title: Time course of ventilatory depression following induction doses of propofol and thiopental.
abstract: To improve our understanding of the respiratory pharmacology of intravenous induction agents, the authors compared the acute effects of intravenous (iv) propofol 2.5 mg.kg-1 and iv thiopental 4.0 mg.kg-1 on the ventilatory response to CO2 (VeRCO2) of eight healthy volunteers. The slope of VeRCO2 decreased from 1.75 +/- 0.23 to a minimum of 0.77 +/- 0.14 1.min-1.mmHg-1 (mean +/- standard error) 90 s after propofol; similarly, the slope of VeRCO2 decreased from 1.79 +/- 0.22 to a minimum of 0.78 +/- 0.23 l.min-1.mmHg-1 30 s after thiopental. For both drugs, the slope was less than control in the 0.5-5-min period after injection (P less than 0.05). The slope returned to baseline within 6 min after thiopental; in contrast, after propofol, the slope remained less than control for the entire 20-min follow-up period (P less than 0.05 at 6-10, 11-15, and 16-20 min after injection). Also, from 6-10, 11-15, and 16-20 min after injection, the slope was less after propofol than at corresponding times after thiopental (P less than 0.05). Recovery of consciousness was approximately 4 min slower after propofol than after thiopental; nonetheless, awareness scores returned to baseline within 14 min after both drugs. The authors conclude that propofol 2.5 mg.kg-1 iv produces longer-lasting depression of VeRCO2 than a 4.0 mg.kg-1 iv dose of thiopental; after propofol, ventilatory depression may persist despite apparently complete recovery of consciousness.
authors.affiliation: Department of Anesthesiology, University of Connecticut School of Medicine, Farmington 06032.
authors.forename: R T
authors.initials: RT
authors.lastname: Blouin
authors.forename: P F
authors.initials: PF
authors.lastname: Conard
authors.forename: J B
authors.initials: JB
authors.lastname: Gross
mesh_terms: D000328:Adult; D000762:Anesthesia Recovery Period; D000771:Anesthesia, Intravenous; D002245:Carbon Dioxide / Q000097:blood*; D006801:Humans; D008297:Male; D015742:Propofol / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects*; D013874:Thiopental / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D013874:Thiopental; D015742:Propofol