Halothane biotransformation in obese and nonobese patients.

Serum levels of inorganic fluoride, trifluoroacetic acid, and bromide ion were measured at various time intervals following two hours of halothane anesthesia in 17 morbidly obese and eight nonobese patients. Ionic fluoride, a marker of reductive halothane metabolism, increased in the obese but not the nonobese patients. This is of concern since reductive halothane metabolism is associated with hepatoxicity in animals. In addition, serum bromide levels were higher after 48 h in the obese patients compared to the nonobese patients (mean +/- SE, 1,311 +/- 114 vs. 787 +/- 115 microM, P less than 0.01). Sedative levels of bromide were not attained in any patient. Peak trifluoroacetic acid levels were similar in the two patient groups. Sex age, medication intake, and smoking history had no influence on the halothane metabolite levels found in this study.