Greener Colonoscopy: Prudent CO2 use and adoption of the Olympus MAJ-2010 valve reduces CO2 emissions during colonoscopy by 89%

Aims Healthcare generates 4.4% of global carbon emissions [1] and endoscopy is the 3rd largest contributor [2]. CO₂ gas insufflation is best practice in colonoscopy, but the volume of CO₂ used has not been measured. This study aimed to quantify CO₂ use and explored ways to reduce it.

Methods An Alicat portable mass flow meter was used to measure pre-procedure CO₂ flow rate (Litres/min) and volume of CO₂ used/colonoscopy (Litres). Case length (min) and type were recorded. Each case used either a standard black Olympus MH-438 valve (continuous CO₂ release) or a grey MAJ-2010 valve (only releases CO₂ when depressed). Endoscopists used CO₂ as standard, or prudently (i.e. only when needed intra-procedurally). Cases were categorised as A (black, standard), B (black, prudent), C (grey, standard) or D (grey, prudent). Average CO₂ use was analysed using a student’s t-test.

Results Average CO₂ flow rate using black valves was 2.68L/min, or 0.98L/min with the valve occluded. Grey valves stopped CO₂ flow unless depressed. CO₂ use was measured in 225 colonoscopies (A=27, B=102, C=34 and D=62). Case mix included service, training, cancer screening, dye spray, surveillance and polypectomy. Mean case length (min) was A=48.6, B=39.7, C=38.5 and D=36.8. Mean volume (L) of CO₂ used/case was A=108.7, B=75.9, C=15.2 and D=12.0. Mean flow rates (L/min) per case were A=2.27, B=1.89, C=0.4 and D=0.31.

Conclusions Being prudent significantly reduces CO₂ use from 108.7 to 75.9L/case (p<0.001). Careful CO₂ use plus grey valve cuts it to 12L/case (89% saving, p<0.0001). 870,000 colonoscopies were performed in the UK in 2023. Assuming 1000L CO₂ weighs 1.836Kg at 25°C and normal atmospheric pressure this equates to 173.6 tonnes (T) of CO₂. Prudent CO₂ use could cut this to 122.8T (average cost 0.377p/LCO₂; annual saving £107,581). If 80% of colonoscopies use Olympus scopes, grey valve adoption could reduce annual emissions by 123.6T (annual saving £253,733). Endoscopy units have a duty to minimise their carbon footprints. We recommend that 1. CO₂ is switched off until the procedure starts and as soon as it finishes, 2.CO₂ is only turned on when required intra-procedurally, 3. Olympus units adopt the MAJ-2010 valve, 4. All manufacturers develop an equivalent valve and 5. These methods are adopted to reduce emissions in flexible sigmoidoscopy and ERCP.

 

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Conflicts of Interest

Authors do not have any conflict of interest to disclose.

• References

• 1 Vaccari et al Waste Manag Res. 2018 36. 39-47
• 2 https://www.arup.com/perspectives/publications/research/section/healthcares-climate-footprint

Publication History

Article published online:
27 March 2025