Flow Manipulation and the Association with Myocardial Systolic Function During Extracorporeal Life Support
Abstract
Background:
Peripheral veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is used to support circulatory failure refractory to conventional therapy. However, data on the heart-ECMO interaction at different levels of ECMO blood flow during the immediate period after ECMO initiation are sparse. We evaluated the effects of varying ECMO blood flow rate on left ventricular systolic function.
Methods:
Adult patients who were supported by peripheral V-A ECMO in a tertiary referral center were recruited. Serial hemodynamic and cardiac performance parameters were measured by transthoracic echocardiogram within the first 48 hours after implementation of V-A ECMO. Measurements at 100%, 120%, and 50% of target blood flow (TBF) were compared.
Results:
A total of 45 patients were included, 32 (71.1%) were male, and the median age was 57 (50-64) years. The main indications for V-A ECMO were myocardial infarction 25 (55.6%) and myocarditis 6 (13.3%). With a decrease in extracorporeal blood flow from 100% to 50% of TBF, mean arterial pressure dropped from 75±18 to 67±20 mmHg (p<0.001), but stroke volume increased from 15 (8-25) to 21 (13-34) mL (p<0.001), and cardiac index increased from 0.8 (0.5-1.3) to 1.2 (0.7-1.7) L/min/m2 (p<0.001). All indices of left ventricular contractility improved at 50% compared with 100% TBF: the global longitudinal strain improved from -2.8 (-5.4-0) to -4.7 (-8.2- -1.1)% (p<0.001); left ventricular ejection fraction increased from 16.8 (10.0-28.5) to 28.2 (18.0-35.5)% (p<0.001); and left ventricular outflow tract velocity time integral increased from 4.7 (2.7-7.8) to 7.7 (3.9-11.3) cm (p<0.001). The addition of echocardiographic parameters improved the discrimination of the SAVE score in predicting hospital mortality (AUROC 0.71 vs 0.58).
Conclusions:
In the initial period of V-A ECMO support, left ventricular systolic function quantified bedside echocardiography was inversely related to ECMO blood flow rate. The heart-ECMO interaction should be considered when determining goals of ECMO flow after initiation.