[Nitrous oxide exposure to personnel in a recovery room with modern climate control]

Exposure of postoperative nurses to exhaled anesthetic gases

The National Institute of Occupational Safety and Health (NIOSH) has established recommended exposure limits of 25 parts per million (ppm) as a time-weighted average for nitrous oxide and a ceiling of 2 ppm for volatile anesthetics. We quantified exposure of postanesthetic nurses to exhaled anesthetic gases. This study was conducted in the postanesthesia care unit (PACU) of a medium-sized hospital. PACU air exchanges averaged 8 vol/h; however, much of this air was recirculated. We evaluated 50 adults anesthetized with either isoflurane (n = 19) or desflurane (n = 31). Roughly half the patients were tracheally extubated in the operating room, whereas the others were extubated just after admission to the PACU. Exhaled anesthetic gases were sampled through a 20-m hose attached to the participating nurses' shoulders (breathing zone). We also evaluated nursing exposure to exhaled anesthetic gases during recovery of 15 patients who had been anesthetized with nitrous oxide. Exposure was quantified with lapel dosimeters. Anesthetic and recovery durations were each approximately 1 h, with most patients being tracheally extubated in the PACU. Breathing-zone anesthetic concentrations in the patients given isoflurane exceeded NIOSH recommendations in 37% of the patients, representing 12% of recovery time. Breathing-zone anesthetic concentrations in the patients given desflurane, however, exceeded NIOSH limits in 87% of the patients, representing 49% of recovery time. Altogether, noncompliant episodes were detected in 68% of these patients, representing 35% of the entire recovery duration. Breathing-zone anesthetic concentrations in the patients given nitrous oxide exceeded NIOSH limits in 53% of the patients. Our data suggest that postoperative nurses' exposure to exhaled anesthetic gases exceeds NIOSH limits under some circumstances.

IMPLICATIONS

Some epidemiological evidence suggests that exposure to waste anesthetic gases may be associated with reproductive toxicity. Accordingly, the National Institute of Occupational Safety and Health has established recommended exposure limits for nitrous oxide and volatile anesthetics. Our data suggest that exposure of healthcare personnel may exceed recommended levels in poorly ventilated postanesthesia care units.