title: Impact of improved survival of very low-birth-weight infants on incidence and severity of bronchopulmonary dysplasia.
abstract: BACKGROUND
  It has been suggested that improved survival of very low birth weight (VLBW) infants may have resulted in increased numbers of patients with bronchopulmonary dysplasia (BPD).
  
  
  OBJECTIVE
  To determine the impact of changes in mortality on the incidence and/or severity of BPD in three different time periods with distinct respiratory support strategies.
  
  
  METHODS
  Retrospective single center cohort study of VLBW infants: Cohort A (1986-1990): pre-surfactant era, use of conventional intermittent mandatory ventilation (IMV); cohort B (1993-1994): use of synthetic surfactant, nasopharyngeal continuous positive airway pressure (CPAP) and conventional IMV; cohort C (2000-2001): use of natural surfactant, early nasal prong CPAP, synchronized IMV with tidal volume monitoring and high frequency oscillatory ventilation (HFOV). BPD was classified as mild, moderate or severe according to Jobe and Bancalari.
  
  
  RESULTS
  The median gestational ages and birth weights were 28 3/7 weeks and 1,120 g for cohort A (n = 97), 30 0/7 weeks and 1,340 g for cohort B (n = 100), and 29 1/7 weeks and 1,200 g for cohort C (n = 135). The use of partial or complete courses of antenatal corticosteroids (ANC) increased over time (58%, 72%, and 82%, p = 0.003). There was a 50% reduction of mortality between each time period with mortality rates of 30%, 14% and 7% in cohorts A, B and C, respectively (p < 0.001). The overall incidence of BPD was 26% in the pre-surfactant era, 11% during the mid-1990s and 19% in the most recent time period (r = -0.05, p = 0.36). Moderate and severe forms of BPD decreased over time and were seen in 11% in cohort A, 3% in cohort B and 2% in cohort C (p = 0.008).
  
  
  CONCLUSIONS
  Changes in neonatal care of VLBW infants, including increased use of ANC and modified respiratory support strategies, have resulted in dramatically improved survival rates over the past 15 years without increasing moderate to severe pulmonary morbidity.
authors.affiliation: Department of Pediatrics, Neonatal and Pediatric Intensive Care, Children's Hospital of Luzern, Luzern, Switzerland. thomas.berger@ksl.ch
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Berger
authors.forename: Iris I
authors.initials: II
authors.lastname: Bachmann
authors.forename: Mark
authors.initials: M
authors.lastname: Adams
authors.forename: Gregor
authors.initials: G
authors.lastname: Schubiger
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage; D001724:Birth Weight; D001997:Bronchopulmonary Dysplasia / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000453:epidemiology / Q000401:mortality / Q000503:physiopathology; D019102:Infant, Very Low Birth Weight; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies; D015996:Survival Rate
chemical_list: D000305:Adrenal Cortex Hormones