Enter the pressure drop (ฮP) across the circulation loop and the flow (Q) through the vasculature into the calculator to determine resistance (often called TPR in physiology contexts).
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TPR Formula
The following formula is used to calculate resistance (often called TPR, โtotal peripheral resistanceโ).
TPR = \Delta P / Q
- Where TPR is the total peripheral resistance (resistance of a chosen circulation segment)
- ฮP is the pressure drop between upstream and downstream points (e.g., arterial โ venous)
- Q is the flow rate through the vasculature
In many courses and clinical contexts, โTPRโ is used synonymously with systemic vascular resistance (SVR). Confirm the definition used by your course/protocol.
- Systemic: SVR โ (MAP โ CVP) / CO
- Pulmonary: PVR โ (mPAP โ PCWP) / CO
To calculate resistance, divide the pressure drop (ฮP) by the flow rate (Q).
What is TPR?
Definition:
TPR, short for total peripheral resistance, is a measure of the total amount of force exerted on circulating blood by the vasculature of the body.
How to calculate TPR?
Example Problem:
The following example outlines how to calculate systemic resistance (often called SVR/TPR) using common clinical approximations.
First, estimate the pressure gradient (ฮP). For systemic circulation, ฮP is often approximated as MAP โ CVP. Example: MAP = 93 mmHg and CVP = 5 mmHg, so ฮP = 88 mmHg.
Next, determine the flow (Q). For systemic circulation, Q is typically cardiac output (CO). Example: CO = 5.0 L/min.
Finally, calculate resistance using the formula above:
TPR = ฮP / Q
TPR = 88 / 5.0
TPR = 17.6 mmHg/(L/min) (โ 1408 dynยทs/cmโต)
