[Anesthetic gas contamination in the operating room--an unsolved problem? Results of our own studies]

Ambient air concentrations of nitrous oxide (N2O) and volatile anesthetics were assessed under routine conditions in a total of 41 surgical suites located at seven Vienna hospitals. Continuous measurements were performed by means of infrared trace gas analyzers throughout a period of approximately 450 h. Additional analyses of ventilation facilities (if installed) revealed no essential deficiencies; however, anesthetic gas scavenging (AGS) systems yielded insufficient flow rates in 32% (less than 25 l/min). In surgical suites without mechanical ventilation or scavenging systems (2 out of 41), maximum occupational threshold limits (i.e., 100 ppm N2O; 5 ppm halothane) were exceeded continuously and to considerable degrees throughout the duration of anesthesia. During measurements conducted in operating rooms (ORs) in otolaryngology departments, extreme peaks (greater than 2600 ppm N2O, greater than 150 ppm halothane) of several minutes duration were documented when open-circuit anesthesia was performed. In the general surgical ORs equipped with modern ventilation facilities ambient air contamination was lowest, time-weighted average (TWA) values ranging from 8 to 15 ppm (mean 11 +/- 3 ppm) for N2O and 0.1 to 0.6 ppm (mean 0.3 +/- 0.2 ppm) for the halogenated anesthetic. Despite good ventilation and scavenging in the gynecological ORs, distinctly higher concentrations (mean 83 +/- 49, range 24-211 ppm N2O; mean 0.75 +/- 0.3, range 0.3 to 1.3 ppm volatile agent) were measured in cases where anesthesia was delivered by mask. TWA values exceeding currently established maximum workplace concentrations were found in an unscavenged but ventilated urological OR. At present, short-term concentration peaks seem to be inevitable even under optimal OR ventilation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)