Effect of buprenorphine on the cardiovascular and respiratory response to visceral pain in conscious rabbits

Objective To evaluate the effect of buprenorphine administration on the cardiovascular and respiratory responses to noxious colorectal distension in conscious rabbits. Study design Prospective experimental trial. Animals Fifteen healthy, young adult New Zealand white rabbits (eight female). Methods Experiments were performed on conscious rabbits that were instrumented with intraabdominal arterial and venous catheters, and diaphragmatic and abdominal electromyographic electrodes. Colorectal distension was achieved by inflation of an acutely placed colorectal balloon catheter until mean arterial pressure increased 10-15 mmHg. Buprenorphine (0.06 mg) or saline was administered intravenously prior to, or during colorectal distension. Arterial blood pressure, heart rate, respiratory rate, abdominal electromyographic activity, and intra-balloon pressure were monitored. Results In the absence of colorectal distension, buprenorphine increased arterial blood pressure and decreased respiratory rate but did not change heart rate. Colorectal distension increased arterial blood pressure and heart rate, and decreased respiratory rate. The increase in arterial blood pressure associated with colorectal distension was attenuated following preemptive buprenorphine, but was not changed by buprenorphine administered during distension. Conclusions and clinical relevance If cardiovascular changes reflect the intensity of noxious stimulation, then these results support the preemptive administration of buprenorphine for visceral analgesia.