The effect of anterior quadratus lumborum block on morphine consumption in minimally invasive colorectal surgery: a multicentre, double-blind, prospective randomised placebo-controlled trial.

We investigated the efficacy and safety of a bilateral anterior quadratus lumborum block in patients undergoing minimally invasive colorectal surgery. This was a two-centre, double-blind, prospective, randomised, placebo-controlled trial including 150 patients undergoing laparoscopic colorectal surgery (left- or right hemicolectomy, sigmoidectomy) who were enrolled in the institutional abdominal enhanced recovery programme. Before induction of anaesthesia, patients received a bilateral anterior quadratus lumborum block in the left and right lateral decubitus position under ultrasound guidance and were allocated randomly to receive 30 ml of ropivacaine 0.375% (n = 75) or placebo (saline 0.9%) (n = 75) bilaterally. Postoperatively, all patients received multimodal intravenous analgesia including paracetamol, ketorolac and patient-controlled analgesia with morphine. The primary outcome was morphine consumption during the first 24 h after tracheal extubation. Secondary outcomes included severity of pain; presence and extent of sensory block; incidence of postoperative nausea and vomiting; and hospital duration of stay. We also investigated the need for, and dose of, rescue analgesia. Safety outcomes included the incidence of adverse events. Mean (SD) 24-hour morphine consumption was no different between patients allocated to ropivacaine and placebo (28.6 (22.3) mg vs. 28.4 (22.5) mg, p = 0.966, respectively). While a sensory block could be detected in significantly more patients allocated to the ropivacaine group, no differences were detected in pain scores or other secondary or safety endpoints. Patient satisfaction scores were high in both groups. In laparoscopic colorectal surgery, adding a bilateral anterior quadratus lumborum block to a standard multimodal analgesia regimen did not reduce opioid consumption or improve pain scores.