Lumbar epidural anaesthesia prevented prostaglandin E₁ - induced diuretic effect in enflurane anaesthetized patients

Prostaglandin E₁, (PGE,) is used to induce deliberate hypotension during anaesthesia. The purpose of this study was to compare the PGE₁ induced diuretic effect in anaesthetized patients with and without lumbar epidural anaesthesia. The changes in haemodynamic variables, urinary flow, one-hour creatinine clearance (Ccr), and fractional excretion of sodium (FE_Na) during injection of PGE₁, or a vehicle were compared in 42 surgical patients during enflurane anaesthesia with lumbar epidural anaesthesia (EPI group) with those in 44 surgical patients during enflurane anaesthesia alone (GA group). Patients in the GA group demonstrated increases in urinary flow (114 ± 46%) (mean ± SE), Ccr (74 ± 26%), and FE_Na (54 ± 23%) during PGE₁, infusion, which were not observed in the patients in the EPI group. Mean arterial pressure decreased during PGE₁, infusion from 92 ± 3 to 70 ± 2 mmHg in the GA group (P < 0.01) and from 85 ± 2 to 65 ± 1 mmHg in the EPI group (P < 0.01). Plasma antidiuretic hormone concentration during surgery was 12.5 ± 2.6 U. L^-1 in the GA group and 2.3 ± 0.8 U· L^-1 in the EPI group (P < 0.001). It is concluded that PGE₁ induced diuresis was prevented by lumbar epidural anaesthesia.