Lung resistance increases after induction of anaesthesia. We hypothesized that prophylactic bronchodilation with i.v. carperitide before tracheal intubation would decrease airway resistance and increase lung compliance after placement of the tracheal tube in both smokers and nonsmokers.Methods
Ninety-seven adults aged between 24 and 59 yr were randomized to receive i.v. normal saline (0.9% saline) (control) or carperitide, 0.2 µg kg−1 min−1 throughout the study. The 97 patients included smokers and nonsmokers. Thus the patients were allocated to one of the four groups: smokers who received normal saline (n=21), nonsmokers who received normal saline (n=27), smokers who received carperitide (n=19) or nonsmokers who received carperitide (n=30). Thirty minutes after starting normal saline or carperitide infusion, we administered thiamylal 5 mg kg−1 and fentanyl 5 µg kg−1 to induce general anaesthesia and vecuronium 0.3 mg kg−1 for muscle relaxation. Continuous infusion of thiamylal 15 mg kg−1 h−1 followed anaesthetic induction. Mean airway resistance (Rawm), expiratory airway resistance (Rawe) and dynamic lung compliance (Cdyn) were determined 4, 8, 12 and 16 min after tracheal intubation and compared between the four groups.Results
At 4 min after intubation, Rawm and Rawe were higher and Cdyn lower in smokers than in nonsmokers in the control group. Rawm and Rawe were lower and Cdyn higher in smokers in the carperitide group than in smokers in the control group. Rawm and Rawe were lower in nonsmokers in the carperitide group than in nonsmokers in the control group.Conclusions
Marked bronchoconstriction occurred in the control groups (smokers and nonsmokers) 4 min after tracheal intubation. Prophylactic treatment with carperitide before induction of anaesthesia and tracheal intubation was advantageous, particularly in smokers.