The coronavirus pandemic and the need for rapid care for patients diagnosed with Covid-19 caused a rush by hospitals and health systems around the world for ventilators. The equipment is used when the patient's body cannot breathe to supply the necessary amount of oxygen. In these cases, machines do the work that the body, within a situation caused by the disease, cannot do alone.
"Mechanical ventilation is not a big-picture issue, but it is relatively complex, because it involves several particularities", says Thiago Martins, head physician of the Intensive Care Unit (ICU) at Hospital de Clínicas (HC) from Unicamp. He explains that the equipment can operate by controlling the volume of air that is released into the lungs or the pressure at which it enters. Furthermore, it is possible to identify whether the patient's body is also capable of participating in breathing. The way the lungs react to ventilators provides doctors with data that indicates disease behavior as well as signs of recovery. Improper use can cause problems such as low blood oxygen levels or even barotrauma, injuries caused by changes in pressure in the lungs.
The work of monitoring all these variables becomes more complicated in a scenario that requires the care of a large number of patients, often performed by relocated or volunteer doctors, who did not perform these procedures in their daily routine. Thinking about facilitating these actions and also contributing to industries that have adapted their production lines to manufacture lung ventilators, researchers at Unicamp developed mathematical modeling capable of simulating the way in which the air released by ventilators can behave in patients' lungs. This would be possible through the resources of computational fluid dynamics, which translates the behavior of gases and liquids into digital form. O project is part of a series of initiatives announced in the platform of the Unicamp Task Force against Covid-19.
The idea came from Sávio Vianna, professor at the Faculty of Chemical Engineering (QEF) from Unicamp, which works with computer modeling systems. He says he thought about this possibility after conversations with friends in the medical field who told him the challenges of dealing with different situations when using ventilators. From this, he thought about creating a system that could show doctors how each piece of equipment might behave on patients.
"One possible scenario is that a doctor is the head of a ward in a field hospital that uses respirators. Everyone operates with a certain type of equipment and the doctors on the team begin to report that problems are arising with patients, either due to oxygen saturation, or due to barotrauma. In a situation like this, the doctor can contact Unicamp, explain that respirators are causing problems in patients and ask to carry out a simulation. We can carry out the simulation, generate a report and send . Then he can identify the cause of the problem and correct it", reports Sávio.
The software generates images in which factors such as the speed and pressure of the air released by a ventilator in the lungs are simulated, indicating the areas of the lung structure where there is greater or lesser pressure, for example. "I have a reddish area on the image. This indicates a pressure between 4 Pa and 5 Pa (Pascal, unit of pressure). Is this acceptable? I don't know, but the doctor knows, he can say whether this could cause problems or not" , demonstrates the teacher. Initially, the project generated images in simplified models of the lungs. However, through collaboration with universities abroad, it was possible to produce simulations based on tomography images, making them closer to reality.
In addition to generating images, the project also allows the production of other models that can also help predict how the fans will behave. Sávio mentions the possibility of connecting the software to 3D printers and, using flexible materials, printing a lung structure and connecting it to the ventilator, checking its operation even more accurately.
The professor comments that the project is not just intended to facilitate the work of doctors and health professionals. Due to the great demand for equipment and the increase in the number of companies dedicated to its production, he believes that the system should also contribute to work in industries. "We created a simple engineering procedure so that any engineer can work. Providing this, the geometry and the set-up more or less ready, so that, if there is a great demand, more people are able to help with the production of respirators. With this , we will then be able to extend the project to the entire country and in open software, without license costs", explains Sávio.
For professionals who are on the front line in the fight against coronavirus, models of this type can make great contributions to making quick decisions. Thiago Martins believes that the systems can be improved to the point of simulating the conditions of a sick lung. "The forces that govern respiratory dynamics can be simulated. If you consider lung resistance, airway resistance, lung compliance, amount of air entering each respiratory cycle, amount of oxygen dissolved in the air, among other parameters, and create a mathematical model that can simulate all these variables, you can get something very close to the real thing", assesses the doctor.