EFFECT OF PROPHYLACTIC BRONCHODILATOR TREATMENT ON LUNG RESISTANCE AFTER TRACHEAL INTUBATION

Background: After induction of anesthesia, lung resistance increases. We hypothesized that prophylactic bronchodilator treatment before tracheal intubation would result in a lower lung resistance after placement of the endotracheal tube. Methods: Forty-two adult patients were randomized to receive one of three inhaled medications 1 h before surgery. All patients first underwent pulmonary function tests. Patients then received either inhaled albuterol (360 mu g) (n = 12), inhaled ipratropium bromide (72 mu g) (n = 15) or a placebo inhalation (n = 15). Two, 5, and 15 min after tracheal intubation, lung resistance was measured using the method of von Neergard and Wirtz. Results: Patients who received either bronchodilator had significantly lower lung resistance after intubation than those receiving placebo. At 2 min, lung resistances were 12.7 +/- 1.4 cmH(2)O.1(-1).s(-1) (mean +/- SEM) for the placebo group, 6.4 +/- 3.1 cmH(2)O.1(-1).s(-1) for the ipratropium-treated group (P < 0.05 vs. placebo), and 7.2 +/- 0.8 cmH(2)O.1(-1).s(-1) for the albuterol-treated group (P < 0.05 vs. placebo). The differences in lung resistance persisted through the final measurement at 15 min. Three of fifteen placebo-treated patients developed audible wheezing whereas no patients developed wheezing in either bronchodilator-treated group (P < 0.05 by Fisher's exact test). Although smokers and nonsmokers in the placebo group developed similar resistances after intubation, bronchodilator treatment resulted in lower resistance in nonsmokers than in smokers (P < 0.05). Conclusions: Prophylactic treatment with either an inhaled beta(2)-adrenergic agonist or an inhaled cholinergic antagonist produced lower lung resistance after intubation when compared with an inhaled placebo medication. The effect was more pronounced in nonsmokers than in smokers.