Study Patients
Eligible infants were born with gestational ages less than 32 weeks, were diagnosed with sBPD at 36 weeks postmenstrual age (PMA) according to the 2001 NIH consensus definition3, and were receiving invasive mechanical ventilation at the time of enrollment. Infants were excluded if they were diagnosed with unilateral lung disease, had an endotracheal tube leak >10%, had prior cardiac arrhythmia, concurrent pulmonary or systemic infection, or were actively treated with high frequency ventilation (HFV), inhaled anticholinergic therapy, or other medication with brochodilatory characteristics (i.e. magnesium sulfate, ketamine, etc.).
Although specific ventilator settings were not mandated for this trial, all subjects were ventilated in a Volume Controlled-Synchronized Intermittent Mandatory Ventilation/Pressure Support (VC-SIMV + PSV) mode with AutoFlow® via the Evita®Infinity® V500 Ventilator (Dräger®, Lűbeck, Germany). Our institution utilizes a common strategy for conventional mechanical ventilation within our Chronic Lung Disease Program, involving SIMV-VC/PS with AutoFlow®, tidal volumes of 8-12 mL/kg, PEEP titrated to generate adequate aeration on chest radiograph and minimize patient ventilator asynchrony, and inspiratory time specific to individual patient needs in accordance with analysis of flow-time scalar tracings.