[Occupational exposure to enflurane and laughing gas in operating rooms]

Current scientific evidence suggests that chronic exposure to trace concentrations of anaesthetic gases may result in various forms of untoward health responses in operating room personnel. Although there are no clear dose-effect-relationships, in Germany threshold values (MAK-values) exist for nitrous oxide of 100 ppm and for enflurane of 20 ppm. Aim of this investigation was, to determine the exposure of the operating room personnel under modern working conditions using a standardized anaesthetic procedure. By means of a direct-reading, high sensitive gas monitor trace concentrations of nitrous oxide and enflurane were measured at three personnel-related (surgeon, anaesthetist, auxiliary nurse) and a potential leakage source (patient's mouth). The calculation and assessment of the measured concentrations followed the prescriptions of the technical rules for hazardous substances 402 and 403 (TRGS 402 and 403). The personnel-related concentrations were clearly under the MAK-values of 100 ppm nitrous oxide and/or 20 ppm enflurane. The time weighted averages were for the personnel-related measurement points, indicated in ppm for nitrous oxide and enflurane, respectively: "surgeon" 28.3/0.25, "anaesthetist" 39.3/0.34 and "auxiliary nurse" 64.6/0.57. At the leakage source "patient's mouth" time weighted averages of 317 ppm nitrous oxide and 3.79 ppm enflurane were measured. Under air-conditioning with a high air change rate, a central scavenging system and low leakage anaesthesia machine low trace concentrations of anaesthetic gases were measured. Despite an average contamination of approx. 300 ppm nitrous oxide at the "patient's mouth" personnel-related values remained clearly under the MAK-values. Outside the mainstream of the air-conditioning system the group "auxiliary nurse" had an approximately 30% higher exposure than the other groups. Under the described conditions, the working environment "operating room" can be classified as a low exposure working area.