The goal of hemodynamic management is to maintain adequate organ perfusion. Since organ perfusion is difficult to measure in vivo, systemic blood pressure is monitored as an indicator of blood flow and organ perfusion. The relationship between systemic blood pressure and systemic perfusion can be modeled by the mechanical analogue of Ohm's Law: MAP − CVP = SVR × CO. Where MAP represents mean arterial pressure, CVP represents central venous pressure, SVR represents systemic vascular resistance, and CO represents cardiac output. As illustrated by the equation, changes in MAP do not always reflect changes in CO.