Infant Pulmonary Function Tests (IPFT)
Parenchymal and airway function were assessed using previously described methods [15, 16]. In brief, infants were first sedated with oral chloral hydrate (85 mg/kg) and measurements of the alveolar volume (VA) and diffusion capacity of the lung to carbon monoxide (DLCO) were performed. In addition, forced expiratory flows (FEFs) using the raised volume rapid thoraco-abdominal compression technique were measured and quantified by forced vital capacity (FVC), forced expiratory flows between 25% and 75% expired FVC (FEF25-75), forced expired flow at 50% and 75% expired FVC (FEF50, FEF75), as well as forced expired volume in 0.5 seconds (FEV0.5). Data quality was determined using published guidelines [17], and only research quality data were used for analysis.