Pre-emptive versus post-surgical administration of ketorolac for hysterectomy

Seventy-seven women who underwent routine vaginal or abdominal hysterectomy were randomly allocated to receive intravenous ketorolac 30 mg either 30 min before surgical incision (pre-emptive group, n = 37), or at the end of the surgical procedure (post-surgical group, n = 40). The patients received routine post-operative care, which included morphine by patient-controlled analgesia, 1 mg per demand with a lockout of 6 min and a background infusion of 1 mg h-1. In addition, pain was assessed at 12 and 24 h using a 100 mm visual analogue scale (VAS), both at rest and on coughing. At 24 h, the median VAS at rest was 24 mm (range 0-80) in the pre-emptive group and 28 mm (range 0-100) in the post-surgical group. The average morphine consumption rate over the first 24 h was 1.9 mg h-1 (SD +/- 0.6) in the pre-emptive group, and 2.2 mg hr-1 (SD +/- 1.1) in the post-surgical group. There were no significant differences on univariate testing. Subsidiary stepwise multiple regression modelling identified age, weight, type of hysterectomy, and the timing of ketorolac administration as significant explanators of post-operative morphine consumption. A statistically significant pre-emptive analgesic effect was therefore identifiable, but the clinical significance is uncertain in relation to the other influences on post-operative analgesic requirements.