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June 1997
Evaluation of morphine vs. fentanyl for postoperative analgesia after ambulatory surgery procedures
Claxton AR, McGuire G, Chung F, Cruise C;Anesthesia & Analgesia 1997; 84:509-14.
[ see abstract below ]
Adequate control of postoperative pain is critical to the success of ambulatory surgical procedures. However, opioids, which are effective in controlling postoperative pain, are also associated with significant side effects. Fentanyl is currently the drug of choice because of fast onset time and reasonable duration of action, but morphine may provide more prolonged pain relief. This study compares morphine with fentanyl for postoperative analgesia after painful ambulatory surgical procedures.
All patients received general anesthesia including fentanyl totaling approximately 130 �g/kg in both groups, for procedures of approximately one-hour duration. Patients received blinded IV solutions of either 1 mg/ml morphine or 12.5 �g/ml fentanyl. Pain was evaluated in Phase I PACU using 100 mm visual analog scales.
A VAS score, 60 received 2 ml, VAS 40-60 received 1 ml, and VAS < 40 received analgesia only on specific patient request. Repeated bolus doses of either study opioid were given every 5 minutes until the VAS score was < 40. In the Phase II PACU, pain was treated by acetaminophen with codeine at patient request, and patients were discharged with a supply of the same oral analgesic. Nausea, sedation and dizziness were also recorded using 100 mm VAS scales.
Morphine and fentanyl achieved equivalent reductions in VAS pain scores; both groups reported statistical decreases from baseline at 20 minutes and VAS < 40 at 40 minutes. The morphine group, however, displayed significantly lower VAS scores persisting into Phase II recovery, and significantly fewer morphine patients required supplemental oral analgesia in Phase II. The incidence of nausea and vomiting was not significantly different between morphine and fentanyl groups during Phase I or Phase II recovery.
However, the incidence of nausea and vomiting after discharge was higher with morphine, 59% vs. 24%, and the overall incidence of nausea and vomiting was also higher, 79% vs. 38%. Antiemetic therapy was required by 24% in the morphine group vs. 14% in the fentanyl group (NS). Other postoperative symptoms such as drowsiness and dizziness were comparable between the groups.
Patients' satisfaction with their postoperative analgesia treatment was comparable between the groups, 76% for morphine and 72% with fentanyl. The shorter duration of fentanyl was not associated with faster discharge times, and most patients required additional analgesia to control pain.
Return to the Current Literature Review Front Page, or read the abstract:
ABSTRACT
Adequate postoperative analgesia without side effects is necessary to facilitate same-day discharge of ambulatory patients after ambulatory surgery. This study compared the use of intravenous morphine and fentanyl after painful ambulatory procedures with respect to analgesic efficacy, the incidence of side effects, and impact on the patient's readiness for discharge.
Fifty-eight patients undergoing ambulatory surgery were prospectively randomized to receive morphine or fentanyl for postoperative analgesia and studied in double-blind fashion. The drugs were administered in equipotent doses in the postanesthesia care unit (PACU) and were titrated against pain scores until a visual analog score < 40 mm was achieved and the patient was satisfied with the level of analgesia. In the ambulatory surgical unit, oral analgesia was available.
Pain scores, amount of analgesia used, the incidence of side effects (nausea and vomiting, sedation and dizziness), the times to achieve recovery milestones, and fitness for discharge were studied. Equal amounts of morphine and fentanyl were used in the PACU, but pain scores were higher in the fentanyl group in the ambulatory surgical unit. In addition, the fentanyl group required more oral analgesia than the morphine group (69% vs 17%; P < 0.0002).
The incidence of in-hospital side effects was similar. However, the morphine group had a more frequent incidence of postdischarge nausea and vomiting than the fentanyl group (59% vs 24%; P < 0.016). There was no significant difference in the duration of stay in the PACU (morphine vs fentanyl, 69 +/- 15 min vs 71 +/- 20 min), the times to achieve recovery milestones, and fitness for discharge (morphine vs fentanyl, 136 +/- 41 min vs 132 +/- 40 min).
The short duration of fentanyl was not associated with faster discharge times; most patients required additional analgesia to control pain. Morphine produced a better quality of analgesia but was associated with an increased incidence of nausea and vomiting, the majority of which occurred after discharge.
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