Postoperative analgesic effects of three demand-dose sizes of fentanyl administered by patient-controlled analgesia

Many studies have demonstrated the postoperative analgesic efficacy of fentanyl delivered IV by patient-controlled analgesia (PCA) devices at demand doses ranging from 10 to 50 mu g,but none has sought to define the optimal fentanyl PCA dose. In this randomized, double-blind, multicenter study, we compared the safety and efficacy of three administered demand-dose sizes of fentanyl (20, 40, and 60 mu g) in 150 patients after major surgery. Efficacy was dose-dependent; positive response rates (i.e., a global assessment score of "very good" or "excellent" and the absence of severe opioid adverse effects) were 42%, 52%, and 68% for the 20, 40, and 60 mu g demand-dose groups, respectively, and were significantly higher in the 60 mu g demand-dose group. The number of doses administered and missed attempts were significantly smaller in the 40 and 60 mu g demand-dose groups compared with the 20 mu g demand-dose group. This suggests that the 20 mu g demand dose provided inadequate pain relief. Adverse respiratory events were more frequent and mean respiratory rates were significantly slower with the 60 mu g demand dose, compared with the 20 or 40 mu g demand doses. These results indicate that, of these three doses, the 90 mu g demand dose was optimal for fentanyl PCA management of moderate to severe pain after major surgery. Implications: The postoperative analgesic efficacy of fentanyl delivered IV by patient-controlled analgesia devices has been demonstrated for demand doses ranging from 10 to 50 mu g, but the optimal fentanyl dose remains unknown. In this randomized, double-blind study, we compared three demand dose sizes of fentanyl (20, 40, and 60 mu g) and found that the 40 mu g demand dose was the most appropriate for fentanyl patient-controlled analgesia management of postoperative pain.