Shunt Fraction Calculator

Variables: Qs/Qt = pulmonary shunt fraction; CcO2 = ideal pulmonary end-capillary oxygen content (mL O2/dL); CaO2 = arterial oxygen content (mL O2/dL); CvO2 = mixed venous oxygen content (mL O2/dL). Transformations: Displayed percentage = 100 × Qs/Qt; Negative calculated percentages are clamped to 0%. Oxygen partial pressure or saturation is not substituted directly for oxygen content.

Variables: PAO2 = alveolar oxygen partial pressure; FiO2 = inspired oxygen fraction; PB = barometric pressure; fixed here at 760 mmHg or 101.3 kPa; PH2O = water vapour pressure; fixed here at 47 mmHg or 6.3 kPa; PaCO2 = arterial carbon dioxide partial pressure; RQ = respiratory quotient; fixed here at 0.8. Note: The alveolar gas calculation is a reference calculation only; PAO2 is not used as a direct replacement for CcO2 in the Berggren equation.