Life-saving microbubbles
Acute oxygen starvation as a result of asphyxia leads to irreversible consequences, including cardiac arrest. If the lack of oxygen is not quickly replenished, a person can die within a few minutes. According to the results of a new study, intravenous administration of oxygen micro-bubbles increases survival in acute conditions. The bubbles dissolve quickly in the blood, so the risk of air embolism is minimal.
The causes of asphyxia can be drowning, accidental ingestion of food into the trachea, an asthma attack, whooping cough or acute heart failure. A chain of pathological processes rapidly leads to cardiac arrest.
A group of researchers from Boston Children's Hospital and Harvard University have developed oxygen micro-bubbles that can save in acute conditions, giving doctors precious time to eliminate the cause of asphyxia or to perform a tracheotomy to restore breathing.
The idea of using microbubbles as a way of delivering various drugs (drugs or contrast agents) is not new. But their intravenous administration was always associated with the risk of pulmonary embolism – a formidable condition that often leads to death. This was due to the fact that the bubbles were in the blood for too long. Other problems were related to instability, non-decomposable components, and the inability to control the size and shape of bubbles.
By creating new bubbles, the researchers were able to solve these problems. The success is due to the use of a new manufacturing method involving nanoprecipitation of biocompatible polymers at the interface of air and liquid media.
The starting material is dextran– a glucose polymer. Acids were attached to it to impart surface-active properties. When a polymer is combined with an organic solvent and water, micelles are formed – lumps of surfactants. The addition of air leads to the formation of foam – microbubbles of oxygen surrounded by micelles. Dilution with water attracts more and more micelles. Connecting, the micelles form a dense shell around the air bubble.
When administered intravenously, the pH of the blood leads to the formation of charged CO-groups of acids. This allows the liquid to penetrate through the micellar membrane, releasing oxygen at the same time. Electrostatic repulsion of similarly charged CO-groups leads to complete destruction of the shell and dissolution in the blood.
The researchers conducted an experiment on rodents. They blocked their airways to cause asphyxia. After 10 minutes, the patency of the respiratory tract was restored – thus, the situation of helping a suffocating patient by a doctor was simulated.
All animals of the control group died. In the experimental group, the rapid repeated introduction of microbubbles into the blood saved the lives of all animals. There were no signs of complications in the form of an embolism. Comparison with other oxygen sources showed the advantage of microbubbles – animals were injected with large volumes of oxygen (up to 12 ml) without complications.
Article by Dr. Yifeng Peng et al. Interfacial Nanoprecipitation towards Stable and Responsive Microbubbles and Their Use as a Resuscitative Fluid is published in the journal Angewandte Chemie International Edition.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on Wiley: Lifesaving Microbubbles: Stable, self-disrupting microbubbles as intravenous oxygen carriers.