Statistical
Fick Cardiac Output, Stroke Volume & Systemic Vascular Resistance (SVR) formulas
Practice a simplified Fick-model calculation, stroke-volume conversion and resistance arithmetic with fictional inputs and explicit units.
Keep a simplified calculation distinct from clinical measurement
This educational worksheet uses fictional values. Fick flow is oxygen consumption divided by arterial-minus-mixed-venous oxygen content. The simplified expression uses 1.34 mL O2/g hemoglobin and omits dissolved oxygen; that omission is an approximation, not always negligible.
Saturations are fractions from 0 to 1, not percentages such as 98. Mixed venous sampling is not interchangeable with an arbitrary peripheral venous sample. Measured and estimated oxygen consumption can lead to different accuracy. These formulas do not diagnose a patient or recommend treatment.
The oxygen-content difference must be positive. Small differences amplify measurement error even when the arithmetic passes. Stroke volume uses unrounded flow and positive heart rate. Resistance uses mmHg for the pressure difference and L/min for flow; the 80 conversion produces dyn*s/cm^5.
| Hemodynamic Metric | Formula / Inputs | Fictional input panel | Calculated output |
|---|---|---|---|
| VO2, Hgb & O2 Saturations | VO2=250, Hgb=14, SaO2=0.98, SvO2=0.73 | CaO2 - CvO2 = 46.9 mL O2 / L | Saturation difference 0.25 |
| Fick Cardiac Output (CO) | B2 / (1.34 * B3 * (B4 - B5) * 10) | 250 / 46.9 | 5.33 L/min |
| Stroke Volume (HR = 75 bpm) | (CO * 1000) / B8 | 5,330.49 mL / 75 bpm | 71.1 mL/beat |
| SVR (MAP = 90, CVP = 10) | 80 * (B6 - B7) / CO | 6,400 / 5.33049 | 1,200.64 dyn*s/cm^5 |
Fick Principle Cardiac Output in liters per minute (L/min)
Enter SaO2 and mixed venous SvO2 as decimal fractions (e.g., 0.98 and 0.73); factor 10 converts g/dL hemoglobin into g/L.
=IF(COUNT(B2:B5)<>4,"Invalid inputs",IF(OR(B2<=0,B3<=0,B4<0,B4>1,B5<0,B5>1,B4<=B5),"Invalid inputs",ROUND(B2 / (1.34 * B3 * (B4 - B5) * 10), 2)))Systemic Vascular Resistance SVR = 80 * (MAP - CVP) / CO in dyn*s/cm^5
Conversion constant 80 converts mmHg / (L/min) into CGS vascular resistance units dyn*s/cm^5.
=IF(COUNT(B2:B7)<>6,"Invalid inputs",IF(OR(B2<=0,B3<=0,B4<0,B4>1,B5<0,B5>1,B4<=B5,B6<B7),"Invalid inputs",ROUND((80 * (B6 - B7)) / (B2 / (1.34 * B3 * (B4 - B5) * 10)), 2)))Stroke volume in mL per beat
Uses unrounded modeled flow and the fictional heart rate.
=IF(OR(COUNT(B2:B5)<>4,COUNT(B8)<>1),"Invalid inputs",IF(OR(B2<=0,B3<=0,B4<0,B4>1,B5<0,B5>1,B4<=B5,B8<=0),"Invalid inputs",ROUND(((B2 / (1.34 * B3 * (B4 - B5) * 10)) * 1000) / B8, 1)))Try the example
Use the original values or change them to test your understanding.