Continuous epidural versus wound infusion plus single morphine bolus as postoperative analgesia in open abdominal aortic aneurysm repair: a randomized non-inferiority trial.

BACKGROUND: We compared a bundle of interventions including wound infiltration and continuous infusion with local anesthetics plus a single morphine bolus (CWI-M) with continuous epidural infusion (CEI) as postoperative analgesia.

METHODS: Fifty-one adults undergoing open abdominal aortic aneurysm repair were randomized in this non-inferiority open-label trial. In the CEI group, patients received thoracic epidural levobupivacaine 0.12% plus sufentanil 0.4 µg/mL infusion for 48 hours. In the CWI-M group, the wound was infiltrated with 10 mL levobupivacaine 0.5%, patients received a morphine bolus before the end of anesthesia and levobupivacaine 0.25% infusion through two multi-holed pre-peritoneal catheters for 48 hours. Systemic morphine was administered as rescue in both groups. The primary endpoint was the mean Numeric Rating Scale score in the first 48 hours after surgery.

RESULTS: Mean NRS was 1.7 (95% CI: from 1.2 to 2.2) in the CEI and 2.2 (95% CI: from 1.7 to 2.7) in the CWI-M group, the 90% CI of difference was from -0.1 to 1.1, not including the non-inferiority margin of 1.3. The cumulative rescue morphine dose per patient was higher in CWI-M than in CEI group (3.7±4.4 vs. 0.8±2.4 mg, P=0.006); moreover, NRS at arousal was higher in CWI-M (P=0.003). No differences were observed in postoperative hemodynamic parameters, recovery-related outcomes, length of stay nor complications.

CONCLUSIONS: CWI-M was comparable to CEI in in postoperative pain control, but it was associated with higher need of rescue systemic opiates and with a worse early pain control.