NCLEX-RNReduction of Risk PotentialMedium
A client has had a nasogastric tube to continuous suction for 3 days. Arterial blood gas results are: pH 7.52, PaCO2 46 mmHg, HCO3 32 mEq/L, PaO2 90 mmHg. How should the nurse interpret these results?
- AUncompensated respiratory alkalosis
- BUncompensated metabolic acidosis
- CCompensated respiratory acidosis
- DPartially compensated metabolic alkalosis
Show answer & explanationAnswer & explanation
Correct answer: D. Partially compensated metabolic alkalosis
The pH (7.52) is elevated, indicating alkalosis. The elevated HCO3 (32, normal 22–26) confirms a metabolic cause from loss of gastric HCl via NG suction. The elevated PaCO2 (46, normal 35–45) shows the lungs are hypoventilating to retain CO2 as compensation. Because the pH remains abnormal despite compensation, this is a partially compensated metabolic alkalosis.
Why the other options are wrong
- A. Respiratory alkalosis would show a low PaCO2, not an elevated one.
- B. Metabolic acidosis would show a low pH and low HCO3, opposite of these findings.
- C. Respiratory acidosis would present with a low pH, not an elevated one.
Metabolic Alkalosis from NG Suction
Loss of gastric hydrochloric acid through NG suction or vomiting leads to metabolic alkalosis, with the lungs compensating by hypoventilating to retain CO2.
- ROME: Respiratory Opposite, Metabolic Equal
- NG suction/vomiting causes H+ loss, raising HCO3 and pH
- Partial compensation exists when pH remains abnormal despite CO2 changes
Memory trick: ROME: pH & HCO3 move together for metabolic