A 55-year-old male patient on mechanical ventilation in Volume Control mode has an arterial blood gas showing pH 7.25, PaCO2 60 mmHg, PaO2 90 mmHg, HCO3- 24 mEq/L. Which ventilator adjustment is most appropriate to correct the acidosis?

Explanation

The arterial blood gas results indicate respiratory acidosis (low pH 7.25, high PaCO2 60 mmHg) with normal bicarbonate, suggesting an acute process. To correct respiratory acidosis, the primary goal is to increase alveolar ventilation, which enhances CO2 elimination. Alveolar ventilation is the product of respiratory rate and effective tidal volume (tidal volume minus dead space). Therefore, increasing either the respiratory rate or the tidal volume will increase alveolar ventilation and decrease PaCO2. Increasing the respiratory rate is a direct and effective way to achieve this. Decreasing respiratory rate or tidal volume would worsen hypercapnia. Increasing PEEP primarily improves oxygenation by recruiting alveoli and preventing collapse, but it has a less direct and often minimal effect on CO2 elimination unless it significantly reduces dead space or improves V/Q matching.