A nurse is caring for a client who has acute kidney injury (AKI). Which of the following arterial blood gas values would the nurse expect this client to have?
A.
pH 7.49, HCO3 24, PaCO2 30
B.
pH 7.26, HCO3 24, PaCO2 46
C.
pH 7.26, HCO3 14, PaCO2 30
D.
pH 7.49, HCO3 30, PaCO2 40
The Correct Answer and Explanation is:
The correct answer is C. pH 7.26, HCO3 14, PaCO2 30.
Explanation:
Acute Kidney Injury (AKI) is a sudden loss of kidney function, which impairs the kidneys’ ability to regulate electrolytes, remove waste products, and balance acid-base status. One of the key consequences of AKI is metabolic acidosis, a condition characterized by an excess of acid in the body.
In metabolic acidosis, the pH decreases (below 7.35), indicating an acidic environment, and the bicarbonate (HCO3) level also drops (normal range: 22-26 mEq/L), as the kidneys lose their ability to effectively excrete hydrogen ions and reabsorb bicarbonate. As the body’s buffer systems attempt to compensate, the PaCO2 (partial pressure of carbon dioxide) often decreases (normal range: 35-45 mmHg) as the lungs try to eliminate excess CO2 through hyperventilation, a compensatory mechanism called respiratory compensation.
In option C, the values are:
- pH 7.26: This reflects acidosis (normal range: 7.35-7.45).
- HCO3 14: This low bicarbonate level is consistent with metabolic acidosis (normal: 22-26 mEq/L).
- PaCO2 30: This is below normal (35-45 mmHg), showing that the lungs are compensating by “blowing off” CO2 to reduce acidity.
The other options represent different acid-base imbalances:
- Option A (pH 7.49, HCO3 24, PaCO2 30): Indicates respiratory alkalosis (high pH, low CO2).
- Option B (pH 7.26, HCO3 24, PaCO2 46): Represents respiratory acidosis (high CO2, normal bicarbonate).
- Option D (pH 7.49, HCO3 30, PaCO2 40): Reflects metabolic alkalosis (high pH, high bicarbonate).
Therefore, C is the correct answer as it aligns with the expected metabolic acidosis in a client with acute kidney injury.