Comparison of lumbar epidural tramadol and lumbar epidural morphine for pain relief after thoracotomy: A repeated-dose study

Abstract

Objective: The purpose of this study was to compare lumbar epidural morphine and lumbar epidural tramadol with respect to onset and duration of analgesia, analgesic efficacy, and drug-related side effects after muscle-sparing thoracotomy. Design: Prospective, randomized, double-blind, clinical study. Setting: Single university hospital. Participants: Forty patients who underwent elective muscle-sparing thoracotomy. Interventions: Before anesthesia induction, an epidural catheter was placed in the L2-3 or L3-4 interspace using the loss-of-resistance technique. On arrival at the intensive care unit, patients were randomized to receive doses of either 100 mg of tramadol (group T) or 4 mg of morphine (group M) via the lumbar epidural catheter. Each dose was diluted in 10 mL of normal saline. On awakening from anesthesia, if the patient's pain score on a 0- to 100-mm visual analog scale was above 40 mm, the initial epidural drug dose was administered. The initial injection in each case was taken as time 0. Subsequent pain scores above 40 mm were considered indications for epidural dosing; each patient was allowed 2 doses in the first 12 hours postoperatively and 2 more in the second 12 hours. Measurements and Main Results: The groups' analgesia onset times were similar, but duration of analgesia was significantly shorter in group T than in group M (p < 0.01). There were no differences between the groups with respect to pain scores at rest or during coughing at any of the time points investigated. Sedation scores were lower in group T than in group M at 1, 2, 3, 4, and 8 hours (p value range, 0.0001-0.05). Compared with group T, group M showed significantly greater drops in arterial oxygen tension from baseline at 3, 4, 8, and 12 hours (p value range, 0.0001-0.05). The group means for arterial carbon dioxide tension and respiratory rate were similar at all time points investigated. Conclusion: The study revealed that the quality of analgesia achieved with repeated doses of lumbar epidural tramadol after muscle-sparing thoracotomy is comparable to that achieved with repeated doses of lumbar epidural morphine. Compared with morphine, lumbar epidural tramadol results in less sedation and a less-pronounced decrease in oxygenation.