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Umbilical artery catheter blood sampling alters cerebral blood flow velocity in preterm infants
J W Lott1, G K Conner, J B Phillips
1Regional Center for Neonatal Intensive Care, Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
Objective:
Changes in cerebral blood flow velocity (CBFV) have been associated with occurrence of intraventricular hemorrhage in preterm infants. Blood sampling from umbilical artery catheters (UACs) may cause changes in CBFV. Two UAC positions are generally used, high (T6 to T10) and low (L3 to L5). We hypothesized that CBFV changes would occur during UAC sampling and that CBFV changes would be greater in the high than the low position.
Study Design:
We measured CBFV in the anterior cerebral artery in 30 very low birth weight infants before, during, and after aspiration and replacement of blood from UACs in both high and low positions. CBFV was calculated as the area under the velocity curve (AUVC) and the pulsatility index. Data were analyzed by paired t tests and repeated-measures multivariate analysis of variance.
Results:
Blood sampling from UACs produced significant changes from baseline in CBFV during aspiration (-19%) and replacement (+9%) of blood from high UACs and during aspiration (-8%) of blood from low-positioned UACs. Overall, there was a 35% difference in AUVC CBFV between sampling and replacement in the high position, compared with a 15% difference in the low position. Changes in AUVC during both aspiration and replacement were significantly greater in the highpositioned UACs. No significant changes were noted for pulsatility index throughout the study.
Conclusions:
Blood sampling from UACs produces clinically significant changes in CBFV and may contribute to intraventricular hemorrhage. Blood sampling from low-positioned UACs caused smaller CBFV changes, thus this position may be safer for use in infants at risk for intraventricular hemorrhage.