Cook L B
Department of Anaesthesia, Royal Oldham Hospital, UK.
Anaesthesia. 1997 Dec;52(12):1182-94.
The degree of rebreathing in Mapleson A, C and D breathing systems for sinusoidal and exponential flow waveforms is analysed mathematically. The effects of altering the I:E ratio and of introducing an expiratory pause are investigated. The results for sinusoidal waveforms closely resemble those for a square wave. Exponential flow waveforms produce results similar to triangular flow waveforms. The Mapleson A system is always the most efficient. The Mapleson C system is efficient when the I:E ratio is 1:1, becoming less efficient with longer expiration and very inefficient with an expiratory pause. The Mapleson D system becomes efficient when the expiratory pause is long.
对Mapleson A、C和D呼吸回路在正弦波和指数流波形下的重复呼吸程度进行了数学分析。研究了改变吸呼比（I:E比）和引入呼气末暂停的影响。正弦波波形的结果与方波的结果非常相似。指数流波形产生的结果与三角流波形相似。Mapleson A系统始终是效率最高的。当I:E比为1:1时，Mapleson C系统效率较高，呼气时间越长效率越低，有呼气末暂停时效率极低。当呼气末暂停时间较长时，Mapleson D系统效率较高。
