OCCUPATIONAL EXPOSURE TO SEVOFLURANE AND NITROUS-OXIDE IN OPERATING-ROOM PERSONNEL

Object: To quantify the exposure of operating room personnel to sevofl urane and nitrous oxide. Design: Prospective study at a university hos pital. Methods: In 25 patients undergoing elective surgical procedures , anaesthesia was induced with thiopentone/etomidate, vecuronium and f entanyl and maintained with fentanyl, sevoflurane in 35% oxygen and 65 % nitrous oxide (N2O). Occupational exposure to sevoflurane and N2O wa s measured in the breathing zone of one representative of each of thre e personnel groups (anaesthetist, surgeon, auxiliary nurse) by means o f a direct reading instrument using photo-acoustic infrared spectromet ry. Results: The mean trace concentrations of sevoflurane for the sing le anaesthetic procedures exceeded the 0.5 ppm level in more than 50% of the measurements. The 2 ppm level was not exceeded in the case of t he anaesthetist and the surgeon, but was exceeded in 16% of the measur ements for the auxiliary nurse. The level of 25 ppm N2O were exceeded in 28% of the measurements for the anaesthetist and in 16% of these fo r the surgeon and for the auxiliary nurse. Conclusions: To keep exposu re low, sevoflurane and N2O were used in a modern working environment: a low-leakage anaesthesia machine, high room ventilation rates, scave nging system, no intermittent mask ventilation, low to medium concentr ations of sevoflurane, and strict control of the cuff pressure. Nevert heless, exposure could not be kept under NIOSH threshold values in all cases.