Effect of preincisional epidural fentanyl and bupivacaine on postthoracotomy pain and pulmonary function.

BACKGROUND: This study attempts to determine whether preemptive thoracic epidural analgesia (TEA) initiated before surgical incision would reduce the severity of acute post-thoracotomy pain, its effects on pulmonary function and stress response.

METHODS: Forty patients undergoing posterolateral thoracotomy received TEA either before (preoperative-TEA group) or after (postoperative-TEA group) surgery. Postoperative analgesia was maintained with epidural infusion of bupivacaine and fentanyl. Pain scores, pulmonary functions, arterial blood gases, plasma glucose, cortisol levels and epidural fentanyl consumption were compared for 48 hours after surgery.

RESULTS: The preoperative-TEA group demonstrated significantly reduced pain scores at 2, 4, 8, 12, 24, and 48 hours at rest (p = 0.001, p = 0.002, p = 0.004, p = < 0.001, p = 0.006, and p = 0.001, respectively) and at 4, 8, 12, 24, 48 hours on coughing (p = 0.001, p = 0.001, p = 0.001, p = 0.001, p = 0.004, respectively), and a significant reduction in epidural fentanyl consumption (208.6 +/- 49.3 mL, versus 260 +/- 28.8 mL, p = 0.001). The preoperative-TEA group showed significant improvement in pulmonary functions as compared with the postoperative-TEA group (p < 0.05), except forced expiratory volume in one second at 24 hours (p = 0.061) and peak expiratory flow rate at 48 hours (p = 0.188). The postoperative-TEA treated patients were more likely to have a higher arterial carbon dioxide pressure at 4, 8, 12, and 24 hours (p = 0.017, p = 0.001, p = 0.003, p = 0.001), respectively. However, we could not demonstrate a statistical difference in oxygenation, cortisol, or glucose level.

CONCLUSIONS: Though preemptive TEA appeared to reduce the severity of acute pain, preserve pulmonary function, and reduce analgesic requirements, these statistically significant differences were not enough to conclude a clinical significant difference between groups.