Plasma fluoride concentration and urinary fluoride excretion in obese and non-obese patients following enflurane anesthesia.

Plasma fluoride concentrations and urinary fluoride excretions were measured following enflurane anesthesia (1.5%, 2 hours) in obese (8 cases) and non-obese (9 cases) patients. At the end of anesthesia, there was no significant difference in plasma fluoride concentrations between the two groups. In the several days following anesthesia, however, plasma fluoride concentrations in obese patients were higher than those in non-obese patients. Urinary fluoride excretions after anesthesia were greater in obese patients than those in non-obese patients, and the period of increased fluoride excretion was prolonged in obese patients. These results suggested that obese patients metabolized more enflurane than non-obese patients during the postanesthetic period. In obese patients, their excess fatty tissue may cause a greater and more prolonged elevation of blood enflurane concentrations after anesthesia.