Nitrous oxide in 50% O2/N2O mixture for pain management: Occupational exposure levels and prevention in a French hospital

Abstract

A 50% O 2 /N 2 O 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 N 2 O concentrations, exceeding the recommended limit (45 mg/m 3 ). Repeatedly occupational N 2 O exposure might have adverse health effects. To assess N 2 O exposure levels of healthcare workers, using different delivery and scavenging systems, and discuss the available preventive measures. Short-term ( n = 78) and long-term ( n = 38) atmospheric samples were collected near the breathing zone of healthcare workers during 50% O 2 /N 2 O 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 N 2 O sampling and analysis was used. The single face mask was associated with N 2 O 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 mask-related N 2 O 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 N 2 O 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). Scavenger systems with high flow rate evacuation capacity are necessary to prevent healthcare workers from N 2 O exposure. Information about risks and protective measures must be provided.