Mechanical Ventilation for Acute Asthma Exacerbations

Abstract

The prevalence and incidence of asthma are high in the Western world, and increasing in developing countries [1]. The risk of an acute attack increases with poor control of the disease, being greater in patients with low socioeconomic stratus and in patients with poor compliance of treatment. Among those patients suffering an acute exacerbation, the risk of needing intensive care unit (ICU) management ranges from 4 to 7 % of all asthma admissions. Mechanical ventilation is required in about 30 % of patients admitted to an ICU [2], and it has been estimated that 6,000–10,000 patients require mechanical ventilation for acute asthma in the United States each year [3]. Mortality is low for acute exacerbations, but increases up to 8 % when mechanical ventilation is required [4], and as the patients at risk are usually young, the social impact is not depreciable. The risk of death depends on the severity of the attack, with the rapidity of onset of the crisis and the response to treatment being crucial. Most deaths are related to the occurrence of cardiac arrest before reaching medical assistance, caused either by cardiac arrhythmias or by severe airflow limitation and hypoxemia leading to muscle exhaustion and respiratory arrest [5]. Another subset of deaths can be related to inappropriate recognition of the severity of the attack and, thus, to inappropriate management, particularly of the mechanical ventilation. Therefore, early identification of the severity and rapidtransfer to an emergency department for early initiation of therapy can prevent morbidity and mortality [5]. Moreover, death must be considered an avoidable event among those patients who reach emergency care. Fast and accurate institution of pharmacologic therapy and especially of endotracheal intubation and mechanical ventilation where necessary is crucial in order to avoid a fatal outcome.