WWhen the heart stops and the circulation stops, the most important thing for life is missing: oxygen. Still, cardiac arrest doesn’t have to be the end. Not even if the lungs fail as a respiratory organ. Provided you are in the clinic and it is equipped accordingly. In the pandemic, thousands of patients have already been saved through the most critical phase with ECMO – “extracorporeal membrane oxygenation”. The blood is routed outside the body and enriched with oxygen in the machine. An American team from the Yale School of Medicine in New Heaven has now tested a machine – “OrganEx” – on pigs, which uses a special artificial and, above all, cell-free solution instead of natural blood to treat the organs for over an hour after cardiac arrest almost completely intact – and even functionally restoring some of the tissue that was damaged first. Even after six hours of perfusion, the damage to blood vessels and cells was less than with ECMO, for example, which makes this system particularly interesting for the “life support” of replacement organs during transport, which sometimes lasts for hours.
The system developed by the American researchers is intended to increase the chances of organ donation from people who have died of circulatory failure. It is designed to minimize organ damage between patient death and transplantation. However, the result, which has now been tested in experiments with some pigs and presented in the journal “Nature”, is still a long way from being usable for human organs. Even more important, at least in this country: In Germany and some countries, such an organ survival machine after cardiac death is out of the question with the current legal situation. Because in this country, organ donation is only allowed after brain death – and not after death caused by cardiac arrest. However, should the system also prove itself in humans elsewhere, the age-old discussion about whether patients who died from cardiovascular disease, such as in the USA, are eligible for organ donation (Donation after Cardiac Death, DCD for short) and thus could reduce the organ shortage should be taken up , gain momentum again.
In general, skepticism still prevails among the experts
Most experts who have seen and evaluated the current Nature publication so far express reservations in this regard. Jan Grummert, Director of the Clinic for Thoracic and Cardiovascular Surgery in Bad Oeynhausen, says: “When donating after cardiac death, perfusion of the whole body is also used, depending on the donation protocol. The OrganEx system could possibly be an option for this. There is hope that one day the DCD donation will also be possible in Germany.”
In general, however, skepticism still prevails among the experts, especially with regard to the data situation for the procedure. Uta Dahmen, Head of Experimental Transplantation Surgery at Jena University Hospital, says: “This system and the knowledge gained with it have great potential for a wide range of clinical applications. In transplantation medicine, use for ‘organ repair’, the improvement of previously damaged organs, before transplantation is conceivable. It can also be used in other situations after a temporary reduced blood flow to organs, such as after a heart attack. However, there is still a long way to go from a promising experimental study to routine clinical use of a new medical device.”
Konrad Fischer from the Technical University of Munich comments on the results in a similar way: “In summary, this is a promising study to reduce graft damage. However, the clinical benefit must first be shown by transplantation experiments.” And the transplantation specialist criticizes: “Although the study provides numerous cell-specific expression data, the determination of inflammatory factors in the perfusion solution, which allow statements to be made as to whether the perfusion solution itself triggers inflammation of the endothelium, is missing. which would only become apparent several hours after the transplant and could lead to transplant rejection.”
Stefan Kluge, Director of the Clinic for Intensive Care Medicine at the University Hospital Hamburg-Eppendorf, is also cautious: “First of all, the study is of course very interesting. As a limitation, however, it must be mentioned that it is a comparatively small study on pigs. And: a mitigation of cell death ultimately says nothing about the actual function of the organ. Still, it is an experimental study that goes in the right direction.”
