Background: In December 2015, the Minnesota Resuscitation Consortium (MRC) initiated a protocol to rapidly mobilize patients suffering refractory ventricular tachycardia/ventricular fibrillation (VT/VF) cardiac arrest and provide advanced hemodynamic support and reperfusion. The hemodynamic support most often necessary for these patients with ongoing cardiopulmonary resuscitation (CPR) was percutaneously placed peripheral veno-arterial extracorporeal membrane oxygenation (VA-ECMO). While VA-ECMO is critical to support these patients early on, it also presents risks which are best mitigated by decannulation as soon as it can be accomplished safely. The aim of this study is to determine whether use of left ventricle ejection fraction (LVEF) assessed by transthoracic echocardiography (TTE) alone is sufficient to guide weaning of VA-ECMO.
Methods: A retrospective analysis of refractory VT/VF out-of-hospital cardiac arrest patients treated with peripheral VA-ECMO between 12/2015 and 4/2017 was performed. Suitability for decannulation was determined in these patients using a daily turndown protocol using TTE each day the patient was on ECMO. TTE was performed at baseline ECMO flow and decreased ECMO flow of 2L/min. LVEF, hemodynamics and arterial blood gasses were obtained at each step. Patients were deemed suitable for decannulation when three criteria were met: 1) LVEF was >25% at ECMO flows of ≤ 2 L/min with or without inotropic support, 2) mean arterial pressure of >55mmHg was maintained under the same conditions, and 3) arterial oxygen saturation of >92% on <10mmHg of PEEP and <50% of FiO2 on the ventilator.
Results: Twenty-six patients were included. Using the above criteria for decannulation, 24 of the 26 (92%) patients were deemed suitable for decannulation. All decannulated patients maintained hemodynamic and respiratory stability. Two patients were deemed unsuitable for decannulation and died from other complications.
Conclusion: Assessment of LVEF by transthoracic echocardiography alone was adequate to successfully guide the timing of decannulation following VA-ECMO for refractory VT/VF.