Cardiac Output — Fick Principle Calculator

The Fick Principle is the gold-standard method for measuring cardiac output (CO) during right heart catheterization. The Fick equation calculates CO based on the relationship between whole-body oxygen consumption (VO₂) and the arteriovenous oxygen content difference: CO = VO₂ / (CaO₂ − CvO₂). The Fick principle is particularly accurate in patients with low cardiac output states (< 3.5 L/min) where thermodilution methods (Swan-Ganz catheter) are less reliable due to variability with low-flow states, tricuspid regurgitation, or intracardiac shunts. The Cardiac Index (CI = CO/BSA) normalizes for body size and is the key prognostic hemodynamic parameter in heart failure, cardiogenic shock, and pulmonary hypertension.