To evaluate the magnitude, consistency, and natural history of reductions in cerebral regional tissue oxygenation (CrSO₂) during umbilical arterial (UA) blood sampling in very low birth weight neonates.

Data were collected during a prospective observational near-infrared spectroscopy survey conducted on a convenience sample of 500-1250 g neonates during the first 10 postnatal days. A before-after analysis of UA blood sampling effects on CrSO₂ absolute values and variability was performed. The present analysis was not designed a priori and was conducted following the bedside observation of CrSO₂ decrements contiguous with UA blood draws.

Fifteen very low birth weight neonates had 201 UA blood draws. Baseline CrSO₂ (mean ± SEM) decreased following UA blood sampling, from 70 ± 1% to a nadir of 63 ± 1% (P < .001) occurring 4 ± 3 (range 2-24) minutes following blood draws. CrSO₂ subsequently increased to 70 ± 1% (P < .001 compared with nadir) at 10 ± 4 (range 4-28) minutes following UA blood sampling. Coefficients of variation (mean ± SEM) increased from 0.02 ± 0.001 at baseline to 0.05 ± 0.004 (P < .001), followed by a decrease to 0.03 ± 0.003 (P < .001 for all comparisons), thus denoting increased CrSO₂ variability following UA blood sampling.

UA blood sampling is associated with significant CrSO₂ decrements with increased variability over clinically significant intervals. Whether these changes impact complications of prematurity, including intraventricular hemorrhage and periventricular leukomalacia, remain unknown.