of worsening ventilation. Typically, we place
premature babies on Hz of 12babies on Hz of 8-10. - 15, and term(^)
(^) HFOV depends on achieving the optimal lung inflation with the optimal MAP.
The aim is to obtain maximal alveolar recruitment without causing over
distension. Consequences of inappropriate lung inflation are:
- Under-inflation results in elevated pulmonary vascular resistance and
higher O2 requirements. Larger changes are needed inΔP for chest
vibration, and there is an increased risk of atelectasis, collapse and loss
of lung recruitment. - Over-inflation results in hemodynamic compromise, hypotension and
hypoxia from decreased cardiac output. Higher amplitudes give rise
to less chest vibration. This has grave clinical consequences and
should be avoided under any circumstances.
HFOV: ADJUSTING THE SETTINGS
(^) HFOV decouples ventilation from oxygenation. Thus, changing ΔP to alter
ventilation has little effect on oxygenation. Likewise, changing the MAP to alter
oxygenation has little effect on ventilation.
Oxygenation (MAP)
To improve oxygenation, increase the MAP and/or the FiO2.
- Be careful... sometimes if an infant is deteriorating, they may need
less MAP rather than more as cardiac output is compromised by
increasing pressure in the chest.