An audit of the safety and effectiveness of an alfentanil:morphine mixture in the postanaesthesia care unit

Summary 

Background

After an initial clinical investigation of the effectiveness of an alfentanil–morphine mixture (AM) for the treatment of postoperative pain in the recovery setting, an audit was conducted to look at the effectiveness, safety and incidence of adverse opioid-related side effects of this mixture compared with morphine (M) alone. Assessment of effectiveness included the time and dose required to achieve patient comfort, the time to discharge from the postanaesthesia care unit (PACU) and pain scores; assessment of safety and side effects included measurement of sedation scores, oxygen saturation and respiratory rate as well as incidence of nausea and vomiting, and pruritus.

Methods

A total of 453 patients were recruited: the M group (221 patients) received a standard IV morphine regimen (morphine concentration 1mg/ml; bolus doses of between 0.5 and 4ml IV given every 3min as needed by nursing staff according to the hospital protocol—see Appendix A); the AM group (232 patients) received a similar IV regimen using the alfentanil:morphine mixture (alfentanil 50μg and morphine 0.75mg/ml; bolus doses given as for morphine).

Results

In the M group, the mean time to comfort was 40.9±34min whilst in the AM group, it was 32.8±26min (significant at p=0.004). The mean (S.D.) volume required to achieve comfort was similar and the mean time to discharge from the PACU was 105.3±75min for the M group and 88.4±55min for the AM group (p=0.5). Neither the sedation scores or pain scores at comfort differed significantly between the groups. The minimum respiratory rates recorded in the PACU were 12±3.2breaths/min for the M group and 11.9±3.1breaths/min for patients given AM. There was no significant difference between the two groups in patients’ reports of nausea, vomiting or pruritus.

Conclusion

Compared with morphine alone, the use of an alfentanil:morphine mixture can reduce the time taken to achieve patient comfort without increasing the risk of opioid-related adverse effects.

Keywords: Alfentanil, Analgesia, Dose to comfort, Morphine, Postoperative pain, Time to comfort