ISOFLURANE SEDATION FOR PATIENTS UNDERGOING MECHANICAL VENTILATION: METABOLISM TO INORGANIC FLUORIDE AND RENAL EFFECTS

The metabolism and renal effects of isoflurane sedation werestudied for 24 h in patients undergoing mechanical ventilation.Forty-six patients admitted to our intensive therapy unit wereallocated randomly to receive either 0.1–0.6% isofluraneor midazolam 0.01–0.2 mg kg^–1 h^–1 for sedation.In 26 patients sedated with isoflurane, plasma inorganic fluorideincreased from a mean concentration of 4.03 µmol litre^–1to 13.57 µmol litre^–1 12 h after stopping sedation.Plasmainorganic fluoride concentrations in 20 patients sedated withmidazolam were unchanged from baseline values (mean 5.32 µmollitre^–). Serum electrolyte, urea and creatinine concentrations,and urine output rates during and after sedation in patientswho receivedisoflurane were similar to those who received midazolam.We conclude that, following isoflurane sedation for up to 24h, metabolism to inorganic fluoride is insufficient to causeclinical renal dysfunction University Department of Anaesthesia, Queen Elizabeth Hospital,Birmingham B15 2TH