Oxygen delivery is the total amount of oxygen the heart pumps out to the body every minute — the product of how much blood is pumped and how much oxygen each unit of blood carries.
Normal delivery (~950–1150 mL/min).
Mildly reduced.
Low — approaching the critical range.
Critically low — anaerobic metabolism likely.
Given: cardiac output 5 L/min, CaO₂ 20 mL/dL.
Delivery is cardiac output multiplied by the oxygen packed into each deciliter of arterial blood.
Tissues shift to anaerobic metabolism, lactate rises, and organ dysfunction can follow. The point where consumption starts to depend on delivery is called the critical DO₂.
Roughly 950–1150 mL/min in an adult, or about 500–600 mL/min/m² when indexed to body surface area.
Increase cardiac output (fluids, inotropes) or increase arterial oxygen content (correct anemia with transfusion, improve saturation with oxygen). Both multiply into the same equation.
Because CaO₂ depends heavily on hemoglobin. Fewer red cells means each unit of blood carries less oxygen, so total delivery falls even if the lungs are working perfectly.