For CaO2, CaO2 = (Hb x 1.34 x SaO2) + (PaO2 x 0.003). If Hb = 15 g/dL, SaO2 = 0.98, PaO2 = 90 mmHg, which value is CaO2?

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Multiple Choice

For CaO2, CaO2 = (Hb x 1.34 x SaO2) + (PaO2 x 0.003). If Hb = 15 g/dL, SaO2 = 0.98, PaO2 = 90 mmHg, which value is CaO2?

CaO2 is the arterial oxygen content, which comes from two parts: oxygen bound to hemoglobin and dissolved oxygen in plasma. The bound portion is Hb × 1.34 × SaO2. With Hb = 15 g/dL and SaO2 = 0.98, that part is 15 × 1.34 × 0.98 = 19.698 mL O2/dL. The dissolved portion is PaO2 × 0.003. With PaO2 = 90 mmHg, that equals 90 × 0.003 = 0.27 mL O2/dL. Add them: 19.698 + 0.27 ≈ 19.968 mL O2/dL, about 19.97. Among the given options, the value closest to this is 19.7, so that matches the correct choice.

CaO2 is the arterial oxygen content, which comes from two parts: oxygen bound to hemoglobin and dissolved oxygen in plasma. The bound portion is Hb × 1.34 × SaO2. With Hb = 15 g/dL and SaO2 = 0.98, that part is 15 × 1.34 × 0.98 = 19.698 mL O2/dL. The dissolved portion is PaO2 × 0.003. With PaO2 = 90 mmHg, that equals 90 × 0.003 = 0.27 mL O2/dL. Add them: 19.698 + 0.27 ≈ 19.968 mL O2/dL, about 19.97. Among the given options, the value closest to this is 19.7, so that matches the correct choice.

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