title: Catch-up alveolarization in ex-preterm children: evidence from (3)He magnetic resonance.
abstract: BACKGROUND
  Histologic data from fatal cases suggest that extreme prematurity results in persisting alveolar damage. However, there is new evidence that human alveolarization might continue throughout childhood and could contribute to alveolar repair.
  
  
  OBJECTIVE
  To examine whether alveolar damage in extreme-preterm survivors persists into late childhood, we compared alveolar dimensions between schoolchildren born term and preterm, using hyperpolarized helium-3 magnetic resonance.
  
  
  METHODS
  We recruited schoolchildren aged 10-14 years stratified by gestational age at birth (weeks) to four groups: (1) term-born (37-42 wk; n = 61); (2) mild preterm (32-36 wk; n = 21); (3) extreme preterm (<32 wk, not oxygen dependent at 4 wk; n = 19); and (4) extreme preterm with chronic lung disease (<32 wk and oxygen dependent beyond 4 wk; n = 18). We measured lung function using spirometry and plethysmography. Apparent diffusion coefficient, a surrogate for average alveolar dimensions, was measured by helium-3 magnetic resonance.
  
  
  RESULTS
  The two extreme preterm groups had a lower FEV1 (P = 0.017) compared with term-born and mild preterm children. Apparent diffusion coefficient was 0.092 cm(2)/second (95% confidence interval, 0.089-0.095) in the term group. Corresponding values were 0.096 (0.091-0.101), 0.090 (0085-0.095), and 0.089 (0.083-0.094) in the mild preterm and two extreme preterm groups, respectively, implying comparable alveolar dimensions across all groups. Results did not change after controlling for anthropometric variables and potential confounders.
  
  
  CONCLUSIONS
  Alveolar size at school age was similar in survivors of extreme prematurity and term-born children. Because extreme preterm birth is associated with deranged alveolar structure in infancy, the most likely explanation for our finding is catch-up alveolarization.
authors.affiliation: Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom. mn87@leicester.ac.uk
authors.forename: Manjith
authors.initials: M
authors.lastname: Narayanan
authors.forename: Caroline S
authors.initials: CS
authors.lastname: Beardsmore
authors.forename: John
authors.initials: J
authors.lastname: Owers-Bradley
authors.forename: Cristian M
authors.initials: CM
authors.lastname: Dogaru
authors.forename: Marius
authors.initials: M
authors.lastname: Mada
authors.forename: Iain
authors.initials: I
authors.lastname: Ball
authors.forename: Ruslan R
authors.initials: RR
authors.lastname: Garipov
authors.forename: Claudia E
authors.initials: CE
authors.lastname: Kuehni
authors.forename: Ben D
authors.initials: BD
authors.lastname: Spycher
authors.forename: Michael
authors.initials: M
authors.lastname: Silverman
mesh_terms: D000293:Adolescent; D001837:Body Weights and Measures / Q000379:methods; D002648:Child; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D011650:Pulmonary Alveoli / Q000033:anatomy & histology*