Dave Mital H, Spielmann Nelly, Mauch Jacqueline, Weiss Markus
Department of Anaesthesia, University Children's Hospital, Steinwiesstrasse, Zurich, Switzerland.
J Intensive Care Med. 2013 Jul-Aug;28(4):247-51. doi: 10.1177/0885066612452847. Epub 2012 Jul 24.
The aim of the present study was to investigate the effect of the Lanz system on air sealing by self-inflation in high volume-low pressure (HVLP) tube cuffs.
In vitro tracheal air sealing was studied in HVLP tracheal tube cuffs (internal diameter [ID] 8.0 mm) made from polyurethane ([PU] Seal Guard tracheal tube, Covidien, Athlone, Ireland) and from polyvinylchloride ([PVC] HiLo tracheal tube, Covidien) with and without Lanz pressure regulating valve. Tube cuffs were placed in a vertical 22 mm ID artificial trachea and inflated to 5, 10, 15, 20, 25, or 30 cm H2O cuff pressures. Pressure control ventilation with peak inspiratory pressures (PIPs) of 20 or 25 cm H2O was applied and air leakage was assessed spirometrically as the ratio of expiratory to inspiratory tidal volumes. Nonparametric Mann-Whitney test was applied to compare the air leakage with and without Lanz system for both cuff types at each cuff pressure and PIP (P < .05).
The PVC tube cuffs with Lanz system resulted in significant air leakage at both 20 and 25 cm H2O PIP as compared to those without the Lanz system, especially at cuff pressures lower than the preset PIP (P < .05). Although PU tube cuffs with Lanz system showed reduced air sealing when compared with cuffs without Lanz, the difference was not statistically significant.
Cuff pressure compensation with the Lanz system during cyclic respiratory pressure changes interferes with the self-sealing mechanism in HVLP tube cuffs at cuff pressures lower than PIP level. This results in larger air leak across tube cuffs particularly in tube cuffs made from PVC.
本研究旨在探讨兰兹系统对大容量低压（HVLP）气管导管套囊自行充气时空气密封的影响。
对由聚氨酯（[PU] Seal Guard气管导管，科惠医疗，爱尔兰阿斯隆）和聚氯乙烯（[PVC] HiLo气管导管，科惠医疗）制成的内径8.0毫米的HVLP气管导管套囊进行体外气管空气密封研究，这些套囊有无兰兹压力调节阀。将导管套囊置于内径22毫米的垂直人工气管中，并充气至5、10、15、20、25或30厘米水柱的套囊压力。施加峰值吸气压力（PIP）为20或25厘米水柱的压力控制通气，并通过呼气潮气量与吸气潮气量之比进行肺活量测定来评估漏气情况。应用非参数曼-惠特尼检验比较两种套囊类型在每种套囊压力和PIP下有无兰兹系统时的漏气情况（P < .05）。
与无兰兹系统的PVC导管套囊相比，有兰兹系统的PVC导管套囊在20和25厘米水柱PIP时均导致明显漏气，尤其是在套囊压力低于预设PIP时（P < .05）。尽管有兰兹系统的PU导管套囊与无兰兹系统的套囊相比空气密封有所降低，但差异无统计学意义。
在周期性呼吸压力变化期间，使用兰兹系统进行套囊压力补偿会干扰低于PIP水平的HVLP导管套囊的自密封机制。这会导致导管套囊出现更大的漏气，尤其是在由PVC制成的导管套囊中。
