A new technique that uses nanometer-sized oxygen bubbles, similar to the cell membrane, may save the lives of those in acute respiratory distress
Damage to the respiratory system due to a disease such as corona (COVID-19), injury or other failure of lung function can cause hypoxemia, a condition in which the level of oxygen in the blood is lower than desired. When such a situation lasts for a few minutes, it may lead to hypoxia, a lack of oxygen in one or more tissues, cause brain damage and even death. In severe cases, respiration will be required and oxygenation will be done outside the body using an ECMO device that replaces the work of the lungs and heart from the outside. But this procedure requires skilled medical staff and involves many risks, such as infections or mechanical damage to the lungs, especially during prolonged use.
In the process of breathing, oxygen enters from the lungs into the bloodstream and reaches every cell in our body, where it is used as an electron acceptor in the process of cellular respiration. In a healthy state, oxygen is abundant in the bloodstream. However, there are medical conditions that include respiratory failure, for example acute respiratory distress syndrome. In most cases, the origin of the syndrome is pneumonia or sepsis. In other cases, trauma to the face or obstruction of the airways may lead to lung edema and limit their ability to absorb oxygen independently.
Recently, researchers from Boston Children’s Hospital and Harvard Medical School have developed an experimental method of introducing oxygen directly into the bloodstream through a vein. The technique is based on turning the oxygen molecules into microscopic particles that are packed in a fatty shell and their controlled release in the patient’s body through infusion.
Various conditions such as pneumonia, airway obstruction or sepsis may lead to respiratory failure. A woman is connected to an Acmo device Kiryl Lis, Shutterstock
The bubbles that carry the oxygen directly into the bloodstream
In the device developed by the researchers, the oxygen is first introduced into a liquid that contains fatty molecules called phospholipids, which are also used as a central component of the cell membrane. The mixture is then injected through a series of three nozzles that get smaller and smaller. As a result, bubbles of oxygen are obtained wrapped in a fatty coating, nanometer in size (billionth of a meter), smaller than a red blood cell.
The fatty mantle is essential because if we inject the oxygen directly into the blood, large oxygen bubbles may form in it that will block the blood vessels. The coating that surrounds the small oxygen bubbles prevents them from merging into large bubbles. The resulting solution is injected directly into the patient’s blood through an infusion, thus allowing a slow release of oxygen in the blood circulation. The method also makes it possible to control the dose of oxygen, which is a crucial element in the treatment of patients. It also reduces the fear of toxicity, since it is a shell that is not foreign to the human body.
The researchers used blood donations from humans and tested the effectiveness of the method by measuring blood oxygen saturation (saturation). The normal saturation level ranges from 95 to 100 percent and reflects the proportion of oxygen bound to hemoglobin, the protein that carries oxygen in the blood. First, the gases nitrogen and carbon dioxide were injected into the blood to simulate a state of hypoxemia. Using the device led to a 15-95 percent increase in oxygen levels within minutes. The method has not yet been tried on humans – its effect was tested on rats, and an increase of 20-50 percent in oxygen levels was observed in them. The method must also be tested on larger animals, but in the meantime, doctor John Kheir from the cardiac intensive care unit at Children’s Hospital in Boston says that “right now it is a good proof of feasibility.”
The main purpose of the technology is to stabilize the condition of those suffering from breathing problems before connecting to the ACMO, to provide a boost of oxygen to damaged lungs and thus reduce the risks associated with the use of ventilators. As mentioned, time is a decisive factor when it comes to a low level of oxygen in the blood. Therefore, providing a quick and available solution may reduce the risks of waiting to be connected to a ventilator. Such a wait could last about 15 minutes at best and an hour at worst. If this simple technology is found to be safe for humans as well, it may save human lives, especially in remote places. Its importance is especially great because in many hospitals around the world the stock of ECMO devices is less than necessary, and in situations such as a global epidemic, the lack of them creates a bottleneck in the treatment of patients suffering from problems in the respiratory system.