A Comparison of Continuous Wound Infiltration Plus Patient Controlled Analgesia Versus Epidural Analgesia after Open Renal Surgery
*Corresponding author: Elizabeth Thompson*, Adam Green, Emma Hartsilver, Mark Stott, Katharine Meikle, Victoria Ormerod, Maytinee Lilaonitkul and Roy Powell
Open nephrectomy is associated with significant post-operative pain. Epidurals have been a core method for provision of analgesia, however, there is increased use of novel analgesic strategies with comparative analgesia but potentially fewer side effects. This pilot study aims to assess the feasibility of a randomised control trial comparing continuous wound infusion (CWI) to epidural analgesia for open renal surgery. Objectives included estimation of recruitment rates, failure rates and complications and refining design of a randomised control trial.
Participants were randomised using randomisation software. Patients received standardised anaesthesia as per the study protocol. Patients randomised to the CWI group had a wound infiltration catheter inserted at the end of surgery. In the epidural group, patients had an epidural sited prior to surgery. Primary outcomes evaluated were visual analogue pain scores. Secondary outcomes included intravenous fluid use, hypotensive episodes, patient mobilisation, evidence of post-operative ileus, respiratory morbidity, demands on medical and nursing care, length of hospital stay and patient acceptability as assessed by the Quality of Recovery (QoR-15) questionnaire.
Pain scores were similar for both groups with marginally higher mean scores in the wound infiltration group on post-operative day 1 and 3. Supplementary analgesia rates were comparable for both groups with tramadol use being higher in the wound infiltration group.
Collecting outcome data for an appropriately powered randomised controlled trial is feasible. Recruitment was challenging due to the increased minimally invasive laparoscopic or robotic nephrectomies and consideration of a multicentre study is warranted. The two analgesic techniques appear broadly comparable in efficacy and time to discharge. CWI potentially presents safety advantages compared to epidural analgesia.