Introduction
Chronic neonatal lung disease (CNLD) is defined clinically as a need for supplemental oxygen therapy or positive pressure support at 36 weeks CGA, at 56 days chronological age if born at ≥ 32 weeks gestational age) or at time of hospital discharge.1 It is pathologically known as bronchopulmonary dysplasia (BPD), a common respiratory complication of low birth weight preterm infants who experience arrested lung development and are susceptible to lung inflammation secondary to early supplemental oxygen, positive pressure ventilation, and sepsis in the postnatal period.2 CNLD and BPD are used interchangeably in the literature with CNLD (or simply chronic lung disease) being the preferred terminology used by the Australian and New Zealand Neonatal Network (ANZNN).3
The worldwide incidence of CNLD has been increasing since 1993 due to an increased survival of extreme preterm infants.4 The 2017 ANZNN prevalence of CNLD was 30.3% with 418 (20.8%) babies with CNLD requiring home oxygen therapy.3 Of those requiring home oxygen, 340 (81.3%) also had very low birthweight (<1,500g).3 In Canada and the United States, the annual reported prevalence of extremely premature infants with CNLD and chronic oxygen dependency is between 25 and 59%.5-8 Home oxygen facilitates earlier hospital discharge and is generally favored as it reduces the risk of nosocomial infections and may improve quality of life in the comfort of a home environment.9,10 Duration of home oxygen therapy varies widely due to unstandardized weaning practices in CNLD.5
Population-based cohort studies have identified predictors of requiring home oxygen at hospital discharge but to our knowledge, no studies have evaluated predictors of home oxygen therapy duration in CNLD.6,7 Thus, the primary aim of this study was to identify predictors of home oxygen therapy duration in premature infants with CNLD. Secondary aims were to identify predictors of home oxygen flow rates at time of hospital discharge and to identify if discharge oxygen flow rates were associated with post-discharge respiratory outcomes up to two years chronological age.