Deck 6: Blood Gases and Related Tests

Question 1

A patient has the following blood gas results performed on room air: These results are best described as:

A) Respiratory alkalosis
B) Metabolic alkalosis
C) Normal
D) Physiologically impossible

Answer 1

D

Question 2

A patient has the following blood gas results reported: What is this patient's calculated oxygen content (CaO₂)?

A) 12.5 ml/dl
B) 12.8 ml/dl
C) 13.4 ml/dl
D) 13.7 ml/dl

Answer 2

B

Question 3

A subject who displays the signs and symptoms of severe hypoxemia has the following blood gases: Which of the following best describes these findings?

A) The subject has metabolic alkalosis.
B) The subject has a decreased CaO_2.
C) The PO₂ measurement is erroneous.
D) The dissolved O₂ content is extremely low.

Answer 3

B

Question 4

A patient is connected to a 12-lead ECG monitor and pulse oximeter before an exercise test.The HR displayed by the ECG monitor is 97;the pulse oximeter reads an HR of 141 with an SpO₂ of 85%.Which of the following would be the most appropriate action?

A) Move the pulse oximeter sensor to an alternate site.
B) Check all ECG lead wires for a good connection.
C) Obtain an arterial blood gas sample as quickly as possible.
D) Document the readings and proceed with the test.

Question 5

Measurement of oxygen saturation by pulse oximetry may produce an erroneous reading in the presence of:

A) Increased concentration of Hb
B) Shivering
C) Metabolic acidosis
D) Respiratory alkalosis

Question 6

What is the C(a - )O₂ in a patient with the following arterial and mixed venous blood gases?

A) 3.01 vol%
B) 3.92 vol%
C) 4.55 vol%
D) 5.11 vol%

Question 7

A 50-year-old subject has the following arterial blood gases: These results are best described as:

A) Normal acid-base and oxygenation status
B) Compensated metabolic alkalosis,moderate hypoxemia
C) Normal acid-base status with mild hypoxemia
D) Compensated respiratory acidosis with moderate hypoxemia

Question 8

If a patient has a fever of 40° C,the pH,as measured by an automated blood gas analyzer,will be which of the following?

A) Higher than measured at 37° C
B) Lower than measured at 37° C
C) Unchanged with temperature correction
D) Dependent on the corrected PO₂

Question 9

A blood gas syringe is prepared using liquid heparin.A volume of 0.5 ml of heparin solution is left in the syringe,and a 1.5-ml specimen is obtained.Which of the following problems will occur with this specimen?

A) The pH will be more acidotic than expected.
B) The PCO₂ will be lower because of dilution.
C) The PO₂ will be greater than 150 mm Hg.
D) Calculated HCO₃^- will be higher because of changes in PCO₂.

Question 10

When the pH falls from 7.40 to 7.10,with no change in the PCO_{2 ,}the concentration of H⁺ has:

A) Decreased by half
B) Increased twofold
C) Changed by 0.3 mEq/L
D) Decreased to 45 mEq/L

Question 11

A 67-year-old patient complaining of shortness of breath has the following blood gases obtained on an F_IO₂ of 0.21: Which of the following best describes the acid-base status of this patient?

A) Mild hypoxemia
B) Respiratory acidosis with hypoxemia
C) Compensated respiratory acidosis with mild hypoxemia
D) Partially compensated respiratory alkalosis

Question 12

Before drawing a specimen for blood gas analysis from the radial artery,the modified Allen's test should be performed.Collateral circulation is adequate if the hand is reperfused within _____ seconds.

A) 1 to 2
B) 10
C) 30 to 40
D) Less than 60

Question 13

A patient with a pulmonary artery (Swan-Ganz)catheter in place has the following blood gas results while breathing 100% O₂ at a barometric pressure of 750 mm Hg: What is the approximate percentage of shunt in this subject?

A) 6%
B) 8%
C) 13%
D) 16%

Question 14

The following serial blood gases are obtained from the same patient breathing room air: Which of the following best explains these results?

A) The subject was hyperventilating.
B) Supplementary O₂ was started on the subject between blood gases.
C) The second sample was contaminated with heparin solution.
D) The first sample contained air bubbles.

Question 15

A subject referred for shortness of breath has the following arterial blood gas test results: Which of the following best describes these?

A) Normal acid-base and oxygenation status
B) Respiratory alkalosis with moderate hypoxemia
C) Uncompensated respiratory acidosis with mild hypoxemia
D) Partially compensated metabolic alkalosis with moderate hypoxemia

Question 16

Carbon monoxide interferes with O₂ transport by:

A) Oxidizing the iron atoms in the Hb molecule
B) Shifting the O₂Hb dissociation curve to the right
C) Competing for O₂ binding sites on the Hb molecule
D) Reducing the solubility of O₂ in the plasma

Question 17

A patient is referred for arterial blood gas testing.She has an SpO₂ of 84% by pulse oximetry,but blood oximetry reveals an SaO₂ of 94%.Which of the following best explains the difference between results?

A) The patient may be severely anemic (Hb less than 8 g/dl).
B) The patient may have respiratory alkalosis (hyperventilation).
C) The patient may have an elevated COHb level.
D) The pulse oximeter reading may have been in error.

Question 18

An outpatient is referred for a shunt study.After 25 minutes of breathing 100% O₂,the patient produces the following arterial blood gas values: If the barometric pressure is 750 and a content difference of 4.5 vol% is assumed,what is this subject's shunt?

A) 20%
B) 22%
C) 24%
D) 25%

Question 19

A patient complaining of shortness of breath has the following blood gases obtained on an F_IO₂ of 0.21: Which of the following best describes the acid-base status of this patient?

A) Metabolic acidosis
B) Respiratory acidosis
C) Compensated metabolic alkalosis
D) Partially compensated respiratory alkalosis

Question 20

How should an infrared analyzer used for capnography be calibrated?

A) Using 5% CO₂ and room air
B) Using 5% CO₂ and 15% O₂
C) Using 10% CO₂ and 16% O₂
D) With 100% CO₂

Question 21

What are the most common wavelengths of light used in pulse oximetry?

A) 600 nm and 760 nm
B) 660 nm and 760 nm
C) 660 nm and 940 nm
D) 600 nm and 940 nm

Question 22

A patient complaining of shortness of breath has the following blood gases obtained on an F_IO₂ of 0.21: Which of the following best describes the acid-base status of this patient?

A) Respiratory alkalosis
B) Moderate hypoxemia
C) Compensated respiratory alkalosis with hypoxemia
D) Compensated metabolic acidosis with hypoxemia

Question 23

A 28-year-old lethargic female is admitted to the emergency department and has the following blood gases obtained on an F_IO₂ of 0.21: Which of the following best describes the acid-base status of this patient?

A) Metabolic acidosis
B) Respiratory acidosis
C) Compensated metabolic alkalosis
D) Partially compensated respiratory acidosis

Question 24

A 47-year-old female patient admitted to the emergency department after 5 days of flulike symptoms had the following blood gases obtained on an F_IO₂ of 0.21: Which of the following best describes the acid-base status of this patient?

A) Metabolic alkalosis
B) Respiratory acidosis
C) Compensated metabolic alkalosis
D) Partially compensated respiratory alkalosis

Question 25

A 40-year-old female patient was admitted to the emergency department with shortness of breath and had the following blood gases obtained on an F_IO₂ of 0.21: Which of the following best describes the acid-base status of this patient?

A) Metabolic alkalosis
B) Respiratory acidosis
C) Acute respiratory alkalosis
D) Partially compensated respiratory alkalosis

Question 26

A 55-year-old male with a history of diabetes complaining of shortness of breath has the following blood gases obtained on an F_IO₂ of 0.21: Which of the following best describes the acid-base status of this patient?

A) Compensated metabolic acidosis
B) Respiratory acidosis
C) Compensated metabolic alkalosis
D) Partially compensated metabolic acidosis

Question 27

What is the P₅₀ in the healthy adult?

A) 27 mm Hg
B) 50 mm Hg
C) 50% COHb
D) 27%

Question 28

A 66-year-old female patient was admitted to the emergency department with shortness of breath and had the following blood gases obtained on an F_IO₂ of 0.21: What is the calculated arterial content?

A) 18.6
B) 18.3
C) 17.8
D) 1.34