Treatment of Respiratory Failure in Newborn: Mechanical Ventilation
Premature delivery is always associated with the failure of respiratory transition and a delayed achievement of an adequate functional residual capacity. For this reason preterm babies (especially the extremely low for gestational age – ELGA – infants) frequently need respiratory support. Noninvasive ventilation (NIV) is in widespread use in the management of respiratory distress even in ELGA infants without increasing neonatal mortality or neurological impairment.
The most recent meta-analysis and reviews of NIV demonstrated that NIV is a valid alternative to mechanical ventilation (MV) in the management of respiratory failure and resulted in significant reductions in the incidence of bronchopulmonary dysplasia (BPD) among surviving infants.
Nevertheless, preterm babies, mainly ELGA infants, require MV because they have unresponsive apnea, or a high and rising PaCO2, and/or a high and rising FiO2 despite treatment with continuous positive airway pressure (CPAP).
Pressure-limited ventilation continues to be the primary mode of ventilation in neonates because of its relative simplicity and ability to ventilate effectively despite large endotracheal tube (ETT) leaks.
The major disadvantage of pressure-limited ventilation is that the tidal volume (VT) varies as the baby alters its breathing pattern and with changes in lung compliance (e.g., after surfactant therapy). The consequences of such rapid improvements in compliance are inadvertent hyperventilation and lung injury from excessively large VT (volutrauma); hyperventilation may induce hypocapnia, with high risk of cerebral damage. There is strong evidence that excessive tidal volumes, rather than the ventilator pressure, are the key determinant of ventilator-induced lung injury (VILI). Inadequate (too small) VT also causes significant problems (atelectrauma): in particular inefficient gas exchange due to increased dead space to VT ratio. Therefore, in the last few years, tidal volume-targeted ventilation has become an important standard of care in neonatal and pediatric respiratory support.
There are many volume-targeted ventilation modes used in neonatal period, but volume guarantee (VG) ventilation is the most extensively studied.
The Cochrane review on volume-targeted ventilation showed significant reductions in duration of ventilation, rates of pneumothorax (PTX), and intraventricular hemorrhage (IVH) and a borderline significant reduction in the incidence of BPD in surviving infants. Also VG ventilation plus adequate PEEP, with an open lung strategy, is an alternative to high-frequency oscillatory ventilation (HFOV) in infants ventilated for severe RDS. Nevertheless in a baby with very stiff lungs, pulmonary interstitial emphysema (PIE) or PTX, the use of HFOV still remains the best ventilator approach.
To optimize ventilatory management of infants with respiratory failure and to adjust the ventilatory settings, it is important to monitor the blood gases and perform chest X-ray. As most modern ventilators have numerical and graphical displays of ventilator parameters, these should be used to guide ventilation management and reduce the risk of lung injury.
It is important to wean babes from the ventilator and extubate them as soon as possible to reduce the risk of pulmonary infections and BPD. In many cases early caffeine administration can reduce the duration of mechanical ventilation, BPD, and the occurrence of respiratory and neurological adverse outcome. It is therefore important to have a respiratory protocol that helps the neonatologist to manage both the acute and the recovery phase of respiratory failure.
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