Ultra-Low Weight < 5 Versus 5-9.9-kg Pediatric Liver Transplant Recipients: Characteristics and Intraoperative Vasopressor Comparisons

Background: Survival in pediatric liver transplantation (PLT) has significantly improved in infants under 1 year, but < 10 kg and < 6 months continue to have poor outcomes with a paucity of information on ultra-low weight (ULW) infants (< 5 kg). We compared intraoperative vasopressor use in < 5 kg versus 5-< 9.9 kg PLT recipients. Methods: We conducted a single-center retrospective review of all PLT recipients < 10 kg at time of transplant from 2009 to 2022, excluding multi-organ transplantation. We collected data on demographics, diagnosis, intraoperative vasoactive infusions, blood loss and requirements, and abdominal closure timing. Outcomes data include total mechanical ventilation, intensive care and hospital length of stay days, 1-year patient and graft survival and thrombotic complications. Results: ULW < 5 kg and 5-9.9 kg patients showed average weight of 4.53 versus 7.30 kg (p-value < 0.0001) and average age of transplant 3.36 versus 7.90 months (p-value 0.0002). The most common etiology of liver disease for ULW versus 5-9.9 kg was neonatal acute liver failure (3 of 5) versus biliary atresia (41 of 63). No significant difference in anhepatic time, abdominal closure, blood products transfused/kg, estimated blood loss/kg was noted. Total days of mechanical ventilation, ICU and hospital LOS were similar between groups. ULW trends toward higher doses of vasopressors during PLT, most notably at end of case compared to 5-9.9 kg (p = 0.06). Overall, 1-year graft and patient