Nasal HFOV vs Nasal CPAP: Effects on Gas Exchange for the Treatment of Neonates Recovering From Respiratory Distress Syndrome. A Multicenter Randomized Controlled Trial

Background - Extremely low birth weight (ELBW) infants usually develop respiratory distress syndrome (RDS), due to lung immaturity, surfactant deficiency and immature respiratory control mechanisms (1). Even though mechanical ventilation is frequently lifesaving, complications are common (2). Tracheal intubation and mechanical ventilation are associated with ventilator-induced lung injury (VILI) and airway inflammation, leading to bronchopulmonary dysplasia (BPD) (3). The mechanisms of this injury involve alveolar over distension, the presence of shear forces and the release of pro-inflammatory cytokines (6), moreover prolonged duration of intubation and mechanical ventilation is associated with an increased risk of death or survival with neurologic impairment (3). In an effort to reduce VILI and so BPD in premature infants, there has been a trend toward increased use of non-invasive forms of respiratory support: nasal continuous positive airway pressure (nCPAP), nasal intermittent positive-pressure ventilation (NIPPV), high-flow nasal cannula (HFNC), nasal high-frequency oscillatory ventilation (nasal-HFOV)(2, 1, 7).

NCPAP is an alternative to intubation and a meta-analysis trials of early nasal CPAP versus intubation and ventilation showed that nasal CPAP reduces the risk of BPD. Nonetheless use of NCPAP in the delivery room may fail in ELBW, with 34 to 83% of such infants requiring subsequent intubation. Furthermore, post extubation support with nCPAP in these infants is associated with a 16-40% failure rate at 1 week (3, 4, 5, 9). NCPAP stabilized the surfactant deficient alveoli and improves oxygenation, but does not necessarily improve alveolar ventilation or partial pressure of carbon dioxide (pCO2) elimination (2, 8).

Some Authors reported the use of nasal high-frequency ventilation (nHFOV) in 14 very low birth weight (VLBW) infants with respiratory failure, using nasopharyngeal tube (3) and they have shown that this technique can lower pCO2 (1).

Other Authors investigated the efficacy of nasal HFOV applied on a single nasopharyngeal tube in an heterogeneous group of 21 infant with moderate respiratory insufficiency and they shown that was effective in reducing pCO2 (10).

No randomized controlled trials have directly evaluated the efficacy of nasal HFOV versus nCPAP with use of nasal prongs/mask in ELBW. There is rationale and support for the idea that high-frequency oscillation using a nasal prongs may improve carbon dioxide elimination in infants and minimizing the need for intubation and mechanical ventilation. In premature infants, HFOV is believed to cause less lung injury than conventional ventilation. So the question can be whether the benefits of HFOV and non invasive (nasal) ventilation are synergistic.