Airway obstruction

Airway obstruction is blockage of airflow in the upper airway (mouth to the trachea) or, less often, in the large bronchi. It can kill within minutes.

Level and degree.

• Supraglottic and pharyngeal: tongue fall back, swelling, infection, foreign body.
• Glottic: laryngeal oedema, vocal cord paralysis, laryngospasm, trauma, tumour.
• Subglottic and tracheal: croup, bacterial tracheitis, stenosis, compression, foreign body.
• Complete obstruction: no air movement, no voice, no cough, cyanosis, loss of consciousness.
• Partial obstruction: stridor, effective cough, ability to speak, with risk of tiring.

Mechanisms. Mechanical blockage (food, object), inflammation and oedema (allergic, infective, thermal, caustic), external compression (haematoma, mass, abscess), neurological or muscular loss of tone (reduced consciousness, vocal cord paralysis), and reflex closure (laryngospasm).

Key distinctions. Inspiratory stridor suggests obstruction at the glottis or higher in the airway, biphasic stridor suggests the glottis or subglottis, and expiratory wheeze suggests intrathoracic or lower airway obstruction. Quiet breathing with a high respiratory effort, a silent chest, drowsiness or a falling oxygen saturation signals imminent arrest and not improvement.

Immediate assessment (seconds). Is the patient able to speak, cough and breathe? Look for the universal choking sign (hands at the throat), cyanosis, paradoxical chest and abdominal movement, accessory muscle use and agitation or drowsiness.

History.

• Sudden onset while eating or with an object in the mouth (foreign body), allergen exposure (anaphylaxis), new drug (ACE inhibitor, angiotensin receptor blocker), previous angioedema or family history.
• Fever, sore throat, drooling, muffled voice, dysphagia, trismus, neck swelling (infection), recent dental infection, recent intubation or tracheostomy.
• Smoke or fire exposure, caustic ingestion, neck injury, recent neck or thyroid surgery.
• Hoarseness, weight loss, smoking (tumour), prolonged intubation (stenosis), neuromuscular disease, sleep apnoea and sedatives.

Examination.

• Respiratory rate, saturation, pulse, blood pressure, position (tripod, sitting forward), voice, stridor, drooling.
• Mouth, lips, tongue, uvula, floor of mouth, neck (swelling, crepitus, wounds, haematoma, tracheal deviation), singed facial hair, soot, burns, and chest signs.
• Do not examine the throat with a spatula or lie flat a patient with suspected epiglottitis, and do not upset a child, because these can precipitate complete obstruction.

Red flags.

• Stridor at rest, tripod posture, drooling, inability to speak or swallow saliva.
• Expanding neck haematoma, subcutaneous emphysema, facial burns or soot in the airway.
• Cyanosis, saturation under 90%, drowsiness, exhaustion, silent chest.
• Rapidly progressive swelling after a known trigger.

Special groups. Children: smaller airway with less reserve, epiglottitis is rare after vaccination, croup and foreign body are common. Pregnancy: oedema and difficult airway. Older adults: dentures, dysphagia and neurological disease. Region specific: diphtheria, retropharyngeal tuberculosis and deep neck abscess.

Foreign body. Food bolus, objects in children, dentures, vomit and blood, endobronchial foreign body.

Allergic and angioedema. Anaphylaxis, ACE inhibitor associated angioedema, hereditary angioedema, acquired C1 esterase inhibitor deficiency, idiopathic angioedema.

Infection. Epiglottitis (supraglottitis), croup, bacterial tracheitis, peritonsillar abscess, retropharyngeal abscess, parapharyngeal abscess, Ludwig angina, diphtheria, infectious mononucleosis with tonsillar enlargement.

Trauma and thermal. Laryngeal fracture, tracheal injury, neck haematoma after thyroid or carotid surgery or anticoagulation, inhalation injury, facial burns, caustic ingestion.

Neoplastic and structural. Laryngeal cancer, hypopharyngeal cancer, thyroid cancer, goitre, lymphoma and mediastinal mass, tracheal tumour, subglottic stenosis, tracheomalacia, laryngeal papillomatosis.

Neurological and functional. Bilateral vocal cord paralysis, laryngospasm, reduced consciousness with tongue fall back, neuromuscular disease, vocal cord dysfunction, anxiety related breathing.

Iatrogenic. Blocked or displaced tracheostomy, post extubation stridor, obstructed endotracheal tube, bronchial mucus plug.

Lower airway mimics. Severe asthma, chronic obstructive pulmonary disease, tension pneumothorax, pulmonary oedema.

Immediate. Diagnosis is clinical. Give oxygen and call the most skilled airway operator (anaesthesia, ENT, emergency medicine) before any tests. Continuous saturation and capnography when available.

Once the airway is secured or the patient is stable.

• Flexible nasendoscopy by an experienced clinician in a setting prepared for immediate intubation or surgical airway: oedema, epiglottis, vocal cord movement, tumour, foreign body.
• Lateral soft tissue neck radiograph has limited sensitivity and must not delay care. CT neck with contrast only when the airway is secure and the patient can lie flat (abscess, mass, haematoma, trauma). Chest radiograph for aspiration, pneumothorax and mediastinal mass. CT chest for tracheal and bronchial lesions.
• Blood gas, full blood count, CRP, blood cultures, throat swab (Corynebacterium diphtheriae where relevant), tryptase for allergic causes, glucose.
• Laryngoscopy or bronchoscopy under anaesthesia for biopsy, foreign body retrieval or stenosis assessment.

Limitations. Saturation falls late. Radiographs can be normal in foreign body obstruction (most objects are radiolucent). Examining or lying flat a patient with epiglottitis can precipitate complete obstruction.

Complete foreign body obstruction in an adult or child over 1 year.

• If the patient is conscious and cannot cough: 5 back blows between the shoulder blades, then 5 abdominal thrusts, alternating until the object is cleared or the patient becomes unconscious. Use chest thrusts in pregnancy and marked obesity.
• If unresponsive: start cardiopulmonary resuscitation (30 compressions to 2 breaths), looking in the mouth before each breath, and remove only visible objects. Direct laryngoscopy with Magill forceps by a trained operator.
• Infants: 5 back blows with the infant head down, then 5 chest thrusts (no abdominal thrusts).

Partial obstruction.

• Allow the patient to find a position of comfort (sitting forward), give high flow oxygen, keep the patient calm and avoid distressing procedures. Encourage coughing for a foreign body. Heliox (70% helium with 30% oxygen) may buy time if available.
• Prepare the airway team, equipment for intubation, video laryngoscope, bougie, smaller tubes and front of neck access, before any intervention.

Airway securing.

• Anticipated difficult airway: awake fibreoptic intubation or inhalational induction in an operating theatre by the most experienced operator, with a surgeon ready for tracheostomy (the double set up). Avoid neuromuscular blockade until the airway is judged safe to lose.
• Rapid sequence intubation for others: ketamine 1 to 2 mg/kg IV (0.5 to 1 mg/kg in shock) and rocuronium 1.2 mg/kg IV, with suxamethonium 1.5 mg/kg IV only if no contraindication (hyperkalaemia, burns or crush injury beyond 24 hours, denervation, neuromuscular disease, malignant hyperthermia risk); sugammadex 16 mg/kg IV reverses rocuronium in a failed airway; monitor blood pressure after induction.
• Can't intubate, can't oxygenate: front of neck access with a scalpel, bougie and cuffed 6.0 mm tube (horizontal stab incision through the cricothyroid membrane, rotate the blade, pass the bougie, railroad the tube), without delay. In children under 12 years use needle cricothyroidotomy with a 14 G cannula and a high pressure oxygen source, with a surgical tracheostomy to follow.
• Blocked tracheostomy: remove the inner tube, suction, deflate the cuff, remove the tube if still blocked, then oxygenate through the mouth and the stoma.
• Post thyroid or neck surgery haematoma: open the wound at the bedside at once and evacuate the haematoma, then intubate.

Cause directed treatment.

• Anaphylaxis or angioedema: adrenaline 0.5 mg IM (0.5 mL of 1 mg/mL) repeated every 5 minutes, nebulised adrenaline 5 mg (5 mL of 1 mg/mL) every 15 to 20 minutes for airway oedema, oxygen, and IV fluids. Hereditary or ACE inhibitor associated angioedema: icatibant 30 mg subcutaneously, or C1 esterase inhibitor concentrate 20 units/kg IV, with early intubation if the airway is threatened; stop the ACE inhibitor.
• Croup in a child: dexamethasone 0.15 mg/kg orally as a single dose (up to 0.6 mg/kg in severe disease; maximum 10 mg), nebulised adrenaline 5 mg (5 mL of 1 mg/mL) for stridor at rest with observation of at least 2 to 4 hours after because of rebound, and oxygen if saturation is under 92%.
• Epiglottitis and deep neck infection: secure the airway in theatre first, then ceftriaxone 2 g IV once daily (children 50 to 80 mg/kg IV once daily, maximum 4 g daily); monitor creatinine and diarrhoea; add metronidazole 500 mg IV every 8 hours (maximum 1.5 g daily; monitor for neuropathy and reduce in severe liver impairment) for deep neck abscess; surgical drainage of abscess; dexamethasone 10 mg IV once for severe oedema (evidence is limited).
• Inhalation injury: early intubation for stridor, hoarseness, facial burns, soot in the airway or carbonaceous sputum, with 100% oxygen for suspected carbon monoxide exposure.
• Caustic ingestion: airway protection first, no induced vomiting or neutralisation, and urgent endoscopy.
• Tumour or compression: dexamethasone 8 to 16 mg IV once then 4 mg every 6 hours (monitor glucose and gastric protection with omeprazole 20 mg daily), specialist airway stenting, radiotherapy or surgery.
• Upper airway obstruction from sedation and sleep apnoea: jaw thrust, airway adjuncts, reverse opioid with naloxone 0.4 mg IV titrated (0.04 to 0.1 mg increments in chronic opioid users; maximum about 10 mg).

Monitoring. Continuous saturation, capnography, ECG and blood pressure. Frequent reassessment of stridor, voice and work of breathing, with the airway kit at the bedside. Post extubation stridor: observe for 24 hours after extubation, give dexamethasone 4 to 8 mg IV every 6 hours for 24 hours when risk of oedema is high, and prepare to reintubate.

Referral and escalation. Anaesthesia, ENT and critical care at first recognition. Thoracic surgery for tracheal lesions. Paediatric airway team for children. Poison centre for caustic ingestion. Allergy services after anaphylaxis.

Admission criteria. All patients with stridor, airway swelling, infection or a retrieved foreign body with continuing symptoms are observed or admitted, with critical care for any threatened airway. A patient who coughed up a small food bolus and is asymptomatic after a period of observation may go home, though objects that may have been aspirated need bronchoscopy.

Discharge and safety netting. Discharge only when the airway is secure, the cause is treated and a plan is in place. Patients are told to return for noisy breathing, voice change, drooling, difficulty swallowing, breathlessness or swelling. Teach choking first aid to families and carers, and provide adrenaline auto-injectors and an action plan after anaphylaxis.