Phase I collaborative pilot study: Waste anesthetic gas levels in the PACU

The National Institute of Occupational Safety and Health (NIOSH) recommends that exposure to waste anesthetic gas (WAG) be minimized to the greatest extent possible. Current recommendations include 2 parts per million (ppm) for 1 hour sample to halogenated agents level or 25 ppm based on nitrous oxide level or combination of 0.5 ppm for halogenated agents and 25 ppm nitrous oxide. The Occupational Safety Health Administration requires that work practices and engineering controls be implemented so that occupational exposure to WAG is controlled. This pilot study was conducted to (1) evaluate the level of WAG in the PACU, (2) analyze the relationship between nurse exposure and self-reported symptoms, and (3) test methods used to describe occupational exposure of PACU staff to WAG. Air sampling to measure levels of WAG in the patient and PACU nurse environment was performed with MIRAN SapphRE (Foxboro Company, Foxboro, MA), a nondispersive infrared spectrophotometer. A personal sampling method was used to measure the level of nurse exposure to WAG on 2 separate days. Self-report of 9 health symptoms using a 10-cm visual analogue scale was obtained before and after the shift from 6 (PACU) nurses. Three nurses from the Medical Intensive Care Unit (MICU) served as a control. Descriptive statistics summarized exhaled gas level and staff exposure. The highest concentrations of nitrous oxide were 283 to 295 ppm in the patient's breathing zone, whereas halogenated agents were below the limit of detection. Staff exposure to nitrous oxide ranged from 2.9 to 8.2 ppm, averaged over the work shift. T test of the pre- and postshift symptoms showed no significant difference in both PACU and MICU nurses. This pilot study identified the potential for staff exposure to WAG in the PACU setting. The methods to detect this exposure were also evaluated. It is recommended that further study be conducted to evaluate PACU staff exposure to WAG. Modifications in some of the measurement methods tested here are also suggested, including the use of procedures to measure the efficacy of air exchange and other engineering controls related to staff exposure.