The Venturi anaesthesia circuit III. Carbon dioxide elimination

The Venturi circuit was studied with regard to CO2 elimination in a model experiment. A mean concentration of 0.6% CO2 in the fresh gas supply to the patient was accepted. The experiments demonstrated that a soda-lime charge of 200 g will cover the elimination requirements of CO2 in a Venturi circuit for any patient below 100 kg b.w. for a period of 3 h, while a soda-lime charge of 300 g will suffice for 5 h. The utilization of the soda lime charge is of the same order of magnitude as that of the much larger canisters used in circle circuits. In the Venturi circuit, the size of the soda-lime charge can be adjusted to suit the body weight of the patient and the expected length of the anaesthetic procedure. One soda-lime charge for each anaesthetic procedure is preferable from the point of view of hygiene. The charge should not be less than 200 g.