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Arousal responses in babies at risk of sudden infant death syndrome at different postnatal ages
Insights
Infants at risk for Sudden Infant Death Syndrome (SIDS) and those with apparent life-threatening events (ALTE) show deficient sleep arousal, particularly to hypoxia. This deficiency persists from the first week of life and is more common in these at-risk infants.
Area of Science:
- Pediatric Sleep Medicine
- Neonatal Physiology
- Sudden Infant Death Syndrome (SIDS) Research
Background:
- Sleep arousal responses are critical for infant survival.
- Sudden Infant Death Syndrome (SIDS) and Apparent Life-Threatening Events (ALTE) represent significant risks in infancy.
- Understanding arousal mechanisms in at-risk infants is crucial for prevention strategies.
Purpose of the Study:
- To compare hypercarbic and hypoxic arousal thresholds in healthy infants, infants with a sibling history of SIDS, and infants with ALTE.
- To determine if arousal responses change with age during the first three months postnatally.
- To identify potential physiological markers for SIDS and ALTE risk.
Main Methods:
- Measured hypercarbic (elevated carbon dioxide) and hypoxic (low oxygen) arousal responses in three infant groups at 1, 6, and 13 weeks postnatal.
- Defined arousal as gross body movement with eye opening/movement or crying.
- Utilized standardized increases in FICO2 and decreases in FIO2 to elicit arousal.
Main Results:
- No significant age-related changes in hypercarbic or hypoxic arousal thresholds were observed within any group.
- Infants with a sibling history of SIDS exhibited a significantly higher hypercarbic arousal threshold compared to controls.
- ALTE infants showed a significantly lower hypoxic arousal response rate (22%) compared to controls (67%), with SIDS siblings also showing a reduced response (40%).
Conclusions:
- Deficient sleep arousal, especially to hypoxia, is prevalent in infants at increased risk for SIDS and those experiencing ALTE.
- This arousal deficiency is present early in infancy and does not significantly change within the first three months.
- Impaired arousal responses may be a contributing factor to SIDS and ALTE, highlighting the need for early identification and intervention.
Abstract:
Hypercarbic and hypoxic arousal responses during sleep were measured in healthy term infants, infants where a previous sibling died from sudden infant death syndrome (SIDS) and infants suffering a clearly defined apparent life threatening event (ALTE) requiring vigorous or mouth to mouth resuscitation. Groups of infants were tested at approximately one, six and 13 weeks postnatally. Arousal was defined as gross body movement with eyes opening and moving or crying. Hypercarbic arousal was by step increases in F1 Co2 until arousal occurred or until endtidal (PETCO2) reached 8.7 KpA (65 mm Hg) Hypoxic arousal was by step decreases in FIO2 until arousal occurred or until an FIO2 of 0.15 had been maintained for 20 minutes. There was no difference in hypercaribic arousal threshold with age in any group. Hypercarbic arousal threshold was significantly higher in siblings (mean 53.4, 53.6, 54.7 mmHg. [7.12, 7.14, 7.29 KPA] at 0, 6, 13 postnatal weeks) compared to controls (mean 50.9, 52.3, 53.0mm Hg. [6.78, 6.97, 7.29 KPS respectively). ALTE infants differed only at 12 weeks having a significantly lower threshold (51.0mmHg. [6.80 KPA] V 53.0mm Hg. (7.06 KPA]) compared to controls. There was no difference in hypoxic arousal response with age in any group. An arousal response to hypoxia occurred in only 22% of ALTE infants and 40% of siblings compared to 67% of normal infants. Deficient sleep arousal, especially to hypoxia, is common in infants and especially those considered at increased risk from SIDS. This deficiency is present in the first postnatal week and did not vary overy the first three months of postnatal life.