Oxygen Delivery Equation
DO2 = CO x {(1.39 x Hb x sO2) + (PaO2 x 0.03)}
DO2 = Rate of oxygen delivery in mL/min
CO = Cardiac Output in L/min
Hb = Concentration of Hemoglobin
1.39 = Maximal oxygen-carrying capacity of hemoglobin: normally 1.39 ml/g
sO2 = % saturation of effective hemoglobin
PaO2 = Partial pressure of oxygen
0.03 = Solubility constant for oxygen at 37° - normally, 0.03 ml/L/mmHg

I used this analogy to understand oxygen delivery capacity of blood (DO₂): 
Imagine you're in a grocery store and have 1 minute to deliver as many apples as you can from the produce display to the cashier, using either baskets or carrying them in your hands... 
Apples = O₂
Total apples delivered = DO₂
Number of baskets = Hemoglobin (Hb) concentration
How full each basket is w/ apples = Hb O₂ saturation
How quickly you can go back and forth delivering apples = Cardiac output (CO)
The apples you carry in your hands = PaO₂

- Avraham Z. Cooper, MD @AvrahamCooperMD

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