Which parameter in HFOV serves as the secondary control for PaCO2?

The parameter that serves as the secondary control for PaCO2 in High-Frequency Oscillatory Ventilation (HFOV) is frequency set in Hertz (Hz).

In HFOV, the primary function of frequency is to increase or decrease the number of oscillations per minute, which directly influences the amount of time gas exchange occurs in the lungs. An increased frequency leads to shorter time for ventilation per breath, thereby potentially increasing the PaCO2 due to less effective gas exchange. Conversely, decreasing the frequency provides longer time for gas exchange, which can help reduce PaCO2 levels.

While other parameters like amplitude or mean airway pressure play significant roles in controlling lung mechanics and oxygenation, frequency specifically impacts ventilation rates and is thus crucial for managing CO2 levels. This makes frequency the secondary control parameter for regulating PaCO2 within the context of HFOV.