Changes in cerebral blood flow velocity (CBFV) have been associated with occurrence of intraventricular hemorrhage (IVH). Blood sampling from umbilical artery catheters (UAC) may cause changes in the CBFV. The primary purpose of this study was to determine if changes in CBFV occurred during blood sampling from high- and low-positioned umbilical artery catheters in preterm infants. Additionally, the study tested for correlations between CBFV and blood pressure, hemoglobin-oxygen saturation, transcutaneous oxygen and carbon dioxide tensions, and behavioral state.

The sample consisted of 30 preterm very low birth weight infants (1500 grams or less). Exclusion criteria were: administration of sedative, anti-seizure, or paralytic medication or presence of an IVH or congenital defect. The study was approved by the University of Alabama at Birmingham Institutional Review Board and the Carolinas Medical Center Institutional Review Committee.

The CBFV measurements were made using a bidirectional ultrasound Doppler transducer with a hand-held 8 mH pencil probe. The CBFV was calculated as the pulsatility index according to the formula (PI = S $-$ D/S) and the area under the velocity curve (AUVC). Repeated measures MANOVA and correlational statistics were used for data analysis.

Findings of the study showed that blood sampling from UACs produced statistically significant changes in the CBFV during aspiration and replacement of blood from high-positioned UACs and during aspiration of blood from low-positioned UACs. No correlations were detected between CBFV and transcutaneous hemoglobin-oxygen saturation, oxygen and carbon dioxide tensions, heart rate, blood pressure, and behavioral state.

The implications from this study are that blood sampling from UACs produces changes in the CBFV and may contribute to IVH and that low-positioned UACs cause less significant changes in the CBFV, and thus, may be safer for use in preterm neonates at risk for IVH. The findings suggest that further studies of the placement and use of UACs are needed.