Epidural analgesia for pain relief in thoracic surgery

The effectiveness and adverse effects of continuous epidural analgesia was studied in 104 patients undergoing thoracic operations at Siriraj Hospital. Patients were divided into 3 groups according to the type of surgical approach and the technique of epidural analgesia. Group 1 patients (n = 72) received thoracic epidural block using bupivacaine and morphine combined with light general anesthesia for exploratory thoracotomy; group 2 patients (n = 21) received the identical anesthetic technique, the operation was achieved through median sternotomy; group 3 patients (n = 11) had a similar type of operation to group 1, the anesthetic technique was lumbar epidural block using morphine and combined with light general anesthesia. Continuous epidural morphine infusion was given 0.1-0.4 mg/h during postoperation in all patients for providing adequate pain relief. The results revealed that a 10 cm visual analogue scale (VAS) pain scores were satisfactory and comparable in all groups. Lumbar epidural patients consumed a significantly larger dose of morphine than thoracic epidural groups (P < 0.01). Intraoperative hypotension occurred 43.05 per cent and 19.05 per cent in group 1 and 2, but none was found in group 3 (P < 0.05). Postoperative respiratory depression was found 54.16 per cent in group 1, 33.33 per cent in group 2 and 9.09 per cent in group 3 (P < 0.05), and was mostly mild to moderate, except three patients in group 1 and one in group 2 who needed mechanical ventilatory support. There were no differences among the groups in the incidence of nausea/vomiting and pruritus. It is concluded that both thoracic and lumbar epidural morphine provide excellent postthoracotomy pain relief, whereas, respiratory depression is more common with thoracic than lumbar epidural morphine.