Abnormal heart rate response to hypercapnia in boys with an apparent life-threatening event

Acta Paediatr. 2002;91(12):1318-23. doi: 10.1080/08035250216101.


Aim: To determine instantaneous cardiac variability responses to increased carbon dioxide (CO2) during quiet sleep in infants who may be at risk for the Sudden Infant Death syndrome (SIDS).

Methods: The cardiac rate variability before, during and after a CO2 challenge was examined in 41 infants who had experienced an apparent life-threatening event (ALTE) and 41 gender- and age-matched control infants.

Results: The ALTE infants responded to CO2 breathing with a significant increase in R-R intervals, i.e. decreases in heart rate, compared to the controls (45.1% increase in R-R intervals vs. 41.4%; p = 0.005). The differences between ALTE infants and controls depended primarily on the boys' responses.

Conclusion: ALTE infants, particularly ALTE boys, have an autonomic dysfunction-lower sympathetic stimulation and/or inhibited vagal withdrawal when stressed with CO2. The outcome might provide clues to the mechanisms underlying the cardiovascular processes contributing to the terminal event in SIDS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autonomic Nervous System / physiopathology*
  • Cardiovascular System / physiopathology
  • Electrocardiography
  • Heart Rate*
  • Humans
  • Hypercapnia / physiopathology*
  • Infant
  • Infant, Newborn
  • Male
  • Signal Processing, Computer-Assisted
  • Sleep Apnea Syndromes / physiopathology*
  • Sudden Infant Death