Local Anesthetic Infiltration to Prevent Postoperative Pain After Lumbar Surgery

Blockade of parietal nociceptive afferents by the use of continuous wound infiltration with local anesthetics may be beneficial in a multimodal approach to postoperative pain management after major surgery. The role of continuous wound parietal paravertebral infiltration of ropivacaine for pain relief and postoperative rehabilitation after posterior lumbar arthrodesis will be evaluated in a randomized, monocentric, double-blinded, superiority controlled trial. The general purpose of this clinical research is the assessment of efficacy and safety of continuous wound infiltration with ropivacaine through a parietal paravertebral catheter for postoperative analgesia, and his repercussions at mid (two months) and long (six months)-term after posterior lumbar arthrodesis on degenerative spine. The principal purpose concerns the assessment of postoperative analgesic efficacy at mid-term (two months after surgery) of continuous wound infiltration with ropivacaine (compared with saline solution), through a parietal paravertebral multi-holed catheter, after posterior lumbar arthrodesis. After obtaining written informed consents, the patients scheduled to undergo posterior lumbar arthrodesis on degenerative spine,.will be randomly allocated to receive a continuous wound infusion of either 0.2% ropivacaine (ropivacaine group A) or 0.9% saline (control group B) when they will arrive in the operating room. The surgeon will perform a standardized posterior median incision at the level of lumbar intervertebral instability. Before putting retractors, he will infiltrate all surgical strata and the paraspinal muscles all long the wound bilaterally with a solution of ropivacaine 0.5% 20 mL (group A) or with a solution of 0,9% NaCl 20 ml (group B). At the end of surgery, a multi-holed wound catheter will be placed by the surgeon, under direct visualization, in the paravertebral space ; between the muscle fascia and subcutaneous tissues all along the wound, and fixed at the skin by a stitch. The patients will be thereafter randomly assigned to receive through the catheter either 0.2% ropivacaine (study group) (5-ml bolus followed by an infusion of 8 ml/h during 48 h) or the same protocol with 0.9% NaCl (control group), thanks to a prefilled elastomeric pump (400ml), set to deliver a 8-ml/h connected with the catheter. In addition, all patients will receive patient-controlled intravenous morphine analgesia. After the induction, the anaesthesist will install a peripheral venous catheter for each patient in order to make blood samples easier (eight peroperative and two postoperative blood samples for each patient, with the aim of ropivacaine pharmacokinetic study).