title: Acute cardiovascular responses in preterm infants at 34-39 weeks of gestational age.
abstract: BACKGROUND
  Premature infants demonstrate immature physiological control mechanisms; however their acute cardiovascular control has not yet been widely studied.
  
  
  OBJECTIVE
  The aim of this study was to analyze heart rate (HR) and blood pressure (BP) control in preterm infants.
  
  
  METHODS
  Twenty preterm infants with a mean gestational age of 31 ± 2.4 (26-34) weeks at birth were evaluated at a gestational age of 36 ± 1.5 (34-39) weeks. Results were compared to twenty, healthy, full-term, control infants studied at the age of 12 ± 3 weeks.
  
  
  METHODS
  HR and BP responses to 45° head-up tilt and side motion tests during non-rapid eye movement sleep were analyzed. In addition, HR responses to spontaneous arousals from non-rapid eye movement sleep were evaluated.
  
  
  RESULTS
  Preterm infants showed significantly smaller initial HR and BP responses compared with controls in head-up tilt (HR p=0.0005, systolic BP p=0.02, diastolic BP p=0.01) and side motion tests (HR p=0.002, systolic BP p<0.0001, diastolic BP p<0.0001). Furthermore, in tilt tests, preterm infants presented with greater intersubject variability in BP responses than controls (systolic BP p=0.009, diastolic BP p=0005). Preterm HR responses to spontaneous arousals were similar to controls.
  
  
  CONCLUSIONS
  This study indicates immature vestibulo-mediated cardiovascular control in preterm infants compared with term infants. This is seen as attenuated BP responses to side motion test and more labile acute BP control to postural challenge.
authors: Children's Hospital, University of Helsinki, Finland. suvi.viskari@helsinki.fi
authors: Suvi
authors: S
authors: Viskari-Lähdeoja
authors: Timo
authors: T
authors: Hytinantti
authors: Sture
authors: S
authors: Andersson
authors: Turkka
authors: T
authors: Kirjavainen
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D016022:Case-Control Studies; D005260:Female; D005865:Gestational Age; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008297:Male