High-Frequency Oscillatory Ventilation
Definition—High-frequency oscillatory ventilation (HFOV) is a rapid rate, low tidal volume form of mechanical ventilation. HFOV uses a constant distending pressure (mean airway pressure) with pressure oscillations around the mean pressure. The ventilatory rates range from 300 to 900 cycles per minute. Tidal volumes are often less than the dead space so HFOV relies on alternative mechanisms of gas exchange to promote carbon dioxide removal from the lung.
Reasons for the development of HFOV:
To improve gas exchange in patients with severe respiratory failure
To reduce ventilator-induced lung injury
Prevention of volutrauma. HFOV dramatically reduces the tidal volume needed to maintain ventilation (normocapnia). During HFOV, the lung can be held close to mean lung volume. There is minimal change in lung volume with each delivered breath. Visually, this translates to chest wall vibration that is barely perceptible. By contrast, during conventional...