Functional evaluation of sublingual microcirculation indicates successful weaning from VA-ECMO in cardiogenic shock

Abstract

Background

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly adopted for the treatment of cardiogenic shock (CS). However, a marker of successful weaning remains largely unknown. Our hypothesis was that successful weaning is associated with sustained microcirculatory function during ECMO flow reduction. Therefore, we sought to test the usefulness of microcirculatory imaging in the same sublingual spot, using incident dark field (IDF) imaging in assessing successful weaning from VA-ECMO and compare IDF imaging with echocardiographic parameters.

Methods

Weaning was performed by decreasing the VA-ECMO flow to 50% (F ₅₀) from the baseline. The endpoint of the study was successful VA-ECMO explantation within 48 hours after weaning. The response of sublingual microcirculation to a weaning attempt (WA) was evaluated. Microcirculation was measured in one sublingual area (single spot (ss)) using CytoCam IDF imaging during WA. Total vessel density (TVDss) and perfused vessel density (PVDss) of the sublingual area were evaluated before and during 50% flow reduction (TVDss _F50, PVDss _F50) after a WA and compared to conventional echocardiographic parameters as indicators of the success or failure of the WA.

Results

Patients (n = 13) aged 49 ± 18 years, who received VA-ECMO for the treatment of refractory CS due to pulmonary embolism (n = 5), post cardiotomy (n = 3), acute coronary syndrome (n = 2), myocarditis (n = 2) and drug intoxication (n = 1), were included. TVDss _F50 (21.9 vs 12.9 mm/mm ², p = 0.001), PVDss _F50 (19.7 vs 12.4 mm/mm ², p = 0.01) and aortic velocity–time integral (VTI) at 50% flow reduction (VTI _F50) were higher in patients successfully weaned vs not successfully weaned. The area under the curve (AUC) was 0.99 vs 0.93 vs 0.85 for TVDss _F50 (small vessels) >12.2 mm/mm ², left ventricular ejection fraction (LVEF) >15% and aortic VTI >11 cm. Likewise, the AUC was 0.91 vs 0.93 vs 0.85 for the PVDss _F50 (all vessels) >14.8 mm/mm ², LVEF >15% and aortic VTI >11 cm.

Conclusion

This study identified sublingual microcirculation as a novel potential marker for identifying successful weaning from VA-ECMO. Sustained values of TVDss _F50 and PVDss _F50 were found to be specific and sensitive indicators of successful weaning from VA-ECMO as compared to echocardiographic parameters.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1855-2) contains supplementary material, which is available to authorized users.