Respiratory Therapy – Formulas Practice Test

CaO2 calculation given Hb 14 g/dL, SaO2 98%, PaO2 95 mmHg yields CaO2 approximately how many mL/dL?

17.5 mL/dL 19.2 mL/dL 18.69 mL/dL 18.0 mL/dL

Correct Answer:

18.69 mL/dL

Explanation:

Oxygen content in arterial blood comes from two sources: oxygen bound to hemoglobin and dissolved oxygen in plasma. The amount bound to Hb is Hb × 1.34 × SaO2 (with SaO2 as a decimal), and the dissolved portion is PaO2 × 0.003. Add them to get CaO2. Compute the bound portion: 14 g/dL × 1.34 × 0.98 ≈ 18.38 mL/dL. Compute the dissolved portion: 95 mmHg × 0.003 ≈ 0.285 mL/dL. Sum: 18.38 + 0.285 ≈ 18.67 mL/dL, which rounds to about 18.69 mL/dL. So the arterial oxygen content is approximately 18.7 mL/dL.

Access more questions from this quiz

Continue to Respiratory Therapy – Formulas Practice Test for more practice questions and the full quiz experience.

Access More Questions