Patients with severe asthma exacerbations, status asthmaticus (SA), or near-fatal asthma, account for almost 2 million emergency department visits annually in the United States, 497,000 hospital admissions, and 5000 deaths. Approximately, 2% to 70% (mean, 30%) of ICU admissions for asthma require mechanical ventilation, and the mortality rate of mechanically ventilated patients can range from 6% to 42% in high-risk populations. Risk stratifying patients presenting with a severe exacerbation is difficult.
In this article, the pathophysiology of near-fatal asthma and SA is reviewed. Many patients who died of SA lack the typical risk factors for death. The 2 phenotypes of severe asthma (acute and subacute onset) are similar with respect to presenting signs but their demographics and rate of decline differ after illness onset. The clinical evaluation and risk stratification of patients presenting with severe asthma exacerbations are a vital and challenging component of their care.
The rational use of inhaled and systemic therapies is also required to minimize complications and maximize benefits. Strategies for the use of mechanical ventilation that minimize the risk of barotrauma and use of permissive hypercapnia are a key to reduce mortality. The use of extrinsic positive end expiratory pressure is not contraindicated and may benefit a subset of patients. At this time, the use of noninvasive mechanical ventilation in the most severe asthma exacerbations cannot be recommended. The use of sedatives, inhalational anesthetics, and paralytics as adjuncts to mechanical ventilation have potential risks and their use must be individualized.