DOSE-RESPONSE TO BRONCHODILATOR DELIVERED BY METERED-DOSE INHALER IN VENTILATOR-SUPPORTED PATIENTS

In nonintubated patients, metered-dose inhalers (MDIs) are accepted as the most convenient, efficient, and cost effective method of administ ering inhaled bronchodilators. Recent studies have demonstrated the ef ficacy of MDIs in ventilator-supported patients; however, the optimal dose of a bronchodilator from a MDI is unknown. We determined the resp onse to increasing doses of albuterol administered by a MDI and cylind rical spacer to 72 mechanically ventilated patients with chronic obstr uctive pulmonary disease (CORD). four, eight, and 16 puffs of albutero l were given at 15-min intervals. Rapid airway occlusions were perform ed before and at 5-min intervals after albuterol for 80 min. Respirato ry mechanics were also measured for 60 min in another group of seven p atients with CORD who received four puffs of albuterol. Significant de crease in airway resistance occurred after administration of albuterol (p < 0.001). The decrease in airway resistance with four puffs of alb uterol was comparable to that observed with cumulative doses of 12 puf fs (p = 0.12) and 28 puffs (p = 0.25). Heart rate increased significan tly (p < 0.01) after a cumulative dose of 28 puffs. The decrease in ai rway resistance was sustained for 60 min in the group that received on ly four puffs of albuterol (p < 0.003). In conclusion, four puffs of a lbuterol given by a MDI and spacer provided the best combination of br onchodilator effect and safety in stable mechanically ventilated patie nts with CORD.