title: Heart rate variability during REM and non-REM sleep in preterm neonates with and without abnormal cardiorespiratory events.
abstract: OBJECTIVE
  Analyse heart rate variability (HRV) of preterm neonates undergoing a polysomnography in relation to the occurrence of abnormal cardiorespiratory events on one hand and the type of sleep states on the other hand.
  
  
  METHODS
  To quantify nonlinear HRV, the numerical noise titration technique is used, adapted to neonatal heart rate data. HRV is calculated for 30 preterm neonates with mean post-conceptional age of 36.4weeks, divided into three groups according to the occurrence of abnormal events during the polysomnographies and the eventual home monitoring.
  
  
  RESULTS
  Periods of non-REM sleep have lower noise limit values and can be distinguished significantly from periods of REM sleep and from the total recording period. The presence of abnormal events does not influence this finding. Significant differences between groups are only found during non-REM segments by means of the noise limit value computed via numerical noise titration while the linear HRV parameters were not able to discriminate.
  
  
  CONCLUSIONS
  ECG measurement of a relatively short non-REM sleep period without specific abnormal events is sufficient to define a mature cardiorespiratory pattern in preterm infants.
authors.affiliation: Department of Electrical Engineering, ESAT-SCD, Kasteelpark Arenberg 10 bus 2446, B-3001 Leuven, Belgium. steven.vandeput@esat.kuleuven.be
authors.forename: Steven
authors.initials: S
authors.lastname: Vandeput
authors.forename: Gunnar
authors.initials: G
authors.lastname: Naulaers
authors.forename: Hans
authors.initials: H
authors.lastname: Daniels
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Huffel
mesh_terms: D001049:Apnea / Q000150:complications; D001919:Bradycardia / Q000150:complications; D006339:Heart Rate; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D017286:Polysomnography; D018570:Risk Assessment; D012895:Sleep, REM / Q000502:physiology*