A comparison between subpleural patient-controlled analgesia by bupivacaine and intermittent analgesia in post-operative thoracotomy: A double-blind randomized clinical trial*

BACKGROUND: The efficacy of subpleural analgesia to reduce postoperative pain intensity in patients after lateral thoracotomy is controversial. In this study, we demonstrated the efficacy of two types of subpleural analgesia. METHODS: This prospective, controlled, randomized, double-blind trial was performed in Department of Thoracic Surgery of Alzahra Hospital associated with Isfahan University of Medical Sciences from June 2009 until August 2010. After posterolateral thoracotomy and admission to the ICU, patients were randomly assigned into two groups of subpleural patient-controlled analgesia (SPCA) (0.02 cc/kg/h of 0.5% bupivacaine) and subpleural intermittent analgesia (SIA) (0.1cc/kg/6h of 0.5% bupivacaine). The data regarding age, sex, visual analog scale (VAS) (at 8, 16 and 24 hours after initiation of analgesia), morphine consumption, systemic adverse effects, length of ICU and hospital stay, complications, public health service (PHS) criteria, and cost was recorded. Data was analyzed by Mann-Whitney U-test, repeated measured test, chi-square test and the Fisher's exact test. A p < 0.05 was considered significant. RESULTS: The study population consisted of 90 patients. There were no significant differences in sex, age, weight, intraoperative analgesics, duration of one-lung ventilation, and adverse effects between the SPCA and SIA groups. Although pain scores were significantly reduced at 16 hours after the first subpleural instillation of bupivacaine 0.5% with patient-controlled analgesia, comparison between mean pain scores in the two groups at 8 and 24 hours after the first subpleural instillation of bupivacaine 0.5% revealed no significant difference. In addition, no significant difference was found in VAS scores at the three evaluated times (p < 0.05). CONCLUSIONS: Optimal use of SPCA bupivacaine for postoperative pain treatment is more effective in pain reduction than SIA bupivacaine. The consumption rate of opioid and bupivacaine was also decreased in SPCA group.