Pinsky M R
Department of Anesthesiology and Critical Care Medicine, University of Pittsburgh, PA.
New Horiz. 1994 Nov;2(4):443-56.
Artificial ventilation using intermittent positive airway pressure is the mainstay support of patients in respiratory failure. By maintaining alveolar ventilation and alveolar stability, positive airway pressure can sustain respiratory gas exchange between the lungs and circulation, thereby supporting pulmonary homeostasis in patients who would otherwise be unable to maintain oxygen transfer and CO2 elimination. However, positive-pressure ventilation (PPV) also results in complex cardiovascular interactions. More often than not, these interactions impede blood flow through ventilated lungs and reduce global cardiac output. Although arterial oxygen content is adequately sustained because oxygen delivery is equal to the product of arterial oxygen content and cardiac output, global oxygen delivery may be reduced by PPV because of a decrease in cardiac output. Because a primary function of the cardiovascular-respiratory system is to deliver sufficient amounts of oxygen to meet systemic metabolic demands, measurement of arterial blood gases alone in monitoring ventilatory support is inadequate in assessing the cardiopulmonary effects of PPV. Clear understanding of cardiopulmonary interactions associated with mechanical ventilation is required in the rational management of critically ill ventilator-dependent patients. The hemodynamic effects of mechanical ventilation are complex and cannot be explained in terms of the interactions of single hemodynamic processes and cardiac function. However, when considered in this manner, such interactions can be understood more easily. In most patients it is usually clear which process is dominant, permitting adjustments in overall therapy in order to optimize care. This review identifies these interactions and demonstrates which are dominant in specific clinical scenarios.
使用间歇正压通气的人工通气是呼吸衰竭患者的主要支持手段。通过维持肺泡通气和肺泡稳定性，气道正压可以维持肺与循环之间的呼吸气体交换，从而在原本无法维持氧转运和二氧化碳清除的患者中支持肺内稳态。然而，正压通气（PPV）也会导致复杂的心血管相互作用。这些相互作用往往会阻碍通气肺的血流并降低心输出量。尽管由于氧输送等于动脉血氧含量与心输出量的乘积，动脉血氧含量能得到充分维持，但由于心输出量降低，PPV可能会降低整体氧输送。由于心血管呼吸系统的主要功能是输送足够量的氧气以满足全身代谢需求，仅通过测量动脉血气来监测通气支持在评估PPV的心肺效应方面是不够的。在合理管理依赖呼吸机的重症患者时，需要清楚了解与机械通气相关的心肺相互作用。机械通气的血流动力学效应很复杂，不能仅用单一血流动力学过程和心脏功能的相互作用来解释。然而，以这种方式考虑时，这种相互作用更容易理解。在大多数患者中，通常很清楚哪个过程占主导地位，从而可以调整整体治疗以优化护理。本综述确定了这些相互作用，并展示了在特定临床场景中哪些相互作用占主导地位。
