High frequency ventilation in the neonatal period.

There are three forms of high frequency ventilation, high frequency jet ventilation (HFJV, up to 400/min), high frequency oscillation (HFO, up to 40 Hz), and high frequency positive pressure ventilation (HFPPV, rates between 60 and 150/min). The first two forms of ventilation are still experimental and have been used only in critically ill children where respiratory failure has been unresponsive to more conventional therapy. Unfortunately, however, HFJV has already been associated with a high incidence of tracheal lesions. High-frequency positive pressure ventilation, on the other hand, using conventional ventilators, has been used and studied widely. Certain neonatal ventilators function suboptimally at increased rates, resulting in a reduction in tidal exchange with a consequent clinical deterioration. Using appropriate ventilators, arterial oxygen tensions improve and carbon dioxide tensions are reduced at fast rates in non-paralysed infants. Air-trapping, however, may be a problem in infants paralysed and ventilated at fast rates. HFPPV have been associated with a reduced incidence of pneumothoraces, but there is no knowledge of the effect of this form of ventilation on subsequent lung growth.