Questions: An infant receives high frequency ventilation at a rate of 150 breaths / min and an F1O2 of 0.50 following diaphragmatic hernia repair. The following arterial blood gases are recorded: pH: 7.30 PaCO2: 60 torr PaO2: 60 torr HCO3: 21 mEq / L The respiratory therapist should increase the A. Inspiratory time. B. Drive pressure. C. Frequency. D. F1O2.

The answer is B: O drive pressure.

Explanation for each option:

A. O inspiratory time: Increasing the inspiratory time might improve oxygenation but is not the primary intervention needed to address the elevated PaCO₂ (60 torr) and the resulting respiratory acidosis (pH 7.30).

B. O drive pressure: Increasing the drive pressure will enhance ventilation by increasing tidal volume, which can help reduce the elevated PaCO₂ and improve the pH. This is the most appropriate intervention to address the respiratory acidosis.

C. O frequency: Increasing the frequency might not effectively reduce PaCO₂ in high-frequency ventilation, as it could lead to inadequate time for exhalation, potentially worsening CO₂ retention.

D. O F₁O₂: Increasing the F₁O₂ would address hypoxemia if it were present, but the PaO₂ is 60 torr, which is not critically low. The primary issue here is the elevated PaCO₂ and respiratory acidosis, not hypoxemia.

In summary, the most appropriate action to address the elevated PaCO₂ and respiratory acidosis is to increase the drive pressure.