Depression of lung mucociliary dlearance by thiopental and halothane

It has previously been demonstrated that an induction dose of thiopental, 25 mg/kg, without continuing anesthesia did not depress peripheral lung mucociliary clearance in the dog, whereas 2 hours of anesthesia with halothane, 1.2 MAC, did depress clearance. To determine whether this was because thiopental depresses the mucociliary apparatus less than halothane, this study compared mucociliary clearance after 2 hours of anesthesia with halothane with clearance after 2 hours of anesthesia with thiopental, 40 mg/kg. With thiopental, 40 mg/kg, 50% mucociliary clearance of tantalum from peripheral airways required 280 +/- 65 (SEM) minutes, which was comparable to clearance obtained with halothane, 1.2 MAC, 382 +/- 27 (SEM) minutes. Hence thiopental depresses mucociliary clearance as much as halothane does when both are administered in equivalent anesthetic doses for equal periods of time.