Evaluation of postoperative respiratory function by serial blood gas analysis in dogs treated with transdermal fentanyl
Version of Record online: 1 JUL 2002
Journal of Veterinary Emergency and Critical Care
Volume 12, Issue 2, pages 81–87, June 2002
How to Cite
Welch, J. A., Wohl, J. S. and Wright, J. C. (2002), Evaluation of postoperative respiratory function by serial blood gas analysis in dogs treated with transdermal fentanyl. Journal of Veterinary Emergency and Critical Care, 12: 81–87. doi: 10.1046/j.1435-6935.2002.00021.x
- Issue online: 1 JUL 2002
- Version of Record online: 1 JUL 2002
- Sources of Support Competitive research grant from Auburn University awarded to Dr Welch
- pain management;
- respiratory depression;
Objective: To perform blood gas analysis of the respiratory response to transdermal fentanyl in dogs which have experienced an open-chest surgical procedure.
Design: Prospective trial.
Setting: Veterinary Teaching Hospital Surgical Research and Student Laboratory.
Intervention: Dogs were purchased for a surgical laboratory. Students performed a cranial abdominal exploratory and diaphragmatic hernia repair. Sixteen dogs were divided into 2 groups. Dogs received transdermal fentanyl (group F), using an average dose of 4.8 µg/kg/hr, applied to the caudal-lateral abdomen 22 hours before surgery, or intravenous buprenorphine (group B; 0.02 mg/kg) given 1 hour prior to anesthetic induction and every 6 hours postoperatively. All dogs received intravenous acepromazine (0.05 mg/kg) preoperatively and every 6 hours postoperatively. Dogs were instrumented with carotid artery catheters.
Measurements and main results: Arterial blood gas values were analyzed every 2 hours postoperatively. Plasma fentanyl levels were analyzed every 4 hours postoperatively. The mean carbon dioxide tension (PCO2) did not exceed 45 mmHg in either group. The range in mean PCO2 levels was 32.9 (± 3.4)−38.1 (± 3.9) in group B and 34.7 (± 3.25)−43.6 (± 5.5) in group F. At 2 time points, the mean PCO2 was significantly lower in group B compared with normal levels in group F. Hypoxemia occurred in both the groups. The range in mean oxygen tension (PO2) was 76.5 (± 18.3)−91.1 (± 16.3) in group B and 76.0 (± 10.8)−96.6 (± 7.6) in group F. There was no significant difference in PO2 between groups. Levels of fentanyl considered to be analgesic were maintained for the postoperative period.
Conclusions: The use of a relatively high dose of transdermal fentanyl did not induce postoperative hypoventilation as evidenced by serial arterial blood gas analysis in this model.