Why environmentally sustainable anaesthesia matters
Climate change is a recognised global emergency . In November 2021 , White et al . [ 16 ] reported that the Earth ' s mean surface temperature was approximately 1.1 ° C higher than pre-industrial levels , and that exceeding a mean 1.5 ° C rise by 2050 will make global adaptation to the consequences of climate change less possible .
To remain under the 1.5 ° C target , we must make changes and reduce annual greenhouse gas emissions [ 16 , 17 ] . Consideration should therefore be given to limiting greenhouse emissions and our carbon footprint by any means available , as well as conserving resources and reducing waste .
Healthcare is responsible for nearly 5 % of total global greenhouse gas emissions . Inhalational anaesthetic agents contribute nearly 3 % of the NHS ’ s carbon emissions in England , most of which are waste anaesthestic gases [ 16 – 18 ] .
Inhaled anaesthetic agents , such as isoflurane and sevoflurane , are well-established greenhouse gases . For standard anaesthesia procedures with the patient maintained on inhalational agents it is recommended that anaesthetists use the agent with the lowest global warming potential ( GWP ) [ 16 ] .
The GWP over 100 years ( GWP 100
) of the available inhalational agents has been calculated and is shown in Table 2 , with equivalents for anaesthesia and motoring . Desflurane and nitrous oxide have the greatest GWP 100 and are the biggest contributors to operating theatre greenhouse gas emissions . This has prompted calls for them to be abandoned as anaesthetic agents [ 16 , 17 ] .
The main ways to achieve a reduction in greenhouse gas emissions from inhalational anaesthetic agents are :
• Using low-flow ( e . g . < 1 l / min ) FGF rates
• Using inhalational agents less often
• Choosing inhalational agents with lower GWP [ 17 , 18 ] .
There are technologies being developed to aid in the confinement and destruction of scavenged agents , which should reduce instances of their release into the atmosphere . Local , regional and intravenous general anaesthesia techniques can be considered for appropriate patients , to minimise greenhouse gas emissions compared with purely inhalational general anaesthesia techniques [ 16 , 17 ] ; however , the total carbon footprint of injectable anaesthetic agents can stem not only from wastage but also from their manufacture , transport , delivery and disposal [ 17 , 18 ] . The effect of the increased use of CO 2 absorbents on carbon footprint has not yet been established [ 18 ] .
Reducing the wastage of anaesthetic gases will reduce the expense of their provision . Adopting a protocol of turning off the flowmeter ( rather than just the vaporiser ) when moving a patient ' s position will also limit agent wastage [ 18 ] .
The use of high-FGF breathing systems with any patient can exacerbate hypothermia , as piped gases are not warmed ; this also dries out the airways as moisture is not conserved within piped oxygen . Rebreathing systems can help to improve this , as rebreathing exhaled gases minus the CO 2 means the patient will not be inspiring 100 % cold , dry fresh gases [ 20 ] . There are also consumables on the market that are designed to help conserve heat and moisture from expired gases . These
Table 2 . Characteristics of anaesthetic gases in the atmosphere [ 16 , 17 , 19 ] .
GWP 100
= Global warming potential over 100 years . MAC = minimum alveolar concentration .
Agent GWP 100
Atmospheric lifetime in years
Carbon dioxide equivalent ( kgCO 2
e ) per MAC-hour for canine anaesthesia at 1 l / min oxygen
Equivalent to car driving ( miles ) per MAC-hour of canine anaesthesia at 1 l / min oxygen
Isoflurane 530 3.2 3 12
Sevoflurane 130 1.2 1 4
Desflurane 2540 14 89 348
Nitrous oxide 265 110 36 140
Carbon dioxide 1 74 – –
38 Veterinary Nursing Journal