Hemodynamic Equations and Definitions


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Robert Donatiello M.D.

Daniel Shindler M.D.


Definitions

Pressure Flow and Derived Variables

Blood Gas Measurement Variables

Pulmonary Artery Occlusion Pressure


Definitions:

Afterload:

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

r = ventricular systolic dimensions

P = pressure during systole

h = wall thickness


Preload:

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


Contractility:

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:

Back

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:

Back

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):

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PAOP and Pulmonary Capillary Filtration Pressure



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e-mail:shindler@umdnj.edu

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