Effect of prophylactic bronchodilator treatment with intravenous colforsin daropate, a water-soluble forskolin derivative, on airway resistance after tracheal intubation

Abstract

Background: After induction of anesthesia, lung resistance increases. The authors hypothesized that prophylactic bronchodilator treatment with intravenous colforsin daropate, a water-soluble forskolin derivative, before tracheal intubation would result in decreased lung resistance and increased lung compliance after tracheal intubation when compared with placebo medication. Methods: Forty-six adult patients were randomized to placebo or colforsin daropate treatment. Patients in the control group received normal saline; patients in the colforsin group received 0.75 μg · kg-1 · min-1 colforsin daropate intravenously until the study ended. Thirty minutes after the study began, the authors administered 5 mg/kg thiamylal and 5 μg/kg fentanyl for induction of general anesthesia and 0.3 mg/kg vecuronium for muscle relaxation. A 15-mg · kg-1 · h-1 continuous infusion of thiamylal followed anesthetic induction. Four, 8, 12, and 16 min after tracheal intubation, mean airway resistance (Rawm), expiratory airway resistance (Rawe), and dynamic lung compliance (Cdyn) were measured. Results: Patients in the colforsin group had significantly lower Rawm and Rawe and higher Cdyn after intubation than those in the control group. Differences in Rawm, Rawe, and Cdyn between the two groups persisted through the final measurement at 16 min. At 4 min after intubation, smokers had a higher Rawm and a lower Cdyn than nonsmokers in the control group. After treatment by intravenous colforsin daropate, Rawm, Rawe, and Cdyn values were similar for smokers and nonsmokers after tracheal intubation. Conclusions: Prophylactic treatment with colforsin daropate produced lower Rawm and Rawe and higher Cdyn after tracheal intubation when compared with placebo medication. Pretreatment before intubation may be beneficial and advantageous for middle-aged smokers.