The popular multi-purpose Humphrey ADE-circle anaesthetic breathing system has two modes of use as a semi-closed system for animals 7kg or less, and a recycling system through soda-lime canister up to 150 kg. Very low flows of just 300-500ml/min are required in either mode. This is possible due to the unique function of the “Automatic Exhaust Valve” that stays closed to save all “anatomical dead space” and then open to eliminate CO2-laden alveolar gas. It doesn’t need adjusting! 

Together with a new two-chamber soda lime canister, the system ensures 100% efficacy in both modes, reducing sevoflurane and isoflurane usage by 50-80%,and costs and pollution by the same amount. 

Sevoflurane is four times less polluting than isoflurane and is ideal for low-flow anaesthesia. Unlike isoflurane uptake by muscle and fat, sevoflurane is very stable and safe even when recycled at just 5 ml/kg/minute. That’s a totally-closed circuit; nothing is lost from the exhaust valve!