In a volume-controlled ventilation scenario for a patient with asthma, what is the most appropriate change to address high CO2?

In a volume-controlled ventilation scenario, high levels of CO2 (hypercapnia) can indicate inadequate ventilation or the presence of a significant amount of dead space, where ventilation is occurring but no gas exchange is happening. Removing or reducing dead space can enhance the effectiveness of ventilation, as it allows more of the inhaled tidal volume to reach the alveoli for gas exchange. By addressing and reducing the dead space, the patient's effective lung capacity for gas exchange increases, which can result in a decrease in CO2 levels.

Although the other options can affect ventilation or oxygenation, they do not directly address the core issue of elevated CO2. For instance, increasing the inspiratory flow rate may enhance the rate of ventilation but does not target dead space. Increasing FIO2 focuses on increasing oxygen delivery rather than removing CO2. Increasing PEEP can help maintain alveolar recruitment, but too much PEEP can also cause over-distention of alveoli or further limit cardiac output and venous return.

By opting to remove dead space, the primary cause of ineffective ventilation can be mitigated, thereby effectively addressing the high levels of CO2 in the patient with asthma.