A prospective comparison of continuous wound infiltration with ropivacaine versus single-injection paravertebral block after modified radical mastectomy

BACKGROUND: The efficacy of continuous wound infiltration with local anesthetic has not been compared with that of thoracic paravertebral lock (PVB) after breast surgery. In this study, we evaluated the analgesic efficacy and morphine consumption of the two techniques after mastectomy. METHODS: Forty-eight patients undergoing modified radical mastectomy with axillary dissection were randomly assigned to either a preoperative PVB with 20 mL of ropivacaine 0.5% (group PVB) or a continuous ropivacaine 0.5% infusion (CRI) at a 2 mL/h rate for each of two multilumen catheters placed subcutaneously at the end of the procedure (group CRI). The catheters were left in place for 24 h postoperatively. A standardized general anesthetic was administered to all patients. Postoperative morphine consumption, pain scores and painful restricted movement of the shoulder for 24 h postoperatively as well as incidence of adverse events, including postoperative nausea and vomiting, were recorded. RESULTS: Morphine consumption was similar between groups (PVB: 42.6 +/- 11 vs CRI: 38.7 +/- 11 mg in 24 h, P = 0.225). Absolute pain scores were low in both groups. Four hours after surgery, group PVB showed a significant reduction in postoperative pain (PVB: 0 [0-10] vs CRI: 0 [0-30], P = 0.002) and reduced painful restricted movement (P = 0.004), whereas the CRI group had lower pain scores (PVB: 10 [0-30] vs CRI: 0 [0-20], P = 0.034) and painful restricted movement (P = 0.043) 16 and 24 h (PVB: 10 [0-30] vs CRI: 0 [0-30], P = 0.012) after surgery. Postoperative nausea and vomiting was significantly more frequent in the CRI group (P = 0.017). CONCLUSIONS: Continuous wound infiltration of local anesthetics is an effective alternative to paravertebral analgesia after mastectomy with axillary dissection.