(P-TA-13) Therapeutic Plasma Exchange in Pediatric Patients with Multi-system Organ Failure and ECMO-associated Mechanical Hemolysis

American Society for Apheresis (ASFA) guidelines categorize therapeutic plasma exchange (TPE) for mechanical hemolysis as a category III, grade 2C indication. While free hemoglobin can directly contribute to tissue injury, pediatric patients with mechanical hemolysis are often have concomitant multi-system organ failure. As such, it is unclear how removal of free hemoglobin by TPE contributes to outcomes in these patients. Further, in-depth evaluation of TPE for pediatric patients with mechanical hemolysis is limited. Thus, we investigated the impact of TPE for mechanical hemolysis in a retrospective cohort of pediatric apheresis patients and multi-system organ failure.

Study

Design/Methods:

This study received institutional board review (IRB) and subsequent site approval by our institution. We queried an internal database of pediatric patients undergoing TPE from Jan 1, 2011, to December 31, 2021. Indication(s) for apheresis included: hemolysis, elevated free hemoglobin, and sepsis with multi-system organ failure.  Plasma free hemoglobin (PFH) was assessed using Hemocue® Plasma/Low Hb Photometer (HemoCue America, Brea, CA), with a reference range of 0 - 100 mg/dL. Multi-system organ failure was defined as failure of 2 or more organ systems. Descriptive statistics were performed, and survival curves were generated using GraphPad PRISM (version 9.5.1, GraphPad Software, Boston, MA).

Results/Findings:

Over an 11-years, 20 patients, consisting of 13 females and 7 males, with a median age of 6 years (IQR=21.3 days to 14 years), who had multi-system organ failure and ECMO-associated mechanical hemolysis were identified. No patients with ECMO-associated hemolysis without multi-system organ failure were identified.  They underwent a total of 40 TPE procedures, with a median of 1.5 procedures (IQR=1-3). The median plasma volume exchanged was 1.1 (IQR=1.1-1.1), and the replacement fluid was: albumin and fresh frozen plasma (FFP) (33/40), FFP only (4/40), or albumin alone (3/20). The side effect rate was 20% (8/40): calcium abnormality (5) or hypotension (3). The median starting PFH was 270 mg/dL (170-770 mg/dL), the post-procedure PFH was 140 mg/dL (80-312.5 mg/dL), and the median decrease in PFH was 49% (IQR 20-67%). Eight patients had increases in PFH after TPE. The median survival was 9 days (4.5-19.5) after the first TPE, and the 30-day mortality was 75% (15/20) (Figure A), with an overall mortality of 85% (17/20).

Conclusions:

Multi-system organ failure with ECMO-associated mechanical hemolysis carries a grim prognosis for pediatric patients. TPE appears to effectively lower PFH in many of these patients. Although, lower plasma free hemoglobin levels should theoretically reduce tissue damage and practically allow for performance of chromogenic or photometric assays, durable benefit is difficult to quantify. Decisions to perform TPE for ECMO-associated hemolysis should be made on a case-by-case basis.