Nitrous Oxide in 50% O2/N2O Mixture for Pain Management: Occupational Exposure Levels and Prevention in a French Hospital

Background. - A 50% O-2/N2O mixture is effectively used for its analgesic and anxiolytic properties in pain management of diverse short-term medical and superficial surgical procedures. However, healthcare workers are often exposed to high N2O concentrations, exceeding the recommended limit (45 mg/m(3)). Repeatedly occupational N2O exposure might have adverse health effects. Objective. - To assess N2O exposure levels of healthcare workers, using different delivery and scavenging systems, and discuss the available preventive measures. Methods. - Short-term (n = 78) and long-term (n = 38) atmospheric samples were collected near the breathing zone of healthcare workers during 50% O-2/N2O mixture administration to patients. Seven different combinations of delivery/scavenging systems were used: single face mask, double face mask connected to a portable aspiration system, both with a demand or a classic valve, connected or not to a central waste gas scavenging system. INRS's method for N2O sampling and analysis was used. Results. - The single face mask was associated with N2O exposure levels exceeding the recommended limit (83/89 (93%) samples > 45 mg/m(3)), including when a demand valve and/or central waste gas scavenging system were used (28/34 (82%) > 45 mg/m(3)). Single face maskrelated N2O values ranged between 17 and 4500 mg/m(3)(median 400 mg/m(3), IQR = 160-1300). Procedures using the double face mask generated lower N2O exposure levels (25/27 samples( 93%) < 45 mg/m(3)); values ranged between 0.85 and 57 mg/m(3)(median 14 mg/m(3), IQR = 6-31). Conclusion. - Scavenger systems with high flow rate evacuation capacity are necessary to prevent healthcare workers from N2O exposure. Information about risks and protective measuresmust be provided. (c) 2021 Societe Francaise de Toxicologie Analytique. Published by Elsevier Masson SAS. Allrights reserved.