Lack of rapid development of opioid tolerance during alfentanil and remifentanil infusions for postoperative pain

Studies in animals and volunteers have suggested the development of acute t olerance to opioid analgesics. In this article, we present data from patien ts who regulated their own target-controlled infusions of alfentanil and re mifentanil to provide analgesia in the immediate postoperative period. Fift y-one patients received alfentanil for 24 h after cardiac surgery, and 30 p atients received remifentanil for 6 h after orthopedic surgery. Satisfactor y analgesia, defined as a rating of less than or equal to 3 on an 11-point visual analog scale, was obtained by patients after each type of surgery. T he target concentrations of the opioids required to produce postoperative a nalgesia and the cumulative opioid doses administered over the course of th e clinical observation suggest there was no tolerance to the analgesic effe cts of the opioids. The requirements for both analgesic drugs in individual patients had a large variation (>200%). We conclude that our results may i ndicate an absence of tolerance to opioids in postoperative analgesia. None theless, our data show that the postoperative requirement for these rapidly acting drugs is qualitatively similar to that for other opioids in that do sage escalation does not occur. Implications: The development of acute tole rance to opioid analgesics has been suggested based on experimental studies in animals and volunteers. Our report from patients who self-controlled th eir analgesic requirements by using target-controlled infusions of alfentan il and remifentanil for postoperative analgesia provides no evidence of tol erance to opioids.