Ventilate the rectum to support breathing

Tokyo, Japan – Oxygen is essential for many life forms. Its delivery to the body’s organs and tissues through the respiratory process is essential for most biological processes. Researchers at Tokyo Medical and Dental University (TMDU) have now shown that oxygen can be delivered through the intestinal wall to compensate for the reduced oxygen availability in the body that occurs in lung diseases that cause respiratory failure.

To breathe is to live. Respiration in higher animals involves absorbing oxygen and expelling carbon dioxide through the gills or lungs. However, some animals have evolved alternative ventilation mechanisms. Loaches, catfish, sea cucumbers, and spiders can absorb oxygen from their hindguts to survive in situations where available oxygen is limited. Inspired by these unique adaptations, the team at TMDU devised a strategy that allows gas exchange through the lining of the intestine, a process called enteric ventilation or EVA.

“Just below the surface of the inner wall of the rectum, there is a network of fine blood vessels, which means that drugs administered through the anus are easily absorbed into the bloodstream,” explained lead author Ryo Okabe. “This led us to wonder if oxygen could be delivered to the bloodstream in the same way. We tested the two methods using experimental models of respiratory failure in mice, pigs, and rats. One method is to deliver oxygen to the rectum in the form of a gas, and the other is by injecting oxygen. An oxygen-enriched fluid is delivered through the same route.”

The researchers rubbed the lining of the rectum to cause inflammation and increase blood flow. These changes were confirmed by an increase in genetic markers and an improvement in the effectiveness of oxygen delivery. However, since the need for such preparations is unacceptable for human patients, the researchers also found that they can be used safely in humans, are already in selective clinical use, and can carry large amounts of substances. We also tried using oxygenated perfluorodecalin (PFD), which is a liquid. Oxygen and carbon dioxide.

The research team demonstrated that it is beneficial to supply oxygen in both gas and liquid form. This meant increased oxygenation levels, normalized behavior, and prolonged survival. The research team also confirmed improved oxygenation at the cellular level using immunochemical staining. Furthermore, we found that minimal amounts of PFD absorbed along with oxygen are not harmful and do not destroy gut bacteria, demonstrating the safety of these methods in animal models.

“Patients with breathing difficulties can be supported with oxygen supply by this method to reduce the negative effects of oxygen deprivation during treatment of the underlying disease,” predicts corresponding author Takanori Takebe. “Enteral ventilation has shown great promise in experimental models such as asphyxiation. The next steps are to better understand the mechanisms by which the EVA approach works, test its safety, and confirm its efficacy in humans in clinical settings.” It’s about establishing your sexuality.”

Traditional respiratory support treatment consists of complex technical protocols such as mechanical ventilation and artificial lungs. The current SARS-CoV-2 pandemic highlights the high need for the development of less invasive alternatives, such as EVA, for short-term support of respiratory function. These new findings by TMDU researchers could pave the way for new ventilation strategies in the future.

###

The article “Enteral ventilation improves respiratory failure in mammals” med At DOI:10.1016/j.medj.2021.04.004