No potentiation of fentanyl by use of transdermal buprenorphine in patients undergoing fast-track anesthesia for open-heart surgery.

Simultaneous use of opioids with a different pharmacological profile during anesthesia may lead to unexpected prolongation of effects. In addition, long-term use of transdermal buprenorphine may result in a reduced sensitivity to opioid anesthesia. In a prospective study, possible overlap of opioid effects and vigilance was determined in a group of patients (n = 22) using a buprenorphine patch for at least two months for treatment of chronic pain, and undergoing fentanyl-based fast-track enflurane anesthesia for open-heart surgery. The patients using buprenorphine were compared with a control group (n = 21) undergoing similar open-heart procedures with no opioid other than fentanyl on board. Aside from time to extubation, total dose of fentanyl, postoperative blood gases, and vigilance assessment score were used to determine possible overlap of opioid effects and/or development of opioid tolerance in the buprenorphine group compared to the control group. Both groups had similar operation and anesthesia times and comparable doses of fentanyl (0.69 mg +/- 0.23 vs. 0.67 mg +/- 0.16 SD). There was no significant difference in postoperative arterial blood gases (PaO2 136 +/- 48 torr vs. 128 +/- 35 torr SD; PCO2 43.3 +/- 3.3 torr vs. 41.9 +/- 1.2 torr SD), time until extubation (27 +/- 22 min vs. 33 +/- 24 min), and postanesthetic vigilance and recovery score (6.8 +/- 1.0 vs. 7.5 +/- 0.8, arbitrary units) between the two groups. Because of adaptive mechanisms and the development of tolerance in patients using buprenorphine, respiratory depression or sedation does not project into the postoperative period. The significant (p < 0.05) lower incidence of nausea and emesis in patients with transdermal buprenorphine owes to the development of tolerance to these opioid-related side effects.