Extracorporeal cardiopulmonary resuscitation: is it futile?

PURPOSE OF REVIEW

Extracorporeal cardiopulmonary resuscitation (ECPR) is a treatment modality used to restore end-organ perfusion in the setting of refractory cardiac arrest in patients receiving cardiopulmonary resuscitation (CPR). Despite advances in medicine, survival from cardiac arrest remains low with conventional CPR. The body of literature relating to ECPR is limited to retrospective studies and case series, with data that are inconsistent. Routine use of ECPR is not currently endorsed by the American Heart Association.

RECENT FINDINGS

In several single-center retrospective studies, ECPR was associated with a higher level of return of spontaneous circulation and survival to hospital discharge, when compared with conventional CPR. However, data from larger population-based registry studies have not reproduced these findings. Implementation of ECPR is a complex endeavor that requires specialized, multidisciplinary expertise to be successful.

SUMMARY

ECPR may be considered as an adjunct to CPR in cases of refractory cardiac arrest. The success of ECPR relies on specialized expertise, thoughtful patient selection, and timely initiation.

Identification of human immune cell subtypes most responsive to IL-1β-induced inflammatory signaling using mass cytometry

IL-1β is a key mediator of the cytokine storm linked to high morbidity and mortality from COVID-19, and IL-1β blockade with anakinra and canakinumab during COVID-19 infection has entered clinical trials. Using mass cytometry of human peripheral blood mononuclear cells, we identified effector memory CD4⁺ T cells and CD4^-CD8^low/-CD161⁺ T cells, specifically those positive for the chemokine receptor CCR6, as the circulating immune subtypes with the greatest response to IL-1β. This response manifested as increased phosphorylation and, thus, activation of the proinflammatory transcription factor NF-κB and was also seen in other subsets, including CD11c⁺ myeloid dendritic cells, classical monocytes, two subsets of natural killer cells (CD16^-CD56^brightCD161^- and CD16^-CD56^dimCD161⁺), and lineage^- (Lin^-) cells expressing CD161 and CD25. IL-1β also induced a rapid but less robust increase in the phosphorylation of the kinase p38 as compared to that of NF-κB in most of these immune cell subsets. Prolonged IL-1β stimulation increased the phosphorylation of the transcription factor STAT3 and to a lesser extent that of STAT1 and STAT5 across various immune cell types. IL-1β-induced production of IL-6 likely led to the activation of STAT1 and STAT3 at later time points. Interindividual heterogeneity and inhibition of STAT activation by anakinra raise the possibility that assays measuring NF-κB phosphorylation in response to IL-1β in CCR6⁺ T cell subtypes could identify those patients at higher risk of cytokine storm and most likely to benefit from IL-1β-neutralizing therapies.