it is still impor- the clinician felt was occurring on clinical assess- tant to understand how the pathologic features of each ment. pattern influence the radiographic appearances and clinical features. Thus, I briefly describe the pathologic fea- the Acronyms Interstitial LungDisease—MakingSenseof

Table 1

Pathologic Pathologic Features (in Effect of the Pathology on Radiographic Effect of the Pathology on Potential Etiologies for each Pattern “Cheung-speak”) Appearance Clinical Features Pathologic Pattern

UIP • endstage fibrosis and • you usually see linear (reticular) • due to the endstage (and • Idiopathic (IPF) distortion of lung archi- opacities (as opposed to airspace likely irreversible) nature • Connective tissue disease tecture disease) with possible honeycomb- of the fibrosis, no medi- • Certain medications ing and distortion of lung architec- cations have been con- • little active inflamma- • Pneumoconiosis tion relative to the fi- ture on CXR or CT clusively proven to halt or brosis • there is little ground glass opacifica- reverse the slow progres- • Inhaled organic antigens

• predominantly a sub- tion on CT relative to the fibrotic sion of the disease pleural and basal distri- changes bution • you see predominantly a peripheral and basal or lower lobe distribution on CXR or CT NSIP • there are two subtypes • you see a relatively large amount of • due to the presence of • Idiopathic of NSIP - one with a ground glass opacification active inflammation, the • Connective tissue disease cellular predominance (signifying active inflammation) on disease is more likely to • certain medications and one with a fibrotic CT, +/- some fibrosis. respond to medications predominance like steroids • hypersensitivity pneu- • the changes mainly have a basal or monitis • both subtypes have lower lobe distribution but the lungs • however, if the fibrosing relatively large can be affected elsewhere as well subtype is present, the amounts of active in- on CXR or CT clinical course can re- flammation. The fi- semble the UIP pattern brotic subtype also has fibrosis present. OP • loose plugs of connec- • because the alveoli plug up with • because the pathologic • Idiopathic (cryptogenic tive tissue form and material, you usually see airspace changes develop rela- organizing pneumonia - plug up the alveoli and disease / consolidation on CXR or tively quickly, the disease COP) alveolar ducts CT, as opposed to the linear or re- tends to present • Overactive inflammatory ticular opacities seen with the more subacutely - over weeks response to infection interstitial fibrotic diseases. or a few months, rather • Reaction to drugs, fumes, than over many months toxic exposures or years as in some of the fibrotic diseases • Connective tissue disease

DAD • diffuse alveolar wall • due to the exudate filling up the • because the pathologic • ARDS due to pulmonary thickening due to pro- alveoli, you usually see airspace changes develop rela- or non-pulmonary causes liferation of connective disease / consolidation on CXR or tively quickly, the disease (see text) tissue and hyaline CT. usually presents acutely - • Connective tissue disease membranes • in the later stages of the disease, over weeks or even days. • Overactive inflammatory • exudate filling up the the diffuse alveolar wall thickening response to infection alveoli may turn into fibrosis, resulting in • Idiopathic (acute intersti- residual linear or reticular changes. tial pneumonitis) Interstitial Lung Disease—Making Sense of the Acronyms

Figure 1: UIP pattern causing IPF. Note the peripheral Figure 2: NSIP pattern (idiopathic). Note the extensive predominance of the fibrosis (black arrow) ground glass opacification (red arrow), as well as some fibrosis (black arrow)

• if no clinically apparent cause for this pattern is iden- • ground glass predominance, mainly in a basal distri- tified, the diagnosis becomes idiopathic pulmonary bution fibrosis (IPF) • some fibrosis may be present if the NSIP - fibrosing subtype is present. • Figure 2 shows the CT of a patient with NSIP - pattern 3. Non-Specific Interstitial Pneu- of unknown cause. monitis (NSIP) A. Histologic Appearance: C. Clinical Features There are two subtypes of NSIP—a cellular pattern and a Because of the pathologic features of the NSIP cellular fibrosing pattern. Features of the cellular pattern in- subtype, the disease is more likely to respond to steroids clude: than the UIP pattern. However, patients with the NSIP - fibrosing subtype are usually less responsive. • mild to moderate interstitial chronic inflammation,

with infiltration of the alveolar walls Cause of the NSIP pattern include the following:

Features of the fibrosing NSIP pattern include the follow- • collagen vascular disease ing: • hypersensitivity pneumonitis • interstitial fibrosis present, but lacking the temporal • drug induced pneumonitis heterogeneity pattern and patchy features of UIP • post—infection • no fibroblastic foci are present (classically seen in • immunodefiency including HIV infection UIP) • if no clinical cause for this histologic pattern can be • a fair bit of active inflammation is present as well identified, the diagnosis becomes idiopathic NSIP.

B. Radiologic Appearance Because of the pathologic features of the NSIP pattern, radiographically you will see the following: Interstitial Lung Disease—Making Sense of the Acronyms

4. Organizing Pneumonia (OP) Figure 3a Figure 3b A. You mean BOOP, right? No, I don’t mean BOOP.

In 2001, the American Thoracic Society and the Euro- pean Respiratory Society organized a committee to develop a Consensus Statement regarding the idiopathic interstitial pneumonias. One of the recommendations was to discourage use of the term “BOOP” - firstly, because it was being confused with the pathologic entity of bronchiolitis obliterans, and secondly, because this non- specific histologic reaction, which can be seen in many conditions, was too often being confused with idiopathic BOOP. (Thirdly, in my opinion, BOOP just sounds silly). So, Figure 3c now, we are being encouraged to use the term “organizing pneumonia”. In the case of idiopathic organizing pneumonia, we use the term “COP”.

B. Histologic Appearance The histologic features of organizing pneumonia include the following: • loose plugs of connective tissue fill up the alveoli and alveolar ducts • there is uniformity (not heterogeneity) in appearance, with all of the connective tissue the same age (ie. temporal uniformity). • mild to moderate inflammation is present

C. Radiologic Appearance Because of the pathologic features of organizing pneumonia, you will see the following radiographic features: • multifocal consolidation or airspace disease, as op- tern). The classic scenario is a patient who presents with posed to linear fibrosis (exceptions may occur but non-specific symptoms of an infection which does not this is a good general rule) improve after several courses of antibiotics administered • ground glass opacification on CT can also be seen over several weeks. • note that consolidation is a non-specific radiographic finding seen in many entities such as infection, hem- Causes of organizing pneumonia include the following: orrhage, edema, alveolar malignancy (eg pus, blood, • after a pneumonia (bacterial, viral, aspiration, etc), fluid, tumor, etc). Thus, it is important to clinically whereby the inflammatory response generated by rule out these possibilities before labelling the con- the infection continues even after the infection is solidation as organizing pneumonia. treated. • Figures 3 (a - c) show the radiographs of a patient • reaction to drugs, fumes, toxic exposures with biopsy proven organizing pneumonia, thought to • collagen vascular disease be cryptogenic. Note the areas of consolidation on • eosinophilic lung disease CXR and CT (red arrows) • hypersensitivity pneumonitis • in the above clinical settings, the diagnosis would be D. Clinical Features “organizing pneumonia pattern due to infection”, or Because the pathologic features of the disease usually “organizing pneumonia pattern due to drug reaction”, develop relatively quickly, organizing pneumonia tends to etc, based on what the clinician felt was occurring on develop over weeks or a few months (as opposed to many months or even years as in IPF due to the UIP pat- Interstitial Lung Disease—Making Sense of the Acronyms

clinical assessment. C. Clinical Features • if the clinician is unable to identify a cause, then the Because the pathologic features of DAD develop quickly, diagnosis would be cryptogenic organizing pneumo- the disease usually develops over weeks or less. nia or “COP”. The histologic pattern of diffuse alveolar damage can be 5. Diffuse Alveolar Damage seen in the following clinical settings: • ARDS—this has many causes (listed below) (DAD) • connective tissue disease A. Histologic Appearance • infections The histologic features include the following: • AIP (Hamman-Rich Syndrome) - if no cause can be • diffuse thickening of the alveolar wall due to prolifer- found, then the clinical syndrome is termed acute ating connective tissue and prominent hyaline mem- interstitial pneumonia branes ARDS is clinically characterized by bilateral lung infil- • exudate filling the alveoli trates, severe hypoxemia, and absence of an elevated • uniformity in appearance left atrial pressure to account for the lung infiltrates (that • pertinent negative findings include lack of granulo- is, exclusion of the presence of pulmonary edema). mas, necrosis, abscesses, prominent eosinophils or neutrophils. ARDS, in turn, is due to many causes including the following: B. Radiologic Appearance • pulmonary causes, such as aspiration, pneumonia, Because of the pathologic features of DAD, you will see trauma, transfusion-related acute lung injury, inhala- the following radiographic features: tion of toxic chemicals, or drug toxicity • extensive consolidation or airspace disease in the • non-pulmonary causes, such as severe pancreatitis, acute phases of the disease severe multiple extremity trauma, massive transfu- • in the later stages of the disease, after the alveolar sion, sepsis exudate clears, the thickening of the alveolar wall may resolve,or it may persist. If it persists, you will often see residual linear fibrosis or scarring for a References while (perhaps permanently). 1. ATS/ERS International Multidisciplinary Consensus • an example of DAD (clinically felt to be due to acute Classification of the Idiopathic Interstitial Pneumo- interstitial pneumonitis) is shown in Figure 4. Note nias. AJRCCM 2002;165:277-304 the extensive consolidation (red arrow) and ground 2. Lynch D et al. Idiopathic Interstitial Pneumonias: CT glass changes (black arrow). features. Radiology 2005;236:10-21 3. The CT scan of diffuse alveolar damage was taken from Lynch’s article. All other radiographs are of Figure 4 patients seen by the Pulmonary division at UAH. Chapter Nine

Approach to Solitary Pulmonary Nodule APPROACH TO SOLITARY PULMONARY NODULE by Dr. L. Cheung • follow the patient with serial CXR’s? 1. Introduction • perform bronchoscopy to obtain a tissue diagnosis? A 62 year old female, who has smoked 1 ppd for 45 • perform transthoracic needle biopsy to obtain a tis- years, is referred to the Pulmonary Clinic for evaluation of sue diagnosis? a 2 cm solitary lung nodule seen on routine CXR which • proceed straight to surgical resection without a tis- her family physician performs every few years. (The sue diagnosis? workup of this case is described at the end of this chapter) The overall diagnostic approach to a solitary pulmonary

lung nodule is illustrated in four flowcharts contained in This chapter will enable you to answer the following clini- Figures 1 - 4. The flowcharts are explained in the rest of cally important questions regarding patients with a soli- this chapter. Note that this chapter only covers the diag- tary pulmonary nodule: nostic approach to the solitary pulmonary nodule. The 1. What is the overall diagnostic approach to a patient preoperative assessment of patients undergoing lung with a solitary pulmonary nodule? resection surgery is described in another chapter. 2. What are the clinical and radiographic features of

the nodule that suggest benign vs malignant dis- As well, this chapter assumes that no clinically obvious ease? metastases are present at the initial presentation, since 3. Under what clinical circumstances would you do the this might significantly change the diagnostic approach. following: For example, if a patient presented with a lung mass, multiple liver lesions, and a palpable supraclavicular lymph node, then fine needle aspiration of the lymph Solitary Nodule node may be all that is needed for diagnosis. Figure 1: seen on CXR Flowchart 1

Perform Clinical As- sessment, Obtain CT Chest with Lung Cancer Protocol, Review Previ- ous Radiographs if This table was adapted from NEJM 2003;348:2535-42 available

Clinical Assessment of the Risk of Lung Cancer in a Patient with a Solitary Pulmonary Nodule

Is there a benign pattern of calcification on Feature Risk of Lung Cancer Yes End CT or stability for > 2 Workup yrs on chest films? Low Intermediate High

No Diameter of < 1.5 1.5 - 2.2 Nodule (cm)

What is the approximate clinical likelihood of cancer? (see Age (yr) < 45 45 - 60 > 60 table)

Smoking Never smoked smokes ≤ 20 smokes > 20 Status cigarettes per cigarettes per day day

Smoking Quit ≥ 7 yrs ago Quit < 7 yrs ago Never quit Low Intermediate High Cessation or never Status smoked

Proceed to Proceed to Characteris- Smooth Scalloped Corona radiate Flowchart 2 Flowchart 4 tics of nod- or spiculated Proceed to ule margins Flowchart 3 APPROACH TO SOLITARY PULMONARY NODULE

Figure 2: Flowchart 2 Figure 4: Flowchart 4

Low clinical likelihood of cancer High clinical likelihood of cancer

Perform serial follow-up radio- Can patient tolerate lung graphs for at least 2 years biopsy or resection?

Yes Yes No Nodule size completely stable? End workup

No Refer to thoracic Consider invasive testing if the surgeon for lung patient can tolerate it resection (bronchoscopy for central le- Reclassify clinical likelihood as sions or transthoracic needle “high” and continue algorithm biopsy for peripheral lesions) or sputum cytology.

After appropriate testing, is a tissue diagnosis made? Figure 3: Flowchart 3

Yes No Intermediate clinical likelihood of cancer Start appro- Follow or consider em- priate piric anti-neoplastic treatment therapy if clinically justified

Consider invasive testing if the patient can tolerate it (bronchoscopy for central lesions or transthoracic needle biopsy for peripheral lesions) or sputum cytology.

After the appropriate testing, is a tissue diagnosis made?

Yes No

Start appropri- Consider lung resection or ate treatment surgical biopsy if the patient can tolerate it or follow-up if the patient cannot tolerate invasive testing. APPROACH TO SOLITARY

PULMONARY NODULE 2. Clinical Assessment and Review 3. Estimate Clinical Likelihood of of Old Radiographs Lung Cancer The initial step in the workup of a solitary pulmonary If reviewing old radiographs or CT chest do not nodule consists of reviewing old CXR and clinical demonstrate findings of benign disease, estimate the assessment. For purposes of this chapter, a nodule is likelihood of cancer based on the patient’s history, defined as < 3 cm in its widest diameter. This is an physical exam, and the nodule’s radiographic features. arbitrary cutoff value between a nodule and a mass (> 3 cm), reflecting the increasing chance of malignancy with The variables listed in Table 1 help clinically predict increasing size of the nodule / mass. whether a nodule is benign or malignant

The approach to the diagnosis of a solitary pulmonary nodule needs to balance the desire to avoid subjecting Table 1: adapted from NEJM 2003;348:2535-42 the patient to unnecessary invasive procedures vs. the desire not to miss a malignancy. Clinical Assessment of the Risk of Lung Cancer in a Patient with a Solitary Pulmonary Nodule Always try to review old radiographs if available. Small Feature Risk of Lung Cancer nodules which have not grown for > 2 years are likely not malignant (the longer the size stability, the less chance of Low Intermediate High malignancy).

Diameter of < 1.5 1.5 - 2.2 How often do we find old radiographs showing nodules Nodule (cm) which are unchanged in size? In other words, why would anyone simply follow a nodule when first detected? Age (yr) < 45 45 - 60 > 60 This often occurs in areas endemic with certain fungi which can cause benign granulomas – if the patient is Smoking Never smoked smokes ≤ 20 smokes > 20 young and has no risk factors for cancer, the chance of Status cigarettes per cigarettes per benign disease is quite high and simple follow-up is the day day most prudent course.

A benign pattern of calcification on CT chest can also Smoking Quit ≥ 7 yrs ago Quit < 7 yrs ago Never quit Cessation or never suggest benign disease (as can be seen in a harmatoma), Status smoked as seen in Figure 5.

Figure 5 Characteris- Smooth Scalloped Corona radiate tics of nodule or spiculated margins

A B C D E

A: central calcification – usually benign B: popcorn calcification – virtually always benign 4. Low Clinical Likelihood of C: laminar calcification – usually benign Cancer D: speckled calcification – may be seen in benign or If the clinical likelihood of cancer is low, follow-up with malignant nodules serial radiographs is a reasonable course. However, E: eccentric calcification – may be seen in benign or patient anxiety and uncertainty about the diagnosis may malignant nodules sometimes prompt further investigation in some circumstances.

APPROACH TO SOLITARY

PULMONARY NODULE

biopsy procedure is “negative”, it would be assumed to be 5. Intermediate Clinical Likelihood a false negative and the next step would be resection. of Cancer Either way, with a negative or positive result, the For patients with an intermediate clinical likelihood of treatment of choice would be nodule resection. With cancer, the clinical suspicion of cancer is great enough to lung resection, diagnosis and treatment are accomplished warrant further testing, but not great enough to proceed simultaneously. Again, this assumes that there is a high directly to resection. The lesion is usually “considered clinical suspicion of cancer to begin with and that the cancer until proven otherwise” and negative biopsy patient could easily tolerate lung resection. findings must be viewed with caution – they may represent false negatives unless an alternate diagnosis is If there are reservations about the patient’s ability to clearly found. tolerate a lung resection, then tests can be done to obtain a tissue diagnosis (e.g. transthoracic percutaneous needle For relatively central lesions (e.g. lesions within the biopsy or bronchoscopy) while other tests are being done middle third of the thorax on both the AP and lateral to determine the patient’s physiologic suitability to views on CXR), bronchoscopy can often make the undergo lung resection surgery. diagnosis. If no finding of malignancy is obtained the first time (i.e. a nondiagnostic result), the bronchoscopy Medical therapy, such as chemotherapy or radiation can be often be repeated with fluoroscopy (if not done the therapy (depending on the clinical circumstances and first time). tumor cell type) can be offered for patients with biopsy proven cancer if they would not tolerate or refuse surgery. For very peripheral lesions (e.g. lesions abutting the pleura or chest wall), a percutaneous transthoracic needle Although in theory, one might consider empiric therapy biopsy under fluoroscopy or CT guidance is often the best (e.g. chemotherapy or radiotherapy) for nodules which are test, simply because the lesion is too far away for very likely malignant clinically but have not been or bronchoscopy to have a sufficient yield. cannot be biopsy proven, in practice this is usually not done because of the risks of adverse effects associated The yield for sputum cytology is low for non-central lesions with this “blind”, empiric therapy. It may be done if a but is non-invasive and may be the best test for patients medical emergency were present (e.g. superior vena cava who are too ill or debilitated to tolerate invasive testing. syndrome with airway edema and obstruction) but usually we are dealing with much more than a simple solitary 6. High Clinical Likelihood of pulmonary nodule.

Cancer In cases where the clinical likelihood of cancer is high, if 7. Conclusion to the Introductory the patient is in otherwise good health, there is no clinical Case or radiographic evidence of metastases, and the Reviewing an old CXR done about 2 years previously anticipated risks of surgery are quite low, often the best revealed that the solitary pulmonary nodule was not course is to proceed directly to lung resection (without the present at that time. A CT chest did not reveal any other inherent delay of performing and waiting for the results of nodules or lymph node enlargement, and further testing other tests), even before a definitive tissue diagnosis is and clinical assessment did not reveal any evidence of made. metastases. It was felt that the patient could tolerate lung resection (based on test like PFT’s, etc) from a The rationale for this is as follows: if another procedure cardiopulmonary viewpoint. (e.g. transbronchial lung biopsy) is performed and shows cancer, under the circumstances described above (ie. a Thus, given the high clinical likelihood of cancer, the lack patient in good health with a high clinical suspicion of of metastases on clinical assessment and radiologic cancer and no radiographic or clinical evidence of studies, and her good cardiopulmonary status, she went metastases) the patient would go for resection. If the APPROACH TO SOLITARY

PULMONARY NODULE straight to resection of the solitary pulmonary nodule which turned out to be a squamous cell lung cancer. Thus, diagnosis and treatment were accomplished simultaneously.

References 1. Ost D. Fein A. Feinsilver S. The Solitary Pulmonary Nodule. NEJM 2003;348:2535-2542. 2. Lillington G. Management of solitary pulmonary nodules. Postgrad Med 1997;101(3):145-150.

Chapter Ten

Preoperative Assessment of Patients with Lung Cancer Undergoing Lung Resection PREOPERATIVE ASSESSMENT OF PATIENTS UNDERGOING LUNG

RESECTION By Dr. L. Cheung 2. What tests help you decide if the patient would toler- 1. Introduction ate surgery? A 69 year old female presents with a solitary lung nodule in her right middle lobe which is proven to be lung cancer. The preoperative assessment of patients with lung can- She has no other medical problems. Prior to referring cer involves two main components: her to a thoracic surgeon for consideration of resection of • staging their lung cancer to determine if it is re- the nodule, you wonder if she would even tolerate lung sectable. resection surgery. (The workup of this case is described • assessing them to see if they could medically toler- at the end of this chapter) ate surgery and lung resection.

This chapter will enable you to answer the following clini- In this chapter, will discuss the latter component. Figure cally important questions regarding the preoperative as- 1 illustrates the approach to assessing patients to deter- sessment of patients undergoing lung resection: mine if they can tolerate lung resection surgery. The rest 1. What is the overall approach to the preoperative as- of this chapter explains the algorithm in more detail. sessment of these patients?

Figure 1 positive Cardiac Cardiac Assessment, Workup History, EKG

negative negative both > 80% Respiratory Assessment predicted (History and PFT, ABG) to Successfully yes Evaluate FEV and DLCO Treated? 1 either one < 80% no predicted Split Function Testing to Estimate Predicted

Postoperative (PPO) FEV1 and DLCO

both < 40% either < 40% both > 40% predicted predicted predicted

Cardiopulmonary Exercise

Test to Measure VO2 max

10 - 20 < 10 mL/kg/min > 20 mL/kg/min mL/kg/min

Surgery Carries Prohibitive Moderately High Risk of Acceptable Operable Risk Post-op Complications Operable Risk Necessitating Careful Consideration Between Medical vs Surgical Options PREOPERATIVE ASSESSMENT OF PATIENTS UNDERGOING LUNG RE-

SECTION lung” to survive. 2. Cardiac Assessment As patients with lung cancer often have co-existing risk First, we need to measure the fraction of ventilation go- factors for coronary artery disease, perform a preliminary ing to the part of lung that is to be resected. This can be cardiac assessment with history, physical exam, and EKG. done using a perfusion study (i.e. the perfusion portion of If the patient is at risk of a perioperative cardiac event, a V/Q scan) which, although it measures perfusion, re- initiate a cardiac workup with appropriate testing. flects relative ventilation (assuming the patient doesn’t have a PE!).

3. Cardiac Workup We then need to determine how many segments of lung If the cardiac workup is unremarkable, or if cardiac dis- are to be resected. The lungs have the following 19 seg- ease is present but can be treated with surgery or opti- ments: right upper lobe (3 segments), right middle lobe mized with medical therapy, proceed to a respiratory as- (2 segments), right lower lobe (5 segments), left upper sessment. If the cardiac disease is not treatable or can lobe (3 segments), lingula (2 segments), and left lower only be minimally optimized with medical therapy, the lobe (4 segments). patient is likely inoperable from a cardiac viewpoint.

The FEV1-ppo can then be calculated by first determining 4. Respiratory Assessment the predicted loss in FEV1 due to the proposed surgery This includes pulmonary function tests, an arterial blood and then subtracting this from the pre-operative FEV1. gas, and an estimate of their exercise tolerance and level of function. Example of FEV1-ppo calculation: Assume we have a 40 year old male with an FEV1 of 1.9 L Although ABG results (PaO2, PaCO2) have not been con- which, for him, is 50% predicted (his predicted FEV1 is clusively shown to be independent risk factors for in- 3.85 L based on his age, gender, height, weight, and race creased perioperative complications, baseline values are - derived from standardized tables). He has a tumor in good to have so that future post-op values can be com- his right middle lobe and we want to determine if he can pared to them. Also, poor ABG results may sway the cli- tolerate a right middle lobectomy - in other words, will he nician towards deciding against surgery if other testing be able to breathe and function OK with his remaining turns out to be equivocal. lung?

If both FEV1 and DLCO are > 80% predicted, then the risk Because his FEV1 is < 80% predicted, we order a perfu- of pulmonary post-op complications is low. sion scan on him, which is reported as follows: right lung perfusion = 40%, left lung perfusion = 60%. He’ll have It is important to use the values as a percent of predicted, 2 / 10 segments resected from the right lung. not the absolute values, as the latter do not take into account the effects of age, gender, and height. Thus, the predicted loss in his FEV1 due to the proposed surgery For example, a 76 year old Caucasian female with a = 40% x (2 /10) x 1.9L height of 149 cm and a weight of 50 kg will have a pre- = 0.40 x 0.2 x 1.9L dicted FEV1 of 1.58 L. If she has a measured FEV1 of = 0.152L 1.39 L, this might seem low; however, this is actually 88% of predicted! A 41 year old Caucasian male with a Then, we subtract this predicted loss in FEV1 from his height of 170 cm and a weight of 73 kg will have a pre- current, pre-operative FEV1 dicted FEV1 of 3.85 L. If his measured FEV1 was 1.39 L, = 1.9L - 0.152L this would only be 36% predicted. = 1.75L.

An FEV1-ppo of 1.75 L represents 45% of 3.85 L (his pre- 5. Split Function Testing dicted FEV1). With respect to this parameter, he should If either FEV1 or DLCO is < 80% predicted, then additional be able to tolerate the lung resection (as reflected in the testing should be done. One option is to calculate what flowchart, his FEV1-ppo is > 40% of predicted). the post-op FEV1 will be (ppo or predicted post-op FEV1) after lung resection to see if the patient has “enough PREOPERATIVE ASSESSMENT OF PATIENTS UNDERGOING LUNG RE-

SECTION The same principle can be used to calculate DLCO-ppo. If, after split function testing, both FEV1-ppo and DLCO- 7. Conclusion to the Introductory ppo are < 40% predicted, the risk of post-op complications will be high enough to consider declining surgery. If Case both values are > 40%, the risk of complications is rea- This patient did not have any indications of cardiac dis- sonable enough to recommend surgery. ease. With regards to her respiratory status, she had a good level of function (traveled around the city on her bicycle). Her PFT results were as follows: FEV1 1.40 6. Cardiopulmonary Exercise (88% predicted), FVC 2.07 (99% predicted), FEV1 / FVC 67%, TLC 4.13L (110% predicted) and DLCO 85% pre- Testing dicted. If the results of split function testing are equivocal, con- Even though her absolute FEV1 seemed rather low, it was sider measuring VO2 max with a cardiopulmonary exer- still 88% predicted for her height, weight, age, gender, cise test or CPET. and race. As well, her DLCO was 85%. Thus, as both values were > 80% predicted, and the patient had a good In Alberta, this is done only in Level IV Pulmonary Func- level of function by history, we deemed the patient a rea- tion Labs (eg. at UAH or RAH). Note that this test is dif- sonable surgical risk and she successfully underwent ferent than an exercise stress test used to look for car- resection of the tumor. diac ischemia.

The CPET measures oxygen consumption (VO2 max), carbon dioxide production, oximetry, etc. VO2 max is a References global, integrative measure of the patient’s cardio- 1. Bollinger C. Evaluation of Operability Before Lung respiratory system function. Resection. Curr Opin Pulm Med 2003;9:321-326. 2. Bollinger C. Koegelenberg C. Kendal R. Preopera- Although, the exact cutoff value to “pass” the test is de- tive assessment for lung cancer surgery. Curr Opin batable, most agree that a VO2 max < 10 mL/kg/min Pulm Med 2005;11:301-306 predicts a high risk of post-op complications and that a VO2 max of > 20 mL/kg/min predicts a low risk of post- op complications (some use a cutoff of > 15 mL/kg/min). Values in-between are equivocal and careful consideration needs to be given between choosing surgical vs. non- surgical treatments.

Because CPET is not always easy to obtain, some clinicians substitute stair climbing.

As a rough estimate, climbing > 5 flights of stairs correlates to a VO2 max of > 20 mL/kg/min and climbing only < 1 flight of stairs correlates to a VO2 max of < 10 mL/ kg/min. (Again, climbing ~ 3 flights of stairs correlates to a VO2 max of ~ 15 mL/kg/min, which some use as a cutoff value).

However, it is important to note that studies using stair climbing have not yet used standardized protocols with respect to duration, coaching, height of steps, elevation gained, etc. Chapter Eleven

Approach to Sudden Respiratory Distress on a Ventilator APPROACH TO SUDDEN RESPIRATORY

DISTRESS ON A VENTILATOR by Dr. L. Cheung (The workup of both of these cases is described at the 1. Introduction end of this chapter.) Case 1: A 55 year old male on the Pulmonary ward on a ventila- This chapter will enable you to answer the following clini- tor complains of worsening dyspnea over the preceding cally important questions regarding patients in sudden hour. respiratory distress on a ventilator: 1. What is the overall approach to a patient who experi- He has been chronically ventilated on Assist / Control ences sudden respiratory distress on a ventilator? ventilation (see the chapter on Mechanical Ventilation if 2. How do changes in the measured airway pressures (if you are not familiar with this mode of ventilation) the patient is on a volume targeted mode of ventila- through a tracheostomy tube for the past 8 months due tion) or changes in the measured tidal volume (if the to severe neuromuscular weakness from advanced multi- patient is on a pressure targeted mode of ventilation) ple sclerosis. He has had increased thick, yellow, pulmo- help you generate a differential diagnosis of the nary secretions over the preceding few days and has cause of the problem? been placed on antibiotics. 3. How does your clinical assessment, as well as other tests, such as the CXR and ABG, also help to deter- On physical exam, he has increased work of breathing, mine the cause of the problem? his BP and heart rate are high, and his oxygen saturations are > 98% on 15 lpm of oxygen. The RT also notes The overall approach to the patient who has sudden dis- that his airway pressures are higher than usual. tress on the ventilator is illustrated in the flowchart in Figure 1. This approach makes the following assump- Case 2: tions: A 45 year old male on the Pulmonary ward who is on a 1. that the patient is on the Pulmonary ward, not the ventilator appears to be in increasing respiratory distress ICU. Although the principles of management are the over the preceding few hours. same, there are differences in the practical details about the management of these patients between He had been in ICU for several months with severe pneu- the two settings. monia leading to ARDS and ultimately was transferred to 2. that the patient is being ventilated through a tracheo- the Pulmonary ward one week ago for further weaning. stomy tube, rather than an endotracheal tube. At that time, his ABG when he was stable was as follows: 3. that you have a basic knowledge of the modes of PO2 79, PCO2 75, , pH 7.37, HCO3 44 on FiO2 of 0.40. ventilation - specifically that you understand the dif- Although he had normal lungs prior to the pneumonia / ference between a volume targeted mode of ventila- ARDS, the severe residual fibrosis from his ARDS led to tion, such as assist control, and a pressure targeted an increased physiologic deadspace, accounting for his mode of ventilation, such as pressure support of persistently high PCO2. As well, he is constantly tachyp- pressure control. The chapter on Mechanical Venti- neic and needs regular sedation. He is on pressure con- lation reviews these concepts in more detail. trol ventilation (see the chapter on Mechanical Ventila- tion if you are not familiar with this mode of ventilation). As well, although the flowchart is presented in a step-by- step algorithmic fashion, experienced clinicians may do However, over the past few hours, he has become even some of the steps simultaneously or in a slightly different more tachypneic than usual despite increasing amounts order. The flowchart merely acts as a guide to assist you. of sedation. On physical exam, he has increased work of breathing. An ABG is done and shows the following: PO2 84, PCO2 106, pH 7.22, HCO3 46 on FiO2 of 0.40. The RT also notes that his tidal volumes are lower than usual on pressure control ventilation. APPROACH TO SUDDEN RESPIRATORY

DISTRESS ON A VENTILATOR

Sudden Obvious cause for distress found Respiratory Quick Treat Distress on the Assessment of Appropriately Ventilator Patient

Cause not obvious

Figure 1: Flowchart illustrating the Remove Patient Distress approach to the patient in sudden res- disappears Problem lies with piratory distress on the ventilator From Ventilator and Manually the ventilator or the Bag Ventilate ventilator settings

Distress continues

Suction Patient

Distress Unable to pass suction Suction catheter passes OK, Disappears catheter down but no secretions present or no tracheostomy tube improvement when secretions suctioned Problem is due to mucus Problem is due to plugging occluded How Hard Is It to tracheostomy tube – Bag the Patient? replace airway

↑ resistance to normal resistance to bagging (↑ airway bagging pressure / decreased tidal volume) See Table 3 for potential causes

Tests such an ABG, CXR, Problem is due to ↑ etc, can help identify the airway resistance or possible cause. ↓ lung compliance. See Tables 1 and 2 for potential causes APPROACH TO SUDDEN RESPIRATORY

DISTRESS ON A VENTILATOR

Table 1: Causes of Increased Resistance to Airflow Table 2: Causes of Decreased Lung Compliance • bronchospasm • pneumothorax

• secretions or mucus plugging • pulmonary edema

• obstruction, mal-alignment, or dislodgement of the • new or worsening consolidation tracheostomy tube • massive pleural effusion

Table 3: Causes of Respiratory Distress without • lobar or whole lung collapse Changes in Lung Mechanics • dynamic hyperinflation / autoPEEP • anxiety or agitation • acute abdomen or massive abdominal distension • metabolic acidosis

• pulmonary embolism

• listen for signs of bronchospasm, pneumothorax, 2. Quick, Focused Assessment of pulmonary edema, or atelectasis / lung collapse

Patient A test that can be performed quickly is an O2 sat meas- Although the approach to a patient in respiratory distress urement. Other tests that can be performed relatively on a ventilator is similar to the approach to a patient who quickly include an ABG, EKG, and CXR if clinically indi- is not on a ventilator, there are some important differ- cated. ences:

1. most patients on a ventilator will not be able to speak because of their tracheostomy tube. Thus, 3. Remove Patient from Ventilator obtaining a detailed history is difficult. 2. problems with the tracheostomy tube or ventilator and Manually Bag itself may be causing the respiratory distress, which If no cause for the patient’s respiratory distress is imme- you would obviously not have to think about if the diately obvious, remove the patient from the ventilator patient was not on a ventilator. and manually bag the patient. Sometimes, mechanical problems can occur with the ventilator (they are, after all, Despite difficulties communicating with the patient, the only machines!) and removing the patient from the venti- first step to perform when you are asked to assess a pa- lator may alleviate the problem. If the patient’s respira- tient in respiratory distress on a ventilator is to try to per- tory distress persists, move to the next step. form a focused history and physical exam to see if you can find an obvious cause for the distress. 4. Suction the Patient Specific things to inquire about include the following: Suctioning the patient can quickly determine a number • the presence of chest pain which might indicate a of things: pneumothorax • if a lot of secretions are suctioned and the patient • the presence of severe abdominal pain which might feels much better, then the likely cause of the prob- indicate the presence of an acute abdomen lem was lung secretions causing increased resis- • any recent attempts at a central line insertion (such tance to airflow or atelectasis. as an IJ or subclavian line) which might have led to a • if you cannot pass the suction catheter through the pneumothorax tracheostomy tube, then you have identified an airway problem which requires urgent management. On physical exam, focus on the following: Causes include a mal-aligned airway, obstruction of • look for signs of pneumothorax (tracheal shift) or the tracheostomy tube (eg. due to secretions), or dis- pulmonary edema (elevated JVP) lodgement of the tracheostomy tube, as illustrated in • feel for subcutaneous emphysema or peritonitis Figure 2. APPROACH TO SUDDEN RESPIRATORY

DISTRESS ON A VENTILATOR

Figure 2: Problems that can arise with the tracheostomy tube - obstruction, mal-alignment, and dislodgement

Dislodgement Obstruction Mal-alignment of the tube in of the tube from a mucus out of trachea plug the tracheal lumen

A mucus plug causing trach tube obstruction will often B. Decreased Lung Compliance require replace of the tube since the plug is often too The causes of decreased lung compliance are listed in thick or hard to be suctioned out. Table 2. These include problems affecting the pleura (eg. pneumothorax, pleural effusion) or the lung parenchyma Mal-alignment of the tube can occur if the trach tube is (pulmonary edema, consolidation, lung collapse). the improper size for the patient or if he has developed tracheomalacia. Sometimes, the tube can be reposi- Note that, as a general rule, although these causes can tioned but occasionally the tube will have to be ex- be suspected on clinical exam, they should also show up changed for a longer tube to achieve better alignment on a CXR. with the tracheal lumen. The exception to this is dynamic hyperinflation or Dislodgement of the trach tube, from the tracheal lumen autoPEEP (explained in the chapter entitled Mechanical into the mediastinal space, can sometimes occur and the Ventilation), which lacks diagnostic findings on CXR. tracheostomy tube needs to be removed and re-inserted Hyperinflation of the lung due to incomplete lung empty- if a mature stoma is present. ing during exhalation, in turn due to bronchospasm (eg. as in COPD) leads to decreased lung compliance (just as If suctioning the patient does not immediately improve it is harder to blow air into a balloon which is already al- the distress or identify the airway as the problem, then most maximally inflated). further measures are needed. As well, an acute abdomen can cause guarding and decreased lung expansion / compliance with a relatively 5. How Hard Is It to Bag the Pa- clear CXR, but should be recognizable on physical exam. tient? C. No Increased Resistance to Bagging At this point, if the problem isn’t evident, clinical assess- If there is no increase in resistance to bagging the patient, ment, CXR, and an ABG can often help determine the then further tests are needed to identify the problem. cause. Table 3 lists some causes of this scenario. Note that all of the entities listed can give rise to a clear CXR. A. Increased Resistance to Bagging If there is increased resistance with bagging the patient, An ABG can determine if metabolic acidosis is causing then the problem is either due to increased resistance to the dyspnea. If so, the cause of the metabolic acidosis airflow or decreased lung compliance. should be identified and treated. An ABG can also determine if the problem lies with the patient’s ventilation, The causes of increased resistance to airflow are listed in manifested as a rising PCO2. Causes of this, in the set- Table 1. Note that, as a general rule, these causes can ting of a normal CXR, can include bronchospasm or often be determined by clinical assessment - wheezing autoPEEP. suggests bronchospasm, etc., and won’t be evident on CXR. If severe hypoxemia is the problem in the setting of a relatively normal CXR, suspect pulmonary embolus or widespread atelectasis which isn’t readily visible on CXR. APPROACH TO SUDDEN RESPIRATORY

DISTRESS ON A VENTILATOR Primary anxiety or agitation can also cause distress on the ventilator and the patient may simply need sedation if no other obvious cause is evident.

6. Conclusion of the Introductory Cases Case 1: The RT removes the patient from the ventilator and notes that it is difficult to bag him. A suction catheter cannot be passed through the tracheostomy tube. Thus, it is suspected that the thick secretions over the preceding few days has led to formation of a thick mucus plug occluding the tracheostomy tube. Because the tracheostomy tube has been in for 8 months, and the stoma is mature, the RT changes the tracheostomy tube, relieving the patient’s airway obstruction and dyspnea.

Case 2: The RT removes the patient from the ventilator and notes that it is difficult to bag him. A suction catheter passes easily through the tracheostomy tube and no secretions are present. Physical exam and subsequent CXR does not reveal any evidence of pneumothorax, pleural effusion, pulmonary edema, or worsening lung infiltrates (lung fibrosis from ARDS is present but no worse than previous CXRs). Abdominal exam is unremarkable. Pul- monary embolism is felt to be unlikely because the patient is on DVT prophylaxis and his oxygen is reasonably well preserved (based on his ABG, his problem was mainly with alveolar ventilation, as evidenced by the rising hypercapnea).

A diagnosis of hyperinflation secondary to tachypnea is made, causing increased physiologic deadspace - the mechanism is dynamic hyperinflation due to incomplete lung emptying on exhalation, in turn due to the rapid respiratory rate with insufficient time for exhalation. He ultimately goes back to ICU where he is heavily sedated and pharmacologically paralyzed to lower his respiratory rate, thus prolonging his expiratory time and allowing for more complete exhalation.

References Oakes D. Shortall S. Ventilator Management: a bedside reference guide. Health Educator Publications, Inc. 2002. Chapter Twelve

Approach to the Patient with Tracheostomy Tube Problems APPROACH TO TRACHEOSTOMY TUBE PROBLEMS By Dr. L. Cheung 1. Introduction: Figure 2: A Shiley trach tube Fenestration This chapter will enable you to answer the following clinically important questions regarding tracheostomy tubes: • what are the components of a tracheostomy tube? • what are the trach tubes commonly used at UAH? • what are other tracheostomy devices you might see on the wards or in the community? • how do percutaneous and surgical tracheostomy insertion techniques differ and why does this matter? • what is the management of short and long term complications of tracheostomy? • how can we determine if a patient is ready for tracheostomy tube removal (decannulation)?

Disposable Inner Cannula (DIC) 2. Trachestomy Tube Components Although tracheostomy tubes made by different compa- nies may differ slightly, they share some common com- will be retained in the pilot balloon (the Luer valve acts to ponents. Photos of the two most commonly used tra- keep the air in the pilot balloon, pilot line, and cuff until a cheostomy tubes at UAH are show in Figures 1 and 2. syringe is reattached and the air suctioned out). The tracheostomy tube components are described below. Trach tubes can have cuffed and uncuffed versions. A. Pilot Balloon, Pilot Line, and Cuff When inflated, the cuff allows the trach tube to sit prop- With the trach tube in place in the trachea, the cuff can erly in the trachea (see Figure 3) and blocks air from be inflated by injecting air via a syringe through the pilot moving through the trachea at that level, thus forcing the balloon and pilot line, which travels alongside the tra- air to move through the trach tube. cheostomy tube wall and connects to the cuff.

When the cuff is appropriately inflated, a pocket of air Figure 3: Illustration of tracheostomy tube with cuff inflated, sitting in the trachea

Figure 1: A Portex Flange Cuff (deflated) trach tube

Pilot Balloon Pilot Line APPROACH TO TRACHEOSTOMY

TUBE PROBLEMS

Most of the trach tubes used in the hospital have a cuff. Most patients can overcome this increase in airway resis- However, there are occasionally situations where you tance without difficulty. However, weak or debilitated might want to use an uncuffed trach tube. For patients patients may experience breathing difficulty because of requiring long term or permanent ventilation, the con- this. stant pressure of the inflated cuff on the tracheal walls can, over years, lead to tracheomalacia. As well, these In theory, a fenestrated tube will allow air to flow both patients can find the pressure of the inflated cuff uncom- through the trach tube and around it, thus decreasing the fortable and it may impair their swallowing. airway resistance imposed by the trach tube (illustrated in Figure 4b). For these reasons, patients in long term care facilities often have uncuffed tubes. If they are also on a ventila- In practice, however, the fenestration may not always tor, the air can not only enter through the trach tube, but work as well as it should. Mucus may occlude the fenes- also pass around the trach tube and enter their mouth in tration, disabling its purpose. a retrograde fashion. To compensate for this lost air, the tidal volumes are often set purposefully higher than normal. As well, if the trach tube doesn’t sit well in the trachea,

the edge of the fenestration may rub up against either If the ventilated patient in a long term care facility has an the anterior or posterior wall of the trachea. uncuffed tube and develops an acute respiratory problem

(eg. pneumonia) requiring hospital admission, higher Over time, this chronic irritation can lead to the creation ventilatory support is often needed and we’ll switch the of granulation tissue which grows inward into the tra- trach tube to a cuffed version. With the cuff inflated, we cheal lumen, obstructing the area above the level of the can better regulate the tidal volumes and oxygenation trach tube. and apply PEEP if necessary.

C. The Disposable Inner Cannula (DIC) B. Fenestration Some trach tubes have a disposable inner cannula – a Some trach tubes come with a fenestration. hollow plastic tube that fits inside the tracheostomy tube.

For example, the Shiley trach tube plus the disposable What is the purpose of having a fenestration? When an inner cannula is shown on Figure 2. unfenestrated trach tube is plugged and the trach cuff is deflated to allow the patient to breathe normally through The DIC can serve two purposes. Firstly, the DIC, when his nasopharynx, the trach tube itself may occasionally inserted into the tracheostomy tube, can be used to block impose an additional work of breathing since it partially the fenestration when necessary. For example, if a pa- obstructs the trachea and air must flow around it tient has a fenestrated tracheostomy tube and needs to (illustrated in Figure 4b). be put on the ventilator, air can not only travel through

the trach tube but can leak out the fenestration as well – this is illustrated in Figure 5 (a—b). The DIC, when in- Figure 4a Figure 4b Without a fenestration With a fenestration APPROACH TO TRACHEOSTOMY

TUBE PROBLEMS

Figure 5a: Trachesotomy Figure 5b: Tracheo- Figure 6: A Portex trach tube with an adjustable flange tube without a DIC in stomy tube with a DIC place - air from the venti- in place - the DIC oc- lator leaks through the cludes the fenstration fenestration.

Attached to Attached to this tracheostomy tube has a ventilator ventilator longer horizontal dimension for patients with thick necks

the flange can slide serted through the trach tube, prevents this from happen- back and forth and be ing. “locked” into place

Secondly, DIC’s are sometimes used in longterm care facilities, even in unfenestrated trach tubes, because it is easier to keep the trach tube clean. For example, if the DIC is kept in the trach tube, any mucus that builds up over time will coat its inner layer.

Eventually, when the mucus buildup becomes too much, the DIC can simply be removed and a new DIC can be inserted. Without a DIC in place, any mucus that accumulates would build-up on the inner wall of the trach tube itself, and the whole trach tube would have to be changed, which is a bit less comfortable for the patient than simply exchanging a DIC.

D. Adjustable Flange Sometimes, for patients with excess adipose tissue around their neck, the distance between the skin surface and the trachea may be too thick to accommodate a regular trach tube.

In these cases, we might need to use a special trach tube with a flange that can be adjusted along the horizontal length of the tube, shown in Figure 6. APPROACH TO TRACHEOSTOMY

TUBE PROBLEMS

3. Miscellaneous Tracheostomy 4. Tracheostomy Insertion Tech- Related Devices niques Some of the devices related to tracheostomy tubes that Tracheostomies can be performed using the standard you may see on your rotation are the T-piece and the surgical technique or the percutaneous dilational tech- trach cradle. nique.

A. The T-piece With the surgical technique, the stoma is created by If a patient is ready for spontaneous breathing through making an incision in the skin (about 2 cm above the the trach tube, we need to apply a humidified air source sternal notch), dissecting the tissue down to the trachea, since breathing nonhumidified air through an open trach and making an incision between the tracheal rings tube could lead to tracheal irritation and drying. The T- through which the trach tube will be inserted. piece is a plastic piece of tubing, in the shape of a “T”. Note that surgical tracheostomy should not be confused As illustrated in Figure 7, one end is attached to the trach with emergency cricothyroidotomy, where the incision is tube and the other port (at a right angle to the first) is made through the cricothyroid membrane (easier to do in an emergency situation than trying to make an incision through the tracheal rings). Figure 7 humidified air flows by In the percutaneous dilational technique, the Seldinger technique is used where a needle is inserted through the skin and into the trachea. A guidewire is then passed into the trachea and a dilating forceps, which is used to dilate the tissues, is passed over the guidewire. After dilation of the stoma, the tracheostomy tube is inserted, as shown in Figure 8. corrugated tub- Figure 8 ing connects to oxygen source attached to patient’s tracheostomy tube attached to a humidified air source, allowing this humidified air to flow perpendicular to the tracheostomy tube. This is the commonest way to supply humidified air to a patient who is spontaneously breathing through a trach tube.

B. The Trach Cradle Another method of supplying humidified air to the patient with a tracheostomy tube is with a trach cradle. This piece of plastic is worn loosely like a necklace and cups Generally, the stoma is a lot tighter around a percutane- the tracheostomy tube. This allows the patient slightly ous trach compared to the surgical technique. more mobility. The technique used has some longer term implications when these patients are eventually transferred out of ICU to the ward. Because the stoma tends to be a lot tighter for percutaneously inserted trach tubes, subsequent trach tube changes can be more difficult. As well, after decannulation (trach tube removal), the stoma tends to close over more quickly. APPROACH TO TRACHEOSTOMY

TUBE PROBLEMS

tracheal incision itself, the thyroid isthmus, or the ante- 5. Complications of Tracheostomy rior jugular veins.

Tubes Bleeding that occurs more than several days after the A. Tube Dislodgement or Unplanned De- procedure is often due to bleeding granulation tissue that cannulation forms where the trach tube rubs against the sides of the If the trach tube becomes dislodged out of the stoma hole in the trachea. Again, this usually requires intraop- before the tract between the skin and trachea has had a erative exploration and management. chance to mature, the tract can close almost immediately, making trach reinsertion very difficult or impossible. The most dreaded late bleeding complication – erosion Atempting trach reinsertion at this stage could lead to of the trach tube into the innominate artery creating a the creation of a false passage and the trach tube could tracheo-innominate artery fistula – is rare but life- end up in the pre-tracheal mediastinal space. Insufflat- threatening. This may be suspected if, bronchoscopi- ing air into this space could lead to disastrous conse- cally, no other cause for the trach site bleeding can be quences. found (eg. minimal tracheitis or granulation tissue) and anterior pulsations are seen. This needs intraoperative Thus, if the trach tube becomes dislodged before the exploration and intervention. Emergently, an experi- tract has had a chance to mature, the safest thing to do enced clinician can insert a finger into the stoma to try to is to reintubate the patient orally and reinsert the trach stop the bleeding. later under controlled circumstances. C. Stoma Infection How long does it take for the tract to mature? Although The stoma becomes infected with tracheal secretions at this is somewhat arbitrary, it takes about 5 to 7 days for the time of tracheostomy creation and is considered a the tract to mature for a surgically inserted tracheostomy clean-contaminated wound. Nevertheless, prophylactic and about 7 to 10 days for a percutaneously inserted antibiotics have not been shown to reduce the incidence tracheostomy. Once the tract has matured, a trach tube of stomal infections, which has an incidence of about 8 that becomes dislodged can be simply reinserted if done to 12%. relatively soon. If the stoma does become infected (eg. a lot of purulent What if the tracheostomy was performed because of up- secretions around the stoma or obvious cellulitis), antibi- per airway obstruction and orotracheally intubating the patient would be nearly impossible? If forced to reinsert otics can be directed against the organisms obtained the trach tube through the stoma before it has matured, from tracheal suctioning since these will likely be present a bronchoscopist can load a trach tube over a broncho- in the stoma as well. scope, insert the bronchoscope through the tract into the trachea and visually confirm endotracheal positioning, D. Stoma skin ulceration then slide the trach tube over the bronchscope which Sometimes, the trach tube, if poorly positioned at the acts as a “guidewire” or stylet. Alternatively, a suction time of insertion, can cause pressure ulceration of the catheter can be passed into the tract blindly. If sputum is skin around the stoma. Again, the surgeon should be suctioned, endotracheal placement is likely and the made aware of this post-operative complication. Al- catheter can act as a guidewire for trach tube insertion. though this is a difficult problem to treat, applying duo- derm where the pressure occurs may help.

B. Bleeding E. Subglottic edema or stenosis Early postoperative trach bleeding can be due to bleeding Granulation tissue may form and grow into the tracheal skin vessels and may respond by injecting xylocaine with lumen, starting at the site where the trach tube rubs up epinephrine around the stoma or by packing the area against the trachea. This granulation tissue may bleed around the stoma with gauze for 24 to 48 hrs. If possi- (as described above) or it may lead to obstruction above ble, correct any coagulopathy that is present. the level of the trach tube, as illustrated in Figure 9.

If bleeding persists or is major, the surgeon should be This usually becomes evident when the patient is ob- notified as this is a postoperative complication, and the served to breathe easily through the trach tube but has bleeding may be coming from other areas such as the APPROACH TO TRACHEOSTOMY

TUBE PROBLEMS

Figure 9 had a prolonged illness with many complications and setbacks.

An algorithm to help decide if a patient can be decannu- lated is outlined in Figure 10:

inflammation causing granulation tissue to Figure 10 form from the trachea

at the point where the Is Patient a Potential Candidate for Decannulation? trach tube enters the •no longer requires ventilator assistance trachea (the site of •able to protect airway tracheal “injury”). •minimal oxygen requirements •minimal secretions or at least able to expectorate secretions if present

Plug trach tube with immediate difficulty when the trach tube is plugged and cuff deflated air must pass through the nasopharynx.

Yes Able to tolerate No As well, the subglottic area (beneath the vocal cords but cuff deflation and above the trach tube) or supraglottic area may become trach plugging? edematous or stenotic, especially if prior intubation was traumatic or prolonged. Stridor No Stridor with with trach trach plugging This problem may improve over time, or it may require plugging surgical correction if it fails to improve with observation. Downsize or Poor switch to a respiratory fenestrated reserve – 6. Algorithm for Tracheostomy trach tube to leave trach decrease in until airway condition Removal (Decannulation) resistance improves Prior to decannulation, the patient should meet the following criteria: Able to tolerate • able to breathe spontaneously without assistance plugging now? from the ventilator Decannulate if tolerates plugging Yes No ~ 48 hrs (wait longer if condition • able to consistently expectorate and clear secretions is “borderline”) Look for and • awake enough to protect his airway if the trach tube correct any cause of upper airway was not present obstruction • on minimal FiO2 (eg. ≤ 0.40 which is roughly equiva- lent to 5 to 6 lpm of O2) no evidence of upper airway obstruction References: The number of consecutive days that these criteria 1. Tobin M. Principles and Practice of Mechanical Ventila- should be met before considering decannulation can be tion. 1st Ed. McGraw-Hill Professional Publishing. 1994. anywhere from 48 hrs (if the patient has had a relatively 2. I took all of the photos in this chapter with a digital cam- short illness) to up to a week or more if the patient has era. Chapter Thirteen

Approach to the Patient with Chest Tube Problems APPROACH TO THE PATIENT WITH CHEST TUBE PROBLEMS (by Dr. L. Cheung) 1. Introduction Figure 2: The “old” 3 bottle system for chest tubes Adjustable Venting This chapter will enable you to answer the following clini- Tube cally important questions regarding patients with chest tubes: 1. How do chest tubes and Pleur-Evacs work? To Patient 2. When inserting a chest tube, how large a chest tube should we use, how far do we push it in, where should we try to direct the tube, should we simply connect it to an underwater seal or is suction required, and 20 when can we remove it? cm 3. What do you do if you encounter one of the following problems with a chest tube: • the underwater seal stops bubbling? Suction Underwater Trap Bottle • there is prolonged, persistent bubbling through the Control Bottle Seal Bottle (Collection underwater seal? Chamber) • there is worsening subcutaneous emphysema? • there is copious fluid draining around the chest tube A. The Underwater Seal insertion site? Let us assume that a chest tube is inserted into a patient for a spontaneous pneumothorax. If the chest tube were left open to the atmosphere, the air in the pleural space 2. The Physiology and Mechanics would exit the pleural space during expiration but re-enter the pleural space with inspiration, in addition to the air of Chest Tubes and Pleurovacs entering the pleural space from the lung.

In order to develop an approach to clinical problems in- Thus, we need something to act as a one-way valve so volving chest tubes and Pleur-Evacs, we first need to un- that air entering the pleural space, from the lung, will be derstand the physiology and mechanics behind this sys- evacuated during expiration through the chest tube and tem. To help us with this, we can look at each component not re-enter from the atmosphere during inspiration. The of the Pleur-Evac or 3 bottle system illustrated in Fig 1 underwater seal bottle acts as this one-way valve, shown and 2, respectively – the underwater seal, the trap or col- in Figure 3. lection chamber, and the suction control or regulation chamber. Figure 3: Underwater Seal Fig 1: Pleur-Evac To Patient Open to Atmosphere

Water Level

Underwater Seal Bottle APPROACH TO THE PATIENT WITH CHEST TUBE PROBLEMS

In this example, the chest tube is connected to flexible tubing which goes into a closed bottle with a layer of wa- If the hole is large and there is a lot of air leaking from the ter. The tubing is submerged into the water such that its lung into the pleural space during inspiration, some of this opening lies 2 cm (arbitrary number) below the water’s air will also bubble through the underwater seal on inspi- surface, as shown in Figure 4. ration as well as expiration – in other words, you may see continuous bubbling of air. Figure 4: Air Bubbling Into the Underwater Seal B. The Collection Chamber or “Trap” To If all we had was the underwater seal bottle, any fluid or Patient blood in the pleural space, with or without co-existing air, Open to would also be pushed into the underwater seal bottle. Atmosphere This would cause the water level in the underwater seal bottle to rise, altering the mechanics of the system (the amount of intrathoracic pressure needed to expel the air or fluid out of the pleural space would progressively rise Water with the rising water level). Level 2 cm To avoid this, we can connect a trap or collection bottle proximal to the underwater seal bottle, shown below in Figure 5. Underwater Seal Bottle Figure 5: The Trap or Collection Chamber The intrathoracic pressure, and thus the intrapleural pressure, only has to exceed the height of the water layer To Underwater Seal Bottle above the tube’s opening, which is 2 cm in this case. To Patient In other words, the pleural pressure only has to become Open to Atmosphere positive by 2 cm H2O pressure for air to be pushed from the pleural space, out the chest tube, into the water and finally exit out above the water’s surface. This degree of positive intrathoracic pressure can easily be accomplished during expiration or coughing. Water Level The water acts as a one-way valve. For air to re-enter the pleural space from the atmosphere, the patient would have to generate sufficient negative inspiratory force to Underwater Seal Bottle Trap Bottle suck the water up into the chest tube and pleural space (Collection Chamber) first. This is physiologically impossible as long as the bottle is on the floor, below the patient’s thorax. Fluid or blood drained from the pleural space will be col- Note that there will be, and should be, some fluctuation of lected in the trap bottle and any air present in the pleural the water in the tube with respiration. The water will be space will be expelled and bubble into the underwater sucked up a few centimetres into the tube on inspiration seal bottle. and will move back down on expiration. C. The Suction Control Chamber Thus, in our example of a patient with a spontaneous To complete our understanding of the Pleurovac system, pneumothorax, if air is leaking into the pleural space from we need to consider the purpose of the third bottle – the the lung – referred to as an “air leak” – this air will bubble suction control bottle. into the underwater seal bottle. The amount of air that bubbles will depend on the size of the hole in the lung. In our example of the patient with a pneumothorax, if air

leaks from the lung into the pleural space faster than it If the hole is small, air will leak from the lung into the can be expelled into the chest tube on expiration alone, pleural space on inspiration but you may only see the air bubbling into the underwater seal during expiration. APPROACH TO THE PATIENT WITH CHEST TUBE PROBLEMS

Figure 7: The Suction Control Bottle

Adjustable Venting Tube

To Underwater Seal Bottle Tube 1 To Wall To Suction Suction Control Bottle Tube 2 To Patient Tube 3

Suction Control Bottle Underwater Seal Bottle Trap Bottle (Collection Chamber) then air will accumulate and the visceral and parietal The only way to increase the amount of suction the pa- pleura will never come together. In other words, in these tient feels would be to increase the distance between the cases, we cannot solely rely on expiration to expel the air water line and the opening of the vent tube (either lower – we need to suck the air out. The same applies to fluid the vent tube deeper or add more water to raise the water which accumulates at a fast rate. level).

To do this, we can attach our drainage system to wall suc- NOTE: The newer Pleur-Evac system has a suction control tion. However, we need to control the amount of suction chamber consisting of dry suction. No water has to be we apply because if we apply too much, we may harm the added to this chamber; rather, the amount of suction is lung. The amount of suction is controlled by the suction controlled by a spring valve which can be adjusted by turn- control bottle, which is connected to the other two bottles ing a dial, thus making it different than the older in our system as shown in Figure 7. Pleurovac system (see Figure 1).

The amount of suction applied to the patient via tube “1” D. Putting The 3 Bottle System Together: is controlled by the suction control bottle, which is attached to wall suction. Note that there is no valve on the The Pleur-Evac wall to accurately regulate the amount of suction. In summary, the current Pleur-Evacs, which use dry suction, contain the 3 bottle system in a single container, The wall suction is gradually increased until the pressure subdivided into 3 compartments as shown in Figure 1. exceeds the distance between the water line and the opening of the “adjustable vent tube” in the suction control bottle. At that moment, the suction pressure trans- Figure 8: Enlarged Photo of the Underwater Seal mitted to the patient via tubes “2” and “3” equals that distance.

For example, if that distance between the water line and the opening of the vent tube is 20 cm, the patient will feel 20 cm H2O of suction. If you continue to increase the wall suction, the patient’s pleural space will still only feel 20 cm H2O of suction – the extra suction pressure will “bleed off” as atmospheric air is sucked in through the adjustable vent tube.

APPROACH TO THE PATIENT WITH CHEST TUBE PROBLEMS

Also note that with these Pleur-Evacs, the underwater seal 3. Common Clinical Questions Re- compartment has vertical columns labelled “1” to “7”, as shown in Figure 8. With greater relative amounts of air garding Chest Tubes leaking into the system, you will see bubbling through suc- A. What Size of Chest Tube is Required? cessively more of the higher numbered columns. The size of chest tube needed depends on the clinical situation and the reason for its insertion. Several exam- Although not a precise quantitative measurement of the ples are given in Table 1. amount of air leaking, this gradation system allows you to compare the amount of air leak over time (i.e., whether it is increasing or decreasing from day to day).

Table 1 Clinical Scenario Chest Tube Size

Simple Pneumothorax • generally, for patients with a spontaneous pneumothorax, a small chest tube such as a 28 FR or even 20 FR tube is reasonable. Exceptions are noted for traumatic or complicated pneumothorax. • for patients with a procedure related pneumothorax, (e.g. post-transbronchial lung biopsy or central line insertion), either a 9, 20, or 28 FR tube can be inserted. The 9 FR chest tube is a percutaneous chest tube (at UAH, we use the Cook Critical Care Pneumothorax set) which should only be inserted blindly if the visceral and parietal pleura is separated along the entire length of the lung. If a loculated pneumothorax is present, the percutaneous chest tube should not be blindly inserted since, if not inserted in the right place, it may puncture the lung which is still up against the parietal pleura.

Traumatic Pneumothorax • since these patients may have large holes in the lung or co-existing pleural hemorrhage, we often need a large 32 FR chest tube.

Complicated pneumothorax • if a pneumothorax occurs in someone with pre-existing lung disease, the hole in the lung may warrant the need for a large tube such as a 32 FR chest tube.

Transudative or serous effusion • if you know that the effusion is transudative or serous, these effusions are often managed with diuresis alone. If a chest tube is required, a 28 FR chest tube should suffice. The 9 FR percutaneous chest tubes may also be used but have a greater chance of becoming occluded with fibrinous tissue or particulate matter.

Empyema or hemothorax • to avoid chest tube occlusion with blood clot or pus, usually at least a 32 FR or 36 FR chest tube is required. APPROACH TO THE PATIENT WITH CHEST TUBE PROBLEMS

B. Upon chest tube insertion, how far Figure 11 should we push it in? With the chest tubes used at UAH, the numbers on the tube indicate the distance in centimetres from the most proximal hole, as shown in Figure 10. mid-axillary line the most proximal (last) hole

Figure 10

distance (cm) from the most proximal hole

Thus, taking into account the thickness of the patient’s D. Should we simply connect the chest tube chest wall, one should advance the tube so that the most to an underwater seal or is suction required? proximal hole is a few centimetres deep to the parietal As explained earlier in “THE PHYSIOLOGY AND MECHAN- pleura. This obviously requires some guesswork. As a ICS OF CHEST TUBES AND PLEUROVACS”, a small pneu- general guide, the chest tube should be inserted up to mothorax or effusion could be managed by simply con- approximately 8 cm at the skin in a thin person and up to necting the chest tube to the Pleurovac relying on the un- around 14 cm at the skin in an obese person. derwater seal alone, without having to turn the suction on.

However, one can never be sure that air or fluid will not C. Where should we try to direct the chest accumulate in the pleural space faster than it can be expelled into the chest tube off suction. tube? Assuming the patient will be spending most of his time in Thus, usually, when the chest tube is first inserted, we a supine or sitting position, one should try to direct the apply 20 cm H2O suction initially to be sure that we evacu- chest tube posterior and inferior if it is being inserted for ate the pleural air or fluid faster than it can accumulate. fluid and anterior and superior if it is being inserted for a pneumothorax. E. When can the chest tube be removed? The key word here is “try”, since this is usually difficult to If the chest tube is inserted for pneumothorax, the under- do with precision. Inserting the chest tube anterior to the water seal should cease bubbling for at least 24 hrs (or mid-axillary line will help direct the chest tube anteriorly even longer if erring on the side of caution) and a CXR (and should be done for pneumothorax), while inserting should confirm lung re-expansion prior to chest tube re- the chest tube posterior to the mid-axillary line will help moval. direct it posteriorly (and should be done for fluid) as illustrated in Figure 11. If the chest tube is inserted for fluid or blood, the fluid volume drained should be less than about 200 mL per day; otherwise the fluid will likely re-accumulate quickly after chest tube removal.

APPROACH TO THE PATIENT WITH CHEST TUBE PROBLEMS

However, many days to a week goes by and the Pleur-Evac 4. Approach to Common Problems still shows bubbling in the underwater seal. What are the potential reasons for this? with Chest Tubes and Pleurovacs • it is possible that the hole in lung isn’t healing - air is Having reviewed how the Pleurovac system works, we can still leaking out of lung into pleural space but is being understand the problems that may arise and develop an expelled before it can accumulate in the pleural space approach to deal with them. - and will likely need surgical intervention or pro-

longed chest tube drainage if the patient cannot toler- Scenario 1: Underwater Seal Stops Bubbling ate surgery. This is called a bronchopleural fistula. A patient develops a pneumothorax. He has a chest tube • it is possible that there is a leak present in the tubing inserted and it is connected to the Pleur-Evac and 20 cm and room air is being sucked into the system. H2O suction. Immediately after insertion, there is bubbling through the underwater seal and a CXR shows com- To differentiate between the two, transiently clamp the plete re-expansion of the lung. chest tube just as it emerges from the patient’s skin. • If bubbling persists, there is a leak in the tubing, distal The next morning on rounds, you notice that there is no to the clamp (ie the problem is not with the patient’s further bubbling of air into the underwater seal chamber. lung). Also, be sure to inspect the site where the What are the potential reasons for this? chest tube exits the skin – if the most proximal hole is outside of the skin, it can suck in room air. • it is possible that the hole in the lung has sealed close • If bubbling stops with transient clamping, the air is (this often happens when the lung re-expands and the entering the chest tube somewhere proximal to the visceral and parietal pleura “stick” together again) skin, likely due to a persistent hole in the lung. In the and no further air is leaking into the pleural space. case of a prolonged air leak, it would be wise to in- • it is possible that air is still present in the pleural volve thoracic surgery. space but cannot get out through the chest tube, which can occur if the chest tube is blocked, plugged, or is in the fissure of the lung and the lung itself is Scenario 3: Persistent Bubbling with a Persis- occluding the holes of the chest tube. tent Pneumothorax A patient develops a pneumothorax. He has a chest tube To determine which of the above is the case, check if inserted and it is connected to the Pleur-Evac and 20 cm there is respiratory fluctuation of the water in the under- H2O suction. water seal or of fluid in the tubing: • If respiratory fluctuation is present, the chest tube is However, despite bubbling in the underwater seal, a CXR still patent and there is likely no further air in the pleu- post chest tube insertion reveals a persistent pneumotho- ral space. A CXR can be done to confirm that the lung rax. What is the reason for this? is still expanded. • the hole in the lung is so big and air is accumulating • If no respiratory fluctuation is present, obtain a CXR – in the pleural space so quickly that one chest tube at if the lung is still fully expanded, everything is O.K. 20 cm H2O suction isn’t evacuating the air fast (the hole in the lung may have sealed off anyway de- enough. spite a plugged chest tube). If the lung is collapsed and a pneumothorax is present, then another chest The following options are available for this problem: tube may be required if the residual pneumothorax is • if the residual pneumothorax is small, it can be fol- large. lowed. It will hopefully resolve. • If the residual pneumothorax is quite large, you can Scenario 2: Persistent Bubbling Through the suck out more air by either increasing the suction to 30 or 40 cm H2O suction, or by inserting another Underwater Seal chest tube. A patient develops a pneumothorax. He has a chest tube inserted and it is connected to the Pleur-Evac and 20 cm Note an important caveat: if the patient was taken down H2O suction. Immediately after insertion, there is bubbling to the radiology department for a PA and lateral CXR, the through the underwater seal and a CXR shows re- Pleur-Evac had to be taken off wall suction for the trans- expansion of lung. port. It is possible that the lung may have been fully expanded with suction but then recollapsed at the time the CXR was being taken, off suction.

APPROACH TO THE PATIENT WITH CHEST TUBE PROBLEMS

To prevent this confounding situation, the initial CXR cutaneous emphysema formation but will not evacuate should be done portably, with the patient on the ward and the amount already present. the Pleur-Evac on suction. In fact, whenever a patient has a large air leak, the CXR should be done portably so that Usually, there is no need to directly remove the air from suction can be maintained. When the air leak is resolved, the subcutaneous tissues. However, in exceptional cases, CXR’s off suction can be done (I actually do this prior to it may be so severe that it is actually compressing the chest tube removal so that I can be sure that a small trachea or restricting the chest wall movement. In these amount of air won’t accumulate in the pleural space off situations, one may consider inserting a chest tube pur- suction) posefully into the subcutaneous space and attaching it to suction, or making slits in the patient’s skin to “milk” the Scenario 4: Worsening Subcutaneous Emphy- subcutaneous air out. These are obviously drastic measures which are rarely performed because they may be sema Despite a Chest Tube associated with their own problems such as infection of A patient develops a pneumothorax. He has a chest tube the chest wall and bleeding. inserted and it is connected to the Pleur-Evac and 20 cm H2O suction. Upon insertion, there is appropriate bubbling through the underwater seal and a CXR shows successful Scenario 5: Fluid Drainage Around the Chest re-expansion of the lung. Tube Insertion Site A patient has a large pleural effusion treated with chest However, over the next 24 to 48 hrs, the patient develops tube insertion. The nurses report that there is a large worsening subcutaneous emphysema. What are the po- amount of fluid leaking around the chest tube insertion tential reasons for this? site and into the dressings. What should be done? • the chest tube may have ceased functioning. • Determine if the chest tube is still functioning – fluid • the most proximal hole of the chest tube may be out- should still be coming out of the chest tube and there side the thorax, in the subcutaneous tissue, and air is should be respiratory fluctuation of the fluid. If it is leaking from the lung, into the pleural space and into still functioning, one can either follow the problem or the chest tube, with some of that air entering the sub- put another suture around the chest tube incision to cutaneous tissue via that hole. tighten the hole around the chest tube. • sometimes the chest tube may be well positioned and • If the chest tube is not functioning, the tube may be functional, but air is leaking from the pleural space occluded with clot or fibrin. Another chest tube may and around the chest tube, where the chest tube need to be inserted so that the fluid drains out of the passes through the parietal pleura, into the subcuta- chest tube, not the incision. neous tissues.

What is the approach to this problem? References • ensure that the chest tube is still functioning – check 1. Rippe J. Irwin R. Fink M. Cerra F. Curley F. Heard S. Pro- for respiratory fluctuation and bubbling in the under- cedures and Techniques in Intensive Care Medicine. water seal. If the chest tube is not functioning, an- Little, Brown, and Company. 1995. other chest tube may be required. 2. Roberts J. Hedges J. Clinical Procedures in Emergency Medicine. 4th Ed. WB Saunders Company. 2003. • check the most recent CXR to ensure that the most 3. I took photos of the Pleur-Evac and chest tube with a proximal hole of the chest tube is within the thorax. If digital camera. the most proximal hole is outside the thorax, another chest tube, properly positioned, may be required. Most of us would not recommend simply pushing the original chest tube deeper for fear of introducing infection into the pleural space. • if the chest tube is functioning and is well positioned, and you suspect air leaking around the chest tube into the subcutaneous tissues, increase the suction on the Pleur-Evac to hopefully direct more air through, rather than around, the chest tube.

Note that subcutaneous emphysema is generally not harmful and will eventually get reabsorbed. The measures described above may help decrease the rate of sub- Chapter Fourteen

Hospital Management of COPD HOSPITAL MANAGEMENT OF THE PATIENT WITH COPD By Dr. L. Cheung

1. Introduction The rest of this article describes the concepts in the flow- This article discusses the in-patient management of the chart in more detail. patient with an acute exacerbation of COPD (AECOPD). Outpatient COPD management is discussed elsewhere. 2. Seeing the Patient Who Presents The flowchart in Figure 1 tracks the course of a typical patient with AECOPD in hospital and consists of two main to the Emergency Department sections. With AECOPD The left side of the flowchart describes the typical course When you are asked to see a patient who presents to the of a patient with AECOPD, from his presentation to the Emergency Department with AECOPD, you should ask emergency department, his subsequent management on yourself two questions: the ward, and his eventual discharge from hospital. 1. Firstly, is this truly an exacerbation of COPD, or is The right side of the flowchart describes the clinical ques- there an alternate diagnosis? tions you should be asking yourself about the diagnosis 2. Secondly, if the diagnosis of COPD is correct, what is and management of the patient with AECOPD in each the initial treatment? particular setting. A. Is this Really COPD? The diagnosis of AECOPD is usually straightforward when Figure 1 the patient presents with the classic symptoms, signs, and findings on investigations such as dyspnea, productive cough, wheezing, lung hyperinflation on CXR and Questions to ask your- hypercapnea on ABG. Clinical Setting self for that clinical set-

ting However, some of these findings, such as dyspnea, are seen in many other diseases other than AECOPD, and misdiagnosis can occur. Here are some clinical warning signs that the patient might not have AECOPD as the cause for his symptoms: You see the patient on Is this really AECOPD presentation to the and, if so, how do we • Severe hypoxemia requiring a significant amount of emergency department treat it? oxygen. The hypoxemia from AECOPD is due to V/Q mismatch, easily corrected with low flow oxygen in most cases. Hypoxemia refractory to a large amount of oxygen signifies a shunt, which should lead one to suspect other disease such as pneumonia or pulmo- What do you do if the nary edema. patient is not improving, You manage the patient or what do you do if the • Infiltrates or pulmonary edema on CXR or clinical on the ward patient is improving? exam. Pneumonia or congestive heart failure can be mistaken for AECOPD and require different treatments.

• Significant extrapulmonary symptoms. Patients with pre-existing COPD may experience worsening dyspnea during severe, acute non-pulmonary disease. What are the things to For example, a patient with COPD who has acute You discharge the pa- do when the patient is bowel obstruction or perforation will experience dysp- tient from hospital ready for discharge? nea in addition to abdominal symptoms, but this does not necessarily mean that AECOPD is the cause of their dyspnea.

HOSPITAL MANAGEMENT OF THE PATIENT WITH COPD

Please refer to the CTS guidelines for details about these • Co-existing severe obesity. A diagnostically difficult therapies. but increasingly common scenario is the obese patient who also smokes and presents with dyspnea, C. Clinical Pearls hypercapnea, and right heart failure. Such patients The following are some clinical pearls to keep in mind could either have COPD, obstructive sleep apnea, when managing the patient with AECOPD: obesity-hypoventilation syndrome, or any combination of the above as a cause of their clinical findings. • when ordering Ventolin and Atrovent, try to synchro- We’ll talk more about this later. nize the doses where possible. For example, avoid ordering Atrovent q6h and Ventolin q4h. This leads When the diagnosis of COPD is uncertain, pulmonary to treatments given practically every 2 hrs. Choose function tests are extremely helpful. Always ask the pa- either a q6h or q4h regimen for both. tient whether PFT’s or spirometry have been previously done and, if possible, obtain those results. • although it is acceptable to order Ventolin as q1h prn,

avoid ordering Atrovent q1h “prn” since it’s duration If no prior lung function tests have been performed, they of action is longer than 1 hr. should be done as soon as the patient is stable (but not while the patient is acutely ill since PFT’s can be difficult • when choosing an antibiotic, follow the CTS guide- for the patient to perform, as those of you who have had lines as outlined in Table 1 (ie, not everyone neces- PFT’s can attest). sarily needs levofloxacin!)

B. If the Patient Truly Does Have an AE- • Note that for “simple AECOPD”, as defined by the COPD, What Should the Treatment In- CTS guidelines, where there are no risk factors for treatment failure, no one group of antibiotics has clude ? been shown to be better than another. Treatment for AECOPD is based on the Canadian Tho- racic Society (CTS) Recommendations for Management of COPD—2003, and includes the following:

• bronchodilators • antibiotics • steroids • possibly NIMV.

Table 1 HOSPITAL MANAGEMENT OF THE PATIENT WITH COPD

tion syndrome, or any combination of the three. 3. Managing the Patient on the Ward Whenever such a patient presents with hypercapnea, it is important to check that the patient’s FEV1, as measured Once the patient moves from the emergency department on the PFT’s, is actually low enough to account for the to the ward, he needs ongoing management for his AE- hypercapnea. Conventional teaching is that the PCO2 COPD. While on the ward, he will either clinically deterio- starts to rise once the FEV1 is approximately 1.0 L or less. rate or improve.

Thus, it is important to note that if the FEV1 is only mildly A. What to Do if The Patient Fails to Clini- or moderately reduced, suspect another cause for the cally Improve. hypercapnea. OSA and OHS can be diagnosed with sleep If the patient fails to improve after a reasonable amount studies, if clinically feasible. of time, consider the following possible reasons: 2. Wean or Stop Steroids • Wrong diagnosis. Generally, if the patient has not received steroids in the • Superimposed problem, such as infection, pulmonary past, they can be stopped without weaning after about 7 edema, etc to 10 days. If, on the other hand, the patient has had • Insufficient medication, such as inadequate dose of multiple courses of steroids for COPD exacerbation in the steroid, etc recent past, the steroids should be tapered (eg. decreased by 10 mg every few days until discontinued).

B. What to Do if The Patient Improves C. What to Do Prior to the Patient’s Dis- 1. Confirm Diagnosis if Not Already Done At some point, once the patient is no longer acutely ill, charge the diagnosis of COPD should be verified with PFT’s if The ongoing chronic management of the patient with these have not already been done sometime in the past. COPD encompasses 8 key items, and you should at least PFT’s are a key tool to diagnose and quantify the severity think about these therapies the patient might require. of COPD. PFT interpretation is covered in the section en- These key components of stepwise therapy are summa- titled “Approach to PFT interpretation”. rized in Diagram 1, copied from the Canadian Thoracic Society Recommendations for the Management of As mentioned previously, a common and potentially con- COPD—2003, and explained further below. fusing scenario is the obese smoker who presents with dyspnea and hypercapneic respiratory failure. As repre- Diagram 1 sented in the Venn diagram below, such a patient may have COPD, obstructive sleep apnea, obesity hypoventila-

COPD

OSA OHS 1. Confirm Diagnosis: once again, if PFT’s have never been done up to this point, they should at least be arranged as an outpatient to confirm the diagnosis of COPD and assess its severity. HOSPITAL MANAGEMENT OF THE PATIENT WITH COPD

2. Smoking Cessation and Education: counsel the patient to stop smoking if he hasn’t already done so and educate the patient about the disease. This includes counselling the patient on the benefits of an- nual influenza vaccinations and receiving the Pneu- movax vaccine. 3. Short acting bronchodilators: salbutamol prn and ipratropium on a regular basis are appropriate for symptom control. 4. Pulmonary rehabilitation: consider referring the patient for pulmonary rehabilitation if medications do not control symptoms or the patient has had multiple exacerbations and declining physical function. 5. Inhaled steroids: although somewhat controversial, inhaled steroids can be added for patients failing other maximal therapy. 6. Oxygen: prior to discharge, the need for chronic oxygen therapy should be assessed. 7. Surgery: certainly, not everyone with COPD will require surgery to manage their disease. However, there are some candidates who might potentially benefit from one of 3 surgical procedures: • Lung volume reduction surgery (in candidates with upper lobe predominant disease and low exercise capacity). • bullectomy (for patients who have one large bulla taking up more than one-third the volume of one hemithorax) • lung transplantation in very highly selected candidates.

References: Canadian Thoracic Society Recommendations for the Management of COPD—2003. Can Respir J Vol 10 Suppl A May/June 2003. Chapter Fifteen

Approach to the CXR - Hilar Enlargement APPROACH TO THE CXR: HILAR ENLARGEMENT By Dr. L. Cheung Thus, the left hilum is usually a little higher than the right 1. Normal Anatomy of the Hilum because the left pulmonary artery has to go over the left The right and left pulmonary arteries contribute to most mainstem bronchus whereas the right pulmonary artery of the shadows seen in the hilum. courses anterior to the right mainstem bronchus.

Figure 1 (a—b) depicts the right hilar structures. On the Note that there is normally little or no opacification infe- PA view in Figure 1a, the right pulmonary artery courses rior to the mainstem bronchi on the lateral view. lateral to the (descending) bronchus intermedius and is inferior to the right upper lobe bronchus. On the lateral view in Figure 1b, it is seen running anterior to the right 2. Causes of Enlarged Hilar upper lobe bronchus (away from the viewer). Shadows Figure 1a Figure 1b Right Upper Lobe Hilar enlargement usually indicates enlargement of the Bronchus structures located in the hilum, such as the pulmonary arteries or hilar lymph nodes. Thus, hilar enlargement can be due to the following causes: • Enlarged pulmonary arteries • Enlarged hilar lymph nodes • Lung mass abutting the hilum (uncommon to see bilateral masses in this fashion) • Masses (either in mediastinal or lung) which overlie the hilum on the PA view but are actually anterior or posterior to the hilum (ie. not actually in the hilum but appearing to be there) on the lateral view

Right and Left Pulmonary 3. Differentiating Enlarged Right Pulmonary Artery Branches Artery Pulmonary Arteries vs Bilateral On the PA view in Figure 1a, the left pulmonary artery Hilar Adenopathy courses over the left mainstem bronchus and continues laterally. On the lateral view in Figure 2b, the left pulmo- When faced with bilateral hilar enlargement, it is neces- nary artery wraps over and posterior to the left mainstem sary to try to distinguish pulmonary artery hypertension bronchus, which is the lower of the two round lucencies from bialteral hilar adenopathy. representing the right (moving away from the viewer) and left (moving towards the viewer) mainstem bronchi. As depicted in Figure 3 (a—b), pulmonary artery enlargement tends to be smooth and, in severe cases, other signs of pulmonary artery hypertension are present in- Figure 2b cluding cardiomegaly, right ventricular enlargement (with filling in of the retrosternal space), and rapid tapering of the vessels as they proceed distally (although, admittedly, this last sign is rather vague as there is no precise definition demarcating the central vs distal arteries.)

Left Upper Lobe Bronchus

Left Pulmonary Artery APPROACH TO THE CXR: HILAR

ENLARGEMENT

Figure 3a Figure 3b 4. Lung Mass Although a unilateral lung mass can abut the hilum, giving rise to hilar enlargement, it is important to confirm its location on the lateral view, as the mass could easily be also anterior or posterior to the hilum. An example of this is shown in Figure 5 (a-b).

Figure 5a Figure 5b

Right PA: short black arrow Enlarged PA anterior to trachea Left PA: long black arrow and pushing it posteriorly: black Cardiomegaly: red double headed arrow arrow

Also, because the pulmonary artery branches create shadows located anterior, superior, or posterior to the mainstem bronchi, the space inferior to the bronchi (on the lateral view, Figure 3b) usually remains lucent.

Whereas enlarged pulmonary arteries classically have On the PA view (Figure 5a), there appears to be a mass in smooth borders, enlarged hilar lymph nodes usually look the left hilum. However, note that the left hilar vessels “lumpy” as depicted in Figure 4 (a—b) can still be seen quite well through this mass.

Figure 4a Figure 4b Known as the “hilum overlay sign”, this indicates that the mass must be anterior or posterior to the hilum. If the mass was within the hilum, the border of the vessels would not be seen (silhouette sign). The lateral view (Figure 5b) shows the mass to be in the posterior mediastinum.

Although theoretically possible, it is clinically uncommon to see only 2 masses, one in either lung, each abutting the hilum in symmetrical locations – therefore, bilateral hilar enlargement due to bilateral, symmetrical lung masses is uncommon.

The enlarged lymph nodes have an irregular border on 5. Causes of Hilar Adenopathy If hilar adenopathy is identified as the cause of hilar the PA view (white arrows in Figure 4a), representing a enlargement on the chest radiographs, the next step is cluster of nodes. As well, there may be opacified nodes to determine the cause. seen inferior to the mainstem bronchi on the lateral view

(black arrow in Figure 4b). A. Causes of Bilateral Hilar Adenopathy Sometimes, it is tough to distinguish adenopathy from 1. Neoplasm: enlarged arteries and CT chest is required. • primary lymph node malignancy - lymphoma, CLL • secondary - metastases from pulmonary tumors (usually see lung nodule / mass with asymmetric adenopathy) or extrapulmonary tumors

APPROACH TO THE CXR: HILAR

ENLARGEMENT

2. Granulomatous disease: • sarcoidosis Therefore, factors which either chronically increase pul- • silicosis (may see calcified hilar nodes – eggshell monary blood flow (leading to eventual re-modeling and calcification) thickening of the pulmonary vessels), elevate pulmonary vessel resistance, or increase left atrial pressure will lead 3. Collagen Vascular Disease: to secondary pulmonary artery hypertension. • systemic lupus with systemic adenopathy Possible causes of secondary pulmonary hypertension are listed below. B. Causes of Unilateral Hilar Adenopathy 1. Increased Left Atrial Pressure 1. Neoplasm: • mitral stenosis • primary lymph node malignancy – lymphoma • left heart failure • secondary – metastases from pulmonary or extrapul- 2. Chronically increased pulmonary blood flow (right to monary tumors left cardiac shunts)

• atrial septal defect 2. Infection / Inflammation: • ventricular septal defect • Tuberculosis • patent ductus arteriosus • fungal infection 3. Increased pulmonary vascular resistance • viral infection (atypical measles) • chronic hypoxemia – COPD, severe restrictive lung • AIDS (as part of systemic adenopathy) disease, severe sleep apnea • rare drug reactions (Dilantin) • vessel destruction – emphysema, vasculitis • vessel obstruction – chronic pulmonary emboli 6. Causes of Pulmonary Artery Reference Hypertension Reed J. Chest Radiology: Plain film patterns and differen- Pulmonary artery hypertension can either be primary tial diagnosis. 4th Ed. Mosby. 1997. (idiopathic) or secondary. By recognizing that blood flow through the pulmonary circulation is a function of the pressure gradient and vascular resistance, we can group the secondary causes of pulmonary artery hypertension into 3 main categories. For example, Q = PAP — LAP

R where Q is blood flow through the pulmonary circulation, PAP – LAP is the pressure gradient between the pulmonary artery pressure and the left atrial pressure, and R is the vascular resistance of the pulmonary vessels.

By rearranging the equation, we can determine the factors that affect pulmonary artery pressure (PAP).

PAP = Q x R + LAP Chapter Sixteen

Approach to the CXR — Lobar Collapse APPROACH TO THE CXR: LOBAR COLLAPSE By Dr. L. Cheung 1. Radiographic Signs of Lobar Figure 1a Figure 1b Collapse The radiographic signs of lobar collapse are listed below: • displacement of the interlobar fissure – this is the only direct sign of collapse as it is direct evidence of RUL loss of lung volume. LUL • increased opacification of the collapsed lobe – this signifies loss of air in that lobe. Due to the loss of aeration, air bronchograms are generally not seen RML (unless there is co-existing consolidation and col- RLL LLL lapse.) • diaphragmatic elevation – tends to be a more prominent feature with lower rather than upper lobe collapse. Admittedly, however, if the lower lobe is collapsed, the diaphragm outline will often be hard to see, and so it may be hard to detect this sign. • mediastinal shift – tends to be seen more with upper Figure 2 illustrates the normal locations of the fissures rather than lower lobe collapse. Also is seen with on the PA CXR view. complete lung collapse. • compensatory overinflation of the contralateral lung Figure 2 – because this usually doesn’t occur quickly, it is found more commonly in chronic volume loss. • hilar displacement – tends to be seen more with upper rather than lower lobe collapse • loss of visibility of the interlobar artery – this applies RUL LUL mainly to left lower lobe collapse, where loss of the air-tissue interface between the left interlobar artery and the left lower lobe occurs.

Not all of these radiographic signs will always be seen RML with lobar collapse, with the exception of displacement of the interlobar fissure which is a very common finding.

2. Normal Locations Of The In- RLL LLL terlobar Fissures Because recognition of displacement of the interlobar fissures is extremely important, we will review the normal locations of the fissures.

Figure 1a illustrates the fissures and lobes of the right lung on the lateral view. Figure 1b illustrates the fis- 3. Specific Radiographic Findings sures and lobes of the left lung on the lateral view. in Lobar Collapse In this section, the radiographic findings found in the collapse of each individual lobe will be examined.

A. Right Upper Lobe Collapse Figure 3 (a—b) illustrates the radiographic features of right upper lobe collapse. APPROACH TO THE CXR: LOBAR

COLLAPSE

Figure 3a Figure 3b Figure 5a

The patient was intubated and a subsequent bronchoscopy revealed copious mucus plugs obstructing the right upper lobe orifice. After suctioning of these secretions, the repeat CXR revealed complete re-expansion of the On the PA view (Figure 3a), the minor fissure gets pulled right upper lobe, shown in Figure 5b. upward and medially. On the lateral view (Figure 3b), the major and minor fissure get pulled upward. If the right Figure 5b upper lobe collapse is due to a central obstructing lesion, one might see the “S sign” of Golden, characterized by a reverse “S” formed by the border of the mass and the minor fissure. This is illustrated in Figure 4.

Figure 4

Central obstructing lesion causing a curve to form at the medial end of the B. Right Middle Lobe Collapse Figure 6 (a—b) illustrates the radiographic features of minor fis- right middle lobe collapse. sure, giving rise to the Figure 6b Figure 6b appearance of a reverse “S”

An example of right upper lobe collapse is shown in Fig- ure 5a. This patient presented with increasing dyspnea after an operation to insert an intra-abdominal catheter for peritoneal dialysis. The minor fissure is shown by the single black arrow and the airless right upper lobe is shown by the double black arrow. APPROACH TO THE CXR: LOBAR

COLLAPSE

The signs of right middle lobe collapse may involve subtle The major fissure shifts backward and medially, so that opacification of the right mid lung zone with loss of the the collapsed lower lobe lies posteromedially in the lower silhouette of the right heart border. On the lateral view, chest. This usually results in a triangular opacity abutting the minor fissure is pulled downward and the anterior the mediastinum and hemidiaphragm on the PA view, as portion of the major fissure is pulled upward. shown in Figure 8a. You might see the minor fissure de- viated inferiorly as well. An example of right middle lobe collapse is shown in Fig- ure 7 (a—b). On the lateral view (Figure 8b), there is usually an ill- defined opacification (somewhat exaggerated in the dia- Figure 7a Figure 7b gram) located posteriorly.

An example of right lower lobe collapse is shown in Fig- ure 9, which depicts a portable CXR done in a trauma patient whose cervical spine is immobilized in a halo.

Figure 9

On the PA view (Figure 7a), a small, vague opacity can be seen next to the right heart border, shown by the black arrow. Based on the PA view alone, it would be hard to determine if this represented consolidation instead of collapse.

However, on the lateral view (Figure 7b), there is airless opacification of the right middle lobe with inferior displacement of the minor fissure, shown by the black ar- The border of the triangular opacity, representing the row. Bronchoscopy revealed narrowing of the RML orifice collapsed right lower lobe, is shown by the black arrows. of unknown cause. This same patient went on to develop right middle and C. Right Lower Lobe Collapse lower lobe collapse, as seen in Figure 10. Note the low Figure 8 (a—b) illustrates the radiographic features of position of the minor fissure (white arrowheads) and the right lower lobe collapse. inferomedial shift of the major fissure (black arrows).

Figure 8a Figure 8b Figure 10 APPROACH TO THE CXR: LOBAR

COLLAPSE

D. Left Upper Lobe Collapse On the PA view (Figure 12a), note the central left hilar Figure 11 (a—b) illustrates the radiographic features of mass (red arrow), the resulting left upper lobe collapse left upper lobe collapse. manifested as a hazy density overlying the upper part of the left hemithorax (black arrow), and the lucent area of lung representing the superior segment of the left lower Figure 11a Figure 11b lobe filling in the area (white asterisk), known as the sign of Luftsichel.

On the lateral view (Figure 12b), note the anterior displacement of the left major fissure (black arrows) and the airless opacification of the left upper lobe.

E. Left Lower Lobe Collapse Figure 13 (a—b) illustrates the radiographic features of left lower lobe collapse.

Figure 13a Figure 13b

Because there is no minor fissure in the left lung, the appearance of LUL collapse differs from RUL collapse.

On the PA view, there is a hazy density without air bronchograms extending out from the left hilum as seen in Figure 11a.

Sometimes, there can be a strip of clear lung abutting the upper mediastinum, representing either the overex- panded superior segment of the LLL (sign of Luftsichel) or herniation of the right lung across the midline.

The major fissure shifts anteriorly on the lateral view and the LUL “flattens”, as seen in Figure 11b. An example of The radiographic features of left lower lobe collapse are left upper lobe collapse is seen in Figure 12 (a—b). similar to those of right lower lobe collapse. Note that the triangular opacity can be “hidden” behind the heart on Figure 12a Figure 12b the PA view.

4. Causes of Lobar Collapse * A. Bronchial lumen obstruction • intrinsic obstruction from mucus, tumor, foreign body aspiration • extrinsic obstruction from enlarged lymph nodes, tumor

B. Lung compression due to • pleural effusion • pneumothorax • emphysematous bullae

APPROACH TO THE CXR: LOBAR

COLLAPSE

C. Cicatrizing Atelectasis • lung fibrosis causing retraction and volume loss

Reference 1. Reed J. Chest Radiology: Plain film patterns and differential diagnosis. 4th Ed. Mosby. 1997. 2. The CXR examples are from patients seen by the Pulmonary division at UAH. 3. I drew the various diagrams illustrating the characteristics of each type of lung collapse. Chapter Seventeen

Approach to the CXR - Lung Cavities APPROACH TO THE CXR: LUNG CAVITIES By Dr. L. Cheung

As well, bowel herniations into the chest (e.g. hiatus her- 1. Introduction nia, Morgagni or Bochdalek’s hernia) can sometimes be Although lung cavities, developmental cysts, pneumato- mistaken for a lung cavity. celes, emphysematous bullae, and bronchiectatic cysts all represent “holes” or empty spaces in the lung, they arise from different pathologic mechanisms. 2. Causes of Lung Cavities The most common causes of lung cavities are infections, As well, although these entities can look similar on CXR, malignancies, and vasculitic lung diseases. they often have certain features which help to distinguish them radiographically. Table 1 compares the pathology A. Infections and CXR findings of these abnormalities. • Bacterial (Staphylococcus, B - hemolytic Streptococ-

cus, gram negatives such as Klebsiella, enterobacte- riaecae, anaerobes)

Table 1 Abnormality Pathology CXR Features

Lung Cavity • necrosis of a localized area of lung parenchyma with • zone of lucency surrounded by a evacuation of necrotic tissue via the tracheobron- demarcated wall > 3 mm diame- chial tree ter. • the necrosis can be due to infection of lung, central necrosis of a tumor as it outgrows its blood supply, or a localized area of infarction due to compromised blood supply (eg. vasculitis of the local arteriole)

Developmental • although congenital, they are usually not detected • usually circular, air-filled, with a until adulthood because they (usually) do not cause thin wall ~ 1-3 mm in thickness. cyst symptoms unless they become infected • when infected, an air-fluid level • a piece of a normal structure breaks off during em- may be seen. bryonic development and develops on its own (e.g. bronchogenic cyst, esophageal cyst)

Pneumatocele • usually develops during resolution of lung infection • usually has a thin wall (< 1 mm) (while the patient is clinically improving, vs. a lung but wall thickness may be hard to cavity where the patient is usually unwell) discern due to surrounding consoli- • develops either from localized small airway disease dation. causing a one-way valve mechanism (air goes in on • can be radiographically hard to inhalation, doesn’t come out with exhalation) leading distinguish from lung cavities to localized air trapping or from a localized alteration in lung elasticity post-infection

Emphysematous • result from destruction of lung tissue as a result of • surrounded by a thin wall which the emphysema may be incomplete or curvilinear. bulla • a bleb is a bulla which abuts the visceral pleura

Bronchiectatic • results from bronchiectasis so severe that the bron- • looks like a cyst but is associated chus develops a localized area of dilatation which with coexisting bronchiectasis. eg. cyst looks like a cyst can be seen in patients with cystic fibrosis APPROACH TO THE CXR: LUNG CAVITIES

• Tuberculosis Example 2 • Non-tuberculous mycobacteria A 20 year old febrile male presented with fever, leukocy- • Fungal (Histoplasmosis, coccidiodomycosis, etc) tosis, and a productive cough. Ultimately, a diagnosis of • Nocardia - usually see multiple cavities Staphylococcus aureus lung abscess was made. Note • Parasites (echinococcus or hydatid infection) the CXR (Figure 2) showing a lung cavity with a thick, • Seeding from another site (e.g. septic emboli from irregular wall. right sided endocarditis) – usually see multiple cavities Figure 2

B. Neoplasms • Bronchogenic cancer (esp. squamous cell, less likely adenocarcinoma) • Metastatic seeding from another site – usually see multiple cavities • squamous cell (nasopharynx, esophagus, cer- vix) • adenocarcinoma (lung, breast, GI tract) • melanoma

C. Vascular or Vasculitis • Wegener’s granulomatosis – usually see multiple cavities +/- areas of airspace disease • Necrotic Rheumatoid nodules – usually see multiple cavities Example 3 • Infarct from pulmonary embolus A 40 year old female intravenous drug user presented with fever, chills, and a new heart murmur. Note the peripheral location of the cavities on CT chest below as well as a left pneumothorax (due to rupture of one of the pe- 3. Clinical Examples ripheral cavities). Ultimately, a diagnosis of septic emboli Example 1 from tricuspid valve endocarditis was made. A 50 year old male presented with persistent nasal discharge, hemoptysis, and urinary red cell casts. Ulti- pneumothorax mately, a diagnosis of Wegener’s granulomatosis was Figure 3 made. The CXR (Figure 1a) and CT scan (Figure 1b) of this patient revealed multifocal opacities, some of which were cavitating (white arrow on CXR and CT).

Figure 1a Figure 1a APPROACH TO THE CXR: LUNG CAVITIES

Example 4 A CT scan done 4 years previously demonstrated a thin A 60 year old female smoker presented with a left upper walled bulla in this exact area. A clinical diagnosis of lobe lung mass on CXR (Figure 4a), ultimately diagnosed hemorrhage into a pre-existing bulla was made. The to be squamous cell cancer. While awaiting surgical re- hemorrhage stopped spontaneously and the air fluid section, she developed fever and chills. Subsequent CXR level resolved. (Figure 4b) showed cavitation of this squamous cell tu- Figure 5c mor.

Figure 4a Figure 4b Air fluid level

Example 6 This is the CXR (Figure 6a—b) of a 17 year old male with severe cystic fibrosis. Note the numerous circular lucencies throughout both lung fields with an upper lung zone predominance.

Example 5 These circular lucencies actually represent dilated bron- This 50 year old man with bullous emphysema presented chi seen end-on. The bronchi are significantly dilated due with hemoptysis. Note the air fluid level on the CXR to the bronchiectasis. These are not lung cavities or con- (Figure 5a—b), revealed to be surrounded by a thin walled gential cysts, although they might be mistaken as such. circular structure on the CT scan (Figure 5c), suggesting This pattern of bronchiectasis is known as cystic bron- that this did not represent a lung abscess cavity. chiectasis.

Also note other general signs of emphysema, such as Figure 6a Figure 6b hyperinflated lungs and multiple bullae.

Figure 5a Figure 5b

Air fluid level APPROACH TO THE CXR: LUNG CAVITIES

References 1. Reed J. Chest Radiology—Plain Film Patterns and Differential Diagnosis. 4th Ed. Mosby. 1997. 2. All CXR’s are from patients seen by the Pulmonary Division at UAH. Chapter Eighteen

Approach to the CXR - Mediastinal Masses APPROACH TO THE CXR: MEDIASTINAL MASSES By Dr. L. Cheung The differential diagnosis of abnormalities in the superior A. Introduction mediastinum includes the following: The mediastinal borders on the plain chest Xray are best • masses extending down from the neck, such as thy- delineated on the lateral view. Of course, it is important roid goiters or cystic hygromas to correlate findings on the lateral view with findings on • mediastinal adenopathy the PA view to ensure that the abnormalities are actually • vascular abnormalities, such as aneurysms in the mediastinum and not in the lung or chest wall (ie. in the description of the mediastinal compartments, it is assumed that they are bordered laterally on both sides by C. Anterior Mediastinum the mediastinal pleurae). The anterior mediastinum is bordered anteriorly by the sternum, posteriorly by the heart and ascending aorta, There are many ways to divide the mediastinal compart- and above by the superior mediastinum, as shown in Fig- ments – one such method is described in this handout. ure 2.

Note that the borders between compartments are “virtual” – masses originating in one compartment can easily grow and expand into another compartment. Thus, Figure 2 CT chest is usually needed for more precise delineation.

B. Superior Mediastinum The superior mediastinum is bordered below by an imagi- nary line drawn between the sternomanubrial joint and the T4 vertebra and bordered above by the thoracic inlet, as shown in Figure 1.

It is often grouped in with the anterior mediastinum because the pathologies that can occur in each compartment are similar.

Figure 1

CXR features may include silhouetting of the upper heart border on the PA view. Often, the abnormality bulges laterally and CT chest is necessary to distinguish a lung mass abutting the mediastinum vs a mediastinal mass extending laterally. On the lateral view, there may be filling of the retrosternal space.

As an example of the radiologic findings of an anterior mediastinal mass, Figure 3 (a - c) below shows the radiographs of a 29 year old male who presented with some vague retrosternal heaviness.

Depending on the exact location of the abnormality, CXR features may include tracheal deviation or silhouetting of the aortic arch on the PA view. It may be hard to see the abnormality on the lateral view due to the overlying structures. APPROACH TO THE CXR:

MEDIASTINAL MASSES

Figure 3a Figure 3b D. Middle Mediastinum Also known as the “vascular space”, it is bordered anteriorly by the anterior surface of the heart and ascending aorta, posteriorly by the vertebral bodies, and inferiorly by the diaphragm, as shown in Figure 4. Figure 4

Figure 3c

Structures in this area (from which abnormalities may CXR and CT chest revealed an anterior mediastinal mass arise) include the heart and great vessels, tracheobron- abutting the aortic arch (the latter is outlined in white in chial tree, lymph nodes, and the phrenic and vagus Figure 3c because it is otherwise hard to see on this non- nerves. augmented study). A CT guided needle core biopsy revealed lymphoma CXR features, on the PA view, may include a mass under the carina, superimposed on the heart (making it difficult Common causes of masses in the anterior mediastinum to see). On the lateral view, the abnormality may be seen include the following: under the trachea. • thymoma • retrosternal thyroid goiter An example of a subtle middle mediastinal mass is found • teratoma in Figure 5 (a—c) which shows the radiographs of an as- ymptomatic 34 year old female. • lymphoma

Less common causes include the following: • vascular abnormalities, such as aneurysms, hemangiomas, etc. • cardiac tumors or epicardial fat • various cysts (cystic hygroma, bronchogenic cyst, pericardial cyst, etc) • mesenchymal tumors, such as fibroma, lipoma, etc.

APPROACH TO THE CXR:

MEDIASTINAL MASSES

Figure 5a Figure 5b E. Posterior Mediastinum Also known as the postvascular space, it extends posterior to the vertebrae, as illustrated in Figure 6. Some au- thors position the border between middle and posterior mediastinum at the posterior border of the heart. Clini- cally, however, most posterior mediastinal abnormalities occur at or posterior to the vertebrae. Structures in this area include lymph nodes, esophagus, descending aorta, and various nerves. Figure 6

Figure 5c

The outline of the mass can barely be seen in Figure 5a (shown by the black arrow). It is more obvious on the CT scan in Figure 5c (shown by the black arrow). The mass was resected and found to be a neurofibroma, a somewhat unusual location for this tumor. The CXR features of a posterior mediastinal mass are usually best seen on the lateral view since, on the PA Common causes for a middle mediastinal mass include view, they are often obscured by overlying structures. the following: When a posterior mediastinal mass is seen on the PA view, it is important not to mistake it for a lung mass (ie. • adenopathy due to infection (eg. fungal or mycobac- always look at the lateral if available!) terial), neoplasm (eg. bronchogenic cancer, metasta-

ses, or lymphoma), or sarcoidosis An example of a posterior mediastinal mass is shown in • aneurysms or vascular abnormalities Figure 7 (a—b) • various cysts, including esophageal, pericardial, or bronchogenic cysts Figure 7a Figure 7b Less common abnormalities include the following: • neural tumors (of the vagus or phrenic nerves) • mesothelioma • giant lymph node hyperplasia (Castleman’s disease)

APPROACH TO THE CXR:

MEDIASTINAL MASSES

The commonest cause of a posterior mediastinal mass is a neural tumor, which can be divided into nerve sheath tumors (schwannomas, neurofibromas, and their malignant correlates) and ganglion cell tumors (neuroblastoma, ganglioneuroma, etc).

Less common abnormalities include the following: • mesenchymal tumors (fibromas, lipomas, leiomyo- mas, hemangiomas, etc) • vertebral tumors (metastases, primary bone tumors) • lymphoma • Bochdalek’s hernia

References 1. Strollo D, Rosado de Christensen M, Jett J. Primary Mediastinal Tumors— Part 1. CHEST 1997;112:511- 22. 2. Strollo D, Rosado de Christensen M, Jett J. Primary Mediastinal Tumors—Part 2. CHEST 1997;112:1344- 57. 3. With the exception of the CXR showing a posterior mediastinal mass, all of the CXR’s in this chapter are from patients seen by the Pulmonary division at UAH. Chapter Nineteen

Common Therapeutic Devices in Respiratory Medicine COMMON THERAPEUTIC DEVICES IN RESPIRATORY MEDICINE by Dr. L. Cheung

Figure 2a: Patient is Exhaling 1. Introduction one way valves in the This chapter will enable you to answer the following prongs close while clinically important questions regarding common prongs fitting patient exhales therapeutic devices in respiratory medicine: into nares 1. How do nasal cannula, an Oxymizer®, and a nonrebreather mask differ in their delivery of oxygen? 2. How do metered dose inhalers, dry powder inhalers, and small volume nebulizers differ in their delivery of medication? 3. How does incentive spirometry work and how does it differ from PFT spirometry?

oxygen tubing the inner reservoir fills 2. Nasal Cannula connected to the with oxygen from the The most commonly used oxygen delivery device, nasal Oxymizer tubing during exhalation cannula are used with oxygen flow rates of 1 to 6 L/min. With continuous oxygen flow, the patient’s own nasopharynx acts as an oxygen reservoir (about 50 mL). Figure 2b: Patient is Starting to Inhale (early inspiration) The often quoted increase in FiO2 of 0.4 (added to a room air FiO2 of 0.21) per 1 L/min of administered oxygen one way valves open and applies to patients with a normal breathing pattern – high patient receives a bolus respiratory rates and tidal volumes can dilute the amount of oxygen in reservoir of inspired O2, resulting in less than expected increases in FiO2.

3. Reservoir cannula The Oxymizer® is the most commonly used reservoir cannula at UAH and is shown in Figure 1. This moustache shaped cannula has an additional inflatable reservoir of 20 mL. Figure 2 (a - c) illustrates how an oxymizer works.

During exhalation, the reservoir fills with oxygen (Figure 2a). Then, during early inspiration, the patient not only Figure 2c: Inhalation Continues reservoir is empty but inhales the O2 coming in by continuous flow, but receives oxygen still flows from a bolus of O2 from the reservoir, increasing the inspired the tubing (as in regu- FiO2 (Figure 2b). Once the reservoir is depleted, O2 is inspired through continuous flow as with the standard lar nasal cannula) nasal cannula (Figure 2c).

Figure 1

The Oxymizer® can be used when high flow oxygen is required but a mask is not needed or desired (e.g. the patient has a normal ventilatory pattern, wants to eat without removing his oxygen, etc). It should only be used in consultation with a respiratory therapist to ensure that use is appropriate.

COMMON THERAPEUTIC DEVICES IN

RESPIRATORY MEDICINE

4. Nonrebreather Mask (NRB 5. Metered Dose Inhaler (MDI), mask) Spacer, and Dry Powder Inhaler A NRB mask has an additional oxygen reservoir of about 600 mL (the size of the bag attached to the mask). (DPI) Figure 3 illustrates how continuous flow O2 enters the See the end of this section for sample instructions as well reservoir, which the patient inhales on inspiration. A one- as illustrations on how to use the various devices. It is way valve between the mask and the reservoir prevents helpful to be familiar with how the devices are used so exhaled gas from entering the reservoir (thus preventing that patient technique can be assessed. Table 1 the oxygen in the reservoir from becoming diluted). On contrasts MDI’s (without a spacer) with DPI’s. the next inspiration, the patient gets a bolus of oxygen from the reservoir bag without rebreathing any CO2 Some medications have multiple delivery systems. For (hence the term “nonrebreather” mask). example, Serevent (salmeterol) comes in a MDI as well as a diskus. The mask usually has two side ports to allow exhaled gas to escape. One-way valves over the side ports prevent If the patient has difficulty coordinating medication inhalation of ambient room air, although a safety valve is release with inspiration, a spacer can be used (NB: present to allow inhalation of room air if the oxygen spacers are only used with MDI’s, not DPI’s). The accidentally becomes disconnected from the mask. Aerochamber® is the commonest spacer used at UAH and, although a couple of deep inspirations is ideal, A NRB mask requires a flow rate of at least 7 L/min (i.e. normal tidal breathing through the spacer’s mouthpiece is when titrating down O2 below this level, remember to also acceptable. switch to nasal cannula). With high O2 flow rates, an FiO2 of about 0.6 to 0.8 might be achieved. Table 1

MDI without DPI Feature a spacer Figure 3: Nonrebreather mask should be slow (over should be fast several seconds)

Inspiration inspiration itself “sucks” need to coordinate the medication into the inspiration with medi- lungs – no coordination cation (spray) release required (breath actuated) Exhaled gas

there is no sensation, patients can feel the therefore patients may One way valve Sensation spray entering the feel like they’re not receiv- mouth ing any medication Oxygen source

a capsule containing the no loading is required dry powder medication Loading the – each press of the needs to be loaded into medication canister releases the the chamber (e.g. by turn- medication as a spray ing a knob, etc) Bag filled with 100% oxygen Types of there is only one type Turbuhaler delivery sys- of MDI in common use tems – the canister Diskus COMMON THERAPEUTIC DEVICES IN

RESPIRATORY MEDICINE

6. Small Volume Nebulizers Figure 4a A small volume of liquid medication is placed into the nebulizer, and a continuous flow of compressed gas (air or oxygen) nebulizes the medication which the patient inhales. A flow rate of about 8 L/min is ideal – a lower flow rate can result in medication being trapped in the nebulizer and a higher flow rate can evaporate the medication too quickly, before the patient has a chance to inhale it.

When used properly, a MDI with spacer results in similar bronchodilator response when compared with a nebulizer. (Emergency Department Treatment of Severe Asthma. CHEST 1993;103:665-672). Of course, it is important to verify proper use of the MDI with spacer.

7. Incentive Spirometer Although most people equate spirometry with exhalation Figure 4b (e.g. measuring FEV1 and FVC), incentive spirometry refers to a sustained, maximal inspiration and is one component of bronchial hygiene therapy. This is achieved by using a device that provides patients with visual or other positive feedback when they inhale a predetermined volume and sustain the inflation for a few seconds.

The goals are to increase transpulmonary pressure and inspiratory volumes, improve inspiratory muscle performance, and re-establish or simulate the normal pattern of pulmonary hyperinflation (e.g. intermittent sighs). With repeated use, incentive spirometry may help reverse or prevent lung atelectasis.

8. Instructions on Using the Medication Delivery Devices Figure 4c Figure 4 (a - c) illustrates instructions for using a turbohaler, metered dose inhaler, and aerochamber.

9. References 1. Branson, RD, Hess, DR, Chatburn RL. (1995) Respiratory Care Equipment. Lippincott. 2. Marino PL. (1998) The ICU Book. 2nd ed. Williams and Wilkins. Chapter Twenty

Common Procedures in Respirology COMMON PROCEDURES IN RESPIROLOGY by Drs. L. Cheung & E. Wong suctioned until a total of 100 – 120 mL has been 1. Introduction: instilled. The sample suctioned represents a lower A patient on the Internal Medicine ward comes back from respiratory tract sample (from the alveoli and small a bronchoscopy done by the Pulmonary Service. The bronchioles), as illustrated in Figure 1. bronchoscopy was done to investigate a left upper lobe Of the fluid instilled, only about 20 – 60% is suctioned nodule seen on CXR and mediastinal lymph nodes seen out (the rest stays in the lung and is absorbed). The on CT chest. On the chart, a description of the procedure return rate is highest from nondependent lung areas is written stating that a bronchial wash and brush was (right middle lobe or lingula in a supine patient), so these done of the left upper lobe and that transbronchial areas are chosen if the lung disease is diffuse. If the lung needle aspirates were done of the mediastinal lymph disease is focal, the sample is taken from the affected nodes. There is no mention of a biopsy being done and area. you wonder why. If evidence for infection is being sought, semi- This chapter will enable you to answer the following quantitative cultures are performed. Bacteria growing at questions regarding common procedures in Respirology: > 108 colony forming units per litre suggests true 1. What is the difference between a BAL, bronchial infection. wash, and bronchial brush, and what are the indications for each? 2. What is a mucosal biopsy and why aren’t they always 3. Bronchial Wash done in a patient with a lung nodule or mass? Technique: 3. What is the difference between a mucosal biopsy, transbronchial lung biopsy, submucosal aspirate, and A bronchial wash differs from a BAL in that about 30 – transbronchial needle aspirate, and what are the 60 mL of saline is instilled and suctioned while the tip of indications for each? the bronchoscope is in a large airway (main or lobar 4. When and why would bronchoscopy under bronchus), thus sampling an area of lung more proximal fluoroscopy be done? than a BAL, as illustrated in Figure 2. 5. What are the few therapeutic indications for bronchoscopy? A wash is useful for sampling a proximal airway lesion 6. How is a closed pleural biopsy performed? (e.g. a visible tumor in the proximal airway).

Also, since a wash samples a larger area, we often use it 2. Bronchoalveolar Lavage (BAL) when a lesion is not visible bronchoscopically and the Technique: precise segment in which it is located is unclear on CXR. The tip of the bronchoscope is wedged into a small airway (usually a segmental or subsegmental bronchus). As well, a wash is done sometimes to determine if Saline is alternately instilled in 20 – 30 mL aliquots and infection is present.

Figure 1: BAL - broncho- Figure 2: wash - scope wedged in a sub- bronchoscope tip segmental bronchus and at the entrance of fluid “bathes” a portion of a lobe (more lung containing mainly al- proximal com- veoli pared with a BAL) COMMON PROCEDURES IN

RESPIROLOGY

4. Bronchial Brush 5. Mucosal Biopsy Technique: Technique: This is usually performed to obtain a cytology specimen Forceps are introduced through the bronchoscope chan- on a tumor. A wire brush is inserted through the broncho- nel and used to biopsy visible mucosal lesions (e.g. tu- scope channel and rubbed back and forth a few times on mor). This is illustrated in Figure 4. We actually get a the area of interest. The hope is that cells (e.g. malignant piece of tissue (in contrast to other techniques like a cells, if present) will cling to the bristles of the brush, wash, BAL, brush, or needle aspirate where we get sam- which is then removed from the bronchoscope and ap- ples for cytology. plied to a slide. A picture of this is shown in Figure 3. Figure 5 Figure 3: a wire brush is about to be rubbed against an abnormal area of mucosa suspected of being malignant

6. Transbronchial Lung Biopsy Note that when we cannot see the nodule endoscopically, (TBBx) we will often do a “blind” brush in the hopes that it will reach the nodule and scrape against it, as illustrated in Technique: Figure 4. Without fluoroscopy, however, there is no way Forceps are passed through the bronchoscope channel. to tell in real time whether we have hit the nodule or not. However, this differs from a mucosal biopsy in that, instead of performing a biopsy of a visible lesion on the bronchial mucosa, the forceps are passed beyond bron- choscopic visualization (distal to the subsegmental bron- Figure 4: a wire brush (in red) is chus). The hope is that the forceps will snag the bifurca- “blindly” inserted through the tion of a small bronchiole, and that a small piece of lung bronchoscope for a nodule visible parenchymal (alveolar) tissue will be caught in the for- on CXR but not too peripheral to ceps when it closes and is withdrawn, thus performing a be seen bronchoscopically small transbronchial lung biopsy. This is illustrated in Figure 6.

Figure 6 Wire brush

Lung parenchyma

We do not perform a mucosal biopsy of lesions visible on CXR but not visible endoscopically, since we cannot see where we are taking the biopsy. Thus, the wash and brush are the standard diagnostic samples we take for this type of clinical scenario. COMMON PROCEDURES IN

RESPIROLOGY

Aside from the risk of bleeding, there is about a 5 to 10% chance of pneumothorax with the procedure. About half 8. Transbronchial Needle Aspira- of the time, the pneumothorax will resolve spontaneously - the rest require a chest tube. We routinely do a post- tion (TBNA) procedure CXR to determine if a pneumothorax is pre- Technique: sent. For tumors or mediastinal lymph nodes outside of but up against the outer tracheobronchial wall, a needle can be passed through the wall of the bronchus, into the lesion. (Note how this differs from SMA where we only 7. Submucosal Needle Aspirate try to embed the needle into the mucosa or visible lesion). A sample can then be aspirated and sent for cy- (SMA) tology. In the case of mediastinal lymph nodes, this can Technique: obviate the need for mediastinoscopy if a positive result For a visible lesion in the airway (either an endobronchial is obtained. This procedure is illustrated in Figure 8. mass or an abnormal appearance to the bronchial mucosa suggesting infiltration by disease), the bronchoscopist may perform a submucosal needle aspirate by jabbing a needle into the abnormal area. The needle Figure 8: embeds into (not through) the mucosa or visible lesion TBNA of a and material is aspirated and then placed on a slide for subcarinal cytologic analysis. lymph node

Figure 7: SMA of a visible endobronchial lesion

The bronchoscopist first reviews the CT to determine the location of the nodes or tumor and their anatomic rela- tion to tracheobronchial landmarks.

Then, during the bronchoscopy, using the landmarks as a guide, the needle is inserted through the tracheobronchial wall into the approximate location of the lesions. Using this method, there is no “real time” way of determining if the needle has truly entered the lesion.

Although lymph nodes may be minimally enlarged on CT (> 1 cm diameter), many bronchoscopists will not attempt TBNA unless the lymph nodes are significantly enlarged (> 1.5 or 2 cm). This is because the chance of “hitting” smaller lesions decreases with their size. As well, enlargement of lymph nodes up to 1.5 to 2 cm may simply be due to inflammatory changes (e.g. lung infection). However, the chance of malignancy increases sub- stantially when lymph nodes are greater than 2 cm. COMMON PROCEDURES IN

RESPIROLOGY

9. Bronchoscopy under Fluoros- 10.Bronchoscopy for Pulmonary copy Hemorrhage Technique: Technique: If a mass is located peripherally and is likely not to be Flexible bronchoscopy is inappropriate for massive pul- visible endoscopically, we may attempt bronchoscopy monary hemorrhage because the view is easily obscured under fluoroscopy. An example of this is shown in the by blood on the fiberoptic tip and therapeutic options are CXR in Figure 10. Here, the bronchoscope is advanced as limited. Thus, for massive lung bleeding, rigid broncho- far as possible and a brush is advanced through the tip of scopy in the OR is the best procedure to control the air- the bronchoscope. After the brush is advanced, fluoros- way and visualize the abnormalities. copy is done to determine if the brush is in the mass. If not, the brush is withdrawn and advanced again and fluo- For non-massive hemorrhage, flexible bronchoscopy may roscopy is repeated. This is done until, by random visualize the site and cause of bleeding. It can help dis- chance, the brush goes down all of the correct bronchi- tinguish airway from alveolar bleeding and focal from oles and passes into the mass. diffuse bleeding.

Bronchoscopy in this setting is mainly used to diagnose Figure 10 the cause of bleeding - our therapeutic options are limited. If the bleeding is focal, xylocaine with epinephrine can be instilled onto the area to vasoconstrict mucosal blood vessels.

11. Bronchoscopy for Secretions Technique: If pulmonary secretions build up to the point of causing lobar or whole lung obstruction and collapse, suctioning with bronchoscopy may help remove the secretions and re-expand those portions of lung.

Bronchoscopy tends to be ineffective for atelectasis in- volving less than an entire lobe, and tends to be less ef- fective for lower lobe collapse.

As well, bronchoscopy is simply a temporary measure – Note the position of the mass and tip of the broncho- secretions usually quickly build up again – and the proce- scope in Figure 10 - most people are surprised at how dure is no substitute for chest physiotherapy, patient mo- little distal the mass has to be before it is too peripheral bilization, etc. to be seen endoscopically.

Unfortunately, because it is labour intensive, exposes the patient to increased radiation, and is more time- consuming than a regular bronchscopy, we only do bronchscopy under fluoroscopy in very select situations. COMMON PROCEDURES IN

RESPIROLOGY

The greatest utility of closed pleural biopsy is in diagnos- 12.Bronchoscopy for Foreign ing tuberculous effusions and, in the right clinical setting, is positive for granulomas in 50 to 80% of patients. Al- Body Removal though needle biopsy can arguably be used to diagnose Technique: metastatic malignant spread to the pleura, simple thora- Numerous devices exist to remove foreign bodies bron- centesis with cytologic exam of the pleural fluid has a choscopically, including forceps which are used to grab higher yield. on to the object and baskets which are used to trap the foreign body. An example of this is illustrated in Figure 11.

Figure 11

13. Closed Pleural Biopsy Technique: It is possible to obtain small samples of parietal pleura through closed pleural biopsy. The technique is similar to thoracentesis (and, in fact, it is important that fluid in the pleural space is present to push the lung away from the chest wall, decreasing the risk of lung puncture with the biopsy needle). The biopsy needle is inserted into the pleural space and a small part of parietal pleura is (hopefully) snagged by the open edge, as illustrated in Figure 12.

Figure 12 Chapter Twenty - One

List of Commonly Used Bronchodilators LIST OF COMMONLY USED BRONCHODILATORS by Dr. L. Cheung

Here is a list of commonly used inhaled medications in alphabetical order. A picture of one or more of the delivery systems for each medication is shown, as well as the trade name, the generic name or names (for inhalers with a combination of medications), the pharmacologic class of medication(s), the delivery systems that are available, and the available dosages. Information on available delivery systems and dosages is obtained from the CPS, and the UAH pharmacy formulary may not necessarily have all forms of the medication available.

The pictures of Atrovent®, Berotec®, Combivent®, and Spiriva® are supplied by Jeff Schroeder from Boehringer Ingelheim (Canada) Ltd. I’ve taken photos of the other inhalers with a digital camera.

Delivery systems include metered dose inhalers (MDI), dry powder inhalers (DPI), and inhalational solutions for use with nebulizers. Dry powder inhalers, in turn, come in many forms such as a Turbuhaler® or Diskus®.

Advair® (salmeterol + fluticasone) Airomir® (terbutaline) – short Atrovent® (ipratropium bromide) – – long acting beta agonist + acting beta agonist. Available as short acting anticholinergic. inhaled corticosteroid. Available a MDI (125ug). Available as a MDI (20 ug) or as a Diskus® (50+100 ug, 50+250 inhalational solution (125 or 250 ug, or 50+500 ug) or MDI (25+125 ug/mL). ug or 25+250 ug).

Berotec® (fenoterol) – short acting Bricanyl® (terbutaline) – short Combivent® (ipratropium bromide beta agonist. Available as a MDI acting beta agonist. Available as + salbutamol) – short acting (100 ug) or inhalational solution a Turbuhaler® (0.5 mg). anticholinergic + short acting beta (0.25, 0.625, or 1 mg/mL). agonist. Available as a MDI (20 + 100 ug) or inhalational solution (0.5 + 2.5 mg / 2.5 mL)

Flovent® (fluticasone) – inhaled Foradil® (formoterol) – long Oxeze® (formoterol) – long acting corticosteroid. Available as a MDI acting beta agonist. Available as beta agonist. Available as (50, 125, or 250 ug) or Diskus® a DPI with a delivery device Turbuhaler® (6 or 12 ug). (50, 100, 250, or 500 ug). unique to the drug (12 ug).

Pulmicort® (budesonide) – inhaled Q VAR® (beclomethasone) – Serevent® (salmeterol) – long corticosteroid. Available as an inhaled corticosteroid. Available acting beta agonist. Available as a inhalational solution (0.125, 0.25, as a MDI (50 or 100 ug). MDI (25 ug) or Diskhaler (50 ug). or 0.5 mg/mL) or Turbuhaler® (100, 200, or 400 ug).

Spiriva® (tiotropium bromide) – Symbicort® (budesonide + Ventolin® (salbutamol) – short long acting anticholinergic. formoterol) – inhaled acting beta agonist. Available as a Available as a Handihaler – a corticosteroid + long acting beta MDI, inhalational solution, or unique DPI device where individual agonist. Available as a Diskus®. capsules (18 ug) are manually Turbuhaler® (100 + 6 ug or 200 + loaded. 6 ug).