Introduction
Sinusoidal obstruction syndrome (SOS), formerly known as veno-occlusive disease (VOD), is a serious complication encountered in the early phase post hematopoietic cell transplant (HCT). The pathogenesis of SOS involves injury to the sinusoidal endothelial cells of the liver, resulting in increased vascular permeability and narrowing of the sinusoids, slowing the blood flow within the vascular lumen (1, 2). The incidence of SOS is typically 5% to 13% but is reported to be higher in the pediatric high-risk population (20-60%) (1-3). Severe SOS is associated with multi-organ dysfunction (MOD) and a higher rate of mortality. Acute kidney injury (AKI) seen in SOS is secondary to kidney hypoperfusion, vasoconstriction, portal hypertension, and fluid overload (3-5). In addition, intra-abdominal hypertension can exacerbate pre-existing kidney injury (3). SOS increases the risk of AKI by 6.02 times in these patients (4). Despite treatment advances, such as the introduction of defibrotide that contributed to reduced mortality and reversal of organ dysfunction, mortality continues to be high if MOD is present, with a 100-day estimated survival rate of only 28% in defibrotide-treated patients (adults and children) who had both ventilator and dialysis dependence (6).
Continuous kidney replacement therapy (CKRT) is used to manage severe AKI and to mitigate the effects of fluid overload (FO), both of which occur in children with SOS. Recent guidelines by the  HCT subgroup of the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) and the Supportive Care Committee of Pediatric Blood and Marrow Transplant Consortium (PBMTC)  recommended consideration of CKRT in children with SOS when FO is  ≥10% (7). Studies that evaluate the use of CKRT in children with SOS following HCT are lacking. Therefore, we sought to examine the use of CKRT in a cohort of critically ill children with SOS following HCT. The primary objective of this study was to assess the outcome of critically ill children post-HCT with severe SOS who received CKRT therapy. In addition, our aim was to assess factors associated with survival and liberation post-CKRT.