[Halothane hazards for the team in the operation theatre (author's transl)]

Reports on undesirable side effects of halothane in patients undergoing anaesthesia and in persons with long-term exposure in the operation theatre require establishment of safe upper limits and of methods for monitoring. The main metabolite trifluoroacetic acid is most suitable for biological monitoring. During systematic exposure with graded halothane concentrations (8, 24 and 50 ppm, 6 hours daily, 5 days weekly, for one and two weeks) trifluoroacetic acid concentrations in blood and urine were determined regularly. It was shown that for biologic monitoring estimation in blood is clearly preferential to estimation in urine because of a narrower scatter. At the end of one week of exposure a steady state concentration is found in blood. There is a linear relation between its height and the inhalation concentration of halothane. A trifluoroacetic acid concentration of 2.5 micrograms/ml is considered as a risk-free value. This corresponds to a maximal theatre air concentration of 5 ppm halothane.