Mechanism of assessment	Limitations	Ability to assess hypervolemia
HR/BP/UOP	Indirect measure	Many confounding factors	No
Serum lactate	Malperfusion causing anaerobic cellular respiration	Decreased clearance in liver disease	No
CVP	Estimate of right-sided filling pressure	Many things falsely elevate CVP including pulmonary HTN and CHF	No
SvO2	Measure of oxygen delivery	Systemic shunting may falsely elevate	No
PAC	Cardiac filling pressures and thermo-dilution	Invasive. Waveforms subject to interpretation	Possibly via elevated PA pressures
PPV/SVV	Cardiac output variation secondary to the respiratory cycle	Irregular HR; low tidal volumes; spontaneous respiration	No
Echocardiography	Direct measure of ventricular filling and cardiac function	Image acquisition and interpretation; learning curve	Possible via RV size and lack of change in caval size with respiration

BP, blood pressure; CHF, congestive heart failure; CVP, central venous pressure; HR, heart rate; HTN, hypertension; PPV, pulse pressure variation; RV, right ventricle; SVO2, mixed venous oxygen saturation; SVV, stroke volume variation; UOP, urine output.