ABG Practice Questions PDF

**Question 1** **A patient presents with the following ABG results:** - pH: 7.29 - PaCO2: 52 mmHg - HCO3⁻: 25 mEq/L What is the acid-base disturbance?\ A. Respiratory acidosis\ B. Metabolic acidosis\ C. Respiratory alkalosis\ D. Metabolic alkalosis **Answer:** A. Respiratory acidosis **...

**Question 1** **A patient presents with the following ABG results:** - pH: 7.29 - PaCO2: 52 mmHg - HCO3⁻: 25 mEq/L What is the acid-base disturbance?\ A. Respiratory acidosis\ B. Metabolic acidosis\ C. Respiratory alkalosis\ D. Metabolic alkalosis **Answer:** A. Respiratory acidosis **Rationale:** - The pH is low, indicating acidosis. - The PaCO2 is elevated, indicating hypoventilation or impaired CO2 elimination. - HCO3⁻ is normal, meaning there is no metabolic compensation. - This indicates a primary **respiratory acidosis**. **Question 2** **A patient with diabetic ketoacidosis (DKA) has the following ABG results:** - pH: 7.22 - PaCO2: 28 mmHg - HCO3⁻: 12 mEq/L What is the primary acid-base disturbance?\ A. Metabolic acidosis\ B. Respiratory acidosis\ C. Metabolic alkalosis\ D. Respiratory alkalosis **Answer:** A. Metabolic acidosis **Rationale:** - The pH is low, indicating acidosis. - The HCO3⁻ is low, indicating metabolic acidosis. - The PaCO2 is low due to respiratory compensation (hyperventilation to \"blow off\" CO2). - The primary disturbance is **metabolic acidosis** due to DKA. **Question 3** **A patient with prolonged vomiting has the following ABG results:** - pH: 7.50 - PaCO2: 47 mmHg - HCO3⁻: 34 mEq/L What is the acid-base disturbance?\ A. Respiratory acidosis with compensation\ B. Metabolic alkalosis with compensation\ C. Respiratory alkalosis\ D. Metabolic acidosis **Answer:** B. Metabolic alkalosis with compensation **Rationale:** - The pH is high, indicating alkalosis. - The HCO3⁻ is elevated, indicating metabolic alkalosis. - The PaCO2 is elevated due to hypoventilation as a compensatory mechanism to retain CO2 and lower pH. - The primary disturbance is **metabolic alkalosis with respiratory compensation**. **Question 4** **A patient with a history of COPD presents with the following ABG results:** - pH: 7.37 - PaCO2: 55 mmHg - HCO3⁻: 30 mEq/L What is the acid-base status?\ A. Respiratory acidosis with compensation\ B. Respiratory alkalosis with compensation\ C. Fully compensated respiratory acidosis\ D. Metabolic alkalosis **Answer:** C. Fully compensated respiratory acidosis **Rationale:** - The pH is normal but slightly on the acidic side (7.37). - The PaCO2 is elevated, indicating hypoventilation and a primary respiratory issue. - The HCO3⁻ is elevated, indicating metabolic compensation. - Since the pH is within normal limits, this is **fully compensated respiratory acidosis**. **Question 5** **A patient presents with the following ABG results:** - pH: 7.60 - PaCO2: 30 mmHg - HCO3⁻: 23 mEq/L What is the acid-base disturbance?\ A. Respiratory alkalosis\ B. Metabolic alkalosis\ C. Respiratory acidosis\ D. Metabolic acidosis **Answer:** A. Respiratory alkalosis **Rationale:** - The pH is high, indicating alkalosis. - The PaCO2 is low, indicating hyperventilation and excessive CO2 elimination. - HCO3⁻ is normal, indicating no metabolic compensation. - The primary disturbance is **respiratory alkalosis**. **Question 6** **A patient experiencing sepsis has the following ABG results:** - pH: 7.31 - PaCO2: 32 mmHg - HCO3⁻: 16 mEq/L What is the acid-base disturbance?\ A. Metabolic acidosis with compensation\ B. Respiratory acidosis\ C. Metabolic alkalosis with compensation\ D. Mixed acid-base disorder **Answer:** A. Metabolic acidosis with compensation **Rationale:** - The pH is low, indicating acidosis. - The HCO3⁻ is low, pointing to a metabolic cause of the acidosis. - The PaCO2 is low, showing respiratory compensation (hyperventilation). - This indicates **metabolic acidosis with respiratory compensation**. **Question 7** **A post-operative patient is hypoventilating and presents with the following ABG results:** - pH: 7.20 - PaCO2: 60 mmHg - HCO3⁻: 24 mEq/L What is the acid-base disturbance?\ A. Respiratory acidosis\ B. Metabolic acidosis\ C. Respiratory alkalosis\ D. Metabolic alkalosis **Answer:** A. Respiratory acidosis **Rationale:** - The pH is low, indicating acidosis. - The PaCO2 is high, pointing to a primary respiratory cause. - HCO3⁻ is normal, indicating no metabolic compensation. - This is **acute respiratory acidosis** caused by hypoventilation. **Question 8** **A patient has the following ABG results:** - pH: 7.45 - PaCO2: 30 mmHg - HCO3⁻: 20 mEq/L What is the acid-base status?\ A. Fully compensated metabolic acidosis\ B. Fully compensated respiratory alkalosis\ C. Uncompensated metabolic acidosis\ D. Mixed acid-base disorder **Answer:** B. Fully compensated respiratory alkalosis **Rationale:** - The pH is normal but on the alkalotic side (7.45). - The PaCO2 is low, indicating a primary respiratory issue. - The HCO3⁻ is low, showing metabolic compensation. - This indicates **fully compensated respiratory alkalosis**. **Question 9** **A patient presents with the following ABG results:** - pH: 7.10 - PaCO2: 60 mmHg - HCO3⁻: 18 mEq/L What is the acid-base disturbance?\ A. Mixed acidosis\ B. Metabolic acidosis with compensation\ C. Respiratory acidosis with compensation\ D. Metabolic alkalosis **Answer:** A. Mixed acidosis **Rationale:** - The pH is severely low, indicating acidosis. - The PaCO2 is high, indicating respiratory acidosis. - The HCO3⁻ is low, indicating metabolic acidosis. - Both respiratory and metabolic systems are contributing to the acidosis, making this a **mixed acidosis**.