Volume and Pressure Delivery During Pediatric High-Frequency Oscillatory Ventilation

Area of Science:

• Pediatric critical care medicine
• Respiratory physiology
• Mechanical ventilation

Background:

• High-frequency oscillatory ventilation (HFOV) is crucial for managing pediatric respiratory failure.
• Accurate delivery of tidal volume (VT) and airway pressures are vital for lung protective strategies.
• Understanding factors influencing these parameters across different endotracheal tube sizes is essential.

Purpose of the Study:

• To identify variables independently associated with delivered tidal volume (VT) and measured mean airway pressure during HFOV.
• To analyze these associations across a range of pediatric endotracheal tube sizes.

Main Methods:

• An in vitro bench model simulating the intubated pediatric respiratory system was utilized.
• Measurements of delivered VT and mean airway pressure were obtained under various HFOV settings (mean airway pressure, amplitude, frequency) and test lung compliances.
• Multiple regression analysis was employed to model the predictors of delivered VT and mean airway pressure.

Main Results:

• Higher delivered VT was independently associated with increased amplitude (ΔP), decreased frequency, and increased lung compliance.
• A significant interaction between frequency and ΔP was observed, magnifying VT at high ΔP and low frequency.
• Delivered mean airway pressure decreased with increasing ΔP and frequency, despite ventilator settings.

Conclusions:

• This study provides the first quantification of the interaction between ΔP and frequency on delivered VT during HFOV.
• The findings underscore the importance of measuring or estimating VT and delivered pressures in HFOV.
• Results can inform optimal lung protective ventilation strategies in pediatric HFOV.