Comparison Between Epidural and Bilateral Paravertebral Blocks in Liver Resection

Background: A number of studies evaluating unilateral continuous paravertebral block demonstrate equal or superior analgesia when compared to epidural analgesia for postoperative pain control (1-7). At the same time, these studies show a decreased incidence of side effects and complications, including: hypotension, pulmonary complications, urinary retention, nausea and vomiting and failed blocks. Several studies also indicate that bilateral paravertebral blocks provide adequate postoperative analgesia (8-14). However, no study has been performed to date that shows a direct comparison between epidural and bilateral paravertebral blocks in patients undergoing open liver resection.Objectives: This prospective, randomized study is intended to assess the efficacy and safety of bilateral continuous paravertebral blocks compared to continuous epidural block for open liver resection. Hypotheses: Bilateral paravertebral blocks are: 1) equally effective in controlling the perioperative pain; and 2) safe, with less frequent complications following open liver resection when compared to continuous epidural block.Methods: A hundred adult patients undergoing elective open liver resection will be randomized to receive a continuous epidural block or continuous bilateral paravertebral blocks for perioperative analgesia. The primary outcome will be the degree of pain control measured by visual analog scale at 24 hours post surgery (at rest and while the patient is performing maximum incentive spirometry). The secondary outcomes will include: 1) Assessment of pain (at rest, with cough, and with ambulation) using the verbal numerical pain scale will be performed postoperatively every 8 hours by floor nursing staff until discharge. During the night the patient will not be awakened for pain assessment. 2) Intravenous opioid requirement: In addition to pain score, postoperative intravenous opioid requirements [hydromorphone (mg)] will also be recorded daily; Frequency of side effects and complications; and other functional status (volume of maximum incentive spirometry, time to extubation, total time for initial ambulation, the length of the hospital stay, time to return of bowel function, readiness for discharge from the hospital, and length of hospital stay). At one month post surgery, health-related quality of life, mortality, and any morbidities will be assessed. Each variable will be compared between the paravertebral group and the epidural group to examine the hypotheses above. Clinical Implications: Bilateral continuous paravertebral blocks could be an equally effective and safe alternative to a continuous epidural block for perioperative pain management in patients who undergo open liver resection.