A comparison of morphine, pethidine and fentanyl in the postsurgical patient-controlled analgesia environment

This study was designed to evaluate whether there is any scientific basis for clinicians' preferences for selecting opioids for use in patient-controlled analgesia (PCA) and to determine whether there are any patients' preferences for being treated with any of these opioids. Results were obtained for 55 postoperative patients recruited to investigate putatively equivalent doses of 3 commonly used opioids--morphine, pethidine and fentanyl--when self-administered postoperatively. No significant differences in the incidence of side effects between groups were found with the exception of more pruritus reported in the group given morphine. Patients who experienced vomiting or pruritus reported a greater intensity of these side effects if receiving morphine and fentanyl than if receiving pethidine. The majority of patients reported being very satisfied with their postoperative pain management and with PCA, with no differences in satisfaction between the 3 opioid-treated groups. A senior consultant anaesthetist, when asked to make a judgement, was not able to identify which agent each patient was receiving with a better than chance accuracy. These findings suggest that while there may be subtle differences in patient response to these 3 commonly used opioids, none was obviously superior when used for postoperative PCA.