The effect of fentanyl on the end-tidal sevoflurane concentration needed to prevent motor movement in dogs
Article first published online: 31 JAN 2013
© 2013 The Authors. Veterinary Anaesthesia and Analgesia © 2013 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia
Veterinary Anaesthesia and Analgesia
Volume 40, Issue 3, pages 290–296, May 2013
How to Cite
Reilly, S., Seddighi, R., Egger, C. M., Rohrbach, B. W., Doherty, T. J., Qu, W. and Johnson, J. R. (2013), The effect of fentanyl on the end-tidal sevoflurane concentration needed to prevent motor movement in dogs. Veterinary Anaesthesia and Analgesia, 40: 290–296. doi: 10.1111/vaa.12013
- Issue published online: 12 APR 2013
- Article first published online: 31 JAN 2013
- Manuscript Accepted: 3 FEB 2012
- Manuscript Received: 1 JUL 2011
- minimum alveolar concentration;
The objectives of this study were to determine the effects of fentanyl on the end-tidal concentration of sevoflurane needed to prevent motor movement (MACNM) in response to noxious stimulation, and to evaluate if acute tolerance develops.
Randomized cross-over experimental study.
Six healthy, adult (2–3 years old), intact male, mixed-breed dogs weighing 16.2 ± 1.1 kg.
Six dogs were randomly assigned to receive one of three separate treatments over a 3 week period. After baseline sevoflurane MACNM (MACNM-B) determination, fentanyl treatments (T) were administered as a loading dose (Ld) and constant rate infusion (CRI) as follows: T1-Ld of 7.5 μg kg−1 and CRI at 3 μg kg−1 hour−1; T2-Ld of 15 μg kg−1 and CRI at 6.0 μg kg −1 hour−1; T3-Ld of 30 μg kg−1 and CRI at 12 μg kg−1 hour−1. The MACNM was defined as the minimum end-tidal sevoflurane concentration preventing motor movement. The first post-treatment MACNM (MACNM-I) determination was initiated 90 minutes after the start of the CRI, and a second MACNM (MACNM-II) determination was initiated 3 hours after MACNM-I was established.
The overall least square mean MACNM-B for all groups was 2.66%. All treatments decreased (p < 0.05) MACNM, and the decrease from baseline was 22%, 35% and 41% for T1, T2 and T3, respectively. Percentage change in T1 differed (p < 0.05) from T2 and T3; however, T2 did not differ from T3. MACNM-I was not significantly different from MACNM-II within treatments.
Conclusions and clinical relevance
Fentanyl doses in the range of 3–12 μg kg−1 hour−1 significantly decreased the sevoflurane MACNM. Clinically significant tolerance to fentanyl did not occur under the study conditions.