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Vasoconstriction following spontaneous sighs and head-up tilts in infants sleeping prone and supine
B C Galland1, B J Taylor, D P Bolton
1Department of Women's and Children's Health, Otago Medical School, Dunedin, New Zealand. barbara.galland@stonebow.otago.ac.nz
Insights
Infant sleep position affects autonomic responses. Prone positioning reduces vasoconstriction, while older infants show stronger sigh responses, indicating developmental changes in sympathetic activity.
Area of Science:
- Physiology
- Neonatal Medicine
- Autonomic Nervous System Research
Background:
- Infant autonomic nervous system development is crucial for physiological regulation.
- Understanding sympathetic activity in infants informs SIDS risk reduction strategies.
- Limited data exists on cutaneous vasoconstrictor responses in infants during sleep.
Purpose of the Study:
- To investigate the effects of age, sleep state, and sleep position on cutaneous vasoconstrictor responses in infants.
- To measure sympathetic activity using head-up tilt and sigh challenges.
- To compare vasoconstrictor responses between 1-month-old and 3-month-old infants.
Main Methods:
- 36 infants aged 1 and 3 months were studied.
- Cutaneous blood flow was measured using laser Doppler flowmetry.
- Responses to 60-degree head-up tilt and spontaneous sighs were recorded in different sleep states and positions (supine vs. prone).
Main Results:
- Head-up tilt elicited a 52% mean reduction in blood flow; spontaneous sighs caused a 33% mean reduction.
- Prone positioning significantly reduced vasoconstriction compared to supine in 1-month-olds.
- Older infants (3 months) exhibited significantly greater vasoconstriction following sighs.
Conclusions:
- Prone sleep position may reduce sympathetic nervous system activity in infants.
- Autonomic responses mature between 1 and 3 months of age.
- Sleep position influences autonomic regulation, with potential implications for infant safety.
Abstract:
The cutaneous vasoconstrictor responses following a 60 degrees head-up tilt and a spontaneous sigh were measured in 36 infants at 1 and 3 months age to investigate the effects of age, sleep state and sleep position on these responses. The vasoconstrictor response was determined by a measure of cutaneous blood flow using a laser Doppler flowmeter. The mean reduction in blood flow (vasoconstriction) was 52% following the tilt, and 33% following the sigh. Prone positioning 1-month-old infants as compared to supine, reduced the degree of vasoconstriction following the tilt (P=0.027) and sigh (P=0.026). The supine to prone reduction was: tilt, -11% in quiet sleep (QS) (from 55.1 to 49.1% vasoconstriction) and -18% in active sleep (AS) (from 52.0 to 42.9%) and; sigh, -26% in QS (35-26%), and -15% in AS (31-26%). The degree of vasoconstriction following the sigh was significantly greater in 3- compared to 1-month-old infants (+26%, P=0.040). The mean response to the tilt in the older age group was 12% greater but this did not reach significance (P=0.069). Sleep state did not affect the degree of vasoconstriction but influenced transmission of the response so that latency to minimal vasoconstriction was 1 s shorter in AS than QS. This study provides data on two simple measures of sympathetic activity during sleep that have not previously been described in any detail in infant studies, and add more evidence that autonomic activity is reduced in the prone position compared to supine during sleep.