227 Effect of Blood Sampling on Cerebral Oxygenation in VLBW Infants: Heel Lance Versus Venepuncture

Abstract

Background: We have shown before that blood sampling from umbilical artery catheters induces a decrease in cerebral oxygenation and cerebral blood volume (CBV) in VLBW infants. The aim of the present study was to assess, if heel lance and venepuncture effect cerebral oxygenation as well. Methods: Seventeen preterm infants (birth weight 355–1280 g, median 790 g; gestational age 24–32 weeks, median 27 weeks) were studied. In 11 cases, heel lance and venepuncture blood sampling were analyzed, in 3 heel lance, and in 3 venepuncture only. Using near infrared spectroscopy changes in oxygenated cerebral hemoglobin (O2Hb) and deoxygenated hemoglobin were measured and changes in cerebral oxygenation (HbD) and CBV were calculated. Arterial oxygen saturation, heart rate, blood pressure and tcPCO2 were registered simultaneously. Results: Blood sampling induced a decrease in cerebral O2Hb (heel lance: −3.1 micromol/L; p = 0.004; venepuncture: −1.7 micromol/L; p = 0.06) and HbD (heel lance: −4.4 micromol/L; p = 0.008; venepuncture: −3.3 micromol/L; p = 0.02) compared to baseline levels which was more pronounced after heel lance. CBV decreased significantly after heel lance blood sampling only. Simultaneously, arterial oxygen saturation as measured by pulse oximetry dropped significantly (from 92.5% to 88.7% during heel lance; p = 0.03; from 92.3% to 89.6% during venepuncture; p = 0.05). Small but significant changes of heart rate and blood pressure were observed. Conclusion: Heel lance and venepuncture for blood sampling induce a decrease in cerebral oxygenation. The decrease is more pronounced and lasting in heel lance compared to venepuncture and it is even of greater magnitude than the decrease during blood sampling from umbilical artery catheters. We speculate that the decrease in cerebral oxygenation during blood sampling from umbilical artery catheters is caused by acute volume loss, whereas the decrease during heel lance and venepuncture might be caused by a stress induced decrease in arterial oxygen saturation.