Investigating Systemic Effects of Lidocaine Infusion for Transversus Abdominis Plane (TAP) Block Catheter

Following IRB approval and written consents, patients undergoing nephrectomy were randomized into 2 groups: standard 0.2% ropivacaine infusion (control) and 0.4% lidocaine infusion for TAP catheter. The TAP catheters were placed by the surgeons under direct vision at the end of surgery before wound closure. All subjects had a general anesthetic in accordance to the discretion of the anesthesiologist in the operating room. At the end of surgery, all patients received a patient-controlled analgesia (PCA) in recovery for 48 hours. The primary outcome was the total opioid consumption at the first 27 hours post-operatively. The secondary outcomes were the total opioid consumption at 4/12/24/36/48/60 hours after the initiation of local anesthetic infusion, the numerical rating scale (NRS) at rest and on movement at 4/12/24/36/48/60 hours after the initiation of the local anesthetic infusion, the incidence of nausea and vomiting, and adverse effects.

The sample size calculation for this non-inferiority trial is based on our previous retrospective study on TAP in nephrectomy patients. A sample of 80 patients is needed, using a power of 90% with the two-sided significance level of 5%. All parametric data will be analyzed using mean and standard deviation. Non-parametric data will be analyzed using median and interquartile range. Student's t-test or Mann-Whitney U test will be used to compare between groups.