Cardiopulmonary effects of three concentrations of isoflurane with or without mechanical ventilation and supramaximal noxious stimulation in New Zealand white rabbits

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Abstract

Objective-To determine the cardiopulmonary effects of 3 doses of isoflurane, with and without controlled mechanical ventilation and noxious stimulation, in healthy adult New Zealand white rabbits. Animals-6 adult female rabbits. Procedures-Each rabbit was administered isoflurane in oxygen at each of 3 anesthetic doses (1.0, 1.5, or 2.0 times the published minimum alveolar concentration of 2.07%). At each anesthetic dose, blood gas and cardiopulmonary measurements were obtained before and during application of a supramaximal noxious stimulus. Effects of spontaneous and mechanical ventilation were assessed during separate anesthetic episodes. Results-Mean ± SEM isoflurane concentrations used were 2.11 ± 0.04%, 3.14 ± 0.07%, and 4.15 ± 0.06%. During spontaneous ventilation, the rabbits' PaCO2 and mixed venous PCO2 significantly increased with concomitant reductions in both arterial and mixed venous pH as isoflurane concentration increased. Cardiac output and vascular resistance did not change significantly. Noxious stimulation minimally affected measured cardiopulmonary variables. During mechanical ventilation, significant reductions in arterial blood pressures and cardiac output occurred with increasing isoflurane dose. Systemic vascular resistance index at the highest anesthetic dose was significantly lower than the value at the lowest anesthetic dose. During noxious stimulation, systolic arterial blood pressure and cardiac output significantly increased at the 2 lower isoflurane concentrations, but not at the highest concentration. Conclusions and Clinical Relevance-In rabbits, isoflurane-induced dose-dependent cardiopulmonary depression was attributable to vasodilation and negative inotropy. At an isoflurane concentration of 4.15% with mechanical ventilation, cardiovascular depression was severe; use of unnecessarily high isoflurane concentrations in this species should be avoided.

Original languageEnglish (US)
Pages (from-to)1274-1280
Number of pages7
JournalAmerican Journal of Veterinary Research
Volume74
Issue number10
DOIs
StatePublished - Oct 2013

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New Zealand White rabbit
Isoflurane
isoflurane
Artificial Respiration
Rabbits
anesthetics
Anesthetics
dosage
cardiac output
rabbits
Cardiac Output
blood vessels
Vascular Resistance
blood pressure
Arterial Pressure
vasodilation
blood gases
Vasodilation
Ventilation
Gases

ASJC Scopus subject areas

  • veterinary(all)

Cite this

@article{d5fe65bf271d4f0b802ad424ae44a7f2,
title = "Cardiopulmonary effects of three concentrations of isoflurane with or without mechanical ventilation and supramaximal noxious stimulation in New Zealand white rabbits",
abstract = "Objective-To determine the cardiopulmonary effects of 3 doses of isoflurane, with and without controlled mechanical ventilation and noxious stimulation, in healthy adult New Zealand white rabbits. Animals-6 adult female rabbits. Procedures-Each rabbit was administered isoflurane in oxygen at each of 3 anesthetic doses (1.0, 1.5, or 2.0 times the published minimum alveolar concentration of 2.07{\%}). At each anesthetic dose, blood gas and cardiopulmonary measurements were obtained before and during application of a supramaximal noxious stimulus. Effects of spontaneous and mechanical ventilation were assessed during separate anesthetic episodes. Results-Mean ± SEM isoflurane concentrations used were 2.11 ± 0.04{\%}, 3.14 ± 0.07{\%}, and 4.15 ± 0.06{\%}. During spontaneous ventilation, the rabbits' PaCO2 and mixed venous PCO2 significantly increased with concomitant reductions in both arterial and mixed venous pH as isoflurane concentration increased. Cardiac output and vascular resistance did not change significantly. Noxious stimulation minimally affected measured cardiopulmonary variables. During mechanical ventilation, significant reductions in arterial blood pressures and cardiac output occurred with increasing isoflurane dose. Systemic vascular resistance index at the highest anesthetic dose was significantly lower than the value at the lowest anesthetic dose. During noxious stimulation, systolic arterial blood pressure and cardiac output significantly increased at the 2 lower isoflurane concentrations, but not at the highest concentration. Conclusions and Clinical Relevance-In rabbits, isoflurane-induced dose-dependent cardiopulmonary depression was attributable to vasodilation and negative inotropy. At an isoflurane concentration of 4.15{\%} with mechanical ventilation, cardiovascular depression was severe; use of unnecessarily high isoflurane concentrations in this species should be avoided.",
author = "Barter, {Linda S} and Epstein, {Steven E}",
year = "2013",
month = "10",
doi = "10.2460/ajvr.74.10.1274",
language = "English (US)",
volume = "74",
pages = "1274--1280",
journal = "American Journal of Veterinary Research",
issn = "0002-9645",
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TY - JOUR

T1 - Cardiopulmonary effects of three concentrations of isoflurane with or without mechanical ventilation and supramaximal noxious stimulation in New Zealand white rabbits

AU - Barter, Linda S

AU - Epstein, Steven E

PY - 2013/10

Y1 - 2013/10

N2 - Objective-To determine the cardiopulmonary effects of 3 doses of isoflurane, with and without controlled mechanical ventilation and noxious stimulation, in healthy adult New Zealand white rabbits. Animals-6 adult female rabbits. Procedures-Each rabbit was administered isoflurane in oxygen at each of 3 anesthetic doses (1.0, 1.5, or 2.0 times the published minimum alveolar concentration of 2.07%). At each anesthetic dose, blood gas and cardiopulmonary measurements were obtained before and during application of a supramaximal noxious stimulus. Effects of spontaneous and mechanical ventilation were assessed during separate anesthetic episodes. Results-Mean ± SEM isoflurane concentrations used were 2.11 ± 0.04%, 3.14 ± 0.07%, and 4.15 ± 0.06%. During spontaneous ventilation, the rabbits' PaCO2 and mixed venous PCO2 significantly increased with concomitant reductions in both arterial and mixed venous pH as isoflurane concentration increased. Cardiac output and vascular resistance did not change significantly. Noxious stimulation minimally affected measured cardiopulmonary variables. During mechanical ventilation, significant reductions in arterial blood pressures and cardiac output occurred with increasing isoflurane dose. Systemic vascular resistance index at the highest anesthetic dose was significantly lower than the value at the lowest anesthetic dose. During noxious stimulation, systolic arterial blood pressure and cardiac output significantly increased at the 2 lower isoflurane concentrations, but not at the highest concentration. Conclusions and Clinical Relevance-In rabbits, isoflurane-induced dose-dependent cardiopulmonary depression was attributable to vasodilation and negative inotropy. At an isoflurane concentration of 4.15% with mechanical ventilation, cardiovascular depression was severe; use of unnecessarily high isoflurane concentrations in this species should be avoided.

AB - Objective-To determine the cardiopulmonary effects of 3 doses of isoflurane, with and without controlled mechanical ventilation and noxious stimulation, in healthy adult New Zealand white rabbits. Animals-6 adult female rabbits. Procedures-Each rabbit was administered isoflurane in oxygen at each of 3 anesthetic doses (1.0, 1.5, or 2.0 times the published minimum alveolar concentration of 2.07%). At each anesthetic dose, blood gas and cardiopulmonary measurements were obtained before and during application of a supramaximal noxious stimulus. Effects of spontaneous and mechanical ventilation were assessed during separate anesthetic episodes. Results-Mean ± SEM isoflurane concentrations used were 2.11 ± 0.04%, 3.14 ± 0.07%, and 4.15 ± 0.06%. During spontaneous ventilation, the rabbits' PaCO2 and mixed venous PCO2 significantly increased with concomitant reductions in both arterial and mixed venous pH as isoflurane concentration increased. Cardiac output and vascular resistance did not change significantly. Noxious stimulation minimally affected measured cardiopulmonary variables. During mechanical ventilation, significant reductions in arterial blood pressures and cardiac output occurred with increasing isoflurane dose. Systemic vascular resistance index at the highest anesthetic dose was significantly lower than the value at the lowest anesthetic dose. During noxious stimulation, systolic arterial blood pressure and cardiac output significantly increased at the 2 lower isoflurane concentrations, but not at the highest concentration. Conclusions and Clinical Relevance-In rabbits, isoflurane-induced dose-dependent cardiopulmonary depression was attributable to vasodilation and negative inotropy. At an isoflurane concentration of 4.15% with mechanical ventilation, cardiovascular depression was severe; use of unnecessarily high isoflurane concentrations in this species should be avoided.

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JF - American Journal of Veterinary Research

SN - 0002-9645

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