A 2-year-old girl with carbamoyl phosphate synthetase deficiency under
went emergency hemodialysis (HD) for treatment of acute life-threateni
ng hyperammonemia. HD was performed via catheters placed in each femor
al vein serving as vascular access. The tip of one of the catheters (a
spirating line) was in the left external iliac vein and the tip of the
other catheter (the return line) was in the inferior vena cava (IVC).
High blood flow rates were used in order to rapidly lower the blood a
mmonia (NH3) levels. However, unanticipated marked recirculation in th
e IVC, between the dialysis aspirating and return catheters. was encou
ntered, preventing significant reduction in blood NH3. The recognition
of this problem, suggested solutions, and prevention are described.