The ETAP study aim to assess the effect of the addition of an ultrasound-guided transversus abdominis plane (TAP) block to a multimodal intravenous analgesia protocol on the postoperative pain control in open surgical repair of abdominal aortic aneurysm. The ETAP study is a single-center open-label randomized controlled trial. Half of patients included will receive the association of TAP block and multimodal intravenous analgesia, and the other half will receive the multimodal intravenous analgesia alone. The multimodal intravenous analgesia includes intravenous paracetamol and intravenous patient-controlled analgesia with morphine.

The open repair of abdominal aortic aneurysm (AAA) is a painful surgery. Patients suffering from AAA are at high risk of perioperative cardiovascular and pulmonary complications. It has been previously suggested that a bad perioperative pain control could increase the incidence of such complications.

Intravenous patient-controlled analgesia (PCA) with morphine is widely considered as the gold standard treatment of the postoperative pain in open repair of AAA. High dose of morphine are often required and could delay the postoperative recovery and discharge. Side effects of morphine, such as respiratory depression, nausea, vomiting or pruritus, are responsible for patient discomfort and dissatisfaction when high doses are used.

The efficacy of the ultrasound-guided transversus abdominis plane (TAP) block has been described for pain management following abdominal surgery, such as gastrectomy or kidney transplantation. The efficacy of the association of TAP block and PCA with morphine was higher than multimodal intravenous analgesia including PCA with morphine and than the combination of PCA with morphine and epidural analgesia. To our knowledge, the efficacy of the ultrasound-guided TAP block has never been studied for the postoperative pain control in AAA surgery.

Inclusion Criteria:

• ASA (American Society of Anesthesiologists) physical status 1, 2 or 3
• Elective surgery for open repair of an aortic abdominal aneurysm performed in the Vascular Surgery Unit of the University Hospital of Besancon
• Informed consent given
• Health medical insurance affiliation

Exclusion Criteria:

• Poor adherence to protocol attended
• Incapacity to consent
• Pregnancy and/or breast feeding
• Endovascular repair of aortic abdominal aneurysm
• Emergent surgery of a rupture or a fissuration of aortic abdominal aneurysm
• Chronic medical treatment by clopidogrel if clopidogrel not stopped 5 days before surgery at least
• Chronic medical treatment by prasugrel if prasugrel not stopped 7 days before surgery at least
• Chronic medical treatment by ticlopidine, inhibitors of phosphodiesterase , inhibitors of glycoprotein IIb/IIIa, adenosine triphosphate analogs or thrombin receptor antagonists
• Congenital or acquired bleeding disorder
• Incapacity to use patient-controlled analgesia device
• Chronic opioid abuse or dependence
• Chronic renal failure defined as a clearance < 30 ml/min
• Severe hepatic failure
• Other contraindications to ropivacaïne (allergy, medical history of porphyria, hypovolemia)
• Contraindications to acetaminophen
• Contraindications to morphine