title: Possible predictors of cardiorespiratory events after immunization in preterm neonates.
abstract: BACKGROUND
  The influence of the first immunization on cardiorespiratory (CR) stability in very preterm infants is still a controversial subject.
  
  
  OBJECTIVE
  To describe the changes induced by immunization on heart and respiratory rate variability (HRV-RRV) and to test a potential association between preimmunization profiles and postimmunization CR events.
  
  
  METHODS
  Continuous 72-hour CR recordings and 2.5-hour polysomnographic recordings were performed on very preterm infants immunized after 7 weeks. The results are expressed as medians (interquartile ranges).
  
  
  RESULTS
  Immunization was performed on 31 very preterm infants [28 weeks' gestation (26.9-29), birth weight: 965 g (795-1,105)], and was associated with an increased incidence (p < 0.01) of events lasting more than 10 s: bradycardia <80 bpm [2.2 (1.1-7) vs. 1.8 (1-4)/12 h], desaturation [17.6 (9.4-36.4) vs. 13.9 (7.7-33.8)/12 h] and associated bradycardia-desaturation [IB+D, 4.1 (1.4-7.3) vs. 2.4 (1-4.6)/12 h], with mild changes in HRV and no change in RRV. The changes in IB+D frequency were correlated with preimmunization IB+D frequency (r = 0.44, p < 0.05), HRV spectral parameter low frequency/high frequency ratio (LF/HF, r = 0.55, p < 0.01) and approximate entropy of HRV (r = -0.39, p < 0.05).
  
  
  CONCLUSIONS
  The increase in CR events after the first immunization in very preterm infants was associated with: (1) sympathetic predominance in heart rate control (high LF/HF ratio), (2) abnormal oversimplification of HRV (low entropy) and (3) persistent respiratory rhythm control immaturity (high IB+D before vaccine).
authors.affiliation: INSERM, U1099, Rennes, France.
authors.forename: Tiphaine
authors.initials: T
authors.lastname: Mialet-Marty
authors.forename: Alain
authors.initials: A
authors.lastname: Beuchée
authors.forename: Wissal
authors.initials: W
authors.lastname: Ben Jmaa
authors.forename: Nga
authors.initials: N
authors.lastname: N'guyen
authors.forename: Xavier
authors.initials: X
authors.lastname: Navarro
authors.forename: Fabienne
authors.initials: F
authors.lastname: Porée
authors.forename: Anne Monique
authors.initials: AM
authors.lastname: Nuyt
authors.forename: Patrick
authors.initials: P
authors.lastname: Pladys
mesh_terms: D001724:Birth Weight; D001919:Bradycardia / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D015716:Electrocardiography, Ambulatory; D004569:Electroencephalography; D005260:Female; D005865:Gestational Age; D006339:Heart Rate; D006801:Humans; D007114:Immunization / Q000009:adverse effects*; D007115:Immunization Schedule; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D012120:Respiration Disorders / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D056152:Respiratory Rate; D012307:Risk Factors; D013997:Time Factors