Does continuous wound infiltration enhance baseline intravenous multimodal analgesia after posterior spinal fusion surgery? A randomized, double-blinded, placebo-controlled study

Purpose: There has been a growing interest in continuous local anaesthetic wound infiltration as a non-opioid technique for postoperative pain relief. The impact of this modality on baseline analgesia after spinal fusion surgery has however been inconclusive. We tested whether continuous wound infiltration with ropivacaine can enhance postoperative analgesia compared to a baseline intravenous multimodal analgesia protocol after spinal fusion surgery. Methods: In this randomized, double-blinded, placebo-controlled study, a multiholed 19-gauge catheter was placed at the end of the surgical procedure through the wound to permit the continuous administration (8 ml/h) of ropivacaine 0.2 % (ropivacaine group; n = 19 patients) or saline (control group; n = 20 patients) during the first 48 postoperative hours (H48). Both groups received intraoperative low-dose ketamine, a combination of acetaminophen, non-steroidal anti-inflammatory drug, and nefopam over the same postoperative period, and morphine delivered by a patient-controlled analgesia (PCA) device. Results: Morphine consumption was comparable between the two groups both at H48, 38 mg (26:52) (median, 25th:75th percentile) (control group) versus 43 mg (19:74) (ropivacaine group), and at H24, 18 mg (16:22) versus 22 mg (9:35) respectively. Pain scores at rest and during mobilization, quality of postoperative sleep, and morphine-related side effects were comparable between the two groups at H24 and H48. Conclusion: Our findings indicate that no additional analgesia was provided with continuous wound infiltration of ropivacaine compared to a baseline intravenous multimodal analgesia protocol after spinal fusion surgery. Trial registration: Clinicaltrials.gov #NCT01743794.