Blood sampling via umbilical vein catheters decreases cerebral oxygenation and blood volume in preterm infants

AIM: We have shown previously that blood sampling via umbilical artery catheters decreases cerebral oxygenation and cerebral blood volume in preterm infants. To evaluate alternative methods, we assessed the effects of blood sampling via umbilical vein catheters in a cohort of preterm infants. METHODS: Twenty neonates (median birth weight 900 g range 410-1900 g], median gestational age 27 weeks 24-31 weeks]) were studied during routine blood sampling via umbilical vein catheters by near-infrared spectroscopy. Tissue oxygenation index and changes in concentrations of cerebral oxygenated and deoxygenated haemoglobin were measured and changes in cerebral oxygenation and cerebral blood volume were calculated. Oxygen saturation and heart rate were recorded simultaneously. RESULTS: There was a significant drop of cerebral oxygenation (-2.135 +/- 0.532 micromol/L) and cerebral blood volume (-0.037 +/- 0.019 mL/100 g tissue) during umbilical vein blood sampling. Although peripheral arterial oxygen saturation remained unchanged, cerebral tissue oxygenation index decreased from 64.8 +/- 2.5% to 62.4 +/- 2.6% (p < 0.01), accompanied by a slight increase in heart rate (from 140 +/- 2.9 to 144 +/- 2.9 beats/min, p < 0.01). CONCLUSIONS: Umbilical vein blood sampling reduces cerebral oxygenation and cerebral blood volume. The magnitude of the effects is similar to those during umbilical artery blood sampling.