Postoperative titration of intravenous morphine

Abstract

Background and objective Intravenous morphine titration is used to obtain postoperative pain relief, but few studies have assessed the appropriate regimen. In a quality programme, we performed a prospective non-randomized study of morphine titration in a postanaesthesia care unit (PACU).

Methods Four regimens of morphine titration were studied: every 10 (group 1, n = 400) or 5min (group 2, n = 400) with a maximum of five intravenous boluses; every 5min, without any limitation in the number of boluses (groups 3 and 4, n = 400 each); in groups 1, 2, and 3, subcutaneous morphine was administered 4 h after titration. In group 4, administration of subcutaneous morphine was allowed only 2h after titration. A visual analogue pain scale (VAPS) > 30 mm was required to administer morphine and pain relief was defined as a VAPS ≤ 30 mm.

Results After morphine titration, VAPS was lower and the number of patients with pain relief was greater in patients from groups 3 and 4. Patients from group 4 had the lowest VAPS (26±17mm) and the highest percentage of pain relief (73%) at the end of the PACU period. The number of sedated patients increased in groups 3 (62%) and 4 (61%) compared with group 1 (27%). No significant differences in morphine-related adverse effects were observed.

Conclusion Intravenous morphine titration every 5min with an unlimited number of boluses and early subcutaneous administration provided the best analgesic regimen.