Carbon dioxide absorbents are critical components of circle breathing systems, allowing fresh gas flow anaesthesia and reducing volatile gas consumption. Traditional Soda Lime contains strong alkalis that produces harmful toxic products like compound A when interacting with volatile anaesthetic agents and contributes to environmental waste. AMSORB® is a calcium-based, alkali-free CO₂ absorbent designed to improve clinical safety and sustainability. This service evaluation compared the clinical performance and environmental sustainability of AMSORB® with Soda Lime.

Methods

Data was collected from two anaesthetic machines in Noah’s Ark Children’s Hospital over 14 days. AMSORB® was used in Theatre 3 and Soda Lime in Theatre 4. Fresh gas flow was recorded on day 0 and 14. To assess consumption and waste production, absorbents were weighed before and after use. Costs were calculated using unit pricing and absorbent usage. Consultant anaesthetists completed an anonymous survey, assessing their views on sustainability and support of department-wide AMSORB® adoption.

Results

Over the 14 days, AMSORB® used 10,409 L of fresh gas using 568g of absorbent, compared with 11,208 L, using 685g of soda lime. AMSORB® showed a greater efficiency at 18.3L/g, versus 16.4L/g for soda lime, representing approximately a 12% improvement. Material consumption per litre of gas was lower with AMSORB® (0.0546g/L vs 0.0611g/L), resulting in a 17% reduction in absorbent waste mass. Although AMSORB® had a higher unit price, efficiency-adjusted costs were comparable. 

Extrapolating this, AMSORB® was estimated to reduce absorbent waste by approximately 3kg per theatre each year. 30 Consultant Anaesthetists completed the survey. 50% experienced issues with Soda Lime such as sevoflurane degradation, carbon monoxide concerns and premature exhaustion. 93% deemed environmental sustainability as important when choosing absorbents, and 93% supported department-wide adoption of AMSORB® if clinical performance remained equivalent and had environmental and safety advantages.

Discussion

AMSORB® demonstrated comparable clinical performance to Soda Lime while offering possible safety and environmental benefits. Consultant feedback showed support in favour of department wide adoption of a more environmentally sustainable absorbent where cost differences are minimal. These findings help support AMSORB® as a sustainable absorbent substitute in anaesthesia.