One step closer towards a greener NHS: decommissioning of piped nitrous oxide manifolds

Abstract

Background: Nitrous oxide (N2O) is a widely used anaesthetic gas that is both a powerful greenhouse agent with 298 times the global warming potential of carbon dioxide (CO2)1 and detrimental to the ozone layer. According to NHS Lothian recent investigations, massive N2O leakage from piped manifold systems has been highlighted.2 One simple solution is to decommission N2O manifolds, with small N2O cylinders on the anaesthetic machines reserved for occasional usage. Hence, this project is initiated at Perth Royal Infirmary (PRI) with the goal of decommissioning the piped N2O manifold facility to meet the NHS Scotland Zero N2O emission by year 2027. Methods: A survey was conducted among all anaesthetists in PRI Anaesthetic department to evaluate their N2O usage preference and feasibility of decommissioning the piped N2O manifold. The N2O supply data provided by the pharmacy team was over a period of 10 months for the year 2021–22. To quantify the clinical usage at PRI, we captured the cumulative N2O usage over a 20-day period, using the data obtained from the service mode on each anaesthetic machine. From there, we extrapolated and calculated the annual estimated supply, usage, and wastage amount. Results: From the survey, all anaesthetists reported that their N2O usage is very low. Seventy-one percent of anaesthetists have decreased N2O usage over the past 5 yr, and there are no objections to the decommissioning of the piped N2O manifold. Based on our calculations, only 5475 L N2O are estimated to be consumed as opposed to 126 890 L supplied per annum. This demonstrates that as much as 96% or 121 415 L N2O are wasted. Financially, this is equivalent to 13.5 size G N2O cylinders worth £3145 per annum. To put into perspective, this corresponds to 64 964 kg CO2 equivalent emission or a staggering 541 366 km of car travel. Conclusions: We found significant wastage of N2O, unnecessary long-term financial expenditure, and adverse consequences to planetary health that could all be prevented. Our next step is to execute the plan of decommissioning piped N2O manifolds in accordance with the interim protocol for decommissioning set by the Scottish Government. Although this is a small step towards a greener sustainable future, multidisciplinary efforts from all related departments are essential in making this vision a reality. Eventually, re-audit will be carried out to evaluate the outcome of this action before rolling this improvement plan out to all sites within NHS Tayside. 1.Myhre G, Shindell D, Breon FM, et al. Anthropogenic and natural radiative forcing. In: IPCC Fifth Assessment Report. 2013.2.Chakera A, Fennell-Wells A, Allen A. Nitrous oxide project: piped nitrous oxide waste reduction strategy. Association of Anaesthetists, 2021 Jan 15. Available from: https://anaesthetists.org/Home/Resources-publications/Environment/Nitrous-oxide-project.