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BROCHURE CPAP in ambulance service

Introductory course This brochure was written in connection with the introduction of CPAP into the ambulance service at University Hospital Northern Norway. The authors of the brochure are Lars-Jøran Andersson, Morten Lyngås Føyen and Johannes Strand. As authors we wish to give special thanks to Ole Magnus Filseth, who made his compendium on respiratory physiology available to us. Portions of this brochure quote directly from it. In addition to this, we have used Knut Dybwik’s book on respiratory treatment as a source for the brochure. Johannes Strand did the layout and design.

2 It has been decided to introduce CPAP into CPAP is an advanced form of care. Knowledge the ambulances at the University Hospital of the indications and contraindications of Northern Norway. is therefore important. Successful CPAP This brochure has been written as part of treatment demands good cooperation this introduction. The brochure will be an between the provider and the patient, introduction about what CPAP is and will and alertness by the provider. Serious provide the necessary basics for using the complications with CPAP are rare and the tool in an ambulance. treatment can, when necessary, be quickly stopped. We believe that CPAP treatment In addition to this, all personnel will receive will be used relatively seldom, but for the a day of training in the CPAP before it is put individual patient the treatment can offer a into service. significant health advantage. It is important Within emergency medicine, CPAP has that one knows the equipment well so that traditionally been a procedure that was the threshold for using it will be low. only available inside the hospital. In the ambulance service, CPAP treatment I n t r o d u c t i o n The reason we wish to start using CPAP will be prescribed by the doctor in the same in the ambulance service is that early way as medicinal treatment. treatment contributes to shorter hospital stays and better care for the patient. What is CPAP and how does it work?

CPAP treatment requires that the 2. By displacing pulmonary fluid in patient breathes in a closed tubal system congestion. Positive airway pressure that registers a continuous positive airway reduces venous return to the heart pressure. In our case, this will be a CPAP (lowers “preload”). In left ventricle mask that is driven by the oxygen we have failure, the heart’s per minute volume in the vehicles. will increase as a consequence of reduced “preload”. In the ambulance service, CPAP is used for 3. By better ( patients with serious respiratory failure. The becomes easier and the quantity of CO2 indications will be: , in the blood is thereby reduced). It is and COPD. easier for the patient to breathe with CPAP improves oxygenation for a lung that is inflated than when the these patients in three ways: resting volume of the lung is reduced. 1. By causing the patient to breathe with In other words, CPAP works in several ways a higher lung volume, which to improve the patient’s oxygenation. In will increase the diffusion order to have a good understanding surface (reducing of how this works, we must delve shunting). The resting a little deeper into respiratory lung volume (functional physiology... residual capacity - FRC) increases and atelectatic tissue (collapsed lung tissue) is inflated and is prevented from reforming. Don’t worry, Some unfamiliarthe words explanation and expressions? is coming ;-) 3 y g o l o i s y h p d n a y m o t a n A Airways the alveoli are covered with a lipoprotein The upper and lower airways have the task (surfactant), which reduces the surface tension of conducting air to and from the . and thereby prevents the alveoli from closing at In addition, they take care of filtering, the same time that it ensures that they don’t also warming and humidifying the air. over-distend. The lungs are very elastic and can be compared Lungs to a rubber band. A network of elastic fibers is The inner surface of the lungs of an adult found all over the lungs. From the person has an area the size of a tennis court. resting position of the lungs, this The primary tasks of the lungs can be can be stretched out and filled divided into three main functions; with air. For this to happen, the oxygen uptake, carbon dioxide force that will expand the lung elimination and pH regulation. must overcome the elastic The alveoli are covered with a single forces of the lung tissue. layer of flat epithelial cells which form a In addition, there is the thin membrane between the air in the alveoli elastic resistance found in and the blood in the capillaries. In addition, the chest wall.

Inspiratory reserve volume approx. 5000 ml approx. 3000 ml

Tidal volume at rest is approx. 500 ml

Expiratory reserve volume approx. 1500 ml

Residual volume approx. 1000 ml

A healthy adult male has a total lung If you add ERV and RV you get capacity (TLC) of approx. 6 liters, functional residual capacity (FRC), that is, the quantity of air found in the which is the normal resting volume lungs after maximal inspiration. of the lungs. (During CPAP The (TV) is the volume treatment, FRC is increased.) If that is inspired in normal respiration after normal inspiration you and is approx. 0.5 liter. continue to breathe in as much as you can, you obtain an inspiratory After normal expiration, a healthy reserve volume (IRV), that is adult male could expire approx. 1.5 approx. 3 liters. liter. This is called expiratory reserve volume (ERV).

Lung capacity and volume What is left in the lungs is called residual volume (RV).

4 The elastic forces in the lungs and chest wall during expiration The organism’s oxygen supply depends ( out) contract the lung upon its ability to take up oxygen and back into the resting position. the ability to transport it out of the body. Under normal circumstances, the oxygen Expiration is therefore normally a supply depends upon the following factors. passive act. In technical literature, 1. level the term compliance is used for 2. the lungs’ elasticity. 3. Cardiac minute volume In order to obtain an adequate supply of oxygen, it is often possible to influence these three factors even by simple means

The body’s oxygen supply The oxygen body’s outside of the hospital. Words and Expressions... Expressions... and Words : Hemoglobin (Hb): Reduction of the oxygen supply in the Oxygen-bearing molecules in tissues, despite adequate blood supply, erythrocytes. Every hemoglobin molecule is usually due to . can bind to four O2 molecules. Each gram Hypoxemia: of hemoglobin can bind to 1.34 ml of oxygen. If we want to indicate whether Reduced oxygenation of the blood causes

hemoglobin is bound to oxygen or not, we Respiratory physiology hypoxia. In practice, hypoxemia and can distinguish between oxyhemoglobin hypoxia are often used interchangeably. (oxygen is bound) and deoxyhemoglobin. Ischemia: The quantity of hemoglobin in the body is Lack of oxygen in tissue, which is due normally 11.5 - 17 g/dl. to reduced blood supply in the tissue, SaO2: as for example in angina pectoris. Oxygen saturation in arterial blood. Asphyxia: When all hemoglobin in the blood is Lack of oxygen in the inspired air, or saturated with oxygen, SaO2 is 100%. If absence of air to breath, synonymous SaO2 is, for example, 60%, this means with asphyxiation. that 60% of the binding sites for oxygen Hypercapnia: are bound to oxygen. Increased quantity of CO2 in the SpO2: blood, synonymous with hypercapnia. The designation for arterial oxygen Hypercapnia is a strong stimulus to saturation when it is measured in increase respiration. Attempt to hold the peripheral arterial blood using a your breath while you measure oxygen pulse oximeter. The pulse oximeter saturation and you will experience a distinguishes between oxygenated and strong need to inhale before oxygen deoxygenated hemoglobin using light saturation falls. with different wave lengths. Hypocapnia: With correct use and interpretation, Reduced quantity of CO2in the blood, SpO2 will correspond to SaO2. for example, a hyperventilating episode.

5 Functional residual capacity (FRC) is the FRC is reduced also by general anesthesia quantity of air that is left in the lungs after (narcosis) because of the loss of muscle tone in normal expiration. When you breathe out and the diaphragm. reach FRC, you are doing fine. You can then In a normal healthy young adult all of the lung’s begin to breathe in, which will be both easy segments will be open at the end of a normal and natural. You can also choose to continue expiration. But when we breathe out to the to breathe out until you reach residual volume, maximum, the small airways that exist farthest which is the amount of air which is left in the down in the lungs are closed. This is called static lungs after maximum expiration; it will feel airway collapse. The lung volume at which this heavier. Ordinarily we do not think about when occurs is called closing capacity. We do not need we should stop breathing out and begin to to worry about this as long as it occurs after we breathe in, this is controlled by the respiratory have reached the functional residual capacity in center in the brainstem. expiration. Thus we choose unconsciously when we should Closing capacity is determined by the lung tissue’s begin to inhale. Even though the choice is elastic properties. Closing capacity can be highly unconscious, it is sensible and oriented toward elevated in COPD. When closing capacity is higher ensuring good ventilation with the least possible than FRC, it means that portions of the airways effort. collapse during normal breathing. This leads to The functional residual capacity is determined an improper relationship between ventilation and therefore by the equilibrium between the circulation in the lungs. Circulated lung segments forces that work in opposite directions. are not ventilated (shunt). The result will be poorer Some forces contribute to pulling the lungs out oxygenation of the blood. (filling the lungs), such as the elastic forces in Closing capacity is an innate property of lung the chest wall and muscle tone in the diaphragm, tissue and is independent of other processes. The while the elastic forces of the lung tissue work functional residual capacity, on the other hand, Static Airwayoppositely Collapse (empty the lungs). In order to empty can be influenced. A patient with an elevated the lungs further once we have reached FRC, we closing capacity and worsening of COPD will thus must use the muscles to force expiration. FRC benefit from measures that increase functional varies significantly, also within an individual residual capacity. To raise into an upright patient. FRC is greater when standing then position in order to get atelectatic (collapsed) when lying down. FRC is reduced in collapse lung tissue to open is an example of a measure (atelectasis) of the lung tissue and in all of the that will increase FRC. CPAP is able to contribute processes that reduce the area of the lungs to the opening of atelectatic tissue and will also (pleural fluid, obesity and distended abdomen). make it easier to breathe with greater volume.

Static airway collapse

In a COPD patient, resting elasticity in the lung tissue is reduced, such that the point at Vital capacity approx. 5000 ml which the lungs begin to close by themselves ( c l o s i n g Tidal volume at c a p a c i t y ) Closing capacity rest approx. 500 ml is reached in a COPD patient during normal expiration. This is a static airway collapse. Closing capacity in a healthy person Residual volume approx. 1000 ml

6 Dynamic airway collapse When we breathe out hard (forced expiration), the diaphragm, stomach and chest wall muscle is used to press together the chest cavity. Instead of negative pressure (as with ordinary expiration) we now have a positive pressure both in the chest cavity and around the lungs. We obtain a large pressure differential and we should expect a large expulsion of air from the airway. Along the airways a gradual fall in pressure from 85 to 0 cm H2O will occur. The pressure in the airways will be lower than the pressure around the lungs. If the airways were rigid tubes this would not mean much, but the alveolar passages and bronchioles are held distended by the surrounding elastic tissue and the bronchioles have cartilage that can only resist a certain outer pressure. In this case, we Blood flow in the will have a total or partial collapse of the airways therefore be equal to the blood flow in the that lasts until the forced expiration ceases. systemic circulation. One has then a dynamic airway collapse, The pressure in the pulmonary arteries is only because it is related to the air expelled out 1/6 of the pressure in the aorta. This means of the lungs. If a person exhales with less that if we measure systolic blood pressure at force, the airway will remain open during 120 mmHg, the pressure in the pulmonary expiration. In normal people, the dynamic arteries will be approx. 20 mmHg. A consequence airway collapse will show itself to be the upper of the lower pressure in the pulmonary arteries limit of how fast the lungs take to empty of is that the blood flow to the lungs is more air (approx. 600 to 700 l/min, far above what dependent upon gravity, such that at any time we have need for under all physiological the lowest lying portions of the lungs have the circumstances). best blood flow. Dynamic airway collapse The tendency to dynamic The tendency to dynamicBlood flow in the lungs will change with collapse increases when collapse increases when the patient’s position. In lower- the airways are narrowed airways are narrowed, as with lying areas, there will be a tendency to poor down, as in the case of pulmonary edema or asthma... pulmonary edema or ventilation, in the higher- asthma. It means that lying areas the tendency will large portions of the be to poor . For the airways will have collapsed before lungs overall, the relationship one has reached FRC. This means also that the between ventilation and lungs contain trapped air that does not come perfusion is good, nearly out. This air is under pressure and will form a 1:1. Normally the “driving pressure” in lung resistance that must be overcome in the next circulation is determined by the difference inspiration. This phenomenon is called auto- between the pulmonary artery pressure and the PEEP or . pulmonary venous pressure. CPAP reduces the pressure differential and Clinical points: If a person has positive therefore combats auto-PEEP. pressure in the airways (for example, CPAP or respiratory treatment), we can get a situation Blood flow and pressure in lung in which the driving pressure (blood pressure) circulation is determined by the difference between The circulatory system consists of the greater the pulmonary arterial pressure and airway (systemic) circulation and the lesser (lung) pressure. With a combination of high airway circulation. The greater and the lesser pressure and low pulmonary artery pressure, we circulations are joined in a series. This does can get a situation where the airway pressure is not apply to the fetus or persons with simple greater than the pulmonary arterial pressure in congenital heart failure. Flow through the all or part of the lung. In a situation such as this, pulmonary vascular bed varies as does systemic we will not get any blood flow to the actual area circulation between 5 l/min at rest to 25 l/min and the entire circulation could be affected. with high activity (in the well-trained).

7 Indications Patients with COPD can go about with chronic The indication for CPAP treatment in the respiratory failure, but with gradual worsening ambulance service must be serious respiratory as a consequence of airway infections. failure. In practice this will be asthma, COPD and heart failure/pulmonary edema. When assessing a patient with respiratory failure, it is necessary, in addition to oxygen Respiratory failure saturation, to evaluate and We have respiratory failure when the gas depth, respiratory pattern, withdrawals, use exchange in the lungs leads to reduced oxygen of accessory muscles, psychic condition and saturation in the blood. If the respiratory whether the labor of breathing is tiring the failure is serious, we often see also an increase patient. in carbon dioxide in the blood (hypercapnia). I n d i c a t i o n s When we use CPAP in the ambulance, the A series of conditions can cause respiratory failure, such as injuries, pneumonia, collapse patient must have a serious respiratory failure of lung tissue (atelectasis), airway obstruction, and one of the following conditions must also be drug reactions (for example, opiates) and sepsis. suspected: pulmonary edema, COPD or asthma.

P u l m o n a r y e d e m a

The most frequent cause of pulmonary CPAP gives results also because it helps the edema is heart failure. Certain toxins and patient to breathe at a higher lung volume, various forms of overhydration can also opens the lungs and reduces atelectasis cause pulmonary edema. Heart failure formation. All these measures lead to lower means that the heart’s function as a pump blood flow in the heart and this is exactly is failing. Heart failure is a condition that the point. The heart receives less blood that can have different causes, for example, must be pumped further, and is relieved. infarction, arrhythmia, valvular disease, This means also that the patient must be infection, sepsis and cardiomyopathy. monitored because the treatment can work When the heart (left side) fails, the blood so strongly that it leads the patient over pressure in the pulmonary circulation is into circulatory shock. Treatment of acute higher. Because of the elevated pressure, heart failure is a balancing art. fluid leaks out into the space between the capillaries and the alveoli, then into the alveoli and leads to pulmonary edema. A patient with pulmonary edema will S y m p t o m s a n d s i g n s : appear to be very affected. It can often be difficult to distinguish pulmonary edema • Agitation or anxiety from worsening of COPD or pneumonia. • Confusion and disorientation because of hypoxia The treatment of heart failure depends upon the cause. For example, it might be • Poor general condition, weakness PCI or valve surgery. Pre-hospital, the • Chest pain possibilities are medicinal treatment, • Cough - frothy, possible bloody positioning, oxygen and CPAP. In expectorate coronary disease (infarct) thrombolysis • Increasing shortness-of-breath and will also be a treatment option. air hunger In order to relieve the heart, the patient • Increased respiratory rate is positioned with the upper body high • Gurgling respiration and crackling and is treated with nitro preparations sounds over the lungs (nitrolingual every 5 to 10 minutes), • Skin: Gray and cold sweats morphine (start dose of 2.5 to 5 mg) and • Cyanosis diuretics (Furosemide 10 to 40 mg). CPAP • Jugular vein stasis has an effect on heart failure because the • Edema in the ankles and legs increase in airway pressure that CPAP provides leads to fluid being pushed back • Drop in blood pressure into the bloodstream. • Tachycardia and arrhythmia

8 Asthma / COPD Symptoms and signs: Chronic obstructive pulmonary disease is • Known primary disease a composite designation for emphysema • Agitation/anxiety and chronic bronchitis, often caused by • Problems speaking entire smoking. sentences Some patients need home oxygen. • Lowering consciousness, possible coma Medicinal treatment includes , for example, salbutamol (ventoline) • Dyspnea at rest and ipratropium bromide (ipraxa) and • Wheezing steroids (for example pulmicort). With • Exhales through pursed lips worsening, steroids may be given by I.V. or • Cough, coughs up peroral, extra treatment with inhalations, • Fever theophylline (aminophylline) and oxygen. • Increased respiratory rate • Shallow breathing If a patient with worsening COPD • Use of accessory muscles needs intubation, it will often be a • Reduced respiratory sounds, long respiratory handling. Early CPAP wheezes treatment can reduce the need for • Tachycardia, rise in blood intubation. CPAP makes it easier for the pressure, fall in blood pressure, patient to breathe at a higher lung volume arrhythmia, cardiac arrest (higher FRC), which allows more parts of the lungs to be ventilated. In other words, the tendency to static collapse of collapse because the pressure differential is alveoli is reduced. Furthermore, CPAP less. Many COPD patients try to obtain this reduces the tendency to dynamic airway effect by breathing out through pursed lips.

C o n t r a - i n d i c a t i o n s Risk of aspiration – If the patient vomits, Systolic blood pressure <90 mmHg – the mask can fill up with vomit and the patient CPAP leads to higher intrathoracic pressure, can aspirate. It is important to assess this risk something that can reduce blood flow to Indications and contra-indications before securing the mask with the straps. the heart. If the patient is about to go into Lowered consciousness – If the patient’s circulatory shock, establishing CPAP can lead consciousness is reduced, such that the to circulatory collapse. patient risks not being able to maintain a free Major bleeding – Risk that the patient can airway, the patient should not receive CPAP. develop circulatory shock which can worsen Increased intracranial pressure – CPAP with the use of CPAP. can contribute to increased intracranial Epiglottitus – All manipulation with airways pressure because of increased intrathoracic can lead to worsening of the condition. pressure. It should not be used when there is a suspicion of head injury or brain hemorrhage. Pneumothorax – CPAP, like intubation, causes higher airway pressure which can lead to worsening of pneumothorax.

9 CPAP treatment in practice Assembly/start-up portable O the oxygen outlet in the vehicle or the ordinary with coupled is This hood. and valve, mask safety and manometer PEEP integrated with generator” “CPAP a of consists system The type. simple the of is UNN of the division ambulance for chosen have we system The flow meter. ordinary simple an to connect to that systems respirators advanced in systems. CPAP of types of number a are There Equipment is disposedofafteruse. The equipment is for one-time use and • • • • • • • • • Maximum air or O2 flow be - 30 l/minute. will pressure measured during blood the CPAP treatment. and SpO2 to reach the highest PEEP resistance. required is l/min 25 of Flow desired. the pressure PEEP the to flow the Adjust using the (when mask patient acceptsthemask). straps the accompanying Secure fits snugly. it that so patient the on mask the Put Start theflowat15l/minute. Connect thetubetoflowmeter. Choose thecorrectmasksize. patient. starting, ensure safety and inform the before available equipment all Have         

oxygen tubing directly with directly tubing oxygen 2 rm PP functions CPAP From cylinder.

Flow/PEEP resistance 10 Flow liter/minute we must keep watch on how much oxygen we oxygen much how on watch keep must we and oxygen-demanding very to is treatment the 15 use normally 25 will system CPAP Our Oxygen consumption Calculating oxygen out againstaresistance. breath to having experiences patient the and face patient’s the over snugly placed is mask the treatment, CPAP In anxiety. and agitation significant to leads often Shortness-of-breath heart and COPD failure/pulmonary edema. with connection in failure An indication for CPAP treatment is respiratory experience/communication, requirements forsuccess Patient with for pauses inthetreatment. planned be must underway oxygen bottles of replacement a transport, long For a timewecancontinuethetreatment. long how and ambulance the in available have ies f xgnmnt. hs en that means This oxygen/minute. of liters 20 liter/min 25 liter/min 10 liter/min 15 liter/min Volume xpressure=availableoxygen available oxygen 20 liter/minute liter permin 1000 liters 5 litersx200bar=1000 CPAP/PEEP = = (cm H 3.0-4.0 6.0-7.0 8.5-10 1.5-2.0 MAX treatment 2 50 minutes O) time

It is not unusual for patients to accept the the treatment occurred, show with “gaps” in the treatment poorly and try to remove the mask. line when there were pauses in the treatment, or when the treatment ended. (see table) For the treatment to succeed it is important for the patient to cooperate. Be calm and inform the patient of what is taking place. Sit together with the patient. Let the patient himself hold the mask snugly over the nose and mouth. Do not secure the mask before PEEP/CPAP pressure the patient is cooperating well and accepts the treatment. Observation and documentation Good patient examination and good observation CPAP treatment is are crucial in deciding that CPAP treatment Pause in treatment should be started. During actual treatment, good administered observation is crucial for evaluating whether the patient is getting a result from the treatment, NOTE: but also to prevent complications from arising that force us to break off or whether there is a Watch to see that the patient is exhaling through failure in the equipment which requires fixing the port in the mask/CPAP generator. In order (leaks, lack of oxygen etc.) for the patient to be able to exhale it is important that it does not become blocked! Note Also, be watchful with regard to the risk of • Consciousness, GCS should be scored, but aspiration in CPAP treatment. Never leave it is a crude tool in this situation, assess the patient during CPAP treatment! also whether the patient is beginning to be sleepy and worn out. (CPAP treatment requires that the patient is awake and can Sources of error keep the airways free.) The Flow-Safe CPAP system is very simple and • Respiratory rate (RR), Respiratory pattern easy to assemble. Nevertheless errors can arise (superficial, accessory muscles etc.), Spo2. in the system. CPAP treatment in practice • Pulse (rate, amplitude and regularity), The most frequent is leaks, most frequently skin (warm, cold, dry, clammy). Blood around the mask. If the mask does not fit tightly, pressure. there will not be the desired pressure in the system and consequently not the desired effect. • Temperature It is also important that the CPAP generator is Documentation properly connected to the mask so that there All observations and measures that are performed is no harm to the O2 tubing, and that the O2 should be documented, also CPAP treatment. tubing is firmly connected to the flow meter. The In addition to the usual vital parameters, it system also requires adequate flow to reach the is important in CPAP treatment to document desired pressure. PEEP/CPAP pressure. Pressure is given in cm H2O, also document O2 l/min, also document how long the patient receives CPAP treatment. Also, be careful to document the changes in respiration of the patient (RR. SpO2). CPAP can be looked up in the ambulance reference under the category of medications. Put in the PEEP/CPAP pressure and draw a line through the boxes for it and show when

11 REFERENCE HANDBOOK CPAP treatment (Continuous Positive Airway Pressure) CPAP provides positive airway pressure both with and . Pre-hospital CPAP care means that we can avoid intubation and long intensive care for some patients. For pulmonary edema, good results are obtained by starting CPAP treatment before beginning medicinal treatment. For COPD/asthma, inhalation treatment with salbutamol and ipratropium bromide should be attempted before beginning CPAP. Indications Serious respiratory failure and suspicion of at least one of these conditions: Pulmonary edema COPD Asthma Contra-indications Risk of aspiration Lowered consciousness Increased intracranial pressure Pneumothorax Hypotension (systolic BT <95 mmHg) Major hemorrhaging Epiglottitis Before beginning, the following should be performed: Listen to the patient Check that we have enough oxygen, and possibly make a plan to order more. Start-up • Have all equipment available for start-up, check for safety and inform the patient. • Chose the correct mask size. • Start CPAP system at a moderate setting (flow at 15 liters) • Place the mask on the patient so that it fits snugly. • When/if the patient accepts the mask, secure the mask using the accompanying straps. • Adjust to the desired PEEP pressure. Usually a pressure between 5 and 10 cm H2O • It is not unusual that patients accept the treatment poorly and attempt to remove the mask. In order for the treatment to succeed, it is important that the patient cooperate. • Be calm and inform the patient about what is happening. Sit together with the patient. Let the patient himself hold the mask tightly over the nose and mouth and do not fasten the mask on the patient before the patient cooperates well and accepts the treatment. Monitoring/Evaluation Monitoring of SaO2, BP and pulse at least every five minutes to begin with. Evaluate the treatment result continually. Pause or termination of the CPAP-treatment should be evaluated when other measures have had time to work; when the patient is improving significantly; if contra-indications arise during treatment; if the patient will not accept the mask or if the patient gets worse from the treatment.