Objective: To compare the bronchodilating effect of a single drug, ipratropium bromide (IBr), with that of its combination with fenoterol (IBr+F).
Design: The study was triple blind and randomized.
Setting: Medical-surgical intensive care unit.
Patients: 12 patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) requiring mechanical ventilation for severe respiratory failure.
Interventions: Before administering each drug, peak airway pressure (Ppeak), end inspiratory pressure (Pei), resistive pressure (Pres), and auto positive--end expiratory pressure (auto-PEEP) were measured. Inspiratory system resistance (Rins) and dynamic respiratory system compliance (C) were calculated. Arterial pH and blood gas determinations were made. These measurements were repeated 60 min after administration of each therapeutic regimen. For ipratropium bromide alone the dose was 0.04 mg. When the combination of drugs was used, the doses were 0.04 mg for ipratropium bromide and 0.1 mg for fenoterol.
Measurements and results: With the combination of both drugs, all the pressures in the airway, as well as the auto-PEEP and the Rins were significantly reduced (p < 0.05) with respect to baseline values. With ipratropium bromide alone, no significant changes were observed either in the pressures or in the inspiratory resistance. No significant changes were observed either in the pH or blood gases with any of the treatments. The combination of both drugs produced significantly reduction in Pei and auto-PEEP when compared with ipratropium bromide alone.
Conclusions: The combination of both drugs is more effective than ipratropium bromide alone at the doses used in this study.