105: Clinical Outcomes in Critically Ill Children on Extracorporeal Membrane Oxygenation with Severe Thrombocytopenia.

Objective: As international guidelines suggest keeping platelet counts above 80x109 cells/L in children on extracorporeal membrane oxygenation (ECMO), platelet transfusions are administered to two-thirds of ECMO days, and up to 70% of these patients still bleed. Our objective was to describe outcomes in children who develop severe thrombocytopenia on ECMO and had a restrictive transfusion strategy. Methods: Single-center retrospective study, enrolling critically ill children on cardiac ECMO, at Memorial Hermann, between 1/2020 and 12/2022, with at least one platelet count below 50x109 cells/L. We report platelet counts measured four times a day, platelet transfusion, bleeding and clotting events within the subsequent 6 hours. Results: We enrolled 34 patients over 3 years, representing 239 ECMO days and 860 platelet counts. Median weight was 3.3kg (IQR 2.7;4.4) and 44% were male. The overall 28-day mortality was 56%. The overall median platelet count was 39 (IQR 27;58). Of the 566 instances with a platelet count below 50, 16% (95%CI 13;19) were transfused platelets in the following 6 hours, 13% (95%CI 10;16) had a bleeding event, and 0.5% (95%CI 0.2;1.6) had a thrombotic event. Only 3% (95%CI 2;5) had both bleeding and platelet transfusions. Discussion: While current recommendations result in large proportion of transfusions of children on ECMO, our results seem to indicate a more restrictive transfusion strategy, where platelet counts are allowed to fall below 50x109 cells/L, isn’t associated with higher proportions of bleeding or transfusion requirements. Multicenter studies are needed to evaluate further the appropriateness of this strategy.