JOURNAL HOME CME HOME THIS MONTH PAST ISSUES ETOC COLLECTIONS AUTHORS REVIEWERS EDITORIAL BOARD FEEDBACK RSS HELP
		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Smith, R. A. Articles by Winter, P. M. Search for Related Content PubMed PubMed Citation Articles by Smith, R. A. Articles by Winter, P. M.

Nonlinear Antagonism of Anesthesia in Mice by Pressure

Raymond A. Smith, PhD^*, Marilyn Smith, BA, Edmond I. Eger, II, MD, Michael J. Halsey, PhD, and Peter M. Winter, MD^||

*Assistant Research Chemist, Department of Anesthesia, University of California School of Medicine, San Francisco, California 94143. Staff Research Associate, Department of Anesthesia, University of California School of Medicine. Professor of Anesthesia, Department of Anesthesia, University of California School of Medicine. Member of Scientific Staff, Clinical Research Centre, Division of Anaesthesia, Harrow, Middlesex, England. ||Professor of Anesthesiology, Department of Anesthesiology & Anesthesia Research Center, University of Washington School of Medicine, Seattle, Washington 98195. Department of Anesthesia, University of California School of Medicine, San Francisco, California 94143.

Abstract

Previous studies have shown a rectilinear antagonism by pressure of nitrous oxide or isoflurane anesthesia in mice (pressure reversal). Since a rectilinear pressure reversal is predicted by the critical volume hypothesis for anesthesia, we examined this phenomenon with two other gases. We measured the doses of argon or nitrogen which abolished the righting reflex in 50% of animals (ED₅₀) at various high pressures produced by the addition of helium. The ED₅₀ values of argon and nitrogen alone are 16.7 ± 1.37 and 38.3 ± 1.62 atmospheres absolute (ATA). Fifty-five percent more argon and 27% more nitrogen is needed to produce anesthesia at 100 ATA. However the increasing anesthetic requirements with pressure were curvilinearly related to pressure, rising most steeply at pressures near the ED₅₀ without helium. This suggests that the pressure reversal of anesthesia is not simply a reciprocal anesthetic expansion-pressure compression phenomenon as predicted by the critical volume hypothesis. It suggests that anesthetics and pressure act at different sites.

Key Words: THEORIES OF ANESTHESIA: pressure reversal • HYPERBARIA: pressure reversal

This article has been cited by other articles:

				J. H. Abraini, B. Kriem, N. Balon, J.-C. Rostain, and J.-J. Risso Gamma-Aminobutyric Acid Neuropharmacological Investigations on Narcosis Produced by Nitrogen, Argon, or Nitrous Oxide Anesth. Analg., March 1, 2003; 96(3): 746 - 749. [Abstract] [Full Text] [PDF]

Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999