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Frontiers in veterinary science2016; 3; 25; doi: 10.3389/fvets.2016.00025

Clinical Use of a Multivariate Electroencephalogram (Narcotrend) for Assessment of Anesthetic Depth in Horses during Isoflurane-Xylazine Anesthesia.

Abstract: To investigate the use of the Narcotrend electroencephalogram (EEG) monitor for the assessment of anesthetic depth in horses undergoing xylazine balanced isoflurane anesthesia. Methods: Blinded experimental study. Methods: Seven healthy warm-blooded horses, aged 10.6 ± 5.9 years, weighing 535 ± 55 kg. Methods: Horses were anesthetized for a terminal surgical trial with xylazine, thiopentone, and guaiphenesin for induction and isoflurane and xylazine continuous rate infusion for maintenance. After surgery, an EEG was recorded and processed by the Narcotrend monitor. It displays an index [Narcotrend index (NI)] between 0 and 100, which is supposed to indicate anesthetic depth. This index was recorded and correlated with eight different end tidal (ET) isoflurane concentrations between 0.8 and 2.2 vol%. In addition, anesthetic depth was numerically scored based on common clinical signs with a score of 1 (plane "too deep") to 4 (plane "too light"). After testing for normal distribution, both clinical scores and NI were correlated with different ET isoflurane concentrations using Spearman rank correlation. Results: Correlation of NI with ET isoflurane concentrations was poor (r s = 0.24). The NI ranged between maximal 48 and minimal 13 in the horses. The clinical scores decreased with increasing ET isoflurane concentrations (r s = 0.80). They ranged from 1 to 4 in different horses at the concentrations investigated. Conclusions: In this study, the NI did not seem to be useful for assessment of anesthetic depth in horses receiving isoflurane anesthesia balanced with a xylazine constant rate infusion.
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Publication Date: 2016-03-17 PubMed ID: 27014707PubMed Central: PMC4794479DOI: 10.3389/fvets.2016.00025Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study investigated the feasibility of using a multivariate electroencephalogram device, the Narcotrend, to assess anesthetic depth in horses undergoing specific anesthetic procedures. However, the research found that the device, which measures EEG signals to provide a numerical measure of anesthetic depth, did not show a strong correlation with changes in the concentration of anesthetic substance used in healthy horses.

Study Design and Methodology

  • The study involved a small sample of seven healthy warm-blooded horses as subjects.
  • These horses underwent xylazine balanced isoflurane anesthesia during a terminal surgical operation. The anesthesia involved initial induction with xylazine, thiopentone, and guaiphenesin followed by sustained supply via continuous rate infusion of isoflurane and xylazine.
  • Drawing upon this scenario, an EEG was recorded and processed using the Narcotrend monitor. This device provides a Narcotrend Index (NI) ranging from 0 to 100, interpreted as a measure of the depth of anesthesia.
  • The researchers then tested and correlated this index with eight different end-tidal (measurement of exhaled air) isoflurane concentrations, from 0.8 to 2.2 vol%.
  • In parallel, they also scored the depth of anesthesia based on clinical signs, ranking it on a scale of 1 (“too deep”) to 4 (“too light”). This act ensured a reference or baseline against which the NI’s performance could be compared.

Findings and Conclusion

  • The end results revealed a poor correlation (r s = 0.24) between the NI and the end-tidal isoflurane concentrations. The recorded NI values varied between 13 and 48 among the participating horses.
  • In contrast, the clinical scores showed a stronger correlation with the end-tidal isoflurane concentrations (r s = 0.80), decreasing as the isoflurane concentrations increased.
  • These findings led to the conclusion that the NI, as provided by the Narcotrend monitor, showed limited usefulness in evaluating anesthetic depth in horses receiving isoflurane anesthesia in combination with a xylazine constant rate infusion.

This implies a need for further research or the development of improved tools and methodologies for accurately and reliably assessing anesthetic depth in horses.

Cite This Article

APA
Tünsmeyer J, Hopster K, Kästner SB. (2016). Clinical Use of a Multivariate Electroencephalogram (Narcotrend) for Assessment of Anesthetic Depth in Horses during Isoflurane-Xylazine Anesthesia. Front Vet Sci, 3, 25. https://doi.org/10.3389/fvets.2016.00025

Publication

Frontiers in veterinary science
ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 3
Pages: 25

Researcher Affiliations

Tünsmeyer, Julia
  • Small Animal Clinic, University of Veterinary Medicine Hannover Foundation , Hannover , Germany.
Hopster, Klaus
  • Equine Clinic, University of Veterinary Medicine Hannover Foundation , Hannover , Germany.
Kästner, Sabine B
  • Small Animal Clinic, University of Veterinary Medicine Hannover Foundation, Hannover, Germany; Equine Clinic, University of Veterinary Medicine Hannover Foundation, Hannover, Germany.

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Citations

This article has been cited 6 times.
  1. 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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