Occupational exposure to sevoflurane during sedation of adult patients

Objectives: In a field study we evaluated the workplace pollution occurring during conscious sedation with sevoflurane in adults. Methods: Sevoflurane was given in 100% oxygen at a fresh gas flow rate of 3 l/min via a nasal mask. This was conducted in 25 patients scheduled for surgical procedures performed under regional anesthesia. Trace concentrations of sevoflurane were directly measured every minute in the breathing zone by means of a photoacoustic infrared spectrometer in an operating room with an air turnover of 20 changes/h. Results: The mean sedation time was 49.6 ± 20.4 min. The average vaporizer setting of the anesthesia machine was 1.63 ± 0.6 vol%, resulting in a patient's mean end-tidal sevoflurane concentration of 0.78 ± 0.2 vol%. The 8-h time-weighted average was calculated to be 0.58 ppm sevoflurane. Conclusions: The trace gas concentrations were low and comparable with values obtained under inhalation induction in adults and children. Although no occupational standard for sevoflurane is currently defined, the measured values are clearly under the standards recommended for enflurane (20 ppm) and isoflurane (10 ppm) by the European health authorities. We conclude that the new anesthesiologic method of conscious sedation with sevoflurane in adults using a nasal mask would not result in a violation of occupational standards, provided that the future value set for sevoflurane would be similar to those recommended for isoflurane or enflurane. Received: 3 August 1998 / Accepted: 14 November 1998