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Effect of maturation on heart rate response to ocular compression test during rapid eye movement sleep in human
J Ramet1, J P Praud, A M D'Allest
1Laboratory of Physiology, CNRS UA 1159, Hospital A. Béclère, Clamart, France.
Insights
Infant heart rate regulation matures with age. While baseline heart rate during REM sleep decreases, the cardiac response to ocular compression, a vagal reflex, becomes blunted in developing infants.
Area of Science:
- Neonatal physiology
- Autonomic nervous system development
Background:
- The autonomic nervous system (ANS) plays a crucial role in cardiovascular regulation in infants.
- Understanding the maturation of ANS reflexes, such as the oculocardiac reflex, is vital for assessing infant health.
Purpose of the Study:
- To investigate the maturation of the oculocardiac reflex during rapid eye movement (REM) sleep in infants.
- To determine how postconceptional age influences heart rate responses to ocular compression.
Main Methods:
- Thirty-three infants (31.5-50 wk postconceptional age) underwent a standardized ocular compression test during polygraphically monitored REM sleep.
- Electrocardiogram (ECG) was used to measure RR intervals before and during ocular compression.
- Heart rate changes were analyzed in relation to postconceptional age, gestational age, and postnatal age.
Main Results:
- Baseline heart rate during REM sleep significantly decreased with increasing postconceptional age.
- A significant negative correlation was observed between the "latency" of the heart rate response to ocular compression and postconceptional age.
- The cardiac response to ocular pressure stimulus, a vagally mediated reflex, was found to be blunted with maturation.
Conclusions:
- Infant heart rate regulation during REM sleep demonstrates maturation, with decreasing baseline heart rate potentially linked to increased vagal activity.
- The oculocardiac reflex, a measure of vagal tone, is significantly influenced by maturation, showing a blunted response in older infants.
- These findings provide insights into the developmental trajectory of autonomic cardiovascular control in neonates and premature infants.
Abstract:
Thirty-three premature and full-term infants (31.5-50 wk postconceptional age) free from neurologic and cardiopulmonary disease at time of testing, underwent a standardized ocular compression test during polygraphically controlled rapid eye movement sleep. RR intervals were measured on the ECG before and during ocular compression. RR interval changes during ocular compression were compared to the preceding 60-s mean RR interval in each infant. Results were analyzed relative to gestational age, postnatal age, and postconceptional age. Baseline heart rate during REM sleep decreased with postconceptional age. During ocular compression, there was a significant negative correlation between the longest RR interval or the "latency" variable with postconceptional age. Latency is defined as the time, in milliseconds, from beginning of eyelid pressure to the first measurable RR increase compared to mean control RR + 1 SD. Our results indicate that during rapid eye movement sleep, "baseline heart rate" decreases with maturation, an effect supposedly related to increased vagal activity, whereas the heart rate response on ocular pressure stimulus, a vagally mediated reflex, is significantly influenced and blunted with maturation.