Saidel G M, Jepson S C
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106.
J Biomed Eng. 1990 Nov;12(6):496-502. doi: 10.1016/0141-5425(90)90060-z.
Ventilation systems that operate at high-frequency and deliver small volumes have the potential to provide adequate alveolar ventilation without excessive pulmonary pressures. One way of producing high-frequency ventilation is by use of jet bursts of an input gas through a cannula controlled by a solenoid valve. This high-frequency jet ventilation has yet to be quantitatively analysed for optimal clinical use. From an analysis of the jet-producing device, we obtained a quantitative relationship which allowed us to predict the gas volume of a jet burst (Vjet) from the driving pressure (Pd), and the jet duration (tI). The device was applied to a mechanical lung model (a tube attached to an elastic bag corresponding to the lung airway and alveolar space). We examined how the control variables of the jet ventilation system changed the bag (alveolar) volume with respect to Vjet, the volume of entrained gas, and the volume of shunted gas. Using a nitrogen washout analysis, we evaluated the operating lung volume, effective dead-space volume (Veds), and effective ventilation rate (Veff). We found that Veds is independent of the individual effects of jet cycle frequency, duty cycle, cannula diameter, and entrainment fraction. While Veds was not affected significantly by the shape of the airway, it did depend on the distance of the jet cannula tip to the ventilated bag (or alveolar region) and on the tidal volume.
高频运行且输送小气量的通气系统有可能在不过度产生肺内压力的情况下提供足够的肺泡通气。产生高频通气的一种方法是通过由电磁阀控制的插管对输入气体进行喷射脉冲。这种高频喷射通气尚未针对最佳临床应用进行定量分析。通过对喷射产生装置的分析，我们得到了一种定量关系，该关系使我们能够根据驱动压力（Pd）和喷射持续时间（tI）预测喷射脉冲的气体量（Vjet）。该装置应用于机械肺模型（一根连接到对应于肺气道和肺泡空间的弹性袋的管子）。我们研究了喷射通气系统的控制变量如何相对于Vjet、夹带气体量和分流气体量改变袋子（肺泡）体积。使用氮洗脱分析，我们评估了工作肺容量、有效死腔量（Veds）和有效通气率（Veff）。我们发现Veds与喷射周期频率、占空比、插管直径和夹带分数的个体效应无关。虽然Veds不受气道形状的显著影响，但它确实取决于喷射插管尖端到通气袋（或肺泡区域）的距离以及潮气量。
