An ABG shows pH 7.13, PaCO2 78 mmHg, PaO2 156 mmHg, HCO3- 20 mEq/L. Which acid-base disturbance is most consistent?

Enhance your readiness for the MEDNAX Neonatal Nurse Practitioner Exam. Utilize flashcards, multiple-choice questions, and detailed explanations. Equip yourself for success!

Multiple Choice

An ABG shows pH 7.13, PaCO2 78 mmHg, PaO2 156 mmHg, HCO3- 20 mEq/L. Which acid-base disturbance is most consistent?

Explanation:
High PaCO2 with an acidotic pH points to a respiratory cause of the acid–base disorder. The elevated CO2 (78 mmHg) indicates CO2 retention from hypoventilation, which drives the pH down. In pure respiratory acidosis you’d expect the bicarbonate to rise as the kidneys compensate; here the bicarbonate is only 20 mEq/L, which is lower than normal and suggests there could be a concurrent metabolic acidosis as well. Nonetheless, the dominant abnormality is the elevated CO2 causing acidemia, making respiratory acidosis the best single fit among the options. Oxygenation appears adequate (PaO2 156 mmHg), so the issue is primarily the CO2 retention rather than low oxygen.

High PaCO2 with an acidotic pH points to a respiratory cause of the acid–base disorder. The elevated CO2 (78 mmHg) indicates CO2 retention from hypoventilation, which drives the pH down. In pure respiratory acidosis you’d expect the bicarbonate to rise as the kidneys compensate; here the bicarbonate is only 20 mEq/L, which is lower than normal and suggests there could be a concurrent metabolic acidosis as well. Nonetheless, the dominant abnormality is the elevated CO2 causing acidemia, making respiratory acidosis the best single fit among the options. Oxygenation appears adequate (PaO2 156 mmHg), so the issue is primarily the CO2 retention rather than low oxygen.

More Multiple Choice Questions
Subscribe

Get the latest from Passetra

You can unsubscribe at any time. Read our privacy policy