Predictors of weaning failure in case of VA ECMO implantation

Abstract

The use of veno-arterial extracorporeal membrane oxygenation (VA ECMO) for the treatment of refractory cardiogenic shock has increased significantly. Nevertheless, early weaning may be advisable to reduce the potential for severe complications. Only a few studies focusing on ECMO weaning predictors are currently available. Our objective was to evaluate factors that may help predict failure during VA ECMO weaning. We included 57 patients on VA ECMO support previously considered suitable for weaning based on specific criteria. Clinical, haemato-chemical and echocardiographic assessment was considered before and after a "weaning test" (ECMO flow < 2 L/min for at least 60 min). ECMO removal was left to the discretion of the medical team blinded to the results. Weaning failure was defined as a patient who died or required a new VA ECMO, heart transplant or LVAD 30 days after ECMO removal. Thirty-six patients (63.2%) were successfully weaned off VA ECMO, of whom 31 (54.4%) after the first weaning test. In case of first test failure, 3 out of 7 patients could be weaned after a 2nd test and 3 out of 4 patients after a 3rd test. Pre-existing ischemic heart disease (OR 9.6 [1.1-83]), pre-test left ventricular ejection fraction (LVEF) ≤ 25% and/or post-test LVEF ≤ 40% (OR 11 [0.98-115]), post-test systolic blood pressure ≤ 120 mmHg (OR 33 [3-385]), or length of ECMO support > 7 days (OR 24 [2-269]) were predictors of weaning failure. The VA ECMO weaning test failed in less than 40% of patients considered suitable for weaning. Clinical and echocardiographic criteria, which are easily accessible by a non-expert intensivist, may help increase the probability of successful weaning.

Figure 1

Flow chart of the population. Weaning failure was defined as a patient who died or required a new VA-ECMO, heart transplant or LVAD 30 days after withdrawal from ECMO.

Figure 2

Evolution of systolic blood pressure (A) and LVEF (B) during the weaning test depending on the success or failure of weaning. Pre-test parameters are represented as blue point and post-test results in red. p value for comparisons between pre and post-test parameters and between successful weaning and failure weaning test groups are presented in Table 2. DBP diastolic blood pressure, LVEF left ventricular ejection fraction.

Figure 3

Decision tree (classification tree diagrams). For example, patients who had a post-test SBP of less than 110 mmHg and a post-test LVEF less than or equal to 40% had a 90.9% chance of weaning failure on D30, whereas those with a post-test SBP of more than 110 mmHg who were not dialyzed with a time to weaning of less than 7 days, had a 95.7% chance of weaning success on D30. LVEF left ventricular ejection fraction, SBP systolic blood pressure.