Journal of the American College of Cardiology, 61 (10), Supplement, 12 March 2013, E436.
BACKGROUND: Currently, there are no established echocardiographic (echo) or hemodynamic predictors of mortality after venous-arterial extracorporeal membrane oxygenation (ECMO) wean in children. We attempted to determine which echo and hemodynamic measurement predicts mortality.
METHODS: Over 2 years, we prospectively assessed 6 echo and 6 hemodynamic variables at 3-5 ECMO flow rates during flow wean. Hemodynamic measurements were: heart rate, inotropic score, arterio-venous oxygenation difference (AV-02), pulse pressure, oxygenation index (OI) and serum lactate. Echo variables included: shortening and ejection fraction, outflow tract Doppler-derived stroke distance (VTI), amount of atrioventricular valve regurgitation, global longitudinal strain (GLS) and global circumferential strain (GCS). Patients were stratified into those who died or needed a transplant (Gr1) and those that did not (Gr2). For each patient, we compared the change within each of these variables between full versus minimum flow for Gr1 versus Gr2 using a paired t-test.
RESULTS: Twenty-one patients were enrolled in the study with an age range of 0.05-15 years. Five had dilated cardiomyopathy while the remaining 16 had structural heart disease with cardiomyopathy. Twelve patients comprised Gr1 with only one heart transplant while 9 who lived constituted Gr2. In Gr1, subjects had a significantly greater increase in AVO2 (31% mean increase, p<0.01) and Ol (43% mean increase, p<0.01) off ECMO compared to full flow but no change in VTI with flow wean. In Gr2, VTI increased significantly (30% mean increase p<0.01) with no change in AVO2 or Ol. GLS was nearly significantly increased off ECMO in Gr2 (p=0.09). Pulse pressure increased significantly in both groups and was not discriminatory (p<0.01).
CONCLUSIONS: Failure to augment VTI during ECMO flow wean or an increase in OI and AVO2 portend poor outcomes in pediatric patients. These measurements should be a part of practice standards for patients weaning from ECMO and may discern who will require alternative methods of support. Future studies appear indicated to confirm these findings with a larger sample size.