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SVR Calculation — FRCA Final MCQ

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ModerateIntensive Care MedicineSVR CalculationFRCA Final

A patient on the ICU has a cardiac output of 5.5 L/min, heart rate 80 bpm, and MAP 75 mmHg. The systemic vascular resistance (SVR) can be calculated. Given CVP of 8 mmHg, what is the SVR?

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Correct answer: A — 973 dynes.s.cm⁻⁵

SVR = (MAP – CVP) / CO × 80 = (75 – 8) / 5.5 × 80 = 67/5.5 × 80 = 12.18 × 80 = 975 dynes.s.cm⁻⁵. Normal SVR is 800-1200 dynes.s.cm⁻⁵. This is within the normal range. The formula is a key exam calculation. The factor of 80 converts Wood units (mmHg.min/L) to CGS units (dynes.s.cm⁻⁵). In septic shock SVR is typically <800, and in cardiogenic shock SVR is typically >1200.

Reference: RCOA – 2023 – Final FRCA curriculum: cardiovascular physiology; ICS – 2023 – Haemodynamic calculations