Nitrous oxide levels in operating room air with various gas flows

Area of Science:

• Anesthesiology
• Environmental Health
• Occupational Safety

Background:

• Unrecognized leaks of nitrous oxide in operating rooms have been a concern.
• Previous measurements of nitrous oxide concentrations were often conducted with high gas flows and inadequate ventilation data.

Purpose of the Study:

• To measure nitrous oxide levels in operating rooms during procedures.
• To assess the effectiveness of scavenging systems in reducing exposure.
• To evaluate the impact of different nitrous oxide flow rates on ambient concentrations.

Main Methods:

• Measurements of nitrous oxide concentrations were taken at six locations within the operating room suite using an infra-red analyzer.
• Experiments were conducted with and without active scavenging systems.
• Nitrous oxide flows varied from 0.1 to 2.5 liters per minute in rooms with 20 air changes per hour.

Main Results:

• Without scavenging, the highest time-weighted average exposure for anesthetists reached 31 ppm with a flow of 500 ml/min.
• With effective scavenging, even at high flow rates (2.5 L/min), the highest average anesthetist exposure was reduced to 7.2 ppm.
• Lower nitrous oxide flow rates resulted in lower measured concentrations.

Conclusions:

• Scavenging systems are crucial for minimizing operating room personnel exposure to nitrous oxide.
• Optimizing gas flow rates and utilizing effective scavenging can significantly reduce anesthetic waste and environmental pollution.
• Addressing leaks and improving ventilation are essential for maintaining safe working conditions in operating rooms.