Nucleated red blood cells are a predictor of mortality in patients under extracorporeal membrane oxygenation

The presence of Nucleated Red Blood Cells (NRBCs) in critically ill patients is associated with higher mortality and poor prognosis. Although patients on extracorporeal support such as veno-venous or veno-arterial extracorporeal membrane oxygenation (VV/VA-ECMO) are severely ill, NRBCs have rarely been investigated regarding their predictive value so far.

As part of a retrospective study, we examined all cardiothoracic surgery patients from July 2019 to September 2020 who received ECMO treatment during their inpatient stay. The aim of this study was to investigate the occurrence of NRBCs during ECMO support in terms of their predictive value for mortality.

In total 30 patients (age at admission: 62.7 ± 14.3 year; 26 male; ECMO duration: 8.5 ± 5.1 days; ICU duration: 18.0 ± 14.5 days) were included. 16 patients (53.3%) died during their inpatient stay. There were no significant differences in demographic characteristics between VA- or VV- ECMO patients. NRBCs occurred in all patients while under ECMO support. NRBC value was significant higher in those who died (2299.6 ± 4356.6 µl) compared to the surviving patients (133.6 ± 218.8 µl, p < 0.001). Univariate analysis found that patients with a cutoff value of ≥ 270 NRBCs/µl during ECMO support were 39 times more likely to die (OR 39.0, 95% CI 1.5-997.5, p < 0.001). 12 out of 13 patients (92.3%) with ≥ 270 NRBCs/µl died. The area under the curve (AUC) of the receiver operating characteristic curve was 0.85 (95% CI 0.69-0.96) with a sensitivity of 75.0% and a specificity of 92.9%.

NRBCs appear to be an accurate biomarker for mortality in patients with ECMO support. They may be helpful in deciding if therapy becomes futile. Trial registration DRKS00023626 (December 20th 2020).