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Responses to an increasing asphyxia in infants: effects of age and sleep state
A J Campbell1, D P Bolton, B J Taylor
1Department of Paediatrics and Child Health, Dunedin School of Medicine and School of Medical Sciences, New Zealand.
Insights
Infants show varied responses to mild asphyxia during sleep, including increased ventilation and arousal. These reactions depend on the infant's age and sleep state (quiet vs. REM sleep).
Area of Science:
- Neonatal physiology
- Sleep studies
- Respiratory control
Background:
- Infant responses to asphyxia are critical for survival.
- Understanding ventilatory and arousal mechanisms during sleep is essential for infant health.
- Age and sleep state significantly influence cardiorespiratory control in infants.
Purpose of the Study:
- To investigate respiratory and arousal responses to mild asphyxia in infants aged 0-6 months during sleep.
- To determine the relationship between ventilatory sensitivity and arousal responses.
- To examine how age and sleep state (quiet sleep vs. REM sleep) affect these responses.
Main Methods:
- Assessed ventilatory sensitivity using the relationship between inspired carbon dioxide (FICO2) and ventilation.
- Monitored respiratory and arousal responses during sleep in infants aged 0-6 months.
- Analyzed data based on infant age and sleep state (quiet sleep and REM sleep).
Main Results:
- Respiratory response to asphyxia increased with age.
- Respiratory response was greater in quiet sleep than in REM sleep.
- Arousal occurred more frequently in REM sleep and in newborns compared to 6-month-olds.
- Arousal in quiet sleep correlated with high ventilatory asphyxial sensitivity (VAS), while in REM sleep it correlated with low VAS.
Conclusions:
- Infants respond to mild asphyxia during sleep with increased ventilation, arousal, or both.
- The specific response pattern is modulated by the infant's age and prevailing sleep state.
- These findings highlight the dynamic nature of cardiorespiratory control in developing infants.
Abstract:
Infants aged 0-6 months were assessed for respiratory and arousal responses to mild asphyxia during sleep. Ventilatory sensitivity was assessed from the relationship between inspired carbon dioxide (FICO2) and ventilation. Arousal and ventilatory sensitivity were significantly related. Respiratory response increased with age and was greater in quiet sleep than in REM sleep. Arousal occurred more frequently in REM sleep (55/102) than quiet sleep (38/165, P < 0.05) and more frequently at the newborn age (54/117) than at 6 months (13/58, P < 0.05). Arousal in quiet sleep occurred in babies with high ventilatory sensitivities (mean ventilatory asphyxial sensitivity (VAS) 0.476 +/- 0.288) and in REM sleep was more associated with low ventilatory sensitivities (mean VAS 0.194 +/- 0.334, P <0.05). We conclude infants respond to mild asphyxia during sleep with an increase in ventilation, an arousal or both. The exact response is dependent on age and sleep state.