Implementing sevoflurane anesthesia with small doses opioid for upper abdominal surgery. Postoperative respiratory function after either remifentanil or fentanyl.

BACKGROUND: The aim of this prospective, randomized study was to compare the effects on intraoperative cardiovascular homeostasis, recovery profile and postoperative oxygen saturation after sevoflurane anesthesia with small doses of either remifentanil or fentanyl in combination with postoperative epidural analgesia. METHODS: With Ethical Committee approval and written patient consent, 30 ASA physical status I-II patients scheduled for elective upper abdominal surgery were randomly allocated to receive sevoflurane general anesthesia implemented with small doses of either remifentanil (n = 15) or fentanyl (n = 15), followed by postoperative epidural analgesia. Remifentanil group patients received a 1 mg kg-1 bolus infused during a 60 sec period followed by a 0.15 mg kg-1 min-1 infusion; while patients of Fentanyl group were given a 3 mg kg-1 initial dose followed by 50 mg boluses as requested (according to the time to peak effect of the two drugs, the initial dose was given 5 min before induction in Fentanyl group, and 1 min before induction in Remifentanil group). Postoperatively, oxygen saturation was continuously recorded and stored on a computer during the first 12 h after surgery. SpO2 decrease < 90% for more than one minute was considered as a minor respiratory complication. RESULTS: The median sevoflurane's MAC-hour was 2.7 (1.4 - 4.9) in patients receiving remifentanil infusion and 4.1 (2.2 - 5.7) in those patients receiving fentanyl during surgery (P = 0.005). However, no differences in the recovery times were observed between the two groups. Similar pain relief was reported during coughing in the two studied groups at discharge from the recovery area and during the following study period. No major respiratory complication was observed throughout the study. Oxygen therapy was required in three patients of Fentanyl group only 20% (P = 0.22); however, 11 patients in the same group (73%) showed at least one minor respiratory complication (SpO2 < 90% for more than 1 min), with a median of 1 (range 0 - 12) episode per patient, compared with no episode in Remifentanil group (P = 0.0005). CONCLUSIONS: Implementing sevoflurane anesthesia with very small remifentanil infusion provides a safe and effective hemodynamic control reducing sevoflurane consumption during the procedure, and produces less respiratory effects postoperatively as compared with intermittent bolus administration of fentanyl.