Managing airway obstruction Introduction commonly be related to the cause or dynamic situations that may rapidly Recognizingairwaycompromiseisafun- pathogenesisofdiseaseprocess. progressfromoneofstabilitytooneofa 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.Byappreciatingthecausesofan importanttolookoutforat-riskgroupsin theseat-riskgroups. obstructedairway,treatmentwithoxygen whom airway compromise is more com- Externalcompressionfromanadjacent andanumberofsimplemanoeuvrescan mon. Patients with a reduced conscious pathology, e.g. goitre, lymphadenopathy, bedeliveredswiftly,preservingairwaypat- level are unable to clear their own secre- tumour and haematoma (e.g. post-thy- ency and passage of oxygen to the lungs tionsandcannotprotecttheirownairway. roidectomy),maybeinsidiousorrapidin forventilation.Ventilationisthemechani- AGlasgowComaScaleof8/15orbelowis onset.Inpatientswithunderlyingmalig- cal movement of air into and out of the often considered the threshold at which nancy,itisimportantforclinicianstobe respiratory system, resulting in the intubation is necessary. Patients with vigilant in identifying features suggestive exchangeofcarbondioxide. reducedconsciouslevelareatriskofaspi- ofairwaycompromise. Airwayobstructionresultsinhypoventi- ration and alveolar hypoventilation, with Airway obstruction may occur at any lation, increased work of breathing and development of hypercarbia and respira- pointfromthemouthdowntothetrachea impairedgasexchange,withdevelopment toryacidosis. and bronchial tree. The commonest site ofhypercarbiaandultimatelyhypoxaemia Inpractice,amorefocusedapproachis for obstruction in the obtunded uncon- ifleftuntreated.Provisionofsupplemental takenwhendecidingtointubatepatients, scious patient is at the pharynx, because oxygeninthesettingofairwayobstruction bearinginmindfactorssuchasthepoten- thetonguefallsbackagainsttheposterior (i.e. oxygenation) will not resolve the tialforfurtherdeterioration,andmoving pharyngealwall,andalackofmuscletone problem of hypercapnia associated with from a place of safety to one of greater causesnarrowingoftheairwaydiameter. hypoventilation and impaired alveolar isolation (e.g. transfer from resuscitation Thesofttissuesinthepharyxandlarynx ventilation.Obstructionmaybepartialor 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 infection. or cause. Complete airway obstruction approach is taken, and patients with a Post-extubationlaryngealoedemamaybe will rapidly cause hypoxia and cardiac higherGlasgowComaScalemaywarrant seenaftertraumaticandmultipleattempts arrest,whereaspartialobstructionmaybe earlyintubation. at intubation, and in patients receiving moreinsidiousinonset.Reducedalveolar Also, think about patients in whom prolonged periods of intubation where ventilation in the obtunded patient and surgery, trauma or burns may contribute highcuffpressuresmaycauseoedemaof the obstructed airway leads to hypercap- to airway compromise, e.g. from hae- laryngealmucosa.Localtraumafollowing nia,respiratoryacidosisandhypoxaemia. matomaandoedema.Inthecaseofburns foreign body ingestion, e.g. a fish bone Noisy breathing characterizes a partially or history of smoke inhalation, adopt a embeddedinsoftpharyngealtissues,can obstructed airway, and ominous absence highindexofsuspicionforairwayinjury. causesignificantairwaycompromise,and of airway noises heralds total airway Signssuchascarbonaceoussputum,soot insomecasesdevelopmentofpharyngeal obstruction around the face and mouth, and singed abscess. In children, whose airways are hair warrant urgent anaesthetic input. relativelysmaller,mucosalswelling,upper Causes of an obstructed airway These patients must always be assessed respiratoryobstructionandstridormaybe Theairwaymaybesubdividedintoupper early by an anaesthetist, as these are associatedwithinfectionssuchaslaryngo- andlowerairway–theupperairwaycom- prisestheconduitfromthenaresandlips Table 1. Classifying causes of airway obstruction tothelarynx,whilethelowerairwaycon- tainsthetracheobronchialtree,consisting Mode of obstruction Example of23generationsofpassagesfromtrachea Intraluminal contents Blood, 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 pressure Registrar in Anaesthesia and Dr Robert External compression Haematoma, tumour, goitre CM Stephens is Consultant Anaesthetist in Direct trauma Blunt trauma to maxilla, larynx, mandible, 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 tissue Prolonged mechanical ventilation, 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 myasthenia gravis C156 BritishJournalofHospitalMedicine,October2012,Vol73,No10 CTD_C156_C160_Airways.indd 156 27/09/2012 15:31 Tips From The shop Floor tracheobronchitis (croup) and epiglottitis. tive intrathoracic pressures exacerbate reservoir bag and an oxygen flow rate of Thelatter(seenlessfollowingtheadventof extrathoracic obstruction during inspira- 15litres/minutewillprovideahighinspired widespread vaccination) causes enlarge- tion. Intrathoracic obstruction may cause fractionofoxygen,andcanbefoundonall mentoftheepiglottis,andmayprogressto expiratorystridor,astheairwaysarecom- wards and resuscitation areas. Remember complete airway obstruction. Classically pressed during expiration. Children are blood oxygen saturation will be restored childrenwilladoptasitting‘tripod’posi- moresusceptibletostridor,giventherela- more quickly if the inspired fraction of tion,withjawthrustforwardanddrooling tivelysmallerdiameteroftheirairways. oxygenishigh. saliva. The importance of getting expert Irritability, agitation and reduced con- The recovery (lateral) position pushes helpswiftlycannotbeover-emphasizedif sciouslevelcommonlyreflecthypoxaemia thetongueandjawforwardundergravity, these pathologies are suspected. Distress andhypercarbia.Donotrelyoncyanosisas improvingtheairway.Thispositionisone andexaminationofthepharynxmaypre- afeatureinidentifyingtheobstructedair- of relative safety for patients with a cipitate complete airway obstruction. Get way–thisisaverylatepreterminalsign. depressedconsciouslevel,e.g.asaresultof helpearly. Observeoraskabout‘bestbreathingposi- 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 enceofsecretionsorinhalationofforeign positionedhim-/herselfforoptimalairflow available on most hospital trolleys) pro- material may cause laryngeal spasm with inthesettingofairwayobstruction.Moving videspassageforsecretionsorvomitoutof adduction of the vocal cords, preventing thepatientintoasupinepositionmaypre- themouth,withthehelpofgravity. passageofairtothelungsandleadingto cipitatelossoftheairwayaltogether. Patients with an artificial airway, e.g. developmentofhypoxaemia. Low pulse oximetry readings (SpO2) tracheostomy, with features of respiratory reflectinadequacyofoxygenation,although distress require urgent and skilled airway Recognizing airway obstruction it is important to remember that pulse help.Donotdelayinsummoningimmedi- Itisimportanttoassessairwaypatencyin 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. devicesmayhavebecomeblockedordis- This forms part of the ABC approach, Arterialbloodgassamplingmaybehelpful placed.Applyhighflowoxygentoboththe sequentiallyassessingairway,breathingand butshouldnotdelaymanagement.Arespi- faceandthetracheostomy. circulation as described by Nolan et al ratoryacidosis,withahighcarbondioxide (2010)inlifesupportalgorithms. tension(PaCO2)andreducedpH,reflects Simple manoeuvres A conscious and alert patient, speaking alveolarhypoventilation. Simplemanoeuvresinanobtundedpatient 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 signs and symptoms and always airway,allowingpassageofairintoandout completeabsenceofairwaysounds(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 Practicethemonamanikinorintheatre laboured breathing where air entry is youngcancompensatewellinitially,mask- withananaesthetist. diminished (partial obstruction). ingimpendingdesaturationandhypoxae- Tachycardia and tachypnoea may reflect mia.Bemindfulofinjuriesthatwillcom- Chin lift respiratorydistress(Table 2). promise the airway, such as facial burns, Head tilt and chin lift can be used to Useofaccessorymusclesofrespirationis bleeding and foreign bodies obstructing relieveupperairwayobstruction.Placethe typical in the partially obstructed airway, theairway.Alwaysprovidehighflowoxy-