Microcirculatory Perfusion Disturbances During Veno-Arterial Extracorporeal Membrane Oxygenation: A Systematic Review

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is used in case of potentially reversible cardiac failure and restores systemic hemodynamics. However, whether this is followed by improvement of microcirculatory perfusion is unknown. Moreover, critically ill patients have possible pre-existing microcirculatory perfusion disturbances. Therefore, this review provides an overview of alterations in sublingual microcirculatory perfusion in critically ill adult patients receiving VA-ECMO support. Pubmed, Embase (Ovid), Cochrane Central Register of Controlled Trials, and Web of Science were systematically searched according to PRISMA guidelines. Studies reporting sublingual microcirculatory perfusion measurements in adult patients supported by VA-ECMO were included. Outcome parameters included small vessel density (SVD), perfused vessel density (PVD), perfused small vessel density (PSVD), proportion of perfused vessels (PPV), microvascular flow index (MFI) and the heterogeneity index (HI). The protocol was registered at PROSPERO (CRD42021243930). The search identified 1215 studies of which 11 were included. Cardiogenic shock was the most common indication for VA-ECMO (n=8). Three studies report increased PSVD, PPV, and MFI 24 hours after initiation of ECMO compared to pre-ECMO. Nonetheless, microcirculatory perfusion stabilized thereafter. Four out of four studies showed higher PSVD and PPV in survivors compared to non-survivors. Over time, survivors showed recovery of microcirculatory perfusion within hours of initiation of ECMO, whereas this was absent in non-survivors. Notwithstanding the limited sample, VA-ECMO seems to improve microcirculatory perfusion shortly after initiation of ECMO, especially in survivors. Further research in larger cohorts is needed to clarify the longitudinal effects of ECMO on microcirculatory perfusion.