<P> In medicine, the mean systemic pressure (mean systemic filling pressure (MSFP), or mean circulatory filling pressure, (MCFP)) is defined as the mean pressure that exists in the circulatory system when the blood has had a chance to redistribute evenly to all vessels and organs . MSP is approximately 7 mm of Hg . It is an indicator of how full the circulatory system is (i.e. the volume of blood in the system compared to the capacity of the system), and is influenced by the volume of circulating blood and the smooth muscle tone in the walls of the venous system (which determines the capacity of the system). </P> <P> MSP is measured in two ways, and as a result has two alternative naming conventions . MSFP is measured after clamping the aortic root and the great veins at point of entry to right atrium . On the other hand, MCFP is measured experimentally by briefly inducing cardiac arrest or naturally during cardiac arrest once the blood redistributes . It can be used to demonstrate effects of drugs on the venous tone while the circulating blood volume remains constant, or to measure haemodynamic changes during haemorrhage . </P>

Difference between mean arterial pressure and mean systemic pressure