Comparison between Ultrasound Guided Abdominal Wall Catheter (by Anaesthetist) and Wound Catheter (by Surgeon) for the Treatment of Postoperative Pain after Abdominal Surgery

The investigators are proposing a prospective, randomized study of 2x41 patients undergoing major abdominal surgery to compare ultrasound-guided TQL block catheters versus surgically placed PP catheters as an active control-group. We have been conservative in estimating the number of patients required, as there are no parallel active trials in the literature to draw from. However a single study using single shot TQl block in the lower abdominal surgery found 25 patients sufficient to get power of 0.8.The study will be conducted with pain score on cough as primary measurable endpoint and Analgesic use as secondary endpoint (cumulative and daily -PACU, day 1, day 2- Fentanyl use) and pain score differences over time as secondary endpoint -PAC, day 1, day 2 at rest.The investigators hypothesize that ultrasound-guided TQL block is superior to surgically guided Pre-Peritoneal block with respect to both end-points and either technique may be superior in discharge times or cost-efficacy. The primary objective of the study is to compare analgesia used and the pain scores with the ultrasound guided TQL vs. surgically placed PP catheter infusion techniques in abdominal surgery. Secondary aim is to assess the subjective quality of pain management (satisfaction score), discharge times and cost analysis of the two methods of delivery. Patients in the PP group will have PP catheters placed under direct vision by the surgeon at the end of the surgery. Initially the surgeon injects 20 ml ropivacaine 0.375% at each site; subcutaneous, sub-fascia and pre-peritoneal levels followed by catheter insertion. This catheter are connected to an elastomeric pump. In the TQL group post-surgery, with the patient in lateral position, under ultrasound guidance, an 18 gauge Tuohy needle will be used to reach the QL muscle posterior aspect. This is confirmed by injecting saline and followed by a bolus dose of 20 ml of ropivacaine 0.375%. Subsequently a catheter is inserted. The same technique is repeated on the other side. Both groups will receive multimodal analgesia with Paracetamol 1 gram QID (orally or IV) and a Fentanyl PCA device (bolus 10 to 40 mcg; lockout time 5 min). Both groups will be infused with 0.2% ropivacaine 5ml/hr on each side during 48 hours via elastomeric pump. Acute Pain Service (APS) personnel will independently assess the postoperative pain scores and analgesia used in recovery and on day one and two. Procedure related technical issues; duration of introduction of catheter insertions and complications related to it will be noted. Patient satisfaction will be assessed on day 2 and during a follow-up telephone call at one month. First flatus or bowels opening time and discharge time will also be tracked. Personnel and material costs will be used for a cost analysis.