Arterial Oxygen Content Study Guide is a series of multiple choice question designed to solve for every possible variable in the calculation.

  • The arterial oxygen content (CaO2) definition is the amount of oxygen bound to hemoglobin (1.34 * Hb * SaO2) plus the oxygen dissolved in plasma (0.0031 * PaO2).
  • The arterial oxygen content equation: CaO2 = (1.34 * Hb * SaO2) + (0.0031 * PaO2).
  • The normal oxygen combining capacity is 1.39 mls/gram, however due to abnormal forms of hemoglobin such as carboxyhemoglobin and methemoglobin this value is reduced to 1.34 mls/gram.
  • Hgb is Hemoglobin, the normal Hgb for males is 14-20 g/dl and females 12-15 g/dl. Hgb expressed as g/dl is equivalent to g Hgb/100 mL of Blood.
  • 0.0031 is the solubility coefficient of oxygen at body temperature.
  • Note: “vol%” is equivalent for “ml O_2/100 ml blood”.

1. Given the following Hgb = 17g Hgb/100 ml blood,  SaO2=90%, PaO2= 100 mmHg. Calculate Arterial Oxygen Content (CaO2).

A. 15.15 vol%
B. 20.81 vol% 
C. 20.5 vol%
D. 11.35 vol%

Answer: B.

2. Given the following,  SaO2 = 92%, PaO2 = 90 mmHg, and  CaO2 = 19.80 Vol%. What is Hgb?

A. 17.23 g Hgb/100ml Blood
B. 15.87 g Hgb/100ml Blood
C. 20.85 g Hgb/100ml Blood
D. 21.37 g Hgb/100ml Blood

Answer: B. 

3. Given the following,  Hgb =17 g Hgb/100ml Blood, PaO2 = 100 mmHg, and  CaO2 = 16.80 Vol%. Calculate SaO2.

A. SaO2 = 62%
B. SaO2 = 72%
C. SaO2 = 82%
D. SaO2 = 92%

Answer: B.

4. Given the following, Hgb = 19 g Hgb/100ml Blood, SaO2 = 95 mmHg, and  CaO2 = 16.80 Vol%. Calculate PaO2?

A. 93.87 mmHg
B. 88.47 mmHg
C. 72.88 mmHg
D. 83.87 mmHg

Answer: D.

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