Mechanical ventilation for asthma: A 10-year experience

Background. Asthmatics requiring admission to the intensive care unit and/or mechanical ventilation have increased morbidity and mortality. The purpose of this study is to examine morbidity and mortality in patients requiring intubation and mechanical ventilation for asthma over a 10-year period. This study also reviews the clinical features and management of these patients. Methods. We performed a retrospective review of medical records over a 10-year period of adult patients who required mechanical ventilation for a primary diagnosis of asthma. The study was conducted at a university-affiliated, county hospital. Results. One hundred twenty-seven patients with 162 episodes of asthma requiring mechanical ventilation were identified. The majority of the patients (64%) were women. The predominant ethnicity was African-American (65%). These patients had multiple risk factors for asthma mortality, including recent hospital admissions, prior episodes of near-fatal asthma, medication non-compliance, and poor outpatient follow-up. Over the 10 years of the study, outpatient management of these patients changed, with the percentage of admissions in which patients had been given inhaled corticosteroids increasing from 18 percent in 1990 to 80 percent in 1998. Management of mechanical ventilation also changed. The average tidal volume settings significantly decreased after 1995. The most common complication was atelectasis, which was seen in 33 cases. Evidence of barotrauma, including pneumothorax, pneumomediastinum, and subcutaneous emphysema, was present in 10 cases. There were four deaths. All four of the patients suffered cardiopulmonary arrest in the field with subsequent anoxic brain injury and withdrawal of care. Conclusions. Although these patients had multiple risk factors for mortality from asthma, no deaths in this study were related to complications of mechanical ventilation. This low mortality may be related to changes in management of mechanical ventilation as well as changes in chronic outpatient asthma therapy.