Thoracic versus lumbar administration of epidural morphine for postoperative analgesia after thoracotomy

The purpose of this study was to compare the effects of thoracic and lumbar epidural morphine on pulmonary function and analgesia after thoracotomy for pulmonary resection.

Twenty-seven patients were randomized into two groups to receive either thoracic or lumbar epidural morphine as needed for postoperative analgesia. Postoperative pain was assessed hourly on a 10-cm visual analog scale (VAS), and epidural morphine was administered in 3 mg doses for a VAS score > 2 cm. Patients underwent pulmonary function tests (forced vital capacity, forced expiratory volume at 1 second, peak expiratory flow) preoperatively, and 24 hours postoperatively. Results were expressed as mean +/- 1 SE and analyzed using Student's t-test and Student-Newman-Keuls test at p < 0.05.

Twenty patients completed the study (n = 10 per group). Patients in the thoracic group required 3.1 +/- 0.4 injections to a total morphine dose of 11.9 +/- 1.4 mg during the first 24 hours postoperatively, and those in the lumbar group required 4.7 +/- 0.4 doses to a total 24-hour morphine dose of 16.4 +/- 1.2 mg (p < 0.05). Median hourly VAS scores were similar in both groups. Postoperative pulmonary function decreased in both groups without intergroup differences.

The authors conclude that thoracic epidural morphine administration in patients after thoracotomy results in decreased morphine requirements and the same degree of analgesia as does lumbar administration.