Recirculation during Veno-Venous Extra-Corporeal Membrane Oxygenation – a Simulation Study

Abstract

therefore total dependency on the ECMO circuit. The optimal degree of lung rest may therefore depend not only on pulmonary pathophysiology, but also the center-specific risk of technical complications during ECMO treatment. Left ventricular and arterial oxygen saturation during VV-ECMO with collapsed lungs may approach the saturation in the pulmonary artery. This saturation is determined by the efficiency of VV-ECMO therapy, lung function, cardiac output, and oxygen consumption. The blood leaving the oxygenator in the ECMO circuit is normally fully saturated, but blood reaching the right ventricle is mixing with venous blood to varying degrees depending on many factors including cannula positions, cardiac output, and ECMO flow (7).Recirculation of oxygenated blood in the ECMO circuit decreases efficiency of oxygen delivery to the patient, but is difficult to measure clinically (8). Reported values vary between 2% and 57% (8-11). Neither measurement of saturation in true mixed venous blood (S v O 2 ) nor conventional thermodilution cardiac output measurements is possible due to venous admixture of oxygenated blood. It is important to realize that blood sampling in the pulmonary artery will result in higher saturation values than S v O 2 and therefore has a questionable clinical value. Since high venous saturation (S preox O 2 ) in the

Individualized real-time clinical decision support to monitor cardiac loading during venoarterial ECMO

“…In order to enhance bedside clinical decision support, we introduced a real-time, patient-specific simulation model of cardiovascular dynamics [ 6 , 7 ]. The model is built with 32 0-D compartments in total; four cardiac chambers, pericardium, intrathoracic space and 27 vascular compartments including systemic circulation, pulmonary circulation and coronary circulation.…”

Venous Cannula Positioning in Arterial Deoxygenation During Veno-Arterial Extracorporeal Membrane Oxygenation-A Simulation Study and Case Report

“…A previous study has shown that preoxygenator saturation ( S preox O 2 ) is an unreliable measure of treatment efficiency in VV‐ECMO . The venous saturations in the superior caval vein and inferior caval vein may differ as much as 25% or more in VA‐ECMO and S preox O 2 is dependent on the relative contribution from these two sources.…”

“…A closed‐loop real‐time simulation model was developed consisting of 27 vascular segments, the four cardiac chambers with corresponding valves, septal interactions, the pericardium and intrathoracic pressure (Fig. ) published elsewhere . The cardiac chambers are represented as time‐varying elastances and the closed‐loop vascular system segments characterized by nonlinear resistances, compliances, inertias and visco‐elastances.…”

Does permissive hypoxaemia during extracorporeal membrane oxygenation cause long-term neurological impairment?

“…Most centers prefer to drain desaturated venous blood via the inferior vena cava and return the saturated blood through the superior vena cava into the right atrium. With this approach, it is possible to achieve higher saturations due to reduced blood recirculation compared to the technique at the ECMO Department Karolinska [28,29]. However, from my clinical experiences, the limitation of the former approach is that the total extracorporeal flow, i.e., the level of oxygen delivery by ECMO that can be reached, is less with this method than with the method used at the ECMO Department Karolinska, particularly in the awake and dehydrated patient, as the venous drainage through the IVC is dependent on the hydration of the patient and the intraabdominal pressure.…”