Background and Goal of Study: Patients scheduled for abdominal aortic aneurysm (AAA) surgery carry a high risk of cardiac, renal or respiratory comorbidities. The post-operative pain control is essential in this population. Transversus abdominis plane (TAP) block has been described as an effective technique to reduce postoperative pain and morphine consumption after gynecologic and lower abdominal surgery but not in open AAA surgery.
The aim of this study was to demonstrate the postoperative analgesic efficacy of bilateral dual TAP block by reducing the amount of morphine consumption during the first 24 hours postoperative.

Materials and Methods: This randomized, double-blind, controlled, prospective trial approved by the local ethics committee enrolled 60 adult patients with AAA or Leriche syndrome scheduled for an aortic surgery through midline laparotomy. Patients were randomized to receive bilateral dual TAP block using 4 x 10 mL of 0.375% ropivacaine (= 150 mg) (TAP group = 30 patients) or not (CONTROL group = 30 patients). Anaesthetic technique (Remifentanil, Sevoflurane) and postoperative analgesia were standardized. All patients received IV morphine via a morphine patient-controlled analgesia device and IV paracetamol every 6 hours for postoperative analgesia. Postoperative assessments were conducted every hour for the first 48 hours after surgery. Postoperatively pain scores at rest and with movement, total morphine consumption and opioid related side effects were recorded. The primary outcome of the study was total morphine (mg) consumption at 24 hours postoperatively.

Results and Discussion: Both groups were comparable as to gender, age, body mass index (BMI), creatinine clearance and ASA physical status. Nine patients (64,3%) in the TAP group had a BMI > 30 kg/m2 and 5 (35,7%) in the CONTROL group. Total morphine consumption at 24 hours was 35,5 mg (+/- 24,2) in the TAP group and 33,3 mg (+/- 19,5) in the CONTROL group (P=0,71). Total morphine consumption at 48 hours was also similar in both groups (58,4 +/- 39 mg vs 60 +/- 35 mg, P=0,85). This non-significant result could be explained by the fact that the dose of ropivacaine wasn’t sufficient.

Conclusion(s): In our study, bilateral dual TAP block performed in open AAA surgery doesn’t show a reduction of morphine consumption during the first 24 hours postoperative. A study with different doses of ropivacaine in this type of surgery could be interesting and refine this work.

01 / Efficacy of bilateral dual transversus abdominis plane (TAP) block for postoperative analgesia after open abdominal aortic aneurysm (AAA) surgery: a prospective monocentric randomized double-blind controlled trial