Oxygen Delivery

DO₂ = CaO₂ × CO × 10

Normal: 900–1100 mL O₂/min; critical threshold: < 300 mL O₂/min

Variables

DO₂

Oxygen delivery to tissues(mL O₂/min)

Normal: 900–1100 mL/min

CaO₂

Arterial oxygen content(mL O₂/dL)

Normal: 18–20 mL/dL

Cardiac output(L/min)

Normal: 4–8 L/min

Unit conversion factor (dL/L × 100)(constant)

Normal: Always 10

What It Measures

Oxygen delivery quantifies the total amount of oxygen transported from the lungs to the systemic circulation per minute. It is the product of how much oxygen the blood carries (CaO₂) and how fast it is delivered (cardiac output). Tissues extract oxygen from this delivery to meet metabolic needs (VO₂).

When to Use

Used in hemodynamic monitoring of critically ill patients via pulmonary artery catheter or cardiac output measurement. Assess DO₂ when managing septic shock, cardiogenic shock, or ARDS to ensure tissues are receiving adequate oxygen supply.

Interactive Calculator

Arterial O₂ Content (CaO₂)(mL/dL)

Cardiac Output (CO)(L/min)

Worked Examples

Normal patient

→ 1000 mL/min

Normal oxygen delivery

Septic shock with anemia

→ 1040 mL/min

High CO compensating for low CaO₂ — borderline delivery

Clinical Significance

DO₂ can be improved by increasing Hgb (transfusion), improving SaO₂ (optimize ventilation/O₂), or increasing cardiac output (inotropes, fluids, vasopressors). Tissues require VO₂ ≈ 200–300 mL/min; the DO₂/VO₂ ratio (O₂ utilization coefficient) is normally 25%. When DO₂ falls critically, tissues shift to anaerobic metabolism → lactic acidosis.

Memory Tips

💡DO₂ = Content × Cardiac Output × 10. The '10' converts dL to L
💡3 ways to improve DO₂: transfuse (↑ CaO₂), oxygenate (↑ SaO₂), pump (↑ CO)
💡Normal DO₂ ≈ 1000 mL/min; tissues use ≈ 250 mL/min (25% extraction)

NBRC Pearls

DO₂ = CaO₂ × CO × 10; VO₂ = C(a-v)O₂ × CO × 10; Fick principle
DO₂ < 300–400 mL/min = critical O₂ delivery — anaerobic threshold crossed
In sepsis, tissues may be unable to extract O₂ even when DO₂ is adequate (O₂ utilization defect)

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What It Measures

Clinical Significance