Contemporary review of critical illness following allogeneic hematopoietic stem cell transplant in adults

Abstract

Significant advancements have been made in the care of the allogeneic hematopoietic stem cell (HCT) recipient. However, they remain one of the most vulnerable groups of patients who may be admitted to the ICU. On the one hand, they have been administered treatment with the goal of achieving cure for their underlying disease, yet their unique immunocompromised trajectory and treatment-associated toxicities continue to challenge the intensivist from a diagnostic and management perspective. While infectious disease, allogeneic HCT and critical care research have improved outcomes, there remain significant areas to advance critical care management to further increase the likelihood of bridging to an acceptable quality of life. This review focuses on care of the critically ill patient undergoing allogeneic HCT for hematologic malignancies, critical care conditions that may arise, contemporary practices in their management, and areas to focus future research.

Keywords: Allogeneic hematopoietic stem cell transplant; Hematologic malignancy; Immunocompromised.

Fig. 1

Immunologic sequelae post-transplant. Allogeneic HCT begins with a pre-engraftment (i.e. aplastic) period, with profound neutropenia. Monocytes are the first cells to engraft, followed by granulocytes, platelets, and natural killer cells, restoring much of the innate immunity (i.e., against bacteria). Recovery of adaptive immunity (B and T-lymphocytes) can extend to a year and differs across allogeneic-HCT depending upon graft sources (HLA-mismatch), and GVHD treatments. During the early post-transplantation period (first 100 days), the cellular immunodeficiency state is dominant with low NK and T-cell counts, exposing patients to opportunistic infections. After 100 days (late post-transplantation period), T-cell counts increase steadily. Active vaccination starts after 6 months. CD19 + B-cell reconstitution may take as long as 2 years and hypogammaglobulinemia can persist. Last, patients who received high-dose total body irradiation present with functional asplenia as well as those with GVHD. GVHD graft versus host disease, HCT hematopoietic stem cell transplant, HLA human leukocyte antigen, NK natural killer

Fig. 2

Unique critical care conditions in allogeneic stem cell transplant recipients. CMV cytomegalovirus, GVHD graft versus host disease, HSV human simplex virus, PRES posterior reversible encephalopathy syndrome, TMA thrombotic microangiopathy, VZV varicella zoster virus