Halothane biotransformation in obese and nonobese patients

Serum levels of inorganic fluoride, trifluroacetic 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 hr in the obese patients compared to the nonobese patients (mean ± SE, 1,311 ± 114 vs. 787 ± 115 μM, P < 0.01). Sedative levels of bromide were not attained in any patient. Peak trifluoracetic 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.