Using Hb 12 g/dL, SaO2 95%, CO 6 L/min, PaO2 100 mmHg, arterial oxygen delivery (DO2) is approximately how many mL/min?

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Multiple Choice

Using Hb 12 g/dL, SaO2 95%, CO 6 L/min, PaO2 100 mmHg, arterial oxygen delivery (DO2) is approximately how many mL/min?

DO2 is the amount of oxygen delivered to the tissues each minute, and it comes from how much oxygen is carried in arterial blood and how much blood is flowing. The arterial oxygen content CaO2 takes into account both oxygen bound to hemoglobin and dissolved oxygen in plasma: CaO2 = (Hb × 1.34 × SaO2) + (PaO2 × 0.003). Compute CaO2: with Hb = 12 g/dL, SaO2 = 0.95, PaO2 = 100 mmHg, - bound O2: 12 × 1.34 × 0.95 ≈ 15.28 mL O2/dL - dissolved O2: 100 × 0.003 = 0.30 mL O2/dL - CaO2 ≈ 15.58 mL O2/dL DO2 = CO × CaO2 × 10 (convert liters to deciliters). With CO = 6 L/min (60 dL/min): DO2 ≈ 60 × 15.58 ≈ 936 mL/min, about 0.94 L/min. So arterial oxygen delivery is roughly 0.93–0.94 L/min. If you omit the conversion from liters to deciliters, you’d get about 93 mL/min, which is a common pitfall.

DO2 is the amount of oxygen delivered to the tissues each minute, and it comes from how much oxygen is carried in arterial blood and how much blood is flowing. The arterial oxygen content CaO2 takes into account both oxygen bound to hemoglobin and dissolved oxygen in plasma: CaO2 = (Hb × 1.34 × SaO2) + (PaO2 × 0.003).

Compute CaO2: with Hb = 12 g/dL, SaO2 = 0.95, PaO2 = 100 mmHg,

  • bound O2: 12 × 1.34 × 0.95 ≈ 15.28 mL O2/dL

  • dissolved O2: 100 × 0.003 = 0.30 mL O2/dL

  • CaO2 ≈ 15.58 mL O2/dL

DO2 = CO × CaO2 × 10 (convert liters to deciliters). With CO = 6 L/min (60 dL/min):

DO2 ≈ 60 × 15.58 ≈ 936 mL/min, about 0.94 L/min.

So arterial oxygen delivery is roughly 0.93–0.94 L/min. If you omit the conversion from liters to deciliters, you’d get about 93 mL/min, which is a common pitfall.

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