Mechanical ventilation in status asthmaticus: experience with 75 episodes.

Mechanical ventilation in 75 out of 560 status asthmaticus episodes during a five-year period (1984-1988) at Chulalongkorn Hospital were analyzed. There were 58 patients with an average age of onset of first asthmatic attack of 18.5 years and an average age when requiring mechanical ventilation of 33 years, which is significantly younger than among those who did not require assisted ventilation. At the time of intubation, four patients were in sudden unexpected arrest and 19 patients were urgently ventilated because of respiratory muscle fatigue or carbon dioxide narcosis; the remaining 52 patients required elective mechanical ventilation. The arterial blood gas of 52 patients revealed a pH of 7.11 +/- 0.66, PaCO2 of 58.0 +/- 5.5 mmHg, and HCO3 of 15.0 +/- 5.8 mEg/L. Controlled mechanical ventilation was maintained for a mean of 38.68 hours. Fifty-one patients required intravenous diazepam (average dose = 24.3 mg) and 37 required morphine (average dose = 11.1 mg) for good syncronization in controlling mechanical ventilation. Pneumothorax was the most common complication with four, nine and one episodes occurring prior to, during and after assisted ventilation, respectively. Four, one and two patients developed the complications of pneumonia, atelectasis of the left lung due to mucous plugging and upper gastrointestinal hemorrhage, respectively. There were six patients who died of complications: four of brain anoxia, one of pneumothorax and another of unexplained cause.