Long-term variation in oxygen consumption rate in preterm infants

Area of Science:

• Neonatal physiology
• Indirect calorimetry
• Energy metabolism

Background:

• Accurate assessment of energy expenditure is crucial for preterm infant growth.
• Previous studies often relied on short-term measurements of oxygen consumption rate (VO2).
• Understanding long-term VO2 variation is essential for precise nutritional management.

Purpose of the Study:

• To investigate the long-term variation in oxygen consumption rate (VO2) in preterm infants.
• To determine the reliability of short-term (e.g., 24-hour) VO2 measurements in this population.
• To assess the impact of measurement duration on the precision of VO2 estimation.

Main Methods:

• Open-circuit, indirect calorimetry was used to measure VO2.
• Four preterm infants (gestational age 27-34 weeks) were studied over 5 days each.
• Between-subject and between-measurement coefficients of variation were calculated for different time intervals.

Main Results:

• Mean VO2 values were within the reported range for preterm infants.
• Between-measurement variation in daily VO2 (3.8%) exceeded between-subject variation (2.1%).
• VO2 measurement variation increased significantly with shorter intervals, reaching 8.3% for 1-hour periods.

Conclusions:

• Even 24-hour VO2 measurements in preterm infants may not accurately represent individual energy expenditure over 3-5 days.
• Short-term VO2 measurements can lead to substantial errors in calculated energy deposition, affecting nutritional studies.
• Longer measurement durations or refined methodologies are needed for reliable energy expenditure assessment in preterm infants.