NBRC Critical Care and ABG Interpretation

Question 1

A patient has ABG values: pH 7.28, PaCO2 55 mmHg, HCO3 24 mEq/L. This represents:

Accepted Answer

Respiratory acidosis (uncompensated)

Answer

pH below 7.35 (acidosis) with elevated PaCO2 and normal HCO3 indicates uncompensated acute respiratory acidosis.

Question 2

A patient has ABG: pH 7.52, PaCO2 28 mmHg, HCO3 22 mEq/L. This is consistent with:

Accepted Answer

Respiratory alkalosis (uncompensated)

Answer

pH above 7.45 (alkalosis) with low PaCO2 and near-normal HCO3 indicates uncompensated acute respiratory alkalosis from hyperventilation.

Question 3

Acute hypoxemic respiratory failure is defined by a PaO2/FiO2 (P/F) ratio below:

Accepted Answer

300

Answer

A P/F ratio below 300 mmHg defines acute hypoxemic respiratory failure; values below 200 define ARDS and below 100 define severe ARDS (Berlin criteria).

Question 4

In diabetic ketoacidosis (DKA), the respiratory compensation (Kussmaul respirations) produces:

Accepted Answer

Respiratory alkalosis to compensate for metabolic acidosis

Answer

Kussmaul respirations are deep, rapid breaths that blow off CO2, lowering PaCO2 to partially compensate for the metabolic acidosis of DKA.

Question 5

The anion gap is calculated as:

Accepted Answer

Na+ – (Cl– + HCO3–)

Answer

The anion gap = Na+ – (Cl– + HCO3–); a normal anion gap is 8–12 mEq/L, and an elevated gap indicates unmeasured anions from conditions like lactic acidosis or DKA.

NBRC - National Board for Respiratory Care Practice Test

NBRC - National Board for Respiratory Care Practice Test

NBRC Critical Care and ABG Interpretation