Blood Gases, pH, and Buffer Systems

Question 1

The presence of dyshemoglobins will cause a calculated % SO2
result to be
falsely (elevated, decreased) and a pulse oximeter % SpO2
result to be
falsely (elevated, decreased).
a. Elevated, elevated
b. Decreased, decreased
c. Elevated, decreased
d. Decreased, elevated

Answer 1

a. Elevated, elevated

Question 2

The preferred anticoagulant for arterial blood gas measurements is _____ in
the _____ state.
a. Lithium heparin; dry
b. EDTA; dry
c. Potassium oxalate; liquid
d. Sodium citrate; dry

Answer 2

a. Lithium heparin; dry

Question 3

At a pH of 7.10, the H+ concentration is equivalent to
a. 80 nmol/L
b. 20 nmol/L
c. 40 nmol/L
d. 60 nmol/L

Answer 3

a. 80 nmol/L

Question 4

In respiratory alkalosis, the kidneys compensate by (excretion, retention) of
bicarbonate and (increased, decreased) excretion of NaH2PO4
.
a. Excretion, decreased
b. Excretion, increased
c. Retention, increased
d. Retention, decreased

Answer 4

a. Excretion, decreased

Question 5

. The normal ratio of carbonic acid to bicarbonate in arterial blood is
a. 1:20
b. 7.4:6.1
c. 0.003:1.39
d. 20:1

Answer 5

a. 1:20

Question 6

. When arterial blood from a normal patient is exposed to room air
a. pCO2 increases; pO2 decreases
b. pCO2 decreases; pO2 increases
c. pCO2 decreases; pO2 decreases
d. pCO2 increases; pO2 increases

Answer 6

a. pCO2 increases; pO2 decreases

Question 7

A patient’s arterial blood gas results are as follows: pH 7.37; pCO2, 75 mm
Hg; HCO3–, 37 mmol/L. These values are consistent with

a. Compensated respiratory acidosis
b. Compensated nonrespiratory acidosis
c. Uncompensated respiratory alkalosis
d. Uncompensated nonrespiratory alkalosis

Answer 7

a. Compensated respiratory acidosis

Question 8

A patient’s arterial blood gas results are as follows: pH 7.48; pCO2 54 mm Hg;
HCO3
– 38 mmol/L. These values are consistent with
a. Compensated nonrespiratory alkalosis
b. Compensated respiratory alkalosis
c. Uncompensated respiratory alkalosis
d. Uncompensated nonrespiratory alkalosis

Answer 8

d. Uncompensated nonrespiratory alkalosis

Question 9

In the circulatory system, bicarbonate leaves the red blood cells and enters the
plasma through an exchange mechanism with _____ to maintain
electroneutrality.
a. Chloride
b. Carbonic acid
c. Lactate
d. Sodium

Answer 9

a. Chloride

Question 10

Hypoventilation can compensate for which of the following acid–base
disorders:
a. Nonrespiratory acidosis
b. Mixed alkalosis
c. Mixed acidosis
d. Nonrespiratory alkalosis

Answer 10

d. Nonrespiratory alkalosis

Question 11

What is the oxygen binding capacity of hemoglobin in a blood sample that is
100% saturated with O2 and has a total hemoglobin value of 12 g/dL

a. 17 mL O2/dL
b. 4 mL O2/dL
c. 8 mL O2/dL
d. 34 mL O2/dL

Answer 11

a. 17 mL O2/dL

Question 12

Carbonic acid concentration in blood plasma is equivalent to
a. 0.0307 mmol/L/mm Hg times the pCO2 value in mm Hg
b. Apparent pKa of carbonic acid, 6.1, plus the pCO2 value in mm Hg
c. pCO2 value in mm Hg plus HCO3
– value in mm Hg
d. Bicarbonate concentration divided by the pCO2 value in mm Hg

Answer 12

a. 0.0307 mmol/L/mm Hg times the pCO2 value in mm Hg

Question 13

Oxygen content in blood reflects
a. pO2 value
b. O2Hb only
c. O2 dissolved in blood plasma only
d. The patient’s total hemoglobin value
e. All of these

Answer 13

e. All of these