LARYNGEAL OEDEMA DEFINITION Laryngeal oedema is a condition characterized by acute or gradual onset with swelling of the larynx (vocal cords), and causing hoarseness, resonant barky cough, stridor and moderate to severe respiratory distress. TOXIC CAUSES (Partial list - many compounds) Ammonia vapour Chlorine gas Mustard gas and other irritants used as chemical weapons Tear gases Dusts, mists and vapours of strong acids, alkali, and other corrosive or irritating compounds NON-TOXIC CAUSES Anaphylaxis Infections (croup, epiglottitis) Thermal burns Trauma CLINICAL FEATURES Stridor and hoarseness are the principle findings. Other features include tachypnoea, respiratory distress, and painful cough. Forceful coughing or straining may produce facial petechiae and subconjunctival haemorrhage. Sudden laryngospasm or complete airway obstruction may occur, leading to acute hypoxaemia and death. There is often other evidence of acute irritant chemical exposure, such as conjunctival redness and excessive tearing, and sore throat. DIFFERENTIAL DIAGNOSIS Asthma Diphtheria Foreign body Laryngeal cysts and tumours RELEVANT INVESTIGATIONS Blood gases: if there is evidence of acute respiratory distress (findings may include decreased pH, decreased pO2, decreased or increased pCO2) X-ray of larynx and chest Laryngoscopy (perform with caution) TREATMENT Humidified oxygen Tracheal intubation or tracheotomy for patients with impending airway obstruction or severe hypoxaemia. Nebulized racemic epinephrine (adrenalin) may be a useful temporizing measure if laryngeal oedema is caused by acute allergic angioedema or viral croup, and is of potential value in the management of toxic laryngeal oedema associated with hyperaemia. The dose of nebulized racemic epinephrine is 0.05 mLs/kg to a maximum of 1.5 mLs diluted in normal saline to a volume of 5 mLs. Oxymetazoline may serve as an alternative if racemic epinephrine is not available. Corticosteroids are of uncertain value and even when injected intravenously have a delayed onset of effect of several hours. CLINICAL COURSE AND MONITORING Frequent re-evaluation of airway patency Vital signs Pulse oximetry LONG-TERM COMPLICATIONS Permanent damage to the larynx Brain damage from hypoxia AUTHOR(S)/REVIEWERS Author: Dr Anthony Wong, Director, Jabaquara Poisons Centre, Sao Paulo, Brazil. Peer review: Cardiff 9/96: V. Afanasiev, M. Burger, T. Della Puppa, L. Fruchtengarten, K. Olsen, J. Szajewski.