Is bias gas flow in ventilated preterm babies related to lung injury and risk of bronchopulmonary dysplasia?

Mechanical ventilation of preterm babies has increased their survival over the last decades; however, ventilation also results in injury to the delicate immature lung. Several aspects of ventilation have been identified as contributing to this injury, including the pressure generated by the ventilator and the volume of gas delivered, which have led to advances in ventilatory strategies. To generate the pressure and tidal volume necessary to ventilate a patient, a ventilator applies a continuous bias gas flow running through the ventilator circuit. During ventilation of the preterm baby, this bias gas flow is normally set at 8-10 L/min, independent of babies’ weights and without evidence for this to be the correct setting. However, high compared to low ventilator bias gas flows have been proven to be more injurious for the immature lamb lung. This study will compare preterm babies ventilated at either the standard gas flow of 10 L/min, or a low gas flow of 4 L/min. Outcomes will be measurement of levels of inflammatory markers and duration and intensity of respiratory support