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Developed by: Committee on Environmental Health
Original Approval: October 23, 2024
Nitrous oxide (N2O), used as an adjunct to general anesthesia or as an analgesic for labor and delivery, and pediatric and dental procedures, has significant environmental consequences. It has recently been discovered that losses from central piped N2O supply systems are common and account for the vast majority of overall N2O consumption at health care facilities, far outweighing the amount used clinically.1 These central supply systems are the standard in most health care facilities, compounding the negative environmental and fiscal impacts of these underrecognized and avoidable losses. Transitioning to a portable source for N2O delivery has proven to be a feasible alternative at a number of large health care facilities in the US and globally with the added benefits of enhanced organizational safety,1 and has been recommended by the Royal College of Anaesthetists in the UK and Ireland.2-4 Therefore, the ASA recommends the deactivation of central piped N2O delivery systems and the transition to portable N2O supply systems for all clinical use. The ASA also recommends that hospitals planned for new construction or major remodeling of an existing operating room should be built without the central piped N2O delivery system. With proper planning, preparation, and training, the transition should not complicate clinician workflow or have any impact on patient care.
The piped N2O supply system consists of a centrally located, pressure regulated, high-volume supply of N2O connected to a downstream delivery system with multiple connections before reaching the site of clinical use. Under constant pressure from the central supply system, these various connections have been shown to generate numerous leaks, resulting in large discrepancies between the amount of N2O supplied by the central system and the amount clinically used.1 Studies in the US, Scotland, and Australia have demonstrated that 70-95% of procured N2O is commonly lost through the central piped system, while only a small fraction can be accounted for by clinical use.1,5,6 Leaks can occur at numerous locations throughout the integrated piped system and are extremely challenging to detect or eliminate, making it unfeasible to effectively mitigate emissions through central system maintenance and repair.
In addition to being an unnecessary cost burden, the wasted N2O has severe environmental consequences, as the gas has a global warming potential 273 times that of carbon dioxide and an atmospheric lifetime of over 100 years.7-9 N2O is currently the single greatest contributor to the destruction of the ozone layer.10 In the US, anesthetic N2O is estimated to comprise approximately 3% of this contribution.11 These negative environmental effects, in turn, generate a number of adverse public health outcomes.12,13
The environmental impacts of N2O are significant, and the large contribution of central supply system N2O leaks/losses to total health care-generated N2O emissions is wasteful and unwarranted. Furthermore, N2O is no longer used as a primary anesthetic in most operating rooms, decreasing the need for ubiquitous central supply lines. Transitioning to a portable source for N2O delivery will substantially improve supply system efficiency and decrease total health care emissions without eliminating or restricting N2O use in the clinic.
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Date of last update: October 23, 2024
