AbstractThe healthcare sector generates 4.4% of global greenhouse gas emissions, with 10% of the National Health Service carbon footprint in England associated with medical equipment. Here, a ‘carbon footprint’ is defined as the estimation of GHGs directly or indirectly associated with a product or process, converting GHGs to carbon dioxide equivalents (CO2e) based on their global warming potential, allowing summation. Surgical operations are resource-intensive, but little evidence existed for mitigating their associated carbon footprint. This thesis begins with a systematic review of sixteen studies evaluating carbon footprint of surgical operations, finding major contributors were single use products, energy consumption, and anaesthesia. The aim of this research was to identify major sources of greenhouse gas emissions (hotspots) associated with products used in common operations, and to evaluate their mitigation.
The carbon footprint of products used for five high volume operations was estimated, finding mean average for carpal tunnel decompression was 12.0 kg CO2e (carbon dioxide equivalents); 11.7 kg CO2e for inguinal hernia repair; 85.5 kg CO2e for knee arthroplasty; 20.3 kg CO2e for laparoscopic cholecystectomy; and 7.5 kg CO2e for tonsillectomy. Across the five operations, 23% of product types were responsible for ≥ 80% of the operation carbon footprint. Greatest contributions were associated with production of single-use products (54%), reusable instrument sterilisation (20%), and waste disposal of single-use products (8%).
Single-use laparoscopic clip appliers, scissors, and ports were responsible for 19% (mean average) of carbon footprint of products used for laparoscopic cholecystectomy. The term ‘life cycle assessment’ can be used to describe the evaluation of a range of environmental impact categories associated with a given product or process, and this approach was used to compare the environmental impact of these single-use products to hybrid (predominantly reusable) equivalents, finding the latter was associated with 60% (mean average) reductions in 17 out of 18 midpoint environmental impact categories.
Carbon footprint of reusable instrument sterilisation was evaluated, finding this could be optimised by 31-42% through processing instruments in sets rather than individually, maximal loading of sterilisation machines, and recycling sterile barrier systems, with further reductions associated with low-carbon energy sources.
The carbon footprint of alternative healthcare waste streams was estimated, finding a 50- fold difference between recycling (21 kg CO2e - 65 kg CO2e per t of waste), compared with high temperature incineration (no energy recovered from waste) (1,074 kg CO2e per t).
Finally, life cycle assessment was used to evaluate the role of repair, finding the carbon footprint of reusable scissors (70 g CO2e per use) could be reduced by 20% through repairing instruments onsite (56 g CO2e per scissors use).
Strategies for mitigating the carbon footprint of products used in common operations include switching single-use products to predominantly reusable equivalents, optimising sterilisation, using low carbon waste streams, and repairing instruments. Financial cost savings were associated with these strategies.
|Date of Award||Jan 2023|
|Supervisor||Malcolm Reed (Supervisor), Mahmood Bhutta (Supervisor) & Dr Robert Lillywhite (Supervisor)|