Assessment of halothane and sevoflurane anesthesia in spontaneously breathing rats

Michele A. Steffey Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.
Present address is the Department of Clinical Science, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Search for other papers by Michele A. Steffey in
Current site
Google Scholar
PubMed
Close
 DVM
,
Robert J. Brosnan Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.

Search for other papers by Robert J. Brosnan in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
, and
Eugene P. Steffey Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.

Search for other papers by Eugene P. Steffey in
Current site
Google Scholar
PubMed
Close
 VMD, PhD

Click on author name to view affiliation information

Abstract

Objective—To characterize halothane and sevoflurane anesthesia in spontaneously breathing rats.

Animals—16 healthy male Sprague-Dawley rats.

Procedure—8 rats were anesthetized with halothane and 8 with sevoflurane. Minimum alveolar concentration (MAC) was determined. Variables were recorded at anesthetic concentrations of 0.8, 1.0, 1.25, and 1.5 times the MAC of halothane and 1.0, 1.25, 1.5, and 1.75 times the MAC of sevoflurane.

Results—Mean (± SEM) MAC for halothane was 1.02 ± 0.02% and for sevoflurane was 2.99 ± 0.19%. As sevoflurane dose increased from 1.0 to 1.75 MAC, mean arterial pressure (MAP) decreased from 103.1 ± 5.3 to 67.9 ± 4.6 mm Hg, and PaCO2 increased from 58.8 ± 3.1 to 92.2 ± 9.2 mm Hg. As halothane dose increased from 0.8 to 1.5 MAC, MAP decreased from 99 ± 6.2 to 69.8 ± 4.5 mm Hg, and PaCO2 increased from 59.1 ± 2.1 to 75.9 ± 5.2 mm Hg. Respiratory rate decreased in a dose-dependent fashion from 88.5 ± 4.5 to 58.5 ± 2.7 breaths/min during halothane anesthesia and from 42.3 ± 1.8 to 30.5 ± 4.5 breaths/min during sevoflurane anesthesia. Both groups of rats had an increase in eyelid and pupillary aperture with an increase in anesthetic dose.

Conclusions and Clinical Relevance—An increase in PaCO2 and a decrease in MAP are clinical indicators of an increasing halothane and sevoflurane dose in unstimulated spontaneously breathing rats. Increases in eyelid aperture and pupil diameter are reliable signs of increasing depth of halothane and sevoflurane anesthesia. Decreasing respiratory rate is a clinical indicator of an increasing dose of halothane. (Am J Vet Res 2003;64:470–474)

Abstract

Objective—To characterize halothane and sevoflurane anesthesia in spontaneously breathing rats.

Animals—16 healthy male Sprague-Dawley rats.

Procedure—8 rats were anesthetized with halothane and 8 with sevoflurane. Minimum alveolar concentration (MAC) was determined. Variables were recorded at anesthetic concentrations of 0.8, 1.0, 1.25, and 1.5 times the MAC of halothane and 1.0, 1.25, 1.5, and 1.75 times the MAC of sevoflurane.

Results—Mean (± SEM) MAC for halothane was 1.02 ± 0.02% and for sevoflurane was 2.99 ± 0.19%. As sevoflurane dose increased from 1.0 to 1.75 MAC, mean arterial pressure (MAP) decreased from 103.1 ± 5.3 to 67.9 ± 4.6 mm Hg, and PaCO2 increased from 58.8 ± 3.1 to 92.2 ± 9.2 mm Hg. As halothane dose increased from 0.8 to 1.5 MAC, MAP decreased from 99 ± 6.2 to 69.8 ± 4.5 mm Hg, and PaCO2 increased from 59.1 ± 2.1 to 75.9 ± 5.2 mm Hg. Respiratory rate decreased in a dose-dependent fashion from 88.5 ± 4.5 to 58.5 ± 2.7 breaths/min during halothane anesthesia and from 42.3 ± 1.8 to 30.5 ± 4.5 breaths/min during sevoflurane anesthesia. Both groups of rats had an increase in eyelid and pupillary aperture with an increase in anesthetic dose.

Conclusions and Clinical Relevance—An increase in PaCO2 and a decrease in MAP are clinical indicators of an increasing halothane and sevoflurane dose in unstimulated spontaneously breathing rats. Increases in eyelid aperture and pupil diameter are reliable signs of increasing depth of halothane and sevoflurane anesthesia. Decreasing respiratory rate is a clinical indicator of an increasing dose of halothane. (Am J Vet Res 2003;64:470–474)

All Time Past Year Past 30 Days
Abstract Views 52 0 0
Full Text Views 318 207 20
PDF Downloads 115 66 13
Advertisement