Cardiac output and venous return as interdependent and independent variables

Cardiology
H S Badeer

Abstract

Under steady states the heart pumps whatever it receives and receives whatever it pumps. In other words, cardiac output (CO) and venous return (VR) are equal and the distinction between the two seems unnecessary. However, under nonsteady states the two are temporarily unequal and the distinction becomes significant. VR varies directly with the difference in pressure between the end of systemic capillaries and the right ventricle during filling and inversely with the total resistance of the venous system. Thus, the energy for VR is derived from CO. In some transient states VR becomes an independent variable and CO dependent until a new steady state is reached (e.g., exercise, hemorrhage, fevers, hyperthyroidism, severe anemia, etc.). In other conditions the opposite is true (e.g., myocardial infarction, altered ventricular contractility, etc.). Explanation of changes in cardiac output in various perturbations of circulation are based on the identification of the independent variable (VR or CO) in a given physiologic or pathologic condition during the period that a nonsteady state exists.

Citations

Oct 1, 1985·Pflügers Archiv : European journal of physiology·A Versprille, J R Jansen
Jan 1, 1997·Nursing Diagnosis : ND : the Official Journal of the North American Nursing Diagnosis Association·C M Dougherty
Nov 1, 1991·Clinical Physiology·J MehlsenJ Trap-Jensen
Jul 1, 1994·Scandinavian Journal of Clinical and Laboratory Investigation·J MehlsenK H Stokholm
Oct 28, 2014·Physiological Reports·Keisho KatayamaShigehiko Ogoh
Oct 25, 2000·American Journal of Physiology. Heart and Circulatory Physiology·L MacéJ Y Neveux

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