Table 2 Physiologic terminology
Term | Definition |
|---|---|
Arterial elastance | The ratio of left ventricular end-systolic pressure and stroke volume |
Intravascular volume | The blood volume within the vascular system (arteries, capillaries, veins) |
Mean systemic filling pressure | The pressure of venous return when cardiac activity is absent |
Preload | Volume defined by the distending pressure it generates. In the heart, preload is LV wall stress at end of diastole (= EDV) |
Stressed volume | The (theoretically measurable) volume of blood that exerts distending pressure against the vascular wall |
Total body water | The amount of sodium-free water in the whole body, commonly divided into the extracellular fluid space and the intracellular fluid space |
Unstressed volume | The volume of blood just to the point of filling the blood vessels but without exerting any pressure on the vessel walls |
Vascular capacitance | The change in volume divided by the change in pressure (i.e., the inverse of elastance) |