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Evaluation of bispectral index (BIS) as an indicator of central nervous system depression in horses anesthetized with propofol.
Abstract: The bispectral index (BIS) was evaluated as an indicator of central nervous system (CNS) depression in horses anesthetized with propofol. Five non-premedicated horses were anesthetized with 7 mg/kg, IV propofol and the minimum infusion rate (MIR) of propofol required to maintain anesthesia was determined during intermittent positive pressure ventilation in each horse. The BIS was determined 20 min later and after stabilization at 2.0 MIR, 1.5 MIR, and 1.0 MIR. The BIS was also recorded after the cessation of propofol infusion when the horses regained spontaneous breathing and swallowing reflex. The MIR and plasma concentration (Cp) of propofol were 0.20 +/- 0.03 mg/kg/min and 17.5 +/- 4.0 microg/ml, respectively. The BIS value and Cp were 59 +/- 13 and 26.7 +/- 8.6 microg/ml at 2.0 MIR, 63 +/- 9 and 22.9 +/- 9.7 microg/ml at 1.5 MIR, 64 +/- 13 and 20.1 +/- 5.9 microg/ml at 1.0 MIR, 64 +/- 24 and 13.0 +/- 2.8 microg/ml at return of spontaneous breathing, and 91 +/- 4 and 11.0 +/- 3.4 microg/ml when the swallowing reflex returned, respectively. The BIS value was significantly less in anesthetized horses compared to horses once swallowing returned (p=0.025). The BIS value was significantly correlated with the propofol Cp (r=-0.625, p=0.001). There was not a significant difference in the BIS values during the MIR multiples of propofol. The BIS was a useful indicator of awakening but did not indicate the degree of CNS depression during propofol-anesthesia in horses.
Publication Date: 2009-12-05 PubMed ID: 19959897DOI: 10.1292/jvms.001465Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Evaluation Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the use of the bispectral index as a measure of effects of propofol on the central nervous system in horses. Although the index proved helpful in indicating when horses started to wake from anesthesia, it did not reflect the level of central nervous system depression during anesthesia.
Study Design and Procedure
- The researchers performed the study on five horses that were not pre-medicated. The horses were anesthetized with an intravenous injection of 7 mg/kg propofol.
- The minimum infusion rate (MIR) of propofol necessary to keep each horse anesthetized was determined while the horses were given intermittent positive pressure ventilation.
- The Bispectral Index (BIS) was measured 20 minutes later, with reading also taken after adjustments to the MIR (at 2.0 MIR, 1.5 MIR, and 1.0 MIR). This study then recorded the BIS upon cessation of propofol infusion when the horses regained spontaneous breathing and a swallowing reflex.
Findings from the Study
- The determined MIR and plasma concentration of propofol were 0.20 +/- 0.03 mg/kg/min and 17.5 +/- 4.0 microg/ml respectively.
- The BIS values and propofol concentrations at differing MIR and after the cessation of propofol were recorded. With each decrease in MIR, there seemed to be no significant change in BIS values, even when spontaneous breathing returned. However, a notable increase in BIS value was recorded when swallowing reflex was regained.
- The BIS values were significantly lower in anesthetized horses compared to when the horses regained swallowing reflex (p=0.025).
- There was a significant negative correlation between BIS values and propofol concentration in the blood (r=-0.625, p=0.001). As the propofol concentration decreased, BIS values increased.
- There was no significant change in BIS values during the various levels of propofol infusion (at 2.0, 1.5 and 1.0 MIR).
Conclusion of the Study
- The BIS proved to be useful in indicating when the horses were waking up from anesthesia. However, it did not reflect the degree of central nervous system depression during propofol-induced anesthesia in horses.
Cite This Article
APA
YAMASHITA K, AKASHI N, KATAYAMA Y, UCHIDA Y, UMAR MA, ITAMI T, INOUE H, SAMS RA, MUIR WW.
(2009).
Evaluation of bispectral index (BIS) as an indicator of central nervous system depression in horses anesthetized with propofol.
J Vet Med Sci, 71(11), 1465-1471.
https://doi.org/10.1292/jvms.001465 Publication
Researcher Affiliations
- Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Faculty of Environment Systems, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
MeSH Terms
- Anesthesia, General / veterinary
- Anesthetics, Intravenous / pharmacology
- Animals
- Central Nervous System / drug effects
- Consciousness Monitors / veterinary
- Female
- Horses
- Male
- Propofol / pharmacology
Citations
This article has been cited 9 times.- Petrucci M, Spadavecchia C, Wanderer S, Boillat G, Marbacher S, García Casalta LG, Casoni D. Usefulness and Reliability of the Bispectral Index during Balanced Anesthesia for Neurovascular Surgery in New Zealand White Rabbits. Brain Sci 2023 Feb 14;13(2).
- Murillo C, Weng HY, Weil AB, Kreuzer M, Ko JC. Perioperative Brain Function Monitoring with Electroencephalography in Horses Anesthetized with Multimodal Balanced Anesthetic Protocol Subjected to Surgeries. Animals (Basel) 2022 Oct 20;12(20).
- Santangelo B, Robin A, Simpson K, Potier J, Guichardant M, Portier K. The Modification and Performance of a Large Animal Anesthesia Machine (Tafonius(®)) in Order to Deliver Xenon to a Horse. Front Vet Sci 2017;4:162.
- Tokushige H, Kakizaki M, Ode H, Okano A, Okada J, Kuroda T, Wakuno A, Ohta M. Validation of the bispectral index as an indicator of anesthetic depth in Thoroughbred horses anesthetized with sevoflurane. J Equine Sci 2016;27(4):169-173.
- Tünsmeyer J, Hopster K, Kästner SB. Clinical Use of a Multivariate Electroencephalogram (Narcotrend) for Assessment of Anesthetic Depth in Horses during Isoflurane-Xylazine Anesthesia. Front Vet Sci 2016;3:25.
- Umar MA, Fukui S, Kawase K, Itami T, Yamashita K. Cardiovascular effects of total intravenous anesthesia using ketamine-medetomidine-propofol (KMP-TIVA) in horses undergoing surgery. J Vet Med Sci 2015 Mar;77(3):281-8.
- Nóbrega Neto PI, Luna SP, Queiroz-Williams P, Mama KR, Steffey EP, Carregaro AB. Cardiorespiratory and antinociceptive effects of two different doses of lidocaine administered to horses during a constant intravenous infusion of xylazine and ketamine. BMC Vet Res 2013 Oct 9;9:199.
- Thorn CA, Wilson DV, Wang S, Horne WA. Impact of sequential administration of detomidine, butorphanol, and midazolam on sedation, ataxia, stimulus response, and bispectral index in horses. Front Vet Sci 2025;12:1691137.
- Figueroa S, Levionnois OL, Mirra A. Quantitative Variables Derived from the Electroencephalographic Signal to Assess Depth of Anaesthesia in Animals: A Narrative Review. Animals (Basel) 2025 Aug 5;15(15).
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