Critical Care and ABG Interpretation Flashcards

The target PaCO2 during CPR for an adult patient is:

Answer: 35–45 mmHg

During CPR, ventilation should target a normal PaCO2 of 35–45 mmHg to avoid hypocapnia-induced cerebral vasoconstriction or hypercapnia-induced acidosis.

Acute cor pulmonale on the 12-lead ECG may show all of the following EXCEPT:

Answer: Peaked P waves in leads II, III, aVF (P pulmonale)

P pulmonale (peaked P waves) reflects chronic right atrial enlargement from pulmonary hypertension, not the acute ECG changes of sudden right heart strain.

Continuous renal replacement therapy (CRRT) is preferred over intermittent hemodialysis in critically ill patients primarily because it:

Answer: Causes less hemodynamic instability in hypotensive patients

CRRT removes solutes and fluid slowly and continuously, making it better tolerated hemodynamically in critically ill patients who cannot tolerate the rapid fluid shifts of intermittent hemodialysis.

Extracorporeal membrane oxygenation (ECMO) provides gas exchange support by:

Answer: Withdrawing blood, oxygenating it externally, and returning it to the patient

ECMO removes blood via cannula, passes it through an oxygenator membrane to add O2 and remove CO2, then returns oxygenated blood to the patient's circulation.

Which ventilator setting directly affects the rate of CO2 elimination?

Answer: Minute ventilation (respiratory rate × tidal volume)

CO2 elimination is directly proportional to alveolar minute ventilation; increasing respiratory rate or tidal volume increases CO2 clearance.

A patient with ARDS has a PaO2 of 55 mmHg on FiO2 of 0.8 and PEEP of 12 cmH2O. The P/F ratio is:

Answer: 69

P/F ratio = PaO2 / FiO2 = 55 / 0.8 = 68.75 ≈ 69, which falls below 100 mmHg, meeting criteria for severe ARDS.