NCLEX Acid-Base Balance and Arterial Blood Gas Interpretation

Question 1

A client with severe vomiting for 3 days has pH 7.50, PaCO2 44 mm Hg, HCO3 33 mEq/L. Which condition does this represent?

Accepted Answer

Metabolic alkalosis

Answer

The pH is high (alkalosis) and HCO3 is high (normal 22 to 26), with a normal PaCO2. Loss of gastric hydrochloric acid through vomiting causes metabolic alkalosis.

Question 2

A client's ABG shows pH 7.30, PaCO2 56 mm Hg, HCO3 25 mEq/L. How should the nurse interpret this result?

Accepted Answer

Respiratory acidosis, uncompensated

Answer

The pH is low (acidosis), and PaCO2 is high (normal 35 to 45), which accounts for the acidosis. HCO3 is normal, so the kidneys have not compensated yet. This is uncompensated respiratory acidosis.

Question 3

Which client is most at risk for metabolic acidosis?

Accepted Answer

A client with diabetic ketoacidosis

Answer

Diabetic ketoacidosis produces ketoacids, lowering bicarbonate and pH. Hyperventilation causes respiratory alkalosis, nasogastric suction causes metabolic alkalosis, and excessive antacids can also cause metabolic alkalosis.

Question 4

A client with DKA has deep, rapid respirations (Kussmaul). What does this breathing pattern represent?

Accepted Answer

Respiratory compensation by blowing off CO2 to raise pH

Answer

Kussmaul respirations are the lungs' attempt to compensate for metabolic acidosis by exhaling carbon dioxide, which reduces carbonic acid and raises the pH.

Question 5

A client with COPD has the following ABG: pH 7.36, PaCO2 58 mm Hg, HCO3 32 mEq/L. What is the best interpretation?

Accepted Answer

Fully compensated respiratory acidosis

Answer

The pH is within normal range but at the low end (7.36), consistent with acidosis. PaCO2 is high (respiratory cause) and HCO3 is high, showing kidney compensation. This is chronic, fully compensated respiratory acidosis.

NCLEX Practice Test

NCLEX Practice Test

NCLEX Acid-Base Balance and Arterial Blood Gas Interpretation