Venous return flow depends on the difference between peripheral venous pressure and central venous pressure, as well as venous resistance to blood flow, including the influence of the following factors.
(1) The average filling pressure of the circulatory system is positively correlated with the degree of intravascular blood flow filling.
(2) Cardiac contractility Cardiac contractility is the driving force of venous return. Venous congestion and pulmonary edema occur in left heart failure, liver and spleen congestion, lower limb edema and other signs occur in right heart failure.
(3) Change of body position When the body changes from lying position to standing position, the amount of blood returned to the heart is reduced.
(4) Skeletal muscle compression The contraction of the skeletal muscle, together with the venous valve, acts as a "pump" to the venous return, called the venous pump or muscle pump, promoting the venous return.
(5) Respiratory movement affects venous return by affecting intrathoracic pressure. For example, the negative pressure in the chest increases during inhalation, promoting venous return; On exhalation, venous return is reduced.