Medical Math Question

Question

What is the most likely value for CaO2, if the hematocrit is 30?

A. 16-20 vols%

B. 12-16 vols%

C. 8-12 vols%

D. 4-8 vols%

Answer 1

Your question is unclear. I do not see SaO2 listed or if the Hct is for a male or female as these ranges differ and are needed to calculate the CaO2 (for pneumonia patients).

CaO2 depends on SaO2 and hemoglobin (Hgb), 1 g of Hgb carries 1.36 mL of O2 (1.34mL - 1.39mL).

Oxygen (O2) content equals the oxygen combined (w/Hgb), usually, ~97%, and the O2 dissolved (in plasma), usually ~3%.

Equation:

CaO2= (Hgbx1.36) (SaO2/100) + (PaO2x0.0031)

However, your question is the volume (in percentage) for a Cao2 with a decrease in Hematocrit (Hct).

If a normal CaO2 is 16-22mL O2/dL, then the normal Hct level is 41-50% in males, and 36-48% in females. I cannot answer this question without the Hgb and SaO2 levels as Cao2 refers to the volume of oxygen delivered to the tissues per unit of blood volume.

However, if you are looking for C(aV)o2 (for seizure or athletic patients) then we still need the CaO2 value.

Equation:

C(a-v)O2= CaO2 - CvO2

= 20 vol% - 15 vol%

= 5 vol%

Normally, 5 vol%