The work of breathing is a major determinant of the success of weaning from
mechanical ventilation. The aim of this study was to assess whether an inhaled
bronchodilator could reduce the mechanical load on the respiratory muscles and diminish the work. For this purpose, 15 intubated patients in the process of weaning from
mechanical ventilation inhaled the beta 2-agonist
bronchodilator albuterol via a spacer device filled with 1 mg of the
drug and connected to the endotracheal tube. During spontaneous breathing, the mean work of breathing diminished significantly after
albuterol, from 9.35 +/- 1.05 to 8.33 +/- 1.13 J/min (p less than 0.01), and seven patients exhibited a decrease superior or equal to 15%. This decrease resulted from a marked reduction in lung and airway resistance, from 12.0 +/- 1.7 to 9.8 +/- 1.4 cm H2O.L-1.s (p less than 0.05). No significant changes were observed in the breathing pattern,
intrinsic PEEP or arterial blood gas measurements after
albuterol, and peripheral cardiovascular effects were not significant. In seven patients, we were able to compare the changes that occurred after
albuterol in the work of breathing during weaning from
mechanical ventilation with the changes in pulmonary function induced by
albuterol after extubation, as assessed by the forced oscillation method. A close correlation was found between the two types of change, further indicating that the reduction in the work of breathing was more likely to occur in patients with the largest bronchodilating effect of
albuterol at baseline.(ABSTRACT TRUNCATED AT 250 WORDS)