Developments in nitrous oxide capture technologies: bridging current research to clinical applications

Many inhaled anaesthetic agents are greenhouse gases. Capture technologies have been developed to prevent environmental emissions of volatile agents, but no such devices exist for nitrous oxide. Further to this, the unique societal position of the use of nitrous oxide for patients in labour means it cannot readily be substituted for alternatives. Currently, there are no mandated scavenging systems for nitrous oxide in maternity wards, resulting in not only loss to the environment, but also occupational exposure among labour ward staff, often at levels well above regulatory limits. Without a suitable analgesic alternative, and with contemporary catalytic destruction (cracking) devices for nitrous oxide relatively underutilised, more work must be done to develop capture technologies. While nitrous oxide capture for anaesthetic purposes is severely under-researched, a wide range of literature exists for other applications, including directly from the atmosphere and from waste effluent during chemical processing.

A literature search was used to identify original research articles describing adsorbents for nitrous oxide uptake. The search was limited to published articles over the last 5 years and relevance was screened by abstract review.

Different classes of adsorbents that could be used for nitrous oxide capture include activated charcoals, zeolites and metal-organic frameworks. We highlight their important properties and describe their key drawbacks. Recent literature was also examined and strategies in nitrous oxide capture across different industries drawn together to address the unique scenario of maternity analgesia.

Metal-organic frameworks are identified as a promising class of porous adsorbents that could be applied to a wide range of anaesthetic settings. With over 100,000 structures identified, they have a remarkable tuneability which should be further exploited in clinical settings to not only further progress towards 'net zero' targets but also to improve safety outcomes.