Mean circulatory filling pressure

In medicine, the mean circulatory filling pressure (Pmcf) is defined as the mean pressure that exists in the vascular system if the cardiac output stops and the pressure within the vascular system redistributes. 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).

The Pmcf can be measured experimentally by inducing cardiac arrest briefly in animals. 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.

A closely related term is mean systemic filling pressure(MSFP). It is same as MCFP except that while MCFP is measured when the heart is made to stop beating, MSFP is measured after clamping the aortic root and the great veins at point of entry to rt. atrium. MSFP is approximately 7 mm of Hg and is practically equal to MCFP. The difference between MSFP and CVP is an important determinant of venous return to the heart