British Journal of Anaesthesia, 1989, Vol. 63, No. 4 453-457
© 1989 The Board of Management and Trustees of the British Journal of Anaesthesia
research-article |
THE CIRCLE SYSTEM AS A HUMIDIFIER
Department of Anaesthesia and Intensive Care, Sahlgren Hospital, University of Göteborg S-413 45 Göteborg, Sweden
In a laboratory model, humidity output was investigated in relation to the design of a circle absorber system. A 70-kg subject was simulated with fresh gas flows of 0.5, 2 or 5 litre min1. Different circle systems, absorption canisters and tubings were studied. It was found that both the type of circle system (according to Eger's classification) and the size of the absorption canister, influenced the humidity of inspired gases. Coaxial tubing only moderately increased the humidity. If a fresh gas flow of 0.5 litre min1 was used, optimum moisture contents were attained, irrespective of the circle system tested. Low fresh gas flows, a small canister and an Eger A type circle system, were factors which increased humidification.