Comparison of the Bain and the ADE systems during controlled ventilation in adults

It has been suggested that Humphrey's ADE system may be an improvement on the Bain system. To compare their efficiencies we have studied 20 anesthetized adults who had controlled ventilation established with a circle absorber system at a VE sufficient to maintain normocapnia. Patients were then randomly allocated to either a Bain or an ADE system. Fresh gas flow was sufficient to keep PE'CO2 constant for 30 min. The other circuit was then used for an additional 30 min. The required FGF was 54 ml kg-1 min-1 for the Bain system, compared with 67 ml kg-1 min-1 for the ADE system. We conclude that, during controlled ventilation, the ADE system is 25% less efficient than the Bain system.