title: Influence of prematurity on postnatal maturation of heart rate and arterial pressure responses to hypoxia in lambs.
abstract: BACKGROUND
  While hypoxic events with bradycardias are a frequent occurrence during the first weeks of life in preterm infants, the impact of preterm birth on maturation of the cardiovascular response to hypoxia in early postnatal life is unknown.
  
  
  OBJECTIVE
  In the present study, we tested the hypothesis that preterm birth influences postnatal maturation of cardiovascular responses to hypoxia.
  
  
  METHODS
  6 preterm lambs (term 132 days, birth weight 2.9 kg) and 6 full-term lambs (term 147 days, birth weight 4.3 kg) were studied without sedation on days 3, 7, 14, 21 and 28 during acute, steady-state hypoxia (FIO(2) = 0.08, 15 min).
  
  
  RESULTS
  Results show that full-term lambs increased their heart rate (HR) in response to hypoxia from the first day of life, with no postnatal maturation thereafter. In preterm lambs, HR did not change before day 14 and the full-term-like response was not acquired before 2 weeks after theoretical term. In both groups, mean arterial pressure tended to decrease below baseline, but the amplitude of variations remained of small magnitude.
  
  
  CONCLUSIONS
  The present results bring unique evidence that preterm birth is associated with a blunted heart response to steady-state hypoxia during the first postnatal week and a delay in the maturation of HR response.
authors.affiliation: INSERM, U642, CHU Rennes, Rennes, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Pladys
authors.forename: Julie
authors.initials: J
authors.lastname: Arsenault
authors.forename: Philippe
authors.initials: P
authors.lastname: Reix
authors.forename: Joelle
authors.initials: J
authors.lastname: Rouillard Lafond
authors.forename: François
authors.initials: F
authors.lastname: Moreau-Bussière
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Praud
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000502:physiology*; D002319:Cardiovascular System / Q000503:physiopathology*; D004195:Disease Models, Animal; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D007231:Infant, Newborn; D007234:Infant, Premature; D012756:Sheep