Changes in peripheral muscle oxygenation measured with near-infrared spectroscopy in preterm neonates within the first 24 h after birth

Abstract

Background: Near-infrared spectroscopy (NIRS) combined with venous occlusions enables peripheral-muscle oxygenation and perfusion monitoring. Objective: The aim of the present exploratory observational study was to evaluate peripheral-muscle oxygenation and perfusion during the first 24 h after birth in stable preterm neonates. Approach: Secondary outcome parameters of prospective observational studies were analysed. Preterm neonates with peripheral-muscle NIRS measurements combined with venous occlusion on the first day after birth were included. Neonates without circulatory support and without signs of infection/inflammation were included. Neonates were stratified in four groups according to their measurement time-point (6 h-periods) and matched 2:1 for gestational age ±1 week. For each group haemoglobin flow (Hbflow), oxygen-delivery (DO2), oxygen-consumption (VO2), fractional-oxygen-extraction (FOE), tissue-oxygenation-index (TOI) and mixed-venous-oxygenation (SvO2) were calculated. Neonates with measurements during the first 6-hour time period were compared to neonates with measurements of the following time periods. Main results: 40 preterm neonates (gestational age (median(IQR)): 33.5(32.5–34.1)weeks) measured during the first 6 h period after birth were compared to 20 preterm neonates measured in each of the following 6 h periods (period two: 33.7(33.1–34.3)weeks; period three: 34.1(33.2–34.6)weeks; period four: 33.8(32.6–34.6)weeks). Hbflow, DO2 and SvO2 were significantly higher in the second and third 6 h time period compared to the first 6 h period. VO2 did not change significantly during the first day after birth. FOE was significantly lower in the second, third and fourth time period compared to the first 6 h period. TOI showed a non-significant trend towards higher values in the third period compared to the first 6 h period. Significance: In preterm neonates Hbflow, DO2, SvO2 increased, FOE decreased and TOI showed a trend towards increase during the first day after birth, whereas VO2 did not change. Changes of peripheral-muscle oxygenation during the first day after birth in stable preterm neonates are different to already published changes thereafter.