Effect of buprenorphine on total intravenous anesthetic requirements during spine surgery.

Buprenorphine is a partial mu receptor agonist and kappa/delta antagonist commonly used for the treatment of opioid dependence or as an analgesic. It has a long plasma half-life and a high binding affinity for opioid receptors. This affinity is so high, that the effects are not easily antagonized by competitive antagonists, such as naloxone. The high affinity also prevents binding of other opioids, at commonly used clinical doses, to receptor sites - preventing their analgesic and likely minimum alveolar concentration (MAC) reducing benefits. This case report contrasts the anesthetic requirements of a patient undergoing emergency cervical spine surgery while taking buprenorphine with anesthetic requirements of the same patient undergoing a similar procedure after weaning of buprenorphine. Use of intraoperative neurophysiological monitoring prevented use of paralytics and inhalational anesthetics during both cases, therefore total intravenous anesthesia (TIVA) was maintained with propofol and remifentanil infusions. During the initial surgery, intraoperative patient movement could not be controlled with very high doses of propofol and remifentanil. The patient stopped moving in response to surgical stimulation only after the addition of a ketamine. Buprenorphine-naloxone was discontinued postoperatively. Five days later the patient underwent a similar cervical spine surgery. She had drastically reduced anesthetic requirements during this case, suggesting buprenorphine's profound effect on anesthetic dosing. This case report elegantly illustrates that discontinuation of buprenorphine is likely warranted for patients who present for major spine surgery, which necessitates the avoidance of volatile anesthetic and paralytic agents. The addition of ketamine may be necessary in patients maintained on buprenorphine in order to ensure a motionless surgical field.