The registered nurse reviews the result of the arterial blood gas values with the licensed practical nurse and tells the LPN that the client has respiratory acidosis. The LPN would expect to note which of the following on the laboratory result report?
A.
pH 7.50, PCO2 30 mmHg
B.
pH 7.45, PCO2 52 mmHg
C.
pH 7.25, PCO2 50 mmHg
D.
pH 7.35, PCO2 40 mmHg
The correct answer and Explanation is :
The correct answer is C. pH 7.25, PCO2 50 mmHg.
Explanation:
Respiratory acidosis occurs when there is an accumulation of carbon dioxide (CO2) in the blood due to inadequate ventilation. This condition is characterized by a decreased pH and an increased partial pressure of carbon dioxide (PCO2).
- Understanding the Values:
- pH: The normal range for arterial blood pH is approximately 7.35 to 7.45. A pH below 7.35 indicates acidosis, while a pH above 7.45 indicates alkalosis.
- PCO2: The normal range for arterial PCO2 is about 35 to 45 mmHg. An increase in PCO2 (greater than 45 mmHg) signifies respiratory acidosis.
- Analyzing the Options:
- Option A (pH 7.50, PCO2 30 mmHg): The pH is elevated (alkalosis) and PCO2 is low, indicating respiratory alkalosis, not acidosis.
- Option B (pH 7.45, PCO2 52 mmHg): The pH is within normal range, but the elevated PCO2 indicates respiratory compensation, not primary respiratory acidosis.
- Option C (pH 7.25, PCO2 50 mmHg): This shows a low pH, confirming acidosis, and the PCO2 is elevated (50 mmHg), which supports the diagnosis of respiratory acidosis.
- Option D (pH 7.35, PCO2 40 mmHg): The pH is at the lower limit of normal, and the PCO2 is normal, indicating neither acidosis nor alkalosis.
- Clinical Context:
In cases of respiratory acidosis, conditions such as chronic obstructive pulmonary disease (COPD), pneumonia, or respiratory failure can lead to CO2 retention. The body may attempt to compensate for the acidosis through renal mechanisms, but initially, the hallmark lab values will show decreased pH and increased PCO2.
In summary, Option C reflects the expected laboratory results for a patient experiencing respiratory acidosis, characterized by a low pH and elevated CO2 levels.