Given the following data, calculate a patient's tissue O2 delivery. SaO2: 95% PaO2 90 mm Hg [Hb]: 14 g% C.O.: 4.5 liters/minute

Question

A. 530 ml O2/minute
B. 580 ml O2/minute
C. 701 ml O2/minute
D. 810 ml O2/minute

Answer 1

?ANS: D
A. Incorrect response: See explanation D.
B. Incorrect response: See explanation D.
C. Incorrect response: See explanation D.
D. Correct response: The calculation of the tissue O2 delivery (DO2) is as follows:
STEP 1: Determine the arterial O2 content.
Arterial O2 content = (SaO2 ? [Hb] ? 1.34 ml O2/g Hb) + (PaO2 ? 0.003 vol%/mm Hg)
= (0.95)(14 g Hb/100 ml blood)(1.34 ml O2/g Hb) + (90 mm Hg ? 0.003 vol%/mm Hg)
= 18.09 volumes %
= 18.09 ml O2/100 ml blood
STEP 2: Express the arterial O2 content 18.09 ml O2/100 ml blood as "ml O2/ml blood."
18.09 ml O2/100 ml blood = 0.180 ml O2/ml blood
STEP 3: Calculate the DO2 using the formula below:
DO2 = (SaO2 ? [Hb] ? 1.34 ml O2/g Hb)C.O.
= (arterial O2 content)(C.O.)
= (0.180 ml O2/ml blood)(4500 ml blood/min)
= 810 ml O2/minute
Alternatively, the formula for the DO2 is:
DO2 = CaO2 ? C.O. ? 10