Etiology of Leukemoid Reaction in Patients Undergoing Extracorporeal Membrane Oxygenation

Abstract

Introduction Nosocomial infections are frequent in patients receiving extracorporeal membrane oxygenation (ECMO). Leukemoid reaction, defined as >50,000 white blood cells (WBCs) per microliter, has been associated with infections in some populations. As ECMO is associated with significant inflammation activation between the patient’s immune system and the circuit components, it is hypothesized that leukemoid reactions may have low specificity for identifying new infections in patients receiving ECMO. Materials and Methods A retrospective cohort study was performed on all adult patients admitted to the Brooke Army Medical Center who received ECMO for greater than 72 hours between 2018 and 2022. Maximum WBCs were obtained for all charts. For those with leukemoid reaction, demographic information and clinical management was obtained. This study was determined to be exempt by Brooke Army Medical Center Institutional Review Board. Results Among 182 patients receiving ECMO for greater than 72 hours, 15 (8%) developed a leukemoid reaction while on ECMO. The median (Interquartile range, IQR) WBC was 53.94 (50.98 to 62.55). Fourteen (93%) patients underwent an infectious evaluation. Patients had a median of 2 (IQR: 2 to 3) etiologies contributing to their leukemoid reaction. At the time of leukemoid reaction, 11 (73%) patients were receiving treatment for a known infection, 6 (40%) were found to have a new thrombus, and 4 (27%) were receiving glucocorticoids. Only 1 (7%) patient was found to have a new infection, an Acinetobacter baumannii bacteremia. Conclusions Leukemoid reactions occur infrequently in patients receiving ECMO and are generally multifactorial. In this cohort, leukemoid reactions rarely occurred in the setting of a new infection and suggest low utility to starting or broadening antimicrobials for these patients. Future studies identifying useful infectious markers are needed for patients receiving ECMO.