The isoflurane-sparing and clinical effects of a constant rate infusion of remifentanil in dogs.

Abstract

OBJECTIVE:

To evaluate the isoflurane-sparing and clinical effects of two constant rate infusions of remifentanil in healthy dogs undergoing orthopaedic surgery.

STUDY DESIGN:

Prospective, randomized clinical study.

ANIMALS:

Forty-one American Society of Anesthesiologists I-II client-owned dogs (age, 7 months-9 years; body mass 11-59 kg).

METHODS:

Dogs were randomly assigned to one of three groups and received either: intramuscular (IM) meperidine 2 mg kg(-1) every 2 hours throughout surgery (control group (C); n = 13); remifentanil infused intravenously (IV) at 0.1 microg kg(-1) minute(-1) (low remifentanil group (L); n = 14) or remifentanil infused at 0.25 microg kg(-1) minute(-1) IV (high remifentanil group (H); n = 14). Anaesthesia was induced with thiopental administered to effect and maintained using isoflurane in 100% oxygen. During controlled ventilation when the end-tidal CO(2) was maintained between 4.65 and 5.98 kPa [35-45 mmHg], the end-tidal isoflurane concentration (e'iso%), mean arterial blood pressure (MAP) and heart rate (HR) were measured every 5 minutes. Bradycardia (HR < 40 minute(-1) lasting >5 minutes) was corrected with 0.01 mg kg(-1) IV glycopyrrolate. Data were analysed using the Kruskal-Wallis test with a post-hoc Mann-Whitney U-test and Bonferroni correction. Statistical significance was accepted at < or = 0.05. Data are expressed as mean +/- standard deviation.

RESULTS:

The e'iso% was reduced in a dose-dependent manner by remifentanil. In C, e'iso% was 1.28 +/-0.13 and was significantly different from L (0.78 +/- 0.17, p < 0.001) and H (0.65 +/- 0.16, p < 0.001). HR was significantly different between groups (p < 0.001). There were no significant differences in MAP between groups. Glycopyrrolate was required in two, three and six dogs in the C, L and H groups respectively.

CONCLUSIONS:

Remifentanil infusion reduced the isoflurane concentration required for surgical anaesthesia during orthopaedic surgery.

CLINICAL RELEVANCE:

Remifentanil infusions may be a useful additive to isoflurane anaesthesia in healthy dogs.

• Authors: Sandra Allweiler, David C Brodbelt, Kate Borer, Richard A Hammond, Hatim I K Alibhai
• Journal: Veterinary anaesthesia and analgesia (Vet Anaesth Analg) Vol. 34 Issue 6 Pg. 388-93 (Nov 2007) ISSN: 1467-2987 [Print] United States
• PMID: 17850226 (Publication Type: Journal Article, Randomized Controlled Trial)

Chemical References

• Anesthetics, Inhalation
• Anesthetics, Intravenous
• Piperidines
• Isoflurane
• Remifentanil

Topics

• Anesthesia (veterinary)
• Anesthetics, Inhalation (administration & dosage)
• Anesthetics, Intravenous (administration & dosage, pharmacology)
• Animals
• Blood Pressure (drug effects)
• Dogs (physiology)
• Female
• Heart Rate (drug effects)
• Infusions, Intravenous (veterinary)
• Isoflurane (administration & dosage)
• Male
• Piperidines (administration & dosage, pharmacology)
• Prospective Studies
• Remifentanil
• Treatment Outcome