Ventilatory Euipment

There are different types of High frequency ventilation.Each type has its own unique advantages and disadvantages. The types of High Frquency Ventilator are characterized by the delivery system and the type of exhalation phase.

High Frequency Oscillatory Ventilation (HFOV)

High Frequency Oscillatory Ventilation is characterized by high respiratory rates up to 15 hertz (900 breaths per minute). The rates used vary widely depending upon patient type and disease condition. In HFOV the pressure vibrates around the constant distending pressure (equivalent to the PEEP). Thus gas is pushed into the lung during inspiration, and then pulled out during expiration. HFOV generates very low tidal volumes that are generally less than the dead space of the lung. Tidal volume is dependent on endotrachial tube size, power and hertz. Different mechanisms of gas transfer come into play in HFOV compared to normal mechanical ventilation. It is often used in patients who have hypoxia refractory to normal mechanical ventilation: severe ARDS, ALI and other oxygenation issues that cannot be corrected with conventional ventilation. In some neonatal patients HFOV may be used as the first-line ventilator due to the high susceptibility of the premature infant to lung injury from conventional ventilation.