Umbilical artery catheters and blood flow velocities in the superior mesenteric artery: Effect of insertion, removal, aspiration, and bolus infusion

Purpose. We studied whether umbilical artery catheters (UACs) affect blood flow in the superior mesenteric artery (SMA) of neonates. Methods. Noninvasive duplex pulsed Doppler sonography was used to measure peak systolic velocity, end-diastolic velocity, and mean flow velocity in the SMA. The resistance index and pulsatility index were calculated from these data. Thirty-two infants weighing 450-2,520 g at birth were enrolled in the study. Gestational age at birth was 24-37 weeks. Eighteen infants were studied before and after UAC insertion. Twenty infants were studied before and after UAC removal. Eleven infants with UACs were studied before and during aspiration of blood from the UAC and during bolus infusion of 5% dextrose solution into the UAC. Data were compared before and after UAC insertion; before and after UAC removal; and before and during aspiration and during bolus infusion. Results. Blood flow velocities and vascular resistance were similar in all comparisons except for increases in end-diastolic and mean velocities after UAC insertion. Conclusions. Insertion and removal of UACs, aspiration of blood from UACs, and bolus infusion of fluids into UACs do not diminish blood flow velocity or increase vascular resistance in the SMA. (C) 1998 John Wiley & Sons, Inc.