Comparison of High-Frequency Oscillatory Ventilators.

Area of Science:

• Biomedical Engineering
• Respiratory Physiology

Background:

• High-frequency oscillatory ventilators (HFOV) exhibit performance variations influenced by waveform generation and circuit characteristics.
• Piston-type HFOV performance is less understood compared to other models.
• This study evaluates four distinct HFOV models: Humming X, Vue (piston), VN500 (diaphragm), and SLE5000 (reverse jet).

Purpose of the Study:

• To compare the amplitude required to achieve target high-frequency tidal volume across different HFOV models.
• To determine the relationship between HFOV settings and actual delivered amplitude and mean airway pressure.
• To analyze the interaction of compliance, frequency, and endotracheal tube (ETT) diameter on HFOV performance.

Main Methods:

• Utilized a test lung with varying compliance (0.5-1.0 mL/cm H2O), frequency (12-15 Hz), and ETT inner diameters (2.0-3.5 mm).
• Assessed target high-frequency tidal volumes from 0.5 to 3.0 mL.
• Measured changes in delivered tidal volume and amplitude from ventilator to Y-piece and alveolar pressure for each HFOV model.

Main Results:

• Humming X and Vue required higher amplitude than SLE5000 to reach target tidal volumes; VN500 had limitations.
• Tidal volume and pressure decreased at the Y-piece for Humming X and Vue, but increased for SLE5000.
• VN500 showed significant tidal volume decrease at 15 Hz; amplitude decreased across all models, with a transient increase at the Y-piece for VN500.

Conclusions:

• Actual delivered alveolar volume and tidal volume vary significantly with HFOV model and ETT inner diameter, despite identical ventilator settings.
• Clinicians must individualize HFOV settings based on the specific ventilator model and patient factors like ETT size.