Hemodynamic Equations and Definitions

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Robert Donatiello M.D.

Daniel Shindler M.D.


Pressure Flow and Derived Variables

Blood Gas Measurement Variables

Pulmonary Artery Occlusion Pressure



Ventricular wall stress during systole, as indicated by the Law of Laplace:

r = ventricular systolic dimensions

P = pressure during systole

h = wall thickness


Ventricular wall tension (force / length) at the end of diastole


Measured by the slope of the end systolic pressure - volume relationship (end systolic elastance)

Arterial Impedance:

All factors that oppose ventricular ejection by absorbing the mechanical energy developed by the left ventricle (aortic impedence) or by the right ventricle (pulmonary artery impedence) during systole

Ventricular Compliance:

Ratio between a given stretch and the resulting tension in the relaxed isolated muscle

Ventricular Interdependence:

Diastolic volume and / or diastolic geometry influences diastolic pressure volume relationship of the contralateral ventricle

Pressure Flow and Derived Variables:


Measured Variables:

Calculated Variables:

Systemic arterial blood pressure

Pulmonary artery pressure

Cardiac Index:

Cardiac Output divided by the Body Surface Area (BSA)

Body Surface Area

Stroke Volume and Stroke Index

Systemic Vascular Resistance (SVR)

SVR in GCS Measurements

Pulmonary Vascular Resistance

Left Ventricular Stroke Work Index

Right Ventricular Stroke Work Index

Blood Gas Measurement Variables:


Measured Variables:

Calculated Variables:

Blood Oxygen Saturation

Blood Oxygen Saturation (Methemoglobinemia / CO Poisoning)

Oxygen Saturation of Mixed Venous Blood

Oxygen Content of Blood

Oxygen Content - End Capillary Blood

Oxygen Delivery

Arteriovenous Oxygen Difference

Oxygen Extraction

Oxygen Uptake (Principle)

Oxygen Uptake (Fick Method)

Pulmonary Artery Occlusion Pressure (PAOP):


PAOP and Pulmonary Capillary Filtration Pressure

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The contents and links on this page were last verified on February 16, 2001.