Marini J J, Crooke P S, Truwit J D
Division of Pulmonary and Critical Care Medicine, University of Minnesota, Minneapolis 55101.
J Appl Physiol (1985). 1989 Sep;67(3):1081-92. doi: 10.1152/jappl.1989.67.3.1081.
In recent years, four square-wave modes of pressure-preset mechanical ventilation (PPV)--pressure control, pressure support, inverse ratio, and airway pressure release ventilation--have been introduced to clinical practice. Conceptually, they share important features. Yet, because there remains widespread uncertainty regarding their ventilatory characteristics, efficacy, and appropriate use, the potential range of application is only now being investigated. To construct a unifying mathematical model of PPV, we developed a system of equations for prediction of the major "outcome" variables of PPV--tidal volume, minute ventilation, auto-positive end-expiratory pressure, mean alveolar pressure, and mechanical work--from the primary clinical "inputs" from patient (resistance, compliance) and clinician (applied pressure, frequency, inspiratory time fraction). Our analysis revealed distinct bounding limits for the outcome variables of ventilation and pressure and important implications for their clinical determinants. Although simplifying assumptions were required to enable construction of this mathematical analogue of respiratory system behavior, this model provides a firm conceptual framework for understanding the physiological interactions between PPV and the patients they are intended to help.
近年来，压力预设机械通气（PPV）的四种方波模式——压力控制、压力支持、反比通气和气道压力释放通气——已被引入临床实践。从概念上讲，它们具有重要的共同特征。然而，由于人们对其通气特性、疗效和正确使用仍普遍存在不确定性，目前才开始研究其潜在的应用范围。为构建PPV的统一数学模型，我们开发了一个方程组，用于根据患者（阻力、顺应性）和临床医生（施加压力、频率、吸气时间分数）的主要临床“输入”来预测PPV的主要“输出”变量——潮气量、分钟通气量、内源性呼气末正压、平均肺泡压和机械功。我们的分析揭示了通气和压力输出变量的明显边界限制及其临床决定因素的重要意义。尽管需要进行简化假设才能构建这个呼吸系统行为的数学模拟模型，但该模型为理解PPV与其旨在帮助的患者之间的生理相互作用提供了一个坚实的概念框架。
