Rebreathing in the Mapleson A, C and D breathing systems with sinusoidal and exponential flow waveforms.
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.
Cook
L B
LB
Department of Anaesthesia, Royal Oldham Hospital, UK.
D000764:Anesthesia, Closed-Circuit / Q000295:instrumentation*; D006801:Humans; D001239:Inhalation; D008433:Mathematics; D008954:Models, Biological; D012119:Respiration; D013990:Tidal Volume; D013997:Time Factors