BJA Advance Access originally published online on August 1, 2006
British Journal of Anaesthesia 2006 97(4):571-575; doi:10.1093/bja/ael210
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Effects of temperature gradient correction of carbon dioxide absorbent on carbon dioxide absorption
Department of Anaesthesiology, Hachioji Medical Center Tokyo Medical University 1163 Tatemachi, Hachioji, Tokyo 193-0998, Japan
*Corresponding author. E-mail: goh{at}tokyo-med.ac.jp
Background. The effects of temperature gradients in CO2 absorbents on water content and CO2 absorption are not clear. We constructed a novel temperature gradient correction (TGC) canister, and investigated the effects of temperature gradient correction on the water content and longevity (time to exhaustion) of CO2 absorbent using a simulated anaesthesia circuit.
Methods. Experiments were divided into two groups according to the type of canister used: the TGC canister (n=6) or the conventional canister (n=6). One kilogram of fresh CO2 absorbent was placed into the canister. The anaesthetic ventilator was connected to a 3 litre bag and 300 ml min1 of CO2 was introduced. Oxygen (500 ml min1) was used as fresh gas. The anaesthetic ventilator was set at a ventilatory frequency of 12 bpm, and tidal volume was adjusted to 700 ml.
Results. Before the experiment, the water content of the fresh CO2 absorbent in the conventional canister and TGC canister was 16.1 (0.9)% and 15.7 (1.1)%, respectively. After the experiment, the water content of CO2 absorbent near the upper outer rim of the canister increased to 32.4 (0.7)% in the conventional canister, but increased to only 20.6 (1.3)% in the TGC canister (P<0.01). The longevity of CO2 absorbent in the conventional canister and TGC canister was 434 (9) min and 563 (13) min (P<0.01).
Conclusions. Temperature gradient correction prevented a local excessive increase in water content and improved the longevity of CO2 absorbent.
Declaration of interest. All experiments were performed in the Department of Anaesthesiology, Hachioji Medical Center Tokyo Medical University.
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