Transversus abdominis plane block versus perioperative intravenous lidocaine versus patient-controlled intravenous morphine for postoperative pain control after laparoscopic colorectal surgery: study protocol for a prospective, randomized, double-blind controlled clinical trial.

BACKGROUND: Despite the laparoscopic approach becoming the standard in colorectal surgery, postoperative pain management for minimally invasive surgery is still mainly based on strategies that have been established for open surgical procedures. Patient-controlled epidural and intravenous analgesia are considered standard postoperative analgesia regimens in colorectal surgery. Epidural analgesia provides excellent analgesia, but is increasingly scrutinized in laparoscopic surgery since postoperative pain after the laparoscopic approach is significantly reduced. Moreover, epidural analgesia can be associated with numerous complications. Therefore, epidural analgesia is no longer recommended for the management of postoperative pain in laparoscopic colorectal surgery. Likewise, patient-controlled intravenous analgesia is subject to significant side effects. Given these important limitations of the traditional strategies for postoperative analgesia, effective and efficient alternatives in patients undergoing laparoscopic colorectal surgery are needed. Both the transversus abdominis plane block and systemically administered lidocaine have already been reported to effectively reduce pain after laparoscopic colorectal surgery. We hypothesize that the transversus abdominis plane block is superior to perioperative intravenous lidocaine.

METHODS/DESIGN: One hundred and twenty five patients undergoing laparoscopic colorectal surgery will be included in this prospective, randomized, double-blind controlled clinical trial. Patients will be randomly allocated to three different postoperative strategies: postoperative patient-controlled intravenous analgesia with morphine (control group, n = 25), a transversus abdominis plane block with ropivacaine 0.375% at the end of surgery plus postoperative patient-controlled intravenous analgesia with morphine (TAP group, n = 50), or perioperative intravenous lidocaine plus postoperative patient-controlled intravenous analgesia with morphine (LIDO group, n = 50). As the primary outcome parameter, we will evaluate the opioid consumption during the first 24 postoperative hours. Secondary endpoints include the Numeric Rating Scale, time to return of intestinal function, time to mobilization, inflammatory response, incidence of postoperative nausea and vomiting, length of hospital stay and postoperative morbidity as assessed with the Clavien-Dindo classification.

DISCUSSION: Recognizing the importance of a multimodal approach for perioperative pain management, we aim to investigate whether a transversus abdominis plane block delivers superior pain control in comparison to perioperative intravenous lidocaine and patient-controlled intravenous analgesia with morphine alone.

TRIAL REGISTRATION: EudraCT Identifier: 2014-001499-73; 31 July 2014.