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Difficulty: EasyPhysiological Adaptation

A client's recent arterial blood gas (ABG) results are as follows: pH=7.51\text{pH} = 7.51, PaCO2=42 mm Hg\text{PaCO}_2 = 42 \text{ mm Hg}, and HCO3−=33 mEq/L\text{HCO}_3^- = 33 \text{ mEq/L}. Which of the following underlying conditions or treatments are most likely responsible for this acid-base imbalance? Select all that apply.

  1. Prolonged nasogastric tube suctioningAnswer
  2. Persistent, severe vomitingAnswer
  3. C
    Frequent, severe episodes of diarrhea
  4. D
    Hyperventilation due to an acute panic attack

Answer

Prolonged nasogastric tube suctioning and persistent, severe vomiting.
The provided ABG values demonstrate an elevated pH\text{pH} (>7.45> 7.45) and an elevated bicarbonate (HCO3−\text{HCO}_3^- >26 mEq/L> 26 \text{ mEq/L}) with a normal carbon dioxide level (PaCO2\text{PaCO}_2 35−45 mm Hg35-45 \text{ mm Hg}). This profile defines uncompensated metabolic alkalosis. Metabolic alkalosis is typically caused by a significant loss of body acid or an accumulation of bicarbonate. Prolonged nasogastric suctioning and persistent vomiting deplete the body of hydrochloric acid from the stomach. Therefore, these two conditions correctly explain the ABG findings.

Step-by-Step Solution

1
Analyze the arterial blood gas (ABG) values.
The pH\text{pH} is 7.517.51 (alkalosis), PaCO2\text{PaCO}_2 is 42 mm Hg42 \text{ mm Hg} (normal), and HCO3−\text{HCO}_3^- is 33 mEq/L33 \text{ mEq/L} (elevated).
Determining the primary acid-base imbalance is necessary to identify the potential underlying causes.
2
Interpret the specific type of acid-base imbalance.
The elevated pH\text{pH} and elevated HCO3−\text{HCO}_3^- with a normal PaCO2\text{PaCO}_2 indicate uncompensated metabolic alkalosis.
Matching the ABG interpretation to clinical scenarios is the core requirement of the question.
3
Evaluate each clinical scenario to see if it causes metabolic alkalosis.
Gastric suctioning and vomiting lead to significant acid loss, which directly causes metabolic alkalosis.
Confirming that the selected options physiologically result in the identified ABG imbalance ensures accuracy.

Key Concept

Metabolic Alkalosis Causes and ABG Interpretation
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Topics

Physiological Adaptation

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