title: Heart rate variability in hypoxic ischemic encephalopathy during therapeutic hypothermia.
abstract: BACKGROUND
  Therapeutic hypothermia (TH) aims to ameliorate further injury in infants with moderate and severe hypoxic ischemic encephalopathy (HIE). We aim to assess the effect of TH on heart rate variability (HRV) in infants with HIE.
  
  
  METHODS
  Multichannel video-electroencephalography (EEG) and electrocardiography were assessed at 6-72 h after birth in full-term infants with HIE, recruited prior to (pre-TH group) and following (TH group) the introduction of TH in our neonatal unit. HIE severity was graded using EEG. HRV features investigated include: mean NN interval (mean NN), standard deviation of NN interval (SDNN), triangular interpolation (TINN), high-frequency (HF), low-frequency (LF), very low-frequency (VLF), and LF/HF ratio. Linear mixed model comparisons were used.
  
  
  RESULTS
  118 infants (pre-TH: n = 44, TH: n = 74) were assessed. The majority of HRV features decreased with increasing EEG grade. Infants with moderate HIE undergoing TH had significantly different HRV features compared with the pre-TH group (HF: P = 0.016, LF/HF ratio: P = 0.006). In the pre-TH group, LF/HF ratio was significantly different between moderate and severe HIE grades (P = 0.002). In the TH group, significant differences were observed between moderate and severe HIE grades for SDNN: P = 0.020, TINN: P = 0.005, VLF: P = 0.029, LF: P = 0.010, and HF: P = 0.006.
  
  
  CONCLUSIONS
  The HF component of HRV is increased in infants with moderate HIE undergoing TH.
authors.affiliation: INFANT Centre, Neonatal Brain Research Group, University College Cork, Cork, Ireland.|Department of Pediatrics and Child Health, Cork University Maternity Hospital, Cork, Ireland.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Goulding
authors.affiliation: INFANT Centre, Neonatal Brain Research Group, University College Cork, Cork, Ireland.
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Stevenson
authors.affiliation: INFANT Centre, Neonatal Brain Research Group, University College Cork, Cork, Ireland.|Department of Pediatrics and Child Health, Cork University Maternity Hospital, Cork, Ireland.
authors.forename: Deirdre M
authors.initials: DM
authors.lastname: Murray
authors.affiliation: INFANT Centre, Neonatal Brain Research Group, University College Cork, Cork, Ireland.
authors.forename: Vicki
authors.initials: V
authors.lastname: Livingstone
authors.affiliation: Department of Pediatrics and Child Health, Cork University Maternity Hospital, Cork, Ireland.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Filan
authors.affiliation: INFANT Centre, Neonatal Brain Research Group, University College Cork, Cork, Ireland.|Department of Pediatrics and Child Health, Cork University Maternity Hospital, Cork, Ireland.
authors.forename: Geraldine B
authors.initials: GB
authors.lastname: Boylan
mesh_terms: D004562:Electrocardiography; D004569:Electroencephalography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007036:Hypothermia, Induced; D020925:Hypoxia-Ischemia, Brain / Q000503:physiopathology* / Q000628:therapy; D007223:Infant; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D013997:Time Factors; D016896:Treatment Outcome