Digestive disorders, male impotence, tiredness, sleepwalking, environmental temperature intolerance, are classic examples of a low-flow-state, resulting in reduced blood flow. Modulators SI variability and MAP variability are accomplished through activity of hemodynamic modulators. The conventional cardiovascular physiology terms for the hemodynamic modulators are preload, contractility and afterload. They deal with (a) the inertial filling forces of blood return into the atrium (preload), which stretch the myocardial fibers, thus storing energy in them, (b) the force by which the heart muscle fibers shorten thus releasing the energy stored in them in order to expel part of blood in the ventricle into the vasculature (contractility), and (c) the forces the pump has to overcome in order to deliver a bolus of blood into the aorta per each contraction (afterload). The level of preload is currently assessed either from the PAOP (pulmonary artery occluded pressure) in a catheterized patient, or from EDI (end-diastolic index) by use of ultrasound. Contractility is not routinely assessed; quite often inotropy and contractility are interchanged as equal terms. Afterload is assessed from the SVRI value. Rather than using the terms preload, contractility and afterload, the preferential terminology and methodology in per-beat hemodynamics is to use the terms for actual hemodynamic modulating tools, which either the body utilizes or the clinician has in his toolbox to control the hemodynamic state: The preload and the Frank-Starling (mechanically)-induced level of contractility is modulated by variation of intravascular volume (volume expansion or volume reduction/diuresis). Pharmacological modulation of contractility is performed with cardioactive inotropic agents (positive or negative inotropes) being present in the blood stream and affecting the rate of contraction of myocardial fibers. The afterload is modulated by varying the caliber of sphincters at the input and output of each organ, thus the vascular resistance, with the vasoactive pharmacological agents (vasoconstrictors or vasodilators and/or ACE Inhibitors and/or ARBs)(ACE = Angiotensin-converting-enzyme; ARB = Angiotensin-receptor-blocker). Afterload also increases with increasing blood viscosity, however, with the exception of extremely hemodiluted or hemoconcentrated patients, this parameter is not routinely considered in clinical practice. With the exception of volume expansion, which can be accomplished only by physical means (intravenous or oral intake of fluids), all other hemodynamic modulating tools are pharmacological, cardioactive or vasoactive agents. The measurement of CI and its derivatives allow clinicians to make timely patient assessment, diagnosis, prognosis, and treatment decisions. It has been well established that both trained and untrained physicians alike are