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Brain oxidative phosphorylation following alteration in head position in preterm and term neonates
1Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia 19104.
Insights
Altering an infant
Area of Science:
- Neonatal physiology and neuroprotection
- Cerebral blood flow and metabolism
- Medical imaging and spectroscopy
Background:
- Head position changes can affect cerebral blood flow, potentially increasing intraventricular hemorrhage risk in critically ill infants.
- Understanding brain oxygen delivery and metabolic responses to head position is crucial for neonatal care.
- Cerebral oxidative metabolism serves as a key indicator of brain blood flow and tissue oxygenation.
Purpose of the Study:
- To evaluate in vivo cerebral oxidative metabolism in healthy preterm and term infants.
- To assess the impact of head position changes (neutral, prone, supine) on brain blood flow.
- To determine if head position alterations affect cerebral phosphoenergetics and bioenergetic reserve.
Main Methods:
- Utilized 31 phosphorus nuclear magnetic resonance spectroscopy (31P-MRS) to measure cerebral phosphoenergetics.
- Studied 10 preterm and 8 term infants who were clinically stable.
- Measured the phosphocreatine to inorganic phosphate (PCr/Pi) ratio, an indicator of bioenergetic reserve, in neutral, prone, and supine head positions.
Main Results:
- The mean PCr/Pi ratio in the neutral position was 1.08 +/- 0.15 in preterm infants and 1.12 +/- 0.21 in term infants.
- No significant changes in the PCr/Pi ratio were observed following changes in head position.
- Cerebral bioenergetic reserve remained stable across different head positions in healthy neonates.
Conclusions:
- Healthy neonates demonstrate physiological and biochemical compensation mechanisms.
- Changes in head position do not significantly alter measurable brain oxidative phosphorylation in healthy infants.
- These findings suggest that healthy term and preterm infants can maintain stable cerebral blood flow and metabolism despite head position alterations.
Abstract:
An alteration in head position, which effects cerebral blood flow, may increase the risk for intraventricular hemorrhage in the critically ill infant. The purpose of this study was to evaluate in vivo cerebral oxidative metabolism as an index of tissue oxygen delivery reflecting brain blood flow, in healthy preterm and term infants following a change in head position. Cerebral phosphoenergetics using 31 phosphorus nuclear magnetic resonance spectroscopy were measured in 10 preterm and eight term infants following three different head positions: neutral, prone, and supine. All infants were clinically stable at the time of study. The phosphocreatine to inorganic phosphate ratio, an indicator of bioenergetic reserve, was determined. The mean +/- SD for phosphocreatine to inorganic phosphate ratio in the neutral position in preterm and term infants was 1.08 +/- 0.15 and 1.12 +/- 0.21, respectively, and did not change significantly following head turning. These data suggest that any alteration in cerebral blood flow as a result of a change in head position in the healthy neonate may be compensated by physiological and biochemical regulations so that no changes in brain oxidative phosphorylation are measurable.