Gentler ventilation thanks to the digital lung model
Artificial ventilation can save lives, but at the same time pressure ventilation is also extremely stressful for the tissue of the lungs. Serious consequences can arise, especially if this has already been damaged. Researchers at the Technical University of Munich (TUM) have now developed a computer model of the lungs that enables gentler ventilation and thus could significantly increase the chances of survival.
In the case of acute lung failure (Acute Respiratory Distress Syndrome, ARDS), artificial respiration is often the solution. If the pressure is too high, however, this can lead to overstretching in some parts of the lungs and ultimately damage them.
Up to now, only a few parameters have been available to medical specialists to set the optimal ventilation of the complex organ, and so far there has been no way of recognizing overdistension. It is currently the clinical standard to calculate the ventilation settings using a rule of thumb based on body weight.
After many years of research, Munich researchers have now developed a digital lung model that is created on the basis of data from a computed tomography examination of the chest and the analysis of a breath. The model uses artificial intelligence to calculate the actual lung volume and outputs values for the mechanical properties of the patient's lungs. A digital twin of the patient's lungs is created, so to speak, with the aim of predicting which settings would lead to damage. In this way, medical professionals can identify which ventilator settings lead to which stresses on the lungs at the micro level, and how they can best adapt the settings accordingly. The gentler ventilation could help to increase the patient's chances of survival.
The researchers now want to bring their results into clinical practice as quickly as possible. The aim of the science team is to have a digital lung model at every ventilation station in the future to help with the optimal setting of ventilation.
Artificial lungs as organ replacements
For people with severe lung disease, a healthy organ transplant is often the only chance of survival. But donor lungs are in short supply. A new artificial lung that is being developed at the Hannover Medical School (MHH) could help.
The German Research Foundation (DFG) has been supporting this scientific approach since 2017 with its nationwide priority program SPP 2014 "Towards an implantable lung". The aim is to develop an artificial lung that can be used permanently as an alternative to a donor organ. A promising project at the MHH, the largest European lung transplant center, is being extended for a further three years.
A biohybrid lung is being researched at the MHH. The basis is extracorporeal membrane oxygenation (ECMO), in which the blood is passed through plastic hollow fibers that act as "artificial alveoli" for gas exchange. This lung support system is already being used clinically - for example to supply oxygen to patients severely ill with COVID-19: inside the intensive care units. "So far, however, we have only been able to bypass lung function with the ECMO for a certain period of time, because the blood forms clots when it comes into contact with the artificial surfaces and clogs the tubes," explains Dr. Bettina Wiegmann, who heads three of the four MHH projects at the Lower Saxony Center for Biomedical Technology, Implant Research and Development (NIFE). This thrombus formation is said to be prevented by colonizing the surfaces of the gas exchange membranes, the blood pump and the tubes with special, vessel-lining endothelial cells. "These non-autologous endothelial cells are also genetically modified in such a way that they are practically invisible to the patient's immune system and are therefore not recognized and fought as foreign."
In the next step, it must now be checked whether the endothelial cells adhere firmly enough to the artificial surfaces and can withstand the frictional load caused by the blood flow. The membranes also have to be further developed so that with the largest possible area for gas exchange, the volume of the artificial organ remains as small and effective as possible, just like in the human lungs. In the human lungs, around 100 to 140 square meters of breathing surface are packed in 300 million alveoli to save space. Another requirement is the shape of the ECMO device, which must be changed during the development of the biohybrid lung so that it can be optimally implanted in the body.
Kidney function must also be considered. Because patients with severe lung disease and who need an ECMO device usually also have an increased risk of acute kidney failure, they need mechanical dialysis in addition to lung replacement therapy. So far, these two procedures have been carried out with separate devices, which, among other things, increases the risk of infections and thrombosis. Wiegmann wants to combine lung and kidney support in a single device. That is another aspect for the development of an individualized implantable lung.
Once all the remaining problems have been resolved, various prototypes of the biohybrid lung will initially be examined under laboratory conditions with the help of artificially generated blood circulation. In a next step, they are then tested first as an acute respiratory aid and later as a permanent lung alternative in an animal model. According to the researcher, it will be a few years before the artificial lungs can be transplanted into the human body.