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safety and efficacy of ECMO , further solidifying its role in LTx . Conclusion : In conclusion , this review underscores ECMO ' s critical role in enhancing outcomes across all stages of lung transplantation . Its various configurations and strategies have shown promise in stabilizing critically ill patients and improving transplant success rates . Looking ahead , it ’ s important to gather more information about the long-term outcomes and potential complications associated with ECMO use . More research and data collection will help us understand the benefits and risks better , leading to improved decision-making and patient care in this field .
Key words : Lung transplantation ( LTx ), ECMO ( Extracorporeal Membrane Oxygenator ), Primary graft dysfunction ( PGD ), Cardiopulmonary bypass ( CPB ).
Introduction
Lung Transplantation ( LTx ) is a life-saving intervention for patients with end-stage lung disease , offering a chance at improved quality of life and long-term survival . However , the success of LTx relies on factors like suitable donor organs , viable transplanted lungs , and effective management of post-transplant complications . Extracorporeal Membrane Oxygenation ( ECMO ) has emerged as a crucial therapy in LTx , revolutionizing patient care before , during , and after the transplant .
ECMO is based on the well-established cardiopulmonary bypass technology used in cardiac surgery . Nowadays circuit sizes are reduced and are often integrated with a sophisticated user interface and monitoring . The key components of an ECMO circuit include the cannulae for access and return of blood to the patient , often coated with biological materials to limit activation of the immune and coagulation pathways . A centrifugal pump is used to pump the blood around the circuit , often magnetically levitated , to limit trauma to blood cells . An oxygenator and gas blender for gas exchange , similar to the native lung , and hence also known as the ‘ membrane lung ’, with a much smaller machine lung surface area than the native lung is used . A heater-cooler to keep the blood traversing the extracorporeal circuit at a set temperature is also incorporated into the circuit .
The two common modalities of ECMO include venovenous or VV ECMO and veno-arterial or VA ECMO and it has recently been proposed that a third entity called venopulmonary or VP ECMO be classified as a separate entity [ 1 ]. VV ECMO , as the name suggests , drains the blood and returns it to the patient ’ s venous system , and by that , it assists only in gas exchange , replacing and or supporting solely the lung function . It may be argued that by supplying oxygenated blood to the pulmonary circulation , it may reverse acute hypoxic pulmonary vasoconstriction and hence offload the right ventricle , which is noted to be strained in up to 50 % of severe ARDS patients [ 2 ]. VA ECMO , on the other hand , returns the oxygenated blood to the patient ’ s arterial system , and hence it supports not only the gas exchange and lung function but by virtue of the centrifugal pump returns the blood with force into the aorta , thus supporting systemic circulation and heart function . VP ECMO returns the oxygenated blood to the pulmonary artery . VP ECMO offloads the right ventricle and supports both lung and right heart function . Recently , VP ECMO has been achieved using a single dual-lumen cannula [ 3 ]. All three modalities of ECMO namely VV , VA , and VP can be utilized in the perioperative period for lung transplant .
While ECMO has been utilized for long for respiratory and or cardiac failure , its use in lung transplantation has gained considerable attention recently for its potential to overcome many a transplant-related hurdle . The role of ECMO in LTx may be described as multi-faceted . It acts as a bridge to transplantation , supporting patients with severe respiratory failure while they await a suitable donor organ . By improving gas exchange and maintaining organ function preoperatively , ECMO increases the chance of successful transplantation and reduces deterioration in organ function during the waiting period . It also offers hope to several patients with end-stage disease who urgently need lung transplants but cannot be listed due to one or more contraindications . In some of these cases , patients can be salvaged with the support of ECMO , while the noted transplant barriers such as infection or other organ dysfunction are being optimised by excellent multidisciplinary care . Additionally , ECMO can assist during the transplantation surgery itself , allowing surgeons more time for the procedure and facilitating optimal organ preservation . In the immediate post-transplant period , complications including primary graft dysfunction , acute rejection , infection and right ventricular failure significantly impact patient outcomes . ECMO support post-lung transplant has shown promise in managing these complications by providing temporary respiratory and cardiac support , enabling the transplanted lungs to recover .
This comprehensive review aims to analyze existing research on ECMO in LTx , discussing its configurations , indications , contraindications , its utility as a bridge to transplantation , donor organ preservation , and post-transplant complications . The review will also explore advancements in ECMO technology that enhance its efficacy and safety providing valuable future considerations in the field of LTX [ 4 ].
History of ECMO and lung transplantation
The roots of ECMO can be traced back to the 1950s when heart-lung bypass machines were first developed . Originally designed for open-heart surgeries , these machines allowed surgeons to divert blood from the heart and lungs , enabling them to operate on the heart while the machine took over the gas exchange and circulation of blood . In the following decades , medical professionals began exploring the potential of this technology for supporting patients with severe respiratory failure . This exploration led to the development of ECMO , a technique that involves extracting blood from the patient , oxygenating it externally , and then returning it to the body , effectively bypassing the lungs . The first successful utilization