Local Anesthetic Infusion and Sternotomy

Overview

Cardiac surgery often induces acute postoperative pain and moreover chronic dysesthesia frequently occur long-term after sternotomy. The high doses of intraoperative opioïds are well known to enhance postoperative hyperalgesia (HA) and a perioperative local anesthetic agent infusion is one of the therapeutic strategies used to limit this phenomena. The aim of this study was to evaluate the effectiveness of a continuous Ropivacaïne sternal infusion compared with a saline serum infusion to limit postoperative HA, pain and morphine consumption (M) after sternotomy in cardiac surgery. This strategy could lead to lower postoperative morphine consumption and opioïd induced hyperalgesia.

* Principal Objective: comparison of peri-incisionnal dynamic hyperalgesia extend evaluated by Von Frey filament during the first postoperative week between the two groups. * Secondary Objective: comparison of peri-incisionnal static hyperalgesia (pain threshold) extend evaluated by Von Frey filament, postoperative pain scores, morphine consumption, hemodynamic and respiratory parameters during the first postoperative week and incidence of chronic pain and dysesthesia at six month between the two groups. Ropivacaïne plasmatic concentration will be monitored, during infusion. * Study design : monocentric, double blind randomized clinical trial comparing two groups of patients with a same intraoperative anesthetic management : * Group 1: Ropivacaïne infiltration before skin incision followed by a 48 hours Ropivacaïne continuous infusion after surgery through a sternal fenestrated catheter * Group 2: same protocol with pre and postoperative saline infusion Postoperative pain management is identical in the two groups based upon a Morphine sulfate PCA pump for the first 48 hours. • Number of subjects : 40 patients, 20 in each group