Randomized clinical trial to assess the ideal mode of delivery for local anaesthetic abdominal wall blocks

BACKGROUND: Adequate post-operative analgesia is essential for recovery following abdominal surgery. Abdominal wall nerve blocks have been shown to be beneficial in this respect following surgery. The purpose of this trial was to examine the efficacy of infusional versus intermittent bolus delivery of abdominal wall blocks in patients undergoing abdominal resectional gastrointestinal surgery. METHODS: A prospective randomized clinical trial, involving 120 patients undergoing gastrointestinal surgery, was undertaken across three hospitals. Insertion of abdominal wall catheters was performed and patients were randomized to receive ropivacaine 0.2% by either continuous infusion or regular intermittent bolus. The primary outcome was respiratory function, as measured by spirometry on post-operative days 1-3 and 30. Secondary outcomes were pain, mobility, return of gut function, length of hospital stay, complication rates and patient satisfaction with analgesia. RESULTS: All 120 patients were followed up to trial completion. Patients were well matched with regards to demographics. There was no difference between groups with regards to the primary outcome of post-operative respiratory function. The bolus group had improved mobility scores on post-operative day 1 (P = 0.025). There were no complications associated with blockade, and no other differences were identified between assessed outcomes. CONCLUSIONS: Continuous infusion and intermittent bolus are both safe ways of delivering abdominal wall nerve blockade, with equivalent analgesic outcomes. Bolus delivery appears to provide superior early mobility in comparison with continuous infusion.