Biological monitoring of exposure to sevoflurane in operating room personnel by the measurement of hexafluoroisopropanol and fluoride in urine

The objectives of this study were to evaluate the value of urinary hexafluo roisopropanol (HFIP) and fluoride (F-) measurement for the biological monit oring of operating room personnel exposed to sevoflurane. Fifty members of operating room staffs from eight different hospitals took part in the study . To assess external exposure to sevoflurane, air samples were collected du ring the whole anaesthesia period by a passive sampling device (3M 3500 org anic vapour monitor) attached close to the breathing zone of each subject. Urine was collected before (BA) and at the end of anaesthesia (EA) for the determination of HFIP, fluoride and creatinine. Average airborne concentrat ion of sevoflurane was 19.0 ppm (range: ND-139.9 ppm) with a mean duration of anaesthesia of 221 min (range: 60-435 min). There was a better correlati on between external and internal exposure as estimated by EA urinary HFIP ( r = 0.78; p<0.0001) compared with EA urinary F- (r = 0.41; p = 0.0031). Fur thermore determination of urinary HFIP seemed more suited than that of F- f or the assessment of sevoflurane exposure because of lower background in BA samples (86 % of BA HFIP values were under the limit of detection). Based on these results, values of 9.6 and 4.3 mg HFIP g(-1) creatinine correspond to airborne concentrations of 50 and 20 ppm of sevoflurane, respectively. Among the confounding parameters investigated (body mass index (BMI), sex, cytochrome P450 polymorphism) only BMI showed statistically significant inf luence on sevoflurane metabolism at these low levels of exposure. The measu rement of HFIP in urine at the end of the surgical procedure constitutes a good index to assess occupational exposure to sevoflurane. Further studies will be necessary to propose an health-based limit value which remains to b e determined from the relationship between effects and internal dose as can be assessed by HFIP measurement in urine.