The management of status asthmaticus using a continuous iv infusion of salbutamol was studied in 14 children with a total of 16 episodes of respiratory failure, unresponsive to conventional bronchodilator therapy. The mean PaCO2 at the start of the infusion was 60 +/- 6 torr. A loading dose of 1 microgram/kg X min body weight was given over 10 min, followed by an infusion of 0.2 microgram/kg X min which was increased in 0.1-microgram/kg steps according to response. The maximum dose was 4 microgram/kg X min. On 11 (69%) occasions a sustained reduction in PaCO2 was achieved within 4 h of starting the infusion. In 5 (11%) instances no reduction in PaCO2 was seen and mechanical ventilation was instituted because of increasing respiratory distress and CO2 retention. Mean heart rate during the infusion increased from 161 to 183 beat/min. Comparison with previous data from 30 pediatric patients (40 infusions) receiving iv isoproterenol showed less effect on heart rate and a more sustained fall in PaCO2 without the recurrence of bronchospasm. We found salbutamol to be a safe and effective bronchodilator capable of reversing severe bronchospasm in most children who would otherwise require mechanical ventilation. Its greater specificity for beta 2-receptors may make it preferable to isoproterenol.