Leukocyte fate in adult patients supported with extracorporeal membrane oxygenation: A retrospective cohort analysis

Introduction Extracorporeal membrane oxygenation (ECMO) is known to influence all blood components. Reduction in leukocyte numbers during ECMO and their slow recovery ECMO have been associated with poorer prognosis. However, few studies on leukocyte fate have been conducted on adult patients on ECMO and are predominately cardiogenic shock-specific cohorts. Here, we attempt to examine the leukocyte profiles of ECMO-supported adult patients with both heart and/or lung failure and their associations with mortality and morbidity. Methods This multicenter, retrospective study included adult patients with refractory cardiac and/or respiratory failure supported by veno-arterial (VA) and veno-venous (VV) ECMO between 2016 and 2017. Data were collected from intensive care units of five ECMO centers in Australia, Italy, Japan, Hong Kong, and Germany. The primary outcome was the temporal trend of differential peripheral blood leukocyte numbers pre, during and post ECMO cannulation and survival in patients receiving venovenous and/or venoarterial ECMO. In addition, we evaluated the associations between leukocyte numbers and bleeding, infection, and organ dysfunction. Results Among 164 ECMO patients, mean age was 51 ± 16 years, and 67.7% of patients were male. 58.5% were placed on VA-ECMO, 39% on VV-ECMO, and 2.4% on VA/VV ECMO. Sixty-six patients who underwent ECMO (40.2%) did not survive hospitalization, and 96.9% of deaths occurred during ICU stay. In univariate analysis, a lower monocyte count (HR 0.45, 95% CI 0.21–0.93, p = 0.032), lower platelet count (HR 0.99, 95% CI 0.99-1.00, p = 0.009), higher lymphocyte count (HR 1.10, 95% CI 1.007–1.19, p = 0.033) and higher International Normalised Ratio (HR 3.98, 95% CI 2.64–5.99, p < 0.001) peri-ECMO were associated with increased risk of death. An elevated neutrophil count (HR 1.19, 95% CI 1.04–1.36, p = 0.013), age and lactate dehydrogenase were associated with mortality in multivariate analysis. There were no correlations between leukocyte variables and the development of infectious or bleeding complications. Integrated Discrimination Improvement index showed that SAPS II score with the addition of peri-ECMO lymphocyte (p = 0.001) or monocyte (p < 0.001) numbers have a better predictive value for death in ICU than SAPS II score alone. Conclusions Assessment of ECMO-related monocyte and lymphocyte numeric changes may be useful outcome prognosticators when used in conjunction with SAPS II score. Further investigation with larger patient cohorts will be required.