Question 1

What is the most common clinical condition associated with respiratory acidosis?&#10;A) Pneumonia&#10;B) ARDS&#10;C) Asthma&#10;D) COPD&#10;

Accepted Answer

Chronic obstructive pulmonary disease (COPD) is the most common cause of respiratory acidosis.

Question 2

When has full acid-base compensation occurred? A) When PaCO₂ and HCO₃^- go in opposite directions B) When PaCO₂ and HCO₃^-go in the same direction C) When pH remains on the alkaline or acid side close to the normal range D) When pH is restored to the normal range

Accepted Answer

If the pH has been restored to the normal range (7.35 to 7.45), full compensation has occurred even though pH remains on the acid or alkaline side of the range.

Question 3

Which of the following is the most common cause of iatrogenic respiratory alkalosis?&#10;A) Oxygen therapy&#10;B) Pulmonary hygiene&#10;C) Mechanical ventilation&#10;D) Bronchodilation therapy&#10;

Accepted Answer

Hyperventilation and respiratory alkalosis may be iatrogenically (via medical treatment) induced. Such hyperventilation is most commonly associated with overly aggressive mechanical ventilation and may also be associated with aggressive deep breathing and lung-expanding respiratory therapy procedures.

Question 4

What is the interpretation of a blood gas that shows a pH of 7.44, a PaCO₂ of 50 mm Hg, a PaCO₂ of 48 mm Hg, and an [HCO₃^-] of 33 mEq/L in a patient with advanced COPD? A) Uncompensated respiratory acidosis B) Partially compensated respiratory alkalosis C) Compensated metabolic alkalosis D) Acute hyperventilation superimposed on chronic respiratory acidosis

Accepted Answer

A patient with advanced but stable COPD and compensated respiratory acidosis may exhibit the following arterial blood gas values: pH = 7.38 PaCO₂ = 58 mm Hg HCO₃^- = 33 mEq/L Note that the HCO₃- level is high due to renal compensatory activity. If the person now experiences an acute exacerbation of his disease and becomes severely hypoxic, this may stimulate the peripheral chemoreceptors enough to increase alveolar ventilation and acutely lower the PaCO? despite the patient's disturbed lung mechanics. In this case, let us assume that the patient was not capable of hyperventilating enough to lower the PaCO₂ all the way down into the normal range. Even though the PaCO₂ is still above normal, the acute lowering of the PaCO₂coupled with the preexisting high compensatory level of HCO₃^- causes the pH to swing from the acidic to the alkalotic side of normal: pH = 7.44 PaCO₂ = 50 mm Hg HCO₃^- = 33 mEq/L If one were to pay attention only to the blood gas data and apply the strict criteria for interpretation, this would lead to the completely incorrect interpretation of compensated metabolic alkalosis. This interpretation would lead the novice to conclude that the patient is hypoventilating to compensate for a preexisting primary metabolic alkalosis; in light of the patient's medical history, this would be an absurd conclusion. This example illustrates the fact that blood gas data alone are not a sufficient basis for rational acid-base assessment. The patient's medical history, the physical examination, and the nature of the current problem are vital in accurately evaluating blood gas abnormalities. The blood gases here are correctly described as acute hyperventilation superimposed on compensated respiratory acidosis.

Question 5

Which of the following are effects of a rapidly rising PaCO₂?
I.Increased intracranial pressure
II.Myoclonus
III.Mental confusion
IV.Cerebral vasoconstriction

A) I, II, III
B) III, IV
C) I, II, III, IV
D) II, III

Accepted Answer

Rapidly rising PaCO₂ causes cerebral vasodilation and increased intracranial pressure, possibly leading to retinal venous distension and retinal hemorrhage. In addition, the patient may develop myoclonus (spasmodic muscle jerks), asterixis (a hand-flapping tremor in which the patient cannot keep the wrists flexed with the arms extended), and mental confusion.

Question 6

Which acute level of PaCO₂ can lead to coma in patients without chronic hypercapnia? A) >45 mm Hg B) >55 mm Hg C) >60 mm Hg D) >70 mm Hg

Accepted Answer

Abrupt hypercapnia above a PaCO₂ of 70 mm Hg can lead to coma, although patients with chronic hypercapnia can tolerate much higher levels.

Question 7

Which of the following is the primary disturbance associated with the following blood gas: pH is 7.36, PaCO₃ is 80 mm Hg, and HCO₃^- is 44 mEq/L? A) Respiratory B) Metabolic C) Combined D) No disturbance is present.

Accepted Answer

The primary disturbance is of respiratory origin, and the increased [HCO₃^-] is a secondary metabolic compensatory response.

Question 8

What is the most common cause of hyperventilation in patients with pulmonary disease?&#10;A) Acidosis&#10;B) Hypercapnia&#10;C) Hypoxemia-induced respiratory alkalosis&#10;D) Hypercapnia not refractory to oxygen therapy&#10;

Accepted Answer

Probably the most common cause of hyperventilation in patients with pulmonary disease is arterial hypoxemia, mediated through the peripheral chemoreceptors.

Question 9

What is the interpretation of the following blood gas reading: pH is 7.15, PaCO₂ is 80 mm Hg, and HCO₃^- is 26 mEq/L? A) Uncompensated respiratory acidosis B) Uncompensated metabolic acidosis C) Uncompensated metabolic alkalosis D) Uncompensated respiratory alkalosis

Accepted Answer

If the pH is 7.15, the PaCO₂ is 80 mm Hg, and the HCO₃^- is 26 mEq/L, no compensation has occurred; that is, the HCO₃^- is still normal, and not high as would be expected if compensatory action were underway.

Question 10

Following a rise in PaCO₂, when is full renal compensation for respiratory acidosis expected to occur? A) Immediately B) In a few minutes C) Over the next 12 hours D) Several days

Accepted Answer

Renal (kidney) compensation for respiratory acidosis begins as soon as PaCO₂ rises. The kidney reclaims HCO₃^- from the renal tubular filtrate, returning it to the blood. This brings the arterial pH into the normal range because the [HCO₃]-dissolved carbon dioxide ratio is restored near its normal 20:1 range. This process cannot keep pace with an acutely rising PaCO₂, however. Full compensation may take several days.

Question 11

Which of the following are causes of hypoxia-induced respiratory alkalosis?
I.High altitude
II.Asthma
III.Pneumonia
IV.Pulmonary edema

A) I, II
B) III, IV
C) I, II, III, IV
D) II, III

Accepted Answer

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Question 12

When does renal compensation begin? A) As soon as PaCO₂ rises B) Within a few minutes after PaCO₂ rises C) Over the next 12 hours after PaCO₂ rises D) Several days after PaCO₂ rises

Accepted Answer

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Question 13

When has partial acid-base compensation occurred? A) When PaCO₂ and HCO₃^- go in opposite directions B) When PaCO₂ and HCO₃- go in the same direction C) When pH is within the normal range D) When the noncausative component (either PaCO₂ or HCO₃^-) is also abnormal in a way that brings the pH back toward the normal range

Accepted Answer

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Question 14

Which of the following are common causes of hypoventilation and respiratory acidosis?
I.Central nervous system depression
II.Extreme obesity
III.Neuromuscular disorders
IV.Pulmonary fibrosis

A) I, II, III
B) III, IV
C) I, II, III, IV
D) II, III

Accepted Answer

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Question 15

Which of the following is an early sign of respiratory alkalosis?&#10;A) Headache&#10;B) Blurred vision&#10;C) Nausea&#10;D) Paresthesia&#10;

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Question 16

Which of the following are associated with hypocapnic cerebral vasoconstriction?
I.Light-headedness
II.Dizziness
III.Tinnitus
IV.Syncope

A) I, II, IV
B) III, IV
C) I, II, III, IV
D) II, III

Accepted Answer

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Question 17

Which of the following laboratory values is typically ignored in the calculation of the anion gap? A) Na+ B) K+ C) Cl- D) HCO₃-

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Question 18

What is the interpretation of a blood gas that shows a low PaCO₂, a low [HCO₃^-], and an alkaline pH? A) Uncompensated respiratory acidosis B) Partially compensated respiratory alkalosis C) Uncompensated metabolic alkalosis D) Partially compensated metabolic alkalosis

Accepted Answer

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Question 19

What is the interpretation of the following blood gas information: pH is 7.36, PaCO₂ is 80 mm Hg, and HCO₃^- is 44 mEq/L? A) Compensated respiratory acidosis B) Compensated metabolic acidosis C) Compensated metabolic alkalosis D) Compensated respiratory alkalosis

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Question 20

What is the interpretation of a blood gas that shows a high PaCO₂, a high [HCO₃^-], and an acid pH not quite in the normal range? A) Uncompensated respiratory acidosis B) Partially compensated respiratory acidosis C) Uncompensated metabolic alkalosis D) Partially compensated metabolic alkalosis

Accepted Answer

The answer of What is the interpretation of a blood...

Question 21

What is the interpretation of a blood gas that shows a pH of 7.10, a PaCO₂ of 50 mm Hg, and an [HCO₃-] of 15 mEq/L? A) Uncompensated respiratory acidosis B) Partially compensated respiratory alkalosis C) Compensated metabolic alkalosis D) Combined respiratory and metabolic acidosis

Accepted Answer

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Question 22

Which of the following acid-base disturbances is associated with the presence of vomiting or with continuous nasogastric suctioning?&#10;A) Mixed metabolic and respiratory alkalosis&#10;B) Mixed metabolic and respiratory acidosis&#10;C) Metabolic acidosis&#10;D) Metabolic alkalosis&#10;

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The answer of Which of the following acid-base disturbances is...

Question 23

Which of the following are categories of tissue hypoxia?&#10;I.Hypoxic&#10;II.Anemic&#10;III.Stagnant&#10;IV.Histotoxic&#10;A) I, II, IV&#10;B) III, IV&#10;C) I, II, III, IV&#10;D) II, III&#10;

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Question 24

On average, how much does the PaCO₂ rise for every 1 mEq/L increase in the plasma [HCO₃-]? A)0.2 mm Hg B)0.5 mm Hg C)0.7 mm Hg D)1.0 mm Hg

Accepted Answer

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Question 25

At which of the following pH levels are most serious cardiac arrhythmias less likely?&#10;A) Below 7.3&#10;B) Below 7.2&#10;C) Below 7.1&#10;D) Below 7.0&#10;

Accepted Answer

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Question 26

How much should the PaO₂ rise for every 10% increase in FIO₂? A) 40 mm Hg B) 50 mm Hg C) 60 mm Hg D) 70 mm Hg

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Question 27

Which of the following conditions is associated with Kussmaul's respiration?&#10;A) Diabetic ketoacidosis&#10;B) CO poisoning&#10;C) Congestive heart failure&#10;D) ARDS&#10;

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Question 28

Which of the following laboratory values is used as an indicator of tissue hypoxia?&#10;A) Glucose&#10;B) pH&#10;C) Tumor necrosis factor&#10;D) Lactate&#10;

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Question 29

Which of the following conditions may limit compensatory hypoventilation for metabolic alkalosis?
I.Anxiety
II.Pain
III.Infection
IV.Fever

A) I, II
B) I, III, IV
C) II, IV
D) I, II, III, IV

Accepted Answer

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Question 30

What is the tissues' resting oxygen consumption?&#10;A) 10% of the oxygen delivered to them&#10;B) 15% of the oxygen delivered to them&#10;C) 20% of the oxygen delivered to them&#10;D) 25% of the oxygen delivered to them&#10;

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Question 31

Which of the following conditions makes metabolic alkalosis the most complicated acid-base imbalance to treat in acutely ill patients?&#10;A) Hyperglycemia&#10;B) Liver disease&#10;C) Fluid and electrolyte imbalances&#10;D) Hypoglycemia&#10;

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Question 32

What is the normal range for the anion gap?&#10;A) 4 to 8 mEq/L&#10;B) 8 to 16 mEq/L&#10;C) 16 to 24 mEq/L&#10;D) 24 to 32 mEq/L&#10;

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Question 33

If Hb and cardiac output are normal, PaO₂ must acutely decrease to which of the following levels before clinical manifestations appear? A) 71 to 80 mm Hg B) 61 to 70 mm Hg C) 50 to 60 mm Hg D) 40 to 49 mm Hg

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Question 34

What will be the expected pH if the PaCO₂ is 50 mm Hg in the presence of a normal metabolic status? A)7.0 B)7.24 C)7.30 D)7.34

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Question 35

Which of the following should be the focus of evaluating oxygenation? A) PaO₂ levels B) PaCO₂ corresponding changes C) Oxygen delivery to the tissues D) FIO₂

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Question 36

Which of the following therapies is considered the best treatment for carbon monoxide poisoning?&#10;A) 100% inspired oxygen&#10;B) 50% inspired oxygen&#10;C) Hyperbaric oxygen&#10;D) Positive pressure ventilation&#10;

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Question 37

Which of the following therapies is considered a response to chronic hypoxemia?&#10;A) Increased cardiac output&#10;B) Increased perfusion&#10;C) Tachycardia&#10;D) Increased red blood cell production&#10;

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Deck 13: Clinical Assessment of Acid-Base and Oxygenation Status