Abstract
BACKGROUND: Continuous epidural infusion (CEI) has some disadvantages, such as increased local anesthetic consumption and limited area of anesthetic distribution. Programmed intermittent bolus (PIB) is a technique of epidural anesthesia in which boluses of local anesthetic are automatically injected into the epidural space. The usefulness of PIB in thoracic surgery remains unclear. In this study, we aimed to compare the efficacies of PIB epidural analgesia and CEI in patients undergoing thoracic surgery. METHODS: This randomized prospective study was approved by the Institutional Review Board. The study included 42 patients, who were divided into CEI (n = 21) and PIB groups (n = 21). In the CEI group, patients received continuous infusion of the local anesthetic at a rate of 5.1 mL/90 min. In the PIB group, a pump delivered the local anesthetic at a dose of 5.1 mL every 90 min. The primary endpoints were the frequency of patient-controlled analgesia (PCA) and the total dose of local anesthetic until 36 h following surgery. Student's t-test, the chi-square test, and the Mann-Whitney U test were used for statistical analyses. RESULTS: The mean number of PCA administrations and total amount of local anesthetic were not significantly different between the two groups up to 24 h following surgery. However, the mean number of PCA administrations and total amount of local anesthetic at 24-36 h after surgery were significantly lower in the PIB group than in the CEI group (median [lower-upper quartiles]: 0 [0-2.5] vs. 2 [0.5-5], P = 0.018 and 41 [41-48.5] vs. 47 [43-56], P = 0.035, respectively). Hypotension was significantly more frequent in the PIB group than in the CEI group at 0-12 h and 12-24 h (3.3% vs. 0.5%, P = 0.018 and 7.9% vs. 0%, P = 0.017, respectively). CONCLUSION: PIB can reduce local anesthetic consumption in thoracic surgery. However, it might result in adverse events, such as hypotension. TRIAL REGISTRATION: This randomized prospective study was approved by the Institutional Review Board (IRB No. 15-9-06) of the Fukuoka University Hospital, Fukuoka, Japan, and was registered in the clinical trials database UMIN ( ID 000019904 ) on 24 November 2015. Written informed consent was obtained from all patients.