Management of acute severe asthma

This review presents a consensus on the emergency management of adult asthma. Management is discussed under six headings: assessment, asthma treatment, supportive treatment, complications, precipitating cause, and disposition/followup; the first four are undertaken concurrently.

The framework for this review is the 1994 "Guidelines for Emergency Management of Adult Asthma" produced by the Canadian Association of Emergency Physicians in collaboration with the Canadian Thoracic Society. This document is supported by 144 English language references in humans.

Papers were selected to emphasize the major points of consensus. About 25% of the above references were included in the bibliography.

Rapid assessment of the severely ill asthmatic patient must include objective features: vital signs, pulsus paradoxus, oxygen saturation, and expiratory flow rates. Asthma therapy should commence immediately with inhaled beta 2 agonist and systemic or ingested corticosteroid; inhaled anticholinergic is added initially or as early second-line treatment. Supportive treatment includes oxygenation, fluid-electrolyte balance, and nonpharmacologic relief of anxiety. When necessary, mechanical ventilation allowing "permissive hypercapnia" using low peak airway pressure (low volume and slow inspiratory flow rate) reduces the risk of barotrauma; the PaO2 and pH are maintained while allowing PaCO2 to rise. Early recognition and treatment of complications, especially pneumothorax, can be life-saving. Identification of precipitating factor(s) occasionally dictates initial therapy (anticholinergic for beta blocker-induced bronchospasm, epinephrine for asthma accompanying a systemic allergic reaction), but is most important as the first step to preventing future episodes. Disposition should be based on objective measurement of flow rates.

Aggressive rapid management of severe asthma by these or similar guidelines should improve morbidity and mortality.