Anesthesia Point-of-Care Nitrous Oxide Cylinder Leakage and a Proposed Engineering Control Solution

Nitrous oxide is a potent greenhouse gas and there are ongoing efforts to reduce the environmental impact of its use in healthcare. Substantial leakage of nitrous oxide from centralized supplies has led some centers to convert to storage in point-of-care cylinders. However, these tanks may also leak if not manually closed between uses, and compliance with such closure by staff may be poor. We endeavored to quantify the leakage from these cylinders connected to an anesthesia machine, and test an engineering control to automatically reduce such leakage. We observed that an E-cylinder of nitrous oxide left open leaks at a rate of 10 mL/min, leading to pollution without clinical utility as well as wasted resources. We developed a system consisting of a valve actuator and countdown timer that was shown to be capable of automatically opening and closing the cylinder as needed to reduce waste, obviating the need for staff to do so manually.