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Energy intake, norepinephrine excretion, and oxygen consumption in low birthweight infants
Insights
Energy intake and norepinephrine levels correlate with metabolic rate (VO2) in low birthweight infants. Postnatal age influences these relationships, suggesting further research is needed.
Area of Science:
- Neonatal Physiology
- Metabolic Research
Background:
- Low birthweight infants face challenges in metabolic regulation.
- Understanding energy metabolism is crucial for infant growth and development.
Purpose of the Study:
- To investigate the relationship between energy intake, urinary norepinephrine excretion, and metabolic rate (VO2) in low birthweight infants.
- To determine the influence of postnatal age on these physiological parameters.
Main Methods:
- Concurrent measurement of energy intake, urinary norepinephrine excretion, and oxygen consumption (VO2) via indirect calorimetry.
- Controlled abdominal skin temperature at 36.5°C using a servo control device.
- Analysis of data using simple and multiple linear regression.
Main Results:
- Energy intake, urinary norepinephrine, and VO2 increased with advancing postnatal age.
- Significant positive correlations were found between energy intake and VO2, norepinephrine and VO2, and postnatal age and VO2.
- Postnatal age significantly influenced the relationship between energy intake and VO2.
Conclusions:
- Energy intake and norepinephrine excretion are key determinants of metabolic rate in low birthweight infants.
- Postnatal age plays a critical role in modulating energy metabolism.
- Further research is required to elucidate the complex interplay between postnatal age and energy intake in this population.
Abstract:
Eleven healthy, appropriately grown low birthweight infants, ages 3-15 days and 28-33 weeks gestation, were the subjects of this study. Energy intake, urinary norepinephrine excretion, and metabolic rate as reflected in VO2 were examined concurrently. Energy intakes were recorded. Simultaneous collection of a timed urine for norepinephrine excretion and measurement of VO2 using indirect calorimetry were performed. A servo control device was used to maintain an abdominal skin temperature of 36.5 degrees C. The results demonstrated increases in energy intake, urinary norepinephrine, and VO2 with advancing postnatal age. Simple linear regression analysis revealed significant positive correlations between energy intake and VO2 (p less than 0.003), norepinephrine excretion and VO2 (p less than 0.003), postnatal age and VO2 (p less than 0.01), and postnatal age and energy intake (p less than 0.001). Multiple regression analysis revealed a strong positive correlation between urinary norepinephrine excretion and VO2, and energy intake and VO2. When postnatal age was added to the multiple linear regression analysis as a variable, energy intake was no longer strongly correlated with VO2. This implies postnatal age and energy intake are closely linked in this study, and further studies are needed to better define these relationships.