The Emergence of a Circadian Pattern in Respiratory Rates: Comparison between Control Infants and Subsequent Siblings of SIDS

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Abstract

Summary: The objective of the present study is to compare the emergence of a circadian respiratory pattern in subsequent siblings of SIDS and control infants to see whether the unique time and age of SIDS is correlated with altered circadian manifestations. During the first three months of life, a pattern in respiratory rates emerged which appeared to be the nightly portion of a circadian rhythm. Subsequent siblings of SIDS exhibited transient accelerated maturation of this circadian pattern. During the first month of life, minima in respiratory rates in quiet sleep occurred during the second and third intervals of the night in subsequent siblings, a pattern not seen until three months of age in control infants.

Speculation: Two recent reports suggest a developmental model in which a physiological deficit can bring about a transient acceleration in maturation. Glück et al. (9) demonstrated an accelerated pattern of lung development as measured by the appearance of phosphatidylglycerol in amniotic fluid as much as eight wk early in intrauterine growth-retarded fetuses. Minkowsky (23) presented preliminary data of increased levels of neurotransmitters such as serotonin and precursors in fetal rats with experimentally induced intrauterine malnutrition. It is tempting to speculate that accelerated maturation in electroencephalographic sleep frequencies and respiratory circadian patterns in subsequent siblings of sudden infant death syndrome are manifestations of a compensatory response to an oxygen deficit.

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Correspondence to Toke Hoppenbrouwers.

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Keywords

  • circadian pattern
  • respiratory rates
  • sleep states
  • sudden infant death syndrome

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