Lanz E, Zimmerschitt W
Anaesthesist. 1976 Oct;25(10):491-8.
Changes of volume and pressure due to N2O-diffusion into PVC and Latex cuffs of endotracheal tubes were measured. Endotracheal tubes with a small-volume cuff (Magill and Portex) and one type of a large-volume, low-pressure cuff (Lanz) were examined. Within 48 h significant changes of volume and pressure were registered at different starting volumes and different N2O-concentrations. In the small-volume cuffs of the Portex and Magill tubes very high pressures were always noted; increases of volume were always seen, which were accompanied by increases, in some cases also by decreases of pressure. In the large-volume cuffs of the Lanz tube there were increases of volume and pressure; the measured pressures where however, in a clinical unimportant range. These changes are caused by N2O-diffusion into the cuff, slowed N2-diffusion out of the cuff, prestretching of the cuff membrane by the starting volume and further stretching by N2O diffusing into the cuff. These measurements are of practical clinical significance: This high-pressures due to starting volume and N2O-diffusion in small-volume cuffs explains the higher rate of trauma to the trachea, even after short term intubation, in contrast to the extremely low pressures in large-volume, low-pressure cuffs.
测量了因氧化亚氮扩散到气管导管的聚氯乙烯和乳胶套囊而导致的容积和压力变化。对带有小容积套囊的气管导管（Magill和Portex）以及一种大容积、低压套囊（Lanz）进行了检查。在48小时内，在不同的起始容积和不同的氧化亚氮浓度下记录到了容积和压力的显著变化。在Portex和Magill导管的小容积套囊中，总是会记录到非常高的压力；总是会出现容积增加，在某些情况下还伴有压力增加，也有压力降低的情况。在Lanz导管的大容积套囊中，容积和压力都增加了；然而，所测得的压力处于临床不重要的范围内。这些变化是由氧化亚氮扩散到套囊中、氮气从套囊中扩散出去减慢、套囊膜因起始容积而预拉伸以及氧化亚氮扩散到套囊中进一步拉伸所致。这些测量具有实际临床意义：小容积套囊中因起始容积和氧化亚氮扩散导致的高压解释了与大容积、低压套囊中极低压力相比，即使短期插管后气管创伤发生率更高的原因。
