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Arterial blood flow and autonomic function in full-term infants
Nili Gabai1, Ayala Cohen, Ayed Mahagney
1The Hannah Khoushy Child Development Center, Bnai Zion Medical Center, Haifa, Israel.
Insights
The prone position in infants is linked to reduced brainstem blood flow and autonomic nervous system function. These physiological measures appear to be independently regulated, suggesting central nervous system autonomy.
Area of Science:
- Neonatal physiology
- Autonomic nervous system function
- Cerebrovascular regulation
Background:
- Infant sleep positioning is crucial for development and safety.
- Understanding autonomic functions and brainstem blood flow is vital for assessing infant well-being.
- Previous studies suggest potential risks associated with prone positioning.
Purpose of the Study:
- To examine how supine and prone positions affect autonomic functions and brainstem arterial blood flow velocity in newborns.
- To investigate the relationship between heart rate variability and arterial blood flow velocity in different sleep positions.
Main Methods:
- Studied 41 full-term infants (24-72 hours old) in both supine and prone positions.
- Assessed respiratory, cardiac, and eye movements.
- Measured arterial blood-flow velocity (ABFV) in basilar and vertebral arteries using Doppler ultrasound.
- Quantified heart rate variability (HRV) using time-domain measures (Standard deviation of normal R-R intervals and pNN50).
Main Results:
- Prone positioning significantly decreased both short-term and long-term HRV compared to supine (P<0.001, P=0.003).
- Active sleep increased short-term HRV, independent of position (P=0.005).
- Mean and peak ABFV in brainstem-supplying arteries were significantly reduced in the prone position (P=0.001-0.003).
- No significant correlation was found between HRV and ABFV in either position.
Conclusions:
- The findings indicate that infants are more vulnerable in the prone position regarding brainstem function.
- Arterial blood-flow velocity and autonomic functions, as measured by HRV, appear to be independent physiological parameters.
- This independence may suggest distinct regulatory mechanisms within the central nervous system.
Objectives:
To investigate variations in the autonomic functions and blood-flow velocity of the arteries supplying to the brainstem in supine and prone positions.
Methods:
Forty-one full-term infants were studied at the age of 24-72 h. Each infant underwent respiratory, cardiac and eye movement analyses in supine and prone positions. In addition, blood-flow velocity of the basilar and vertebral arteries was measured with a 2 MHz probe for 5 min in each position. Two time domain measures of heart rate variability (HRV) (Standard deviation of normal R-R intervals for long-term and pNN50 for short-term variability) were employed.
Results:
Significantly decreased short- (P<0.001) and long (P = 0.003)-term variabilities were observed in prone when compared with supine position. Increased short-term variability in active sleep with no interaction with position was observed (P = 0.005). A significant decreased mean (P = 0.001) and peak (P = 0.001-0.003) blood-flow velocity in prone when compared with supine position were measured in all three arteries supplying to the brainstem. No significant correlation between HRV and arterial blood-flow velocity (ABFV) was observed in either position.
Comment:
The results of the present study in agreement with previous studies reflect the vulnerability of infants in prone position as related to brainstem function. However, it appears that ABFV and autonomic functions as reflected by HRV are independent physiological measures, possibly indicating regulation autonomy of the central nervous system.
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