Continuous thoracic epidural fentanyl for post-thoracotomy pain relief: with or without bupivacaine?

Twenty-five ASA 1 or 2 patients undergoing thoracotomy were entered into a prospective, randomised, double-blind study comparing thoracic epidural fentanyl alone and thoracic epidural fentanyl combined with 0.2% bupivacaine. Pain relief, pulmonary function and cardiovascular stability were assessed. Pain relief was superior in the bupivacaine series (p less than 0.05) during the first day after operation and this was accompanied by better oxygenation (p less than 0.05); the difference did not persist into the second day. Forced expiratory variables were reduced in both series to 50-60% of the values before operation throughout the study (p less than 0.05) and differences did not occur between the groups. The incidence of side effects attributable to epidural fentanyl was high, but hypotension did not occur. Small doses of bupivacaine administered together with fentanyl into the thoracic epidural space improve analgesia without causing hypotension.