Postoperative analgesia with continuous wound infusion of local anaesthesia vs saline: a double-blind randomized, controlled trial in colorectal surgery.

AIM: The aim of this prospective double-blind randomized clinical trial was to determine whether preperitoneal continuous wound infusion (CWI) of the local anaesthetic ropivacaine after either laparotomy or video-assisted laparoscopy for colorectal surgery would reduce patient consumption of morphine.

METHOD: Patients scheduled for colorectal surgery randomly received a 48-h preperitoneal CWI of either 0.38% ropivacaine or 0.9% saline at rates of 5 ml/h after laparotomy or 2 ml/h after laparoscopy. The primary end-point was total morphine consumption in surgery and afterwards through a patient-controlled analgesia device. Results in the laparotomy and laparoscopy subgroups were also compared.

RESULTS: Sixty-seven patients were included, 33 in the ropivacaine CWI group and 34 in the saline group. Median [interquartile range (IQR)] morphine consumption was lower in the ropivacaine group [23.5 mg (11.25-42.75)] than in the saline group [52 mg (24.5-64)] (P = 0.010). Morphine consumption was also lower in the laparotomy subgroup receiving ropivacaine [21.5 (15.6-34.7)] than in the saline group [52.5 (22.5-65) ml] (P = 0.041). Consumption was statistically similar in laparoscopy patients on ropivacaine or saline. No side effects were observed. Sixteen patients had a surgical wound infection (23.9%); 11 (16.4%) presented wound infection and five (7.5%) organ space infection. Forty-six catheter cultures were obtained; 10 (21.7%) were positive, assessed to be due to contamination.

CONCLUSION: Preperitoneal CWI of ropivacaine is a good, safe addition to a multimodal analgesia regimen for colorectal surgery. CWI can reduce morphine consumption without increasing adverse effects.