Cochrane Summaries

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Long versus short inspiratory times in neonates receiving mechanical ventilation

Kamlin COF, Davis PG
Published Online: 
21 January 2009

Endotracheal intubation and positive pressure ventilation of newborn infants with respiratory failure has revolutionised neonatal intensive care. The majority of infants are ventilated because of lung immaturity and hyaline membrane disease, respiratory difficulties that resolve for most of these infants. Use of ventilators can cause lung inflammation and ventilator-induced lung injury, particularly in the neonate with compliant chest walls, highlighting the importance of protective ventilation strategies. In addition, an infant's own breathing efforts, when combined with ventilator inflations, can exacerbate lung injury. Managing the mean airway pressure is important to improve oxygenation and not cause excessive airway pressures that can damage the lungs and impede venous return (a factor implied in spontaneous intraventricular haemorrhage in preterm infants). Clinicians still need to set an inspiratory time on the ventilator, making it important to determine whether the use of a long rather than a short inspiratory time reduces the rates of death, air leak and bronchopulmonary dysplasia (BPD, requiring supplemental oxygen at 28 days) in mechanically ventilated newborn infants (term and preterm). The review authors identified five randomised studies reported from 1980 to 1992. These trials recruited a total of 694 newborn infants with acute respiratory failure mainly caused by hyaline membrane disease. A long inspiratory time was associated with a significant increase in air leak from the lungs (NNT 8). There was no significant difference in the incidence of BPD but an increase in mortality before hospital discharge reached borderline statistical significance. Caution should be exercised in applying these results to modern neonatal intensive care because these studies were conducted before the introduction of antenatal steroids, postnatal surfactant and the use of synchronised modes of ventilatory support. Whilst there is increasing use of non-invasive ventilation such as nasal continuous positive airway pressure to avoid ventilator-induced lung injury, mechanical ventilation will continue to have a role in extremely immature infants and those with hyaline membrane disease complicated by apnea.