NEWBORN HIGH FREQUENCY VENTILATION
Category: Child Health
Abstract : High-frequency ventilation: High-frequency ventilation (HFV) may improve blood
gases because, in addition to the gas transport by convection, other mechanisms
of gas exchange may become active at high frequencies (variable velocity
profiles of gas during inspiration and exhalation, gas exchange between parallel
lung units, increased turbulence and diffusion).Extensive clinical use of the
High-frequency ventilation: High-frequency ventilation (HFV) may improve blood
gases because, in addition to the gas transport by convection, other mechanisms
of gas exchange may become active at high frequencies (variable velocity
profiles of gas during inspiration and exhalation, gas exchange between parallel
lung units, increased turbulence and diffusion).Extensive clinical use of the
various HFVs has occurred in newborns.
High-frequency positive-pressure
ventilators employ standard ventilators modified with low-compliance tubing and
connectors, thus an adequate tidal volume may be delivered despite very short
inspiratory time. High-frequency jet ventilation (HFJV) is characterized by the
delivery of gases from a high-pressure source through a small-bore injector
cannula.
The fast gas flowing out of the cannula possibly produces areas
of relative negative pressure that entrain gases from their surroundings.
High-frequency flow interruption (HFFI) also delivers small tidal volumes by
interrupting the flow of the pressure source, but in contrast to jet
ventilation, HFFI does not use an injector cannula.
High-frequency
oscillatory ventilation (HFOV) delivers very small volumes (even smaller than
dead space) at extremely high frequencies. Oscillatory ventilation is unique
because exhalation is generated actively, as opposed to other forms of HFV, in
which exhalation is passive. The largest randomized trial of HFV revealed that
early use of HFOV did not improve outcome.
However, the trend is toward
decreases in BPD, increases in severe intraventricular hemorrhage and in
periventricular leukomalacia, and small increases in air leaks with HFOV and/or
HFFI. However, if used properly, HFV is a safe alternative for infants for whom
CMV fails.
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