The Venturi anaesthesia circuit II. Carbon dioxide production and gas flow requirements.

Carbon dioxide production was measured in 20 adult patients undergoing alloplastic operation of the hip. Body weight ranged from 40 to 81 kg. Anaesthesia consisted of lumbar plexus block, i.v. diazepam, pethidine, pavulon and N2O/O2 under controlled ventilation. CO2 production was 2.13 ml kg-1 min-1 (interquartile range 2.09-2.23). A fresh gas flow rate of about 30 ml kg-1 min-1 was required for the elimination of CO2 produced when using the Venturi system for inhalation anaesthesia.