Veno - left atrial extracorporeal membrane oxygenation for respiratory failure

The development of ECMO technology allows a new approach for the intensive care management of acute cardiac and/or respiratory failure in adult patients who are not responsive to conventional treatment. The ECMO circuit is composed of three main components including a pump, oxygenator, and heat exchanger. Venous blood is drained and then pumped through the heating component, the oxygenator, and then returned to the patient. The circuit blood is returned to an artery (venoarterial ECMO [VA ECMO]) or a vein (venovenous ECMO [VV ECMO]). VV ECMO can be performed with different cannulation strategies. While VV ECMO circuits usually include the cannulation of two vessels, femoro-jugular or femoro-femoral, the use of a dual-lumen single cannula is also possible for VV-ECMO support. The oxygenated blood mixes with the native venous circulation such that the resultant arterial oxygen tension and saturation represents a mixture of the oxygenated extracorporeal blood and the unoxygenated venous blood that passes through the resting native lungs.

However, by virtue of being positioned in the venous side of the vascular system, these cannulation techniques have the inherent issue of recirculation and mixing. Recirculation is a phenomenon wherein reinjected oxygenated blood is withdrawn by the drainage venous cannula without passing through the systemic circulation. This recirculation fraction is not available for systemic oxygenation and may contribute to ineffective ECMO and hypoxemia. With typical ECMO flows of 3–4 L/min, some of the blood flows through the ECMO circuit and some is shunted past the ECMO circuit into the diseased native lung. This leads to a mixing of well-oxygenated ECMO blood with poorly oxygenated shunted blood, which lowers total oxygen saturation. We hypothesize that a higher oxygen delivery to the systemic circulation may be achieved by returning oxygenated blood directly into the left atrium (LA). It may also achieve greater degree of lung rest and recovery as the lower ventilatory settings may be needed consequent to reduced pulmonary blood flow. Also, improved oxygen delivery to the heart may prevent myocardial dysfunction and the need to convert to VA ECMO. Therefore, we propose the V-LA cannulation technique for ECMO wherein the drainage cannula will be placed via the femoral vein and the LA return cannula will be placed by trans-septal puncture via the internal jugular vein (IJV).