It is an exaggeration of the inspiratory drop in systolic pressure, and thus in the fullness of the pulse.
Inspiration lowers intrathoracic pressure, which then increases venous return to the “right” ventricle.
Conversely, it reduces venous return to the left ventricle (because of blood pooling in the inflated
lungs and a leftward shift in the ventricular septum).
In turn, the smaller end-diastolic left ventricular volume results in lower stroke volume and, thus,
lower systolic pressure.
Exhalation, on the other hand, increases left ventricular filling (because of blood being “squeezed” by lung deflation, and also because of rightward shift in the ventricular septum). This increased ventricular filling results in higher left ventricular stroke volume and systolic pressure.
All these respiratory variations are physiologic, but in certain pathologic states they become large enough
to cause more profound (and detectable) changes in blood pressure and pulse volume.
Inspiration lowers intrathoracic pressure, which then increases venous return to the “right” ventricle.
Conversely, it reduces venous return to the left ventricle (because of blood pooling in the inflated
lungs and a leftward shift in the ventricular septum).
In turn, the smaller end-diastolic left ventricular volume results in lower stroke volume and, thus,
lower systolic pressure.
Exhalation, on the other hand, increases left ventricular filling (because of blood being “squeezed” by lung deflation, and also because of rightward shift in the ventricular septum). This increased ventricular filling results in higher left ventricular stroke volume and systolic pressure.
All these respiratory variations are physiologic, but in certain pathologic states they become large enough
to cause more profound (and detectable) changes in blood pressure and pulse volume.