A comparison of lumbar epidural and intravenous fentanyl infusions for post- thoracotomy analgesia

This double-blind randomised study compared the analgesic efficacy, respiratory effects, side effects, and pharmacokinetic disposition of 24 hr lumbar epidural and intravenous infusions of the same dosage regimen of fentanyl (1.5 μg · kg−1 bolus then 1 μg · kg−1 · hr−1 infusion) in 50 patients after thoracotomy. Patients received either epidural fentanyl and intravenous normal saline, or epidural normal saline and intravenous fentanyl, for postoperative analgesia, after a standard low-dose alfentanil and isoflurane general anaesthetic. Visual analogue pain scores were lower in the epidural group (P 50 mmHg, and one patient in the intravenous group had the infusions stopped because of PaCO2 elevation and somnolence. In patients who did not receive naloxone, the epidural route produced better analgesia throughout the study period (P 15 sec, slow respiratory rate < 10 min−1, oxyhaemoglobin desaturation < 90% and PaCO2) spirometric measures of pulmonary function, haemodynamic variables, morbidity, and other side effects, were similar in both groups, irrespective of naloxone therapy. Patients who had no respiratory depression and did not require naloxone had better analgesia with epidural fentanyl. However, this advantage did not result in better pulmonary function.