Right atrial pressure

Right atrial pressure (RAP) is the blood pressure in the right atrium of the heart. RAP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood into the arterial system. RAP is often nearly identical to central venous pressure (CVP),{{cite web |url=http://www.healthsystem.virginia.edu/internet/anesthesiology-elective/cardiac/cvcphys.cfm |title=Central Venous Catheter Physiology |access-date=2009-02-27}} although the two terms are not identical, as a pressure differential can sometimes exist between the venae cavae and the right atrium. CVP and RAP can differ when venous tone (i.e the degree of venous constriction) is altered. This can be graphically depicted as changes in the slope of the venous return plotted against right atrial pressure (where central venous pressure increases, but right atrial pressure stays the same; VR = CVP − RAP).

File:Vascular function curve.png as a consequence of variations in cardiac output. The three functions indicate the trend in physiological conditions (in the centre), in those of decreased preload (e.g. in hemorrhage, bottom curve) and in those of increased preload (e.g. following transfusion, top curve).]]