Deck 13: Blood Gases, PH, and Acid-Base Balance

Question 1

What is the most probable acid/base imbalance in the patient described below?
26-year-old male presents with the following signs and symptoms:
Extreme hysteria
Hyperventilating
Pulse 110 BPM
Lab data for ABGs:
PH = 7.550
PCO₂ = 27 mmHg
HCO₃^- =27 mEq/L
PO₂ = 98 mmHg

A) Respiratory alkalosis
B) Respiratory acidosis
C) Metabolic alkalosis
D) Metabolic acidosis

Answer 1

Respiratory alkalosis

Question 2

Which of the following compensatory mechanisms is correct for a patient in respiratory acidosis?

A) Decrease respiration rate
B) Increase the movement of electrolytes such as Na⁺ and H⁺ out of the cells and into the blood while increasing K⁺ from blood into cells.
C) Decrease whole blood pCO₂
D) Decrease plasma bicarbonate concentration

Answer 2

Decrease whole blood pCO₂

Question 3

A 43-year-old female arrived at the emergency department with altered level of consciousness. She complained of chronic but moderate severity acid indigestion. This was partially relieved by taking antacids. Her blood gases results are as follows:
RESULTS:
PH 7.60
PCO₂ 38 mm Hg
HCO₃^- 40 mEq/L
This patient demonstrates:

A) Respiratory acidosis.
B) Metabolic alkalosis.
C) Respiratory alkalosis.
D) Metabolic acidosis.

Answer 3

Metabolic alkalosis.

Question 4

Which of the following represents the compensatory response of the kidney and lungs to a patient who is in metabolic acidosis?

A) The kidneys will increase bicarbonate reabsorption and the patient will begin to breathe very deeply and often gasp for air.
B) The kidneys will decrease bicarbonate reabsorption and the patient will begin to hyperventilate.
C) The kidneys will increase retention of hydrogen ions and the patient will begin to hold their breath for as long as possible.
D) The kidneys will "shut down" in an attempt to retain all electrolytes and the patient will place a bag over their face to conserve oxygen and carbon dioxide.

Question 5

A patient's blood gas results are shown below:
PH 7.32; pCO₂ = 58 mm Hg; HCO₃^- = 28 mEq/L.
These results indicate:

A) Respiratory acidosis.
B) Metabolic alkalosis.
C) Respiratory alkalosis.
D) Metabolic acidosis.

Question 6

Which of the following mechanisms is responsible for metabolic acidosis?

A) Bicarbonate deficiency
B) Diminished production of fixed acids
C) Rapid and efficient elimination of organic acids
D) Increased retention of HCO₃^-

Question 7

What is the calculated pH for a patient sample if the measured bicarbonate concentration is 22 mEq/L and the pCO₂ is 57 mmHg?

A) 6.8
B) 7.0
C) 7.2
D) 7.4

Question 8

Hypercapnia is defined as:

A) A decreased blood level of carbonic acid.
B) A decreased blood level of oxygen.
C) An elevated blood level of carbon monoxide.
D) An elevated blood level of carbon dioxide.

Question 9

The specimen of choice for measuring blood pH, pO_2, and pCO₂ is:

A) Heparinized capillary blood.
B) Heparinized arterial blood.
C) Heparinized venous blood.
D) Serum.

Question 10

Name the equation shown below.
PH = pK' + log
$\frac{\mathrm{cHCO}_{3-}^{-}}{\alpha \times \mathrm{pCO}_{2}}$

A) Anion gap transformation
B) Henderson-Hasselbalch equation
C) Isohydric shift algorithm
D) Negative log of the hydrogen ion concentration formulation

Question 11

Convert pCO₂ of 40 mmHg to the SI equivalent in kilopascals (kPa).

A) 4.33
B) 5.00
C) 5.33
D) 5333

Question 12

The reaction that allows CO₂ to move from peripheral tissue cells to plasma, then to erythrocytes and O₂ from erythrocytes to plasma, and then into peripheral tissue cells is termed:

A) Chloride momentum.
B) Isothionate shift.
C) Cytochrome P450 shift.
D) Isohydric shift.

Question 13

Which of the following is a derived blood gas parameter?

A) Actual base excess
B) pCO₂
C) pO₂
D) pH

Question 14

Which of the following materials represents the appropriate calibrator used to calibrate the pCO2 electrode?

A) A gas cylinder containing impure carbon dioxide
B) A gas cylinder containing a known amount of carbon dioxide
C) A buffer solution containing a known amount of carbon dioxide and hydrogen ions
D) A gas cylinder containing an estimated amount of carbon dioxide and oxygen

Question 15

Which of the following statements reflects the appropriate action to take after receiving an arterial blood gas specimen for analysis?

A) Dispense an aliquot of the sample into a test tube and transfer it into the blood gas analyzer.
B) Do not gently push out any bubbles or clots that may collect at the end of the syringe.
C) Gently push out any bubbles or clots that may collect at the end of the syringe.
D) Remove any cap that may be at the end of the syringe and mix sample while exposing it to air.

Question 16

Which of the following contributes the most to the serum total CO₂?

A) Carbonium ion
B) HCO₃^-
C) Dissolved carbon dioxide
D) PCO₂

Question 17

Which of the following effects result from exposure of a normal arterial blood sample to room air?

A) PO₂ decreased, PCO₂ decreased, pH decreased
B) PO₂ increased, PCO₂ decreased, pH increased
C) PO₂ decreased, PCO₂ increased, pH decreased
D) PO₂ decreased, PCO₂ decreased, pH increased

Question 18

A patient's blood gas results are as follows: pH = 7.25; dissolved CO₂ = 1.8 mEq/L; HCO₃^- = 27 mEq/L.
These results would be classified as:

A) Metabolic acidosis.
B) Metabolic alkalosis.
C) Respiratory acidosis.
D) Respiratory alkalosis.

Question 19

A patient's blood gas results are: pH= 7.48; PCO₂ = 52 mmHg; HCO₃^- = 40 mEq/L; pO₂ = 98 mmHg.
These results are consistent with which of the following?

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

Question 20

Which condition results in metabolic acidosis with severe hypokalemia and chronic alkaline urine?

A) Drug-induced acidosis
B) Renal tubular acidosis
C) Diabetic ketoacidosis
D) Acidosis caused by starvation

Question 21

Which of the following mechanisms can cause metabolic acidosis?

A) Hyperventilation
B) Accumulation of volatile acids
C) Excessive retention of dissolved CO₂
D) Bicarbonate deficiency

Question 22

A patient has the following arterial blood gas results:
PH = 6.55; pCO₂ = 26 mmHg; pO₂ = 99 mmHg; HCO₃^- = 22 mEq/L.
Which of the following is most likely to account for these results?

A) Hypokalemia
B) Hyperventilation
C) Hypoventilation
D) Improper specimen collection

Question 23

What is the blood pH when the PCO₂ is 60 mmHg and HCO₃^- is 18 mEq/L?

A) 6.99
B) 7.10
C) 7.30
D) 7.40

Question 24

What is the normal ratio of bicarbonate to dissolved CO₂ in arterial blood?

A) 1:5
B) 1:10
C) 20:1
D) 40:1

Question 25

Diffusion of gases in the body is defined as:

A) The movement of charged protein carriers through the alveoli.
B) The movement of charged, hydrophilic ions through a nonpolar lipid layer.
C) The movement of an uncharged, hydrophobic solute through a lipid bilayer.
D) The passive movement of bound ions through cell membranes that results in the active transport of gases.

Question 26

An increase in temperature will result in a change to hemoglobin-oxygen dissociation curve. This change reflects which of the following?

A) A shift in the curve to the left
B) A shift in the curve to the right
C) A downward shift in the curve
D) An upward shift in the curve