Cardiovascular Resistance Calculator

Calculate systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR) to assess blood flow resistance in the circulatory system.

How to Use This Calculator

Enter the mean arterial pressure (MAP) in mmHg
Enter the central venous pressure (CVP) in mmHg
Enter the cardiac output (CO) in liters per minute
Select the resistance type you want to calculate (SVR or PVR)
Click Calculate to see the vascular resistance value and interpretation

Formula Used

Resistance = (Mean Pressure - Venous Pressure) ÷ Cardiac Output × 80

Where:

Resistance = Systemic Vascular Resistance (SVR) or Pulmonary Vascular Resistance (PVR)
Mean Pressure = Mean Arterial Pressure (MAP) or Mean Pulmonary Artery Pressure (MPAP)
Venous Pressure = Central Venous Pressure (CVP) or Pulmonary Capillary Wedge Pressure (PCWP)
Cardiac Output = CO in L/min
80 = Conversion factor to express resistance in dynes·sec·cm⁻⁵

Example Calculation

Real-World Scenario:

A 65-year-old patient with hypertension undergoes cardiac catheterization. The hemodynamic measurements show a MAP of 100 mmHg, CVP of 5 mmHg, and cardiac output of 5 L/min.

Given:

Mean Arterial Pressure (MAP) = 100 mmHg
Central Venous Pressure (CVP) = 5 mmHg
Cardiac Output (CO) = 5 L/min

Calculation:

SVR = (MAP - CVP) ÷ CO × 80

SVR = (100 - 5) ÷ 5 × 80

SVR = 95 ÷ 5 × 80

SVR = 19 × 80 = 1520 dynes·sec·cm⁻⁵

Result: The patient's systemic vascular resistance is 1520 dynes·sec·cm⁻⁵, which is elevated compared to the normal range (800-1200), indicating increased vascular resistance consistent with hypertension.

Why This Calculation Matters

Practical Applications

Assessing severity of hypertension and heart failure
Guiding medication therapy for vasodilators or vasoconstrictors
Evaluating response to cardiovascular interventions
Monitoring critically ill patients in intensive care settings

Key Benefits

Quantifies afterload on the heart
Helps differentiate types of shock
Assists in managing fluid therapy
Provides objective measure of vascular tone

Common Mistakes & Tips

For SVR calculations, use mean arterial pressure (MAP), not systolic or diastolic pressure. For PVR calculations, use mean pulmonary artery pressure (MPAP), not systolic pulmonary pressure. MAP can be calculated from systolic and diastolic pressures using the formula: MAP = Diastolic + 1/3(Systolic - Diastolic).

Cardiac output must be in liters per minute (L/min) for the formula to work correctly. If your cardiac output is measured in milliliters per minute (mL/min), divide by 1000 to convert to L/min. If measured in liters per second (L/s), multiply by 60 to convert to L/min.

Frequently Asked Questions

Normal SVR ranges from 800-1200 dynes·sec·cm⁻⁵. Normal PVR ranges from 20-130 dynes·sec·cm⁻⁵. These values can vary based on age, sex, and individual patient factors. Values below normal range may indicate vasodilation or sepsis, while values above normal range may indicate vasoconstriction or vascular disease.

Hematocrit affects blood viscosity, which is a component of vascular resistance. Higher hematocrit levels increase blood viscosity and consequently increase vascular resistance. This is why anemia (low hematocrit) often results in decreased SVR, while polycythemia (high hematocrit) increases SVR. The body compensates for these changes through various mechanisms to maintain adequate tissue perfusion.

Many medications affect vascular resistance. Vasodilators like nitroglycerin, ACE inhibitors, and calcium channel blockers decrease SVR. Vasoconstrictors like norepinephrine, phenylephrine, and vasopressin increase SVR. In pulmonary circulation, medications like sildenafil and prostacyclin decrease PVR, while hypoxia and certain inflammatory mediators increase PVR.

References & Disclaimer

Medical Disclaimer

This cardiovascular resistance calculator is for educational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.

References

Hemodynamic Monitoring - National Center for Biotechnology Information
Hemodynamic Calculations - American Heart Association
Systemic Vascular Resistance: Clinical Significance - Journal of Critical Care

Accuracy Notice

The accuracy of vascular resistance calculations depends on precise hemodynamic measurements. This calculator provides estimates based on standard formulas and should be interpreted in the context of the patient's overall clinical condition by qualified healthcare professionals.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

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