Veterinary surgery : VS1998; 27(5); 480-485; doi: 10.1111/j.1532-950x.1998.tb00160.x

Recovery from sevoflurane anesthesia in horses: comparison to isoflurane and effect of postmedication with xylazine.

Matthews, NS
·
Hartsfield, SM
·
Mercer, D
·
Beleau, MH
·
MacKenthun, A

Abstract: To compare recovery from sevoflurane or isoflurane anesthesia in horses. Methods: Prospective, randomized cross-over design. Methods: Nine Arabian horses (3 mares, 3 geldings, and 3 stallions) weighing 318 to 409 kg, 4 to 20 years old. Methods: Horses were anesthetized on three occasions with xylazine (1.1 mg/kg), Diazepam (0.03 mg/kg intravenously [i.v.]), and ketamine (2.2 mg/kg i.v.). After intubation, they were maintained with isoflurane or sevoflurane for 90 minutes. On a third occasion, horses were maintained with sevoflurane and given xylazine (0.1 mg/kg i.v.) when the vaporizer was turned off. Horses were not assisted in recovery and all recoveries were videotaped. Time to extubation, first movement, sternal, and standing were recorded as was the number of attempts required to stand. Recoveries were scored on a 1 to 6 scoring system (1 = best, 6 = worst) by the investigators, and by three evaluators who were blinded to the treatments the horses received. These blinded evaluators assessed the degree of ataxia present at 10 minutes after each horse stood, and recorded the time at which they judged the horse to be ready to leave the recovery stall. Results: Mean times (+/- SD) to extubation, first movement, sternal, and standing were 4.1 (1.7), 6.7 (1.9), 12.6 (4.6), and 17.4 (7.2) minutes with isoflurane; 3.4 (0.8), 6.6 (3.1), 10.3 (3.1), and 13.9 (3.0) minutes with sevoflurane; and 4.0 (1.2), 9.1 (3.3), 13.8 (6.5), and 18.0 (7.1) with sevoflurane followed by xylazine. Horses required a mean number of 4 (2.3), 2 (0.9), and 2 ( 1.6) attempts to stand with isoflurane, sevoflurane, and sevoflurane followed by xylazine respectively. The mean recovery score (SD) for isoflurane was 2.9 (1.2) from investigators and 2.4 (1.1) from blinded evaluators. For sevoflurane, the mean recovery score was 1.7 (0.9) from investigators and 1.9 (1.1) from evaluators, whereas the recoveries from sevoflurane with xylazine treatment were scored as 1.7 (1.2) from investigators and 1.7 (1.0) from blinded evaluators. Conclusions: Recoveries appeared to vary widely from horse to horse, but were significantly shorter with sevoflurane than isoflurane, although sevoflurane followed by xylazine was no different from isoflurane. Under the conditions of the study, recoveries from sevoflurane and sevoflurane followed by xylazine were of better quality than those from isoflurane. Conclusions: Sevoflurane anesthesia in horses may contribute to a shorter, safer recovery from anesthesia.

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Publication Date: 1998-09-28 PubMed ID: 9749520DOI: 10.1111/j.1532-950x.1998.tb00160.xGoogle Scholar: Lookup

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Clinical Trial
Comparative Study
Journal Article
Randomized Controlled Trial
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Non-U.S. Gov't

Summary

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The research investigates the effects of two types of anesthesia, sevoflurane and isoflurane, on horses, and whether using xylazine post-anesthesia makes any difference. The study indicates that recovery times from anesthesia were significantly shorter with sevoflurane, compared to isoflurane. However, the addition of xylazine after sevoflurane did not further decrease recovery time.

Research Methodology

The study used a prospective, randomized cross-over design involving 9 Arabian horses of varied weights, ages, and sexes.
The horses were anesthetized on three different occasions using a standard combination of xylazine, Diazepam, and ketamine, followed by either isoflurane or sevoflurane. On the third occasion, the horses were given xylazine post-anesthesia.
The researchers measured and recorded various stages of the horses’ recovery from anesthesia, including extubation (removal of the breathing tube), first movement, and the times to become sternal (lying on their chest) and to stand.
To assess the quality of recovery, a 1-6 scoring system was used by both the researchers present and evaluators who were blind to the treatments the horses received.

Key Findings

The average time for extubation, first movement, sternal recumbency, and standing was significantly shorter with sevoflurane than with isoflurane.
Furthermore, the administration of xylazine post-anesthesia did not appear to further shorten the recovery times when compared to isoflurane or sevoflurane alone.
The horse’s attempts to stand after anesthesia were fewer with sevoflurane, suggesting a smoother recovery.
The recovery score was also better for sevoflurane, as judged by both the researchers and blind evaluators. The recovery after sevoflurane with xylazine was also better than isoflurane but similar to sevoflurane alone.

Conclusions

Despite some variation across horses, the study found that recovery was generally quicker and smoother with sevoflurane compared to isoflurane.
The addition of xylazine post-anesthesia did not result in any additional improvement in recovery times or quality.
Given the shorter and safer recovery observed, the use of sevoflurane anesthesia is suggested as potentially beneficial for horses.

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APA

Matthews NS, Hartsfield SM, Mercer D, Beleau MH, MacKenthun A. (1998). Recovery from sevoflurane anesthesia in horses: comparison to isoflurane and effect of postmedication with xylazine. Vet Surg, 27(5), 480-485. https://doi.org/10.1111/j.1532-950x.1998.tb00160.x