sign in sign up
<<
Home , Airway obstruction, Oropharyngeal airway, Respiratory system, Stridor

Managing

Introduction commonly be related to the cause or dynamic situations that may rapidly Recognizing airway compromise is a fun- pathogenesis of disease process. progress from one of stability to one of a damental skill for junior doctors as they There are a large number of causes of threatened and compromised airway. As will frequently be first managing these airway obstruction (Table 1), and it is such early intubation is undertaken in patients. By appreciating the causes of an important to look out for at-risk groups in these at-risk groups. obstructed airway, treatment with whom airway compromise is more com- External compression from an adjacent and a number of simple manoeuvres can mon. Patients with a reduced conscious pathology, e.g. goitre, lymphadenopathy, be delivered swiftly, preserving airway pat- level are unable to clear their own secre- tumour and haematoma (e.g. post-thy- ency and passage of oxygen to the tions and cannot protect their own airway. roidectomy), may be insidious or rapid in for ventilation. Ventilation is the mechani- A Glasgow Scale of 8/15 or below is onset. In patients with underlying malig- cal movement of air into and out of the often considered the threshold at which nancy, it is important for clinicians to be , resulting in the intubation is necessary. Patients with vigilant in identifying features suggestive exchange of . reduced conscious level are at risk of aspi- of airway compromise. Airway obstruction results in hypoventi- ration and alveolar , with Airway obstruction may occur at any lation, increased work of and development of hypercarbia and respira- point from the down to the impaired , with development tory acidosis. and bronchial tree. The commonest site of hypercarbia and ultimately hypoxaemia In practice, a more focused approach is for obstruction in the obtunded uncon- if left untreated. Provision of supplemental taken when deciding to intubate patients, scious patient is at the , because oxygen in the setting of airway obstruction bearing in mind factors such as the poten- the falls back against the posterior (i.e. oxygenation) will not resolve the tial for further deterioration, and moving pharyngeal wall, and a lack of muscle tone problem of associated with from a place of safety to one of greater causes narrowing of the airway diameter. hypoventilation and impaired alveolar isolation (e.g. transfer from The soft tissues in the pharyx and ventilation. Obstruction may be partial or department to radiology department). In are vulnerable to swelling and oedema if complete, depending on the mechanism these instances, a more conservative traumatized, or at the site of . or cause. Complete airway obstruction approach is taken, and patients with a Post-extubation laryngeal oedema may be will rapidly cause and cardiac higher Glasgow Coma Scale may warrant seen after traumatic and multiple attempts arrest, whereas partial obstruction may be early intubation. at intubation, and in patients receiving more insidious in onset. Reduced alveolar Also, think about patients in whom prolonged periods of intubation where ventilation in the obtunded patient and surgery, trauma or may contribute high cuff may cause oedema of the obstructed airway leads to hypercap- to airway compromise, e.g. from hae- laryngeal mucosa. Local trauma following nia, and hypoxaemia. matoma and oedema. In the case of burns foreign body ingestion, e.g. a Noisy breathing characterizes a partially or history of smoke , adopt a embedded in soft pharyngeal tissues, can obstructed airway, and ominous absence high index of suspicion for airway . cause significant airway compromise, and of airway noises heralds total airway Signs such as carbonaceous , soot in some cases development of pharyngeal obstruction around the face and mouth, and singed abscess. In children, whose airways are hair warrant urgent anaesthetic input. relatively smaller, mucosal swelling, upper Causes of an obstructed airway These patients must always be assessed respiratory obstruction and may be The airway may be subdivided into upper early by an anaesthetist, as these are associated with such as laryngo- and lower airway – the upper airway com- prises the conduit from the nares and Table 1. Classifying causes of airway obstruction to the larynx, while the lower airway con- tains the tracheobronchial tree, consisting Mode of obstruction Example of 23 generations of passages from trachea Intraluminal contents , vomitus, foreign body, secretions, intraluminal tumours to alveoli. The level of obstruction will Central drive (obtunded) Head injury (with reduced conscious level), drugs: benzodiazepine, Dr Kirstie McPherson is Specialist opiates, alcohol, raised intracranial Registrar in Anaesthesia and Dr Robert External compression Haematoma, tumour, goitre CM Stephens is Consultant Anaesthetist in Direct trauma Blunt trauma to maxilla, larynx, , burns, smoke inhalation the Department of Anaesthetics, University Artificial airways Blockage or displacement of tracheostomy, displacement of tracheal stent College Hospital, London NW1 2BU Excessive granulation Prolonged , tracheal stenosis, supraglottic stenosis Correspondence to: Dr K McPherson Neurocognitive and Increased risk of aspiration, e.g. Parkinson’s disease, post-stroke, ([email protected]) neuromuscular disorders

C156 British Journal of Hospital , October 2012, Vol 73, No 10

CTD_C156_C160_Airways.indd 156 27/09/2012 15:31 Tips From The Shop Floor

tracheobronchitis () and . tive intrathoracic pressures exacerbate reservoir bag and an oxygen flow rate of The latter (seen less following the advent of extrathoracic obstruction during inspira- 15 litres/minute will provide a high inspired widespread vaccination) causes enlarge- tion. Intrathoracic obstruction may cause fraction of oxygen, and can be found on all ment of the , and may progress to expiratory stridor, as the airways are com- wards and resuscitation areas. Remember complete airway obstruction. Classically pressed during expiration. Children are blood will be restored children will adopt a sitting ‘tripod’ posi- more susceptible to stridor, given the rela- more quickly if the inspired fraction of tion, with jaw thrust forward and drooling tively smaller diameter of their airways. oxygen is high. saliva. The importance of getting expert Irritability, agitation and reduced con- The recovery (lateral) position pushes help swiftly cannot be over-emphasized if scious level commonly reflect hypoxaemia the tongue and jaw forward under gravity, these pathologies are suspected. Distress and hypercarbia. Do not rely on as improving the airway. This position is one and examination of the pharynx may pre- a feature in identifying the obstructed air- of relative safety for patients with a cipitate complete airway obstruction. Get way – this is a very late preterminal sign. depressed conscious level, e.g. as a result of help early. Observe or ask about ‘best breathing posi- alcohol excess, or in a post-ictal state. In Upper airway stimulation in the pres- tion’. Be aware that the patient may have addition, a head-down tilt (tilting facility ence of secretions or inhalation of foreign positioned him-/herself for optimal airflow available on most hospital trolleys) pro- material may cause laryngeal spasm with in the setting of airway obstruction. Moving vides passage for secretions or vomit out of adduction of the , preventing the patient into a supine position may pre- the mouth, with the help of gravity. passage of air to the lungs and leading to cipitate loss of the airway altogether. Patients with an artificial airway, e.g.

development of hypoxaemia. Low readings (SpO2) tracheostomy, with features of respiratory reflect inadequacy of oxygenation, although distress require urgent and skilled airway Recognizing airway obstruction it is important to remember that pulse help. Do not delay in summoning immedi- It is important to assess airway patency in oximetry provides a measure of oxygena- ate assistance from an anaesthetist. These any patient at risk of airway obstruction. tion and is not the same as ventilation. devices may have become blocked or dis- This forms part of the ABC approach, gas sampling may be helpful placed. Apply high flow oxygen to both the sequentially assessing airway, breathing and but should not delay management. A respi- face and the tracheostomy. circulation as described by Nolan et al ratory acidosis, with a high carbon dioxide

(2010) in life support algorithms. tension (PaCO2) and reduced pH, reflects Simple manoeuvres A conscious and alert patient, speaking alveolar hypoventilation. Simple manoeuvres in an obtunded patient in full sentences, is reassuring. Features When assessing patients look carefully may help to improve the patency of the suggestive of obstructed airway include for these and always airway, allowing passage of air into and out complete absence of airway sounds (com- call for help early from an anaesthetist if of the lungs. These are described below. plete obstruction), or added sounds of you suspect airway compromise. The Practice them on a manikin or in theatre laboured breathing where air entry is young can compensate well initially, mask- with an anaesthetist. diminished (partial obstruction). ing impending desaturation and hypoxae- Tachycardia and tachypnoea may reflect mia. Be mindful of that will com- Chin lift respiratory distress (Table 2). promise the airway, such as facial burns, Head tilt and chin lift can be used to Use of accessory muscles of is and foreign bodies obstructing relieve upper airway obstruction. Place the typical in the partially obstructed airway, the airway. Always provide high flow oxy- fingertips underneath the patient’s chin and signs include tracheal tug, paradoxical gen with a reservoir bag at 15 litres/minute, and gently lift upwards. chest and abdominal movement (‘see-saw- and reassess frequently, looking for signs of ing’), with supraclavicular and intercostal deterioration. Jaw thrust in-drawing. Stridor is the harsh, high- The jaw thrust is achieved by combined pitched sound occurring in upper airway Managing a compromised flexion of the and extension at the obstruction. Its origin is from the Latin airway atlanto-occipital , lifting the angles of stridere, ‘to creak’. Inspiratory stridor indi- is required urgently in the the mandible forward (Figure 1). This cates laryngeal obstruction, since the nega- obstructed airway. An oxygen mask with Figure 1. Jaw thrust. Table 2. Features of airway obstruction

Snoring Stridor (caused by obstruction at or above the laryngeal level) Expiratory (caused by obstruction of lower airways) Gurgling (vomit, blood or secretions in airway) Reduced conscious level ‘Tripod positioning’ seen in children (for maximal air passage to lungs)

British Journal of Hospital Medicine, October 2012, Vol 73, No 10 C157

CTD_C156_C160_Airways.indd 157 27/09/2012 15:31 manoeuvre lifts the tongue and moves the An oropharyngeal airway is sized by available on all wards and resuscitation larynx forward, allowing passage of air into measuring the distance from the incisors to areas). This will require a two-person tech- the lungs. the angle of the jaw. The most common nique to achieve a gas-tight seal between technique for placing an oropharyngeal the patient’s face and the mask, enabling Cautionary points airway is by inserting the airway into the ventilation without leak. One person Avoid neck extension and risks to the spi- mouth upside-down, and then rotating should hold the mask onto the face, main- nal cord in patients in whom a cervical through 180° at the junction between the taining a jaw thrust, while the assistant spine injury is suspected. In these patients soft and hard palate. The airway is then squeezes the bag. jaw thrust in combination with manual advanced until it rests in the pharynx. in-line stabilization is recommended. Suction should always be available to clear Upward pressure on the soft tissues of the the airway of any visible secretions or for- Should bag-valve-mask ventilation prove floor of the mouth in young children can eign body. difficult with the two-person technique cause obstruction. Be mindful of this when Conscious patients, in whom laryngeal and the use of the oropharyngeal airway performing jaw thrust in this population. reflexes are present, will not tolerate an adjunct, alternative means of ventilation oropharyngeal airway and inserting one are needed. In these instances, senior sup- Adjuncts may precipitate gagging, vomiting and port should be sought early, with involve- The oropharyngeal airway (Guedel) and . ment of an anaesthetist with expert airway are simple adjuncts, management skills. useful in maintaining a patent airway Bag-valve-mask ventilation The laryngeal mask airway is a device for (Figure 2). They relieve backward tongue Patients with reduced conscious level and supporting and maintaining the airway displacement and soft palate obstruction. inadequate spontaneous ventilation will without . It does not Careful insertion under direct vision is require in addition to protect the airway from soiling unlike tra- important. Avoid using a nasopharyngeal the manoeuvres described above. Connect cheal intubation and is not a secure airway. airway in patients for whom a base of a bag-valve-mask apparatus (ambu-bag) to However, it may serve as an interim meas- fracture or coagulopathy is suspected. a high flow oxygen source (this should be ure in the unconscious patient, when intu- bation has failed, or lack of skill and experi- Figure 2. Adjuncts for supporting airway and laryngeal mask. a. Bag-valve-mask system with high flow ence precludes intubation. The head of the oxygen source. b. Oropharyngeal and nasopharyngeal airways. c. Laryngeal mask. d. Wide-bore rigid laryngeal mask is inserted into the mouth sucker. to lie against the back of the pharynx. A circumferential cuff is then inflated to pro- vide an adequate seal to enable ventilation. The end can then be connected to an ambu-bag device to provide artificial venti- lation. Incorrect placement increases the risk of aspiration of contents, as the stomach may become gas-filled during ventilation. The laryngeal mask does not guarantee protection from aspiration of gastric con- tents into the bronchial tree and will not be tolerated in patients in whom laryngeal reflexes are preserved. Again, try to famil- iarize yourself with the insertion tech- nique with practice on a manikin, or under supervision from an anaesthetist in theatre. Securing an airway A secure airway is one in which the trachea and bronchial tree are protected from aspi- ration of gastric contents or secretions by the presence of a cuffed endotracheal tube (or a tracheostomy). This is the gold stand- ard for an unconscious patient at risk of aspiration, but should only be attempted a b c d by those trained and familiar with the tech- nique of tracheal intubation. This will

C158 British Journal of Hospital Medicine, October 2012, Vol 73, No 10

CTD_C156_C160_Airways.indd 158 27/09/2012 15:31 Tips From The Shop Floor

most frequently be the anaesthetist, and it and relaxation of the vocal cords must be rupture of the oesophagus. Pressure is is important to stress again the importance provided for passage of the endotracheal applied until the anaesthetist has con- of calling early for help and advice from an tube into the trachea. Given the risk of firmed placement of the endotracheal tube anaesthetist in patients with a reduced con- aspiration in a population presenting with the cuff inflated. Incorrectly per- scious level. with reduced conscious level, a rapid formed cricoid pressure may distort the Meticulous attention to detail is needed sequence induction provides these opti- laryngeal , making successful when preparing for intubation, to avoid mal conditions in the larynx with rapid extremely difficult for the mishaps and potentially life-threatening onset. operator. consequences of aspiration and hypoxia. Preparation is vital for rapid sequence A rapid sequence induction comprises Equipment required for intubation induction, as the anaesthetist needs to quick intravenous induction of anaesthesia includes an appropriately sized endotra- react quickly in the event of aspiration. and neuromuscular blockade facilitating cheal tube, a tie to secure it, a laryngoscope Drugs are prepared beforehand and the intubation. Following administration of (with alternative blade size available), and tilting capacity of the trolley is confirmed, these drugs, laryngoscopy may be per- equipment on standby should intubation with suction (wide bore rigid sucker) formed securing the airway with a cuffed prove difficult (Figure 3). This includes a under the pillow (important in the event endotracheal tube in the trachea to prevent gum-elastic bougie, and alternative means of aspiration). further soiling of the airway. of ventilating, e.g. with a laryngeal mask The patient is preoxygenated with a The combination of thiopentone and airway. An ambu-bag or alternative means tight-fitting mask, for at least 3 minutes or suxamethonium have been described in of ventilation connected to a high flow until end-tidal oxygen fraction >0.8. the classical rapid sequence induction, oxygen source will be connected to the Reassure the patient about what is hap- and while still in use, a greater variety of endotracheal tube once in place. Guidelines pening and when possible explain your drugs are now used in a modified rapid published by the Difficult Airway Society actions, as this will be an alarming time for sequence induction, largely for their supe- (Henderson et al, 2004) provide algo- the patient. Before loss of consciousness, rior side-effect profile, as demonstrated by rithms on procedure for failed intubation, cricoid pressure is applied – pressure with Morris and Cook (2001) in a national and it is advisable to be familiar with these the thumb and index finger over the cri- survey of practice of the technique. A if you have responsibility for managing coid (used since it forms the only predetermined dose of induction agent is airways in patients. complete ring of the larynx and trachea). administered, followed by a muscle relax- Most importantly, a trained anaesthetic Pressure over this cartilage displaces the ant, with rapid onset of action. This nurse or practitioner must assist, and all larynx backwards, compressing the negates the need to provide facemask ven- equipment needs checking and carefully oesophagus between the cricoid cartilage tilation while waiting for onset of neu- assembly before commencing intubation. and the vertebrae behind. This prevents romuscular blockade, which risks insuffla- In an emergency setting, where patients passive regurgitation of gastric contents tion of the stomach and aspiration of its are not starved and are at risk of aspira- during induction of anaesthesia. In the contents. The choice of drugs used will tion, a rapid sequence induction for tra- event of active vomiting, cricoid pressure depend on both the pharmacodynamic cheal intubation is performed. Anaesthesia should be released, as this could cause characteristics and the experience of the doctor. The dose should reflect the Figure 3. Equipment required for intubation. a. Gum elastic bougie. b. Suxamethonium and thiopentone. haemodynamic status of the patient, and c. Endotracheal tube with tie and syringe to inflate cuff. d. Laryngoscope. e. Wide bore rigid sucker. hypotension should be anticipated, with readily available provision for vasopressors and sufficient intravenous access to opti- mize preload. After successful intubation with connec- a tion of the to a ventilating device, checks must be carried out to con- firm correct placement of the tube in the trachea. These include of both lungs, observing chest movement, fogging of the tube as warm humidified air is expired from the lungs and confirming the presence of end-tidal car- d bon dioxide. Consecutive breaths seen on capnography remain the gold standard for ruling out oesophageal intubation, and b c e guidelines published by the Association of Anaesthetists of Great Britain and Ireland (2011) require its provision for all anaes- thetized patients and those undergoing

British Journal of Hospital Medicine, October 2012, Vol 73, No 10 C159

CTD_C156_C160_Airways.indd 159 27/09/2012 15:31 advanced life support, regardless of the plications in the intensive care unit and the Many of the key findings of the report location of the patient. A flat capnograph . Several major relate specifically to the vigilant approach trace indicates lack of ventilation of the events occurred when there were clear indi- that must be taken when performing rapid lungs: the tube is either not in the trachea cations for a rapid sequence induction but sequence induction in the emergency or the airway is completely obstructed. this was not performed. Failure to correctly department and in settings outside of the Only when you are satisfied with the cor- interpret a capnograph trace led to several safer confines of the anaesthetic room. rect placement of the endotracheal tube, oesophageal intubations going unrecog- Most events in the emergency department should you ask the assistant to release the nized. The absence of capnography, or the were complications of rapid sequence cricoid pressure. failure to use it properly, contributed to induction. Rapid sequence induction out- Failure to identify an endotracheal tube 80% of deaths from airway complications side the operating theatre requires the same misplaced in the oesophagus will lead to in the intensive care unit and 50% of level of equipment and support as is need- life-threatening hypoxia. The National deaths from airway complications in the ed during anaesthesia. This includes cap- Audit Project on emergency department. Active efforts nography and access for equipment needed (Cook et al, 2011) found evidence of should be taken to positively exclude these to manage routine and difficult airway avoidable deaths as a result of airway com- diagnoses. problems. Conclusions KEY POINTS Recognizing and acting on airway compro- n Be aware of features of airway compromise, and identify and treat patients with airway obstruction mise reduces morbidity and mortality in early. patients. Pulse oximetry is a poor indicator of airway compromise, and falling arterial n Call for help early from an anaesthetist, and anticipate deterioration in patients with airway haemoglobin oxygen saturation reflects compromise. depleted stores of oxygen in the lungs and n Use of simple airway manoeuvres, with basic adjuncts (as required), will often achieve a patent is a late sign of impending hypoxaemia. airway. Basic airway manoeuvres (with supplemen- tary oxygen) will often improve the paten- n Remember, oxygenation is paramount. Make every attempt to provide high oxygen to cy of an obstructed airway. Getting help patients in whom airway compromise is suspected. from an anaesthetist early is a priority. n Delivering oxygen at the mouth that does not reach the alveolus is not a treatment for airway Before definitive control of the airway is obstruction. These patients require artificial ventilation for adequate gas exchange. possible, provide 100% oxygen with a tight-fitting mask to optimize body oxygen n Call for help early, and prepare for intubation in a timely fashion. stores. BJHM n Recognize the dangerous sequelae of hypoxia and aspiration. Expert help from an anaesthetist will help reduce these risks. Conflict of interest: none.

n Practice in a simulation centre and in theatre, with an anaesthetist, will improve your skills in Association of Anaesthetists of Great Britain & recognizing, managing and treating these patients. Ireland (2011) AAGBI safety statement capnography outside the operating theatre. Updated statement from the Association of Anaesthetists of Great Britain & Ireland (AAGBI) May 2011. www.aagbi.org/sites/default/files/ Safety%20Statement%20-%20The%20use%20 TOP TIPS of%20capnography%20outside%20the%20 operating%20theatre%20May%202011_0.pdf n Check all your equipment before using it; inflate and deflate cuffs of laryngeal mask and (accessed 24 July 2012) endotracheal tubes and lubricate well with jelly. Cook TM, Woodall N, Harper J et al (2011) Fourth National Audit Project. Major n Always have a variety of sizes available for laryngeal mask or endotracheal tube and oropharyngeal complications of airway management in the UK: results of the Fourth National Audit Project of airway insertion. the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care n Familiarize yourself with the ‘kit’ available in your own hospital, including that available on airway and emergency departments. Br J Anaesth 106: trolleys in the emergency department and on the resuscitation trolleys found on the wards. 632–42 Henderson JJ, Latto IP, Pearce AC, Popat MT n Think carefully about the safety of your patient when planning a transfer, within or outside of the (2004) Difficult Airway Society guidelines for hospital. Is the airway protected or at risk? An anaesthetist should assess and may decide to management of the unanticipated difficult intubation. Anaesthesia 59: 675–94 pre-emptively secure the airway with an endotracheal tube and artificial ventilation. Morris J, Cook TM (2001) Rapid sequence n induction: a national survey of practice. When performing preoxygenation for rapid sequence induction, position the patient semi-inclined, Anaesthesia 56: 1090–7 with ‘head up’ and a tight seal around the face mask to maximize body oxygen stores once the Nolan JP, Soar J, Zideman DA et al (2010) patient is apnoeic. European resuscitation council guidelines for resuscitation 2010 section 1 Executive summary. Resuscitation 81: 1219–76

C160 British Journal of Hospital Medicine, October 2012, Vol 73, No 10

CTD_C156_C160_Airways.indd 160 27/09/2012 15:31