title: Longitudinal assessment of heart rate variability in very low birth weight infants during their NICU stay.
abstract: BACKGROUND
  Maturation of the autonomic nervous system has not been studied in high-risk very low birth weight (VLBW) infants in the first few weeks of life.
  
  
  OBJECTIVE
  To characterize developmental changes in autonomic nervous system activity of high-risk VLBW infants from 23 to 38 weeks post-menstrual age by measuring heart rate variability (HRV).
  
  
  METHODS
  In this prospective cohort study 38 infants admitted to Children's Memorial Hermann Hospital NICU were longitudinally followed weekly or biweekly. Heart period data were recorded while infants were resting in active sleep.
  
  
  METHODS
  Growth of spectral power of HRV in low-frequency (0.05-0.25 Hz) and high-frequency (0.25-1.00 Hz) bands was modeled with linear mixed-effects models. The high-frequency power provides a measure of respiratory sinus arrhythmia (RSA).
  
  
  RESULTS
  Low-frequency power increases with post-menstrual age, and intubated infants have lower HRV. The increase in low-frequency power is faster (0.50+/-0.12 dB/week) than the increase in RSA (0.17+/-0.09 dB/week).
  
  
  CONCLUSIONS
  This longitudinal data exhibits developmental maturation of the RSA and of the low-frequency power of HRV in high-risk VLBW infants.
authors.affiliation: The University of Texas Medical School at Houston, Department of Pediatrics, 6431 Fannin Street, Houston, TX 77339, USA. asif_khattak@pediatrix.com
authors.forename: Asif Z
authors.initials: AZ
authors.lastname: Khattak
authors.forename: Nikhil S
authors.initials: NS
authors.lastname: Padhye
authors.forename: Amber L
authors.initials: AL
authors.lastname: Williams
authors.forename: Robert E
authors.initials: RE
authors.lastname: Lasky
authors.forename: Fernando R
authors.initials: FR
authors.lastname: Moya
authors.forename: M Terese
authors.initials: MT
authors.lastname: Verklan
mesh_terms: D000367:Age Factors; D001341:Autonomic Nervous System / Q000254:growth & development*; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000502:physiology*; D007363:Intensive Care Units, Neonatal; D008137:Longitudinal Studies; D013781:Texas