The Integrative Effect of Changes in Intrathoracic Pressure on Cardiac and Cerebrovascular Function.

呼吸过程中胸腔内压力(胸腔内压力)的变化可以通过对心脏的左右两侧施加不同的挑战来改变心脏的充盈和排空方式。由于肺、心和脑循环都是串联的，胸腔内压的变化不仅会影响心肺内的血液流动，还可能通过改变动脉流入、头骨内压力和静脉流出而改变脑血流。据我们所知，这三个内在联系的系统之间的这种重要的相互作用从未被研究过，胸腔内压的变化可能具有超越肺和心脏的重大意义，特别是在挑战身体的自然生理平衡(动态平衡)的时候。这项研究的目的是同时测量胸腔内压、心脏充盈和排空、脑血流量以及进出大脑的血流量，并研究胸腔内压的变化如何同时改变这些系统。此外，我们将通过各种挑战来改变动态平衡，包括血液容量负荷以及血液中氧气和二氧化碳水平的变化。因此，仅在研究这三个系统在任何生理刺激期间如何相互作用方面就有相当大的新颖性。到目前为止，很少有研究研究胸腔内压的变化如何影响心脏功能，特别是当身体充满液体或存在血气变化时，即低氧和高二氧化碳水平。此外，还没有研究系统地研究胸内压如何影响脑血流。因此，这三个系统的结合将大大增加我们目前在影响人体血流调节的机械因素这一重要领域的知识。

Changes in pressures within the chest cavity (intrathoracic pressure) made during breathing can alter how the heart fills and empties by placing different challenges to the right and left sides of the heart. As the lungs, heart and brain circulation are all in series, changes in intrathoracic pressure will not only influence blood flow in the heart and lungs but may also alter brain blood flow through changes in arterial inflow, pressure within the skull and venous outflow. To our knowledge, this important interaction between three intrinsically linked systems has never been studied and changes in intrathoracic pressure could have significant implications beyond the lungs and heart, especially during challenges to the body's natural physiological balance (homeostasis). The aim of this program of research is to simultaneously measure intrathoracic pressure, heart filling and emptying, brain blood flow as well as blood flow into and out of the brain and examine how changes in intrathoracic pressure simultaneously alter these systems. Additionally, we will alter homeostasis with a variety of challenges including blood volume loading and changes in oxygen and carbon dioxide levels within the blood. As such, there is considerable novelty alone in investigating how all three of these systems interact during any physiological stimulus. To date there have been few studies that have investigated how changes in intrathoracic pressure affect cardiac function especially when the body is fluid loaded or there are changes to blood gases i.e. low oxygen and high carbon dioxide levels. Additionally, no study has systematically investigated how intrathoracic pressure effects brain blood flow. Therefore, the combination of the three systems approach will add considerably to our present knowledge in this important area of mechanical factors that affect blood flow regulation in humans.