The biological monitoring of inhalation anaesthetics

The biological monitoring of inhalation anaesthetics. Occupational exposure to inhalation anaesthetics is an undesired consequence of the work in the operating theatre. Anaesthesia is currently practised using nitrous oxide associated with one or more potent anaesthetics (halothane, enflurane, isoflurane). In the present study we evaluated the occupational exposure to inhalation anaesthetics during anaesthesia in 190 operating theatres of 41 hospitals in Italy. Nitrous oxide, halothane, enflurane, isoflurane were detected in the urine of 1521 exposed subjects (anaesthetists, surgeons and nurses). Significant correlations were found between the anaesthetic concentrations in urine produced during the shift (Cu) and anaesthetic environmental concentrations (CI). The results show that the urinary anaesthetic concentration can be used as an appropriate biological exposure index. The biological threshold values (urinary concentration values) proposed are the following: nitrous oxide, 15, 28 and 57 micrograms/L for an environmental exposure of 25, 50 and 100 ppm respectively; halothane, 97 micrograms/L (for an environmental exposure of 50 ppm), 6.1 micrograms/L (for an environmental exposure of 2 ppm) and 3.3 micrograms/L (for an environmental exposure of 0.5 ppm); enflurane, 145 micrograms/L (for an environmental exposure of 50 ppm), 22.7 micrograms/L (for an environmental exposure of 10 ppm), 3.7 micrograms/L (for an environmental exposure of 1 ppm); isoflurane, 5.3 micrograms/L (for an environmental exposure of 2 ppm) and 1.8 micrograms/L (for an environmental exposure of 0.5 ppm). These values apply to urine samples collected at the end of 4-hours' exposure to the anaesthetics.