Consideration of the optimal epidural fentanyl doses in abdominal surgery

Study Objective: To determine an optimal dose of epidural fentanyl in open abdominal surgery by examining the effects of different doses of epidural fentanyl in combination with or without low concentration of lidocaine on hemodynamic and endocrine responses to surgical stress. Design: Prospective, randomized study. Setting: University hospital. Patients: 40 ASA physical status I and II patients scheduled for elective abdominal surgery including gastrectomy (n = 20), colectomy (n = 10), liver tumor resection (n = 2), pancreatectomy (n = 3), pancreaticoduodenectomy (n = 1), low anterior resection (n = 3), and cholecystectomy (n = 1). Interventions: Patients were randomly allocated to one of two groups: epidural fentanyl with 0.5% lidocaine (Group L + F; n = 25) or epidural fentanyl alone (Group F; n = 15). Both two groups were divided into subgroups; in Group L + F, epidural fentanyl was administered as doses of 0, 0.3, 1, 3, and 5 μg/kg in 5 patients each. In Group F, epidural fentanyl was administered as doses of 1, 3, and 5 μg/kg in 5 patients each. Hemodynamic data and plasma catecholamine concentrations were compared between before the epidural injection and immediately after peritoneal incision. Measurements and Main Results: There was no difference in mean arterial pressure (MAP) and heart rate (HR) between Group L + F and Group F at the time before epidural administration of fentanyl, 20 minutes after epidural fentanyl, and immediately after peritonal incision. However, there were significant decreases in MAP immediately after skin incision in epidural fentanyl 0 and 3 μg/kg in Group L + F patients and also in epidural fentanyl 1 and 3 μg/kg in Group F patients. HR significantly decreased in epidural fentanyl 5 μg/kg of Group L + Fat peritoneal incision (p < 0.05). Plasma epinephrine decreased significantly in fentanyl 3 and 5 μg/kg in Group L + F immediately after peritoneal incision (p < 0.05), whereas the increase in norepinephrine was significant in Group F (p < 0.01). Plasma dopamine significantly increased only in fentanyl 1 μg/kg in Group F (p < 0.05). Conclusion: Epidural fentanyl 3 μg/kg with 0.5 % lidocaine may be most adequate for laparotomy because these doses caused neither bradycardia nor increments of norepinephrine perioperatively.