SummaryAlthough extracorporeal membrane oxygenation (ECMO) is widely used as temporary circulation support, there are no reports of direct parameters indicating cardiac recovery to determine the timing of weaning off.Twenty-five patients supported by ECMO due to hemodynamic deterioration were divided into 2 groups according to their outcome: weaned ECMO (W: n = 18) or not (NW: n = 7). In the W group, we examined the differences in parameters between the 2 time points, ECMO introduction, and the reduction in ECMO flow to 40% of the initial setting known as the conventional recovery point (C-point). Significant differences were observed in systolic pulmonary artery pressure, the cardiac index measured by the thermodilution method, C-reactive protein, lactate, base excess, and the end-tidal CO 2 concentration (ETCO 2 ). Next, by closely examining these 6 parameters measured every 12 hours, we found that only ETCO 2 had always changed steeply, like a 'flexion point' (E-point), in all W cases, but not in NW. The E-point was defined as an initial increase in ETCO 2 of ≥ 5 mmHg over the preceding 12 hours with a continued rise over the next 12 hours. E-points appeared as much as 95 ± 60 hours earlier than C-points and also preceded weaning off of ECMO.ETCO 2 can be a useful continuous parameter for predicting the adequate timing of weaning off of ECMO for circulatory failure at the bedside. (Int Heart J 2010; 51: 116-120) Key words: End-tidal carbon dioxide, Extracorporeal membrane oxygenation, Hemodynamic deterioration, Clinical predictor, Weaning E xtracorporeal membrane oxygenation (ECMO) is widely used not only for temporary cardiopulmonary support in cases of hemodynamic deterioration, but also in bridge therapy for left ventricular assist system (LVAS) as well as cardiac transplantation.1,2) Although setting up the equipment is easy, a quick overall methodology during management has not been fully established. There have been few guidelines concerning its utilization in relation to the treatment of fulminant myocarditis.3) The guidelines say, for example, that ECMO flow of 3-3.5 L/min initially should be reduced gradually with improved cardiac function to around 1.0 L/min, followed by weaning off. As for the predictive indicators, resultant ECMO flow fell to about 40% of the initial flow, implying cardiac recovery, and patients can subsequently be weaned off ECMO.3) Under conventional methodology using 'trial and error' as described above, however, there are no reports of direct parameters indicating cardiac recovery to determine the timing of weaning patients off ECMO. In this study, we focused on clinical variables measured continuously at the patient's bedside, especially the end-tidal carbon dioxide concentration (ETCO 2 ), to determine the appropriate time to wean patients off ECMO.
MethodsPatient population and clinical classification: Thirty-seven consecutive patients with cardiovascular disorders treated with ECMO at our institution between 1996-2008 were investigated. We excluded patients in whom ECMO wa...