What is venous pooling ?
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31
Dec
"When standing from a supine position, gravitational forces “pull” venous blood to the lower limbs (this also occurs on the arterial side). Due to the high compliance of veins, ~500 ml of blood can be redistributed to peripheral veins (9); this is known as venous pooling. The term venous pooling is sometimes misunderstood by students. It does not refer to a stagnant pool of blood, rather it refers to the slower transit time of blood through the venous circulation. This venous pooling leads to an immediate drop in stroke volume of 40% and an overall drop in cardiac output of 20%. However, mean arterial blood pressure is normally preserved, as there are compensatory increases in vascular tone mediated by the autonomic nervous system. Nevertheless, even healthy humans sometimes experience lightheadedness due to a transient drop in arterial pressure that occurs in the initial few seconds of standing".
This excerpt is taken directly from the following article:
Tansey EA, Montgomery Understanding basic vein physiology and venous blood pressure through simple physical assessments. Tansey EA, Montgomery LEA, Quinn JG, Roe SM, Johnson CD. Advances in Physiology Education • doi:10.1152/advan.00182.2018
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