Hypotensive anesthesia with propofol and remifentanil: protective effect of alpha tocopherol on renal function

Study objective: To determine the effect of α-tocopherol in patients receiving hypotensive anesthesia with propofol-remifentanil. Study design: Prospective, randomized study. Setting: University hospital. Patients: 66 ASA physical status I and II patients, aged 32 to 56 years, scheduled for nasal polypectomy. Interventions: Patients were allocated into two groups, the treatment and the control groups (T group and C group). T group received α-tocopherol 300 mg orally 5 to 6 hours before surgery. Measurements: Sampling times and measurements were done before hypotension (t0), 45 minutes after starting hypotension (t1), 90 minutes after starting hypotension (t2), 45 minutes after recovery of normotension (t3), and 24 hours after surgery (t4). Renal function was assessed by testing glomerular and tubular functions: glomerular filtration rate, fractional excretion of sodium (FENA); fractional excretion of urea (FEUN); and urinary N acetyl-1-β-D-glucosoaminidase (NAG) index (NAGi). Main results: Glomerular filtration rate values remained unchanged in all patient populations. Fractional excretion of sodium was within reference ranges in both groups at times t0, t1, and t2. At time t3, a significant FENA peak was observed. At this time, FENA was significantly higher in C group than T group (P b 0.001). FEUN time course was similar to the FENA trend. At time t4, FENA and FEUN returned to basal values. At time t3, NAGi was also increased without significant intergroup differences (P b 0.01, P b 0.001, and P b 0.01 vs times t0, t1, t2 in C group, respectively; P b 0.01, P b 0.01, and P b 0.001 vs times t0, t1, and t2 in T group, respectively). Conclusions: In patients without any renal disease, hypotensive anesthesia with propofol and remifentanil results in a transient tubular dysfunction, which appears to be minimized by the preoperative administration of α-tocopherol.