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Cardiology
Cardiac Output (Fick Method)
🫀 Cardiology
Cardiac Output — Fick Method
CO, CI, SV, SVR, and PVR from right heart catheterization data
Overview
The Fick principle states that cardiac output equals oxygen consumption divided by the arteriovenous oxygen difference. Used during right heart catheterization to precisely quantify hemodynamic parameters.
Patient Demographics (for BSA & estimated VO₂)
kg
cm
bpm
VO₂ Method
Estimated VO₂ (BSA × 125): — mL/min
mL/min
Oxygen Saturation & Hemoglobin
%
%
g/dL
Hemodynamic Pressures (for SVR/PVR)
mmHg
mmHg
mmHg
mmHg
Hemodynamic Profile
Cardiac Output
—
L/min
Cardiac Index
—
L/min/m²
Stroke Volume
—
mL/beat
SVR
—
dyn·s/cm⁵
PVR
—
dyn·s/cm⁵
BSA
—
m²
Hemodynamic Reference Values
| Parameter | Normal Range | Abnormal |
|---|---|---|
| CO | 4–8 L/min | <4 low; >8 high |
| CI | 2.2–4.0 L/min/m² | <2.2 shock/low output |
| SV | 60–100 mL/beat | <60 reduced |
| SVR | 800–1200 dyn·s/cm⁵ | >1200 vasoconstriction |
| PVR | <250 dyn·s/cm⁵ | >250 pulmonary HTN |
CO = VO₂ / [(SaO₂ - SvO₂)/100 × Hgb × 13.4]
BSA = 0.007184 × Wt⁰·⁴²⁵ × Ht⁰·⁷²⁵
CI = CO / BSA
SV = CO × 1000 / HR
SVR = (MAP - CVP) × 80 / CO
PVR = (mPAP - PCWP) × 80 / CO
BSA = 0.007184 × Wt⁰·⁴²⁵ × Ht⁰·⁷²⁵
CI = CO / BSA
SV = CO × 1000 / HR
SVR = (MAP - CVP) × 80 / CO
PVR = (mPAP - PCWP) × 80 / CO
Clinical Notes:
• CI <2.2 L/min/m²: cardiogenic shock — consider inotropes, MCS
• CI <1.8 L/min/m²: profound shock — urgent hemodynamic support
• Elevated PVR (>3 WU): pre-capillary pulmonary hypertension
• Fick method most accurate at low CO states; thermodilution preferred at high CO
• CI <2.2 L/min/m²: cardiogenic shock — consider inotropes, MCS
• CI <1.8 L/min/m²: profound shock — urgent hemodynamic support
• Elevated PVR (>3 WU): pre-capillary pulmonary hypertension
• Fick method most accurate at low CO states; thermodilution preferred at high CO
⚕️ For use by qualified healthcare professionals only. Not a substitute for clinical judgment.
