One of the most perplexing features of COVID-19 is the so-called “silent hypoxemia” or “happy hypoxia.” that occurs spontaneously in many patients.
People who undergo this disease have extreme lung inflammation with dramatically decreased arterial blood oxygen levels (known as hypoxemia). However, they do not report signs of breathing problems or elevated respiratory rate, which are typically associated with difficulties in breathing due to pneumonia.
Patients with “silent hypoxemia” appear to have sudden cardiac arrest and may have a fatal result. When people are hypoxic (lack oxygen), they usually experience shortness of breath and a fast breathing rate, which increases how much oxygen is absorbed.
This reflex function relies on innervation from the carotid bodies.
These small organs, located on either side of the neck, sense the drop in oxygen in the blood, and then send signals to the brain that promote respiration.
A group of researchers from the Institute of Biomedicine in Seville – IBiS/University Hospitals Virgen del Rocío y Macarena/CSIC/University of Seville, led by Dr. Javier Villadiego, Dr. Juan José Toledo-Aral and Dr. José López-Barneo, specialists in the study of the circulatory system, suggest that the “silent hypoxemia” in COVID-19 cases may be caused by coronavirus infection (SARS-CoV-2).
This theory, which has piqued the attention of the scientific community because of its novelty and possible therapeutic importance, is focused on studies that indicate a high abundance in the carotid artery of the enzyme ECA2, the protein used by the coronavirus to infect human cells.
In people infected with coronavirus, the virus circulates through blood.
Researchers suggest that infection of the human carotid body by SARS-CoV-2 in the early stages of the disease could alter its ability to detect blood oxygen levels, causing it to fail to “notice” the drop in oxygen levels in the arteries.
If this theory is confirmed, carotid body activators will be prescribed as respiratory stimulants for chronic obstructive pulmonary disease patients with COVID, despite the lack of oxygen detection.
In line with the option of article: Reference, “Is Carotid Body Infection Responsible for Silent Hypoxemia in COVID-19 Patients?” by Javier Villadiego, Reposo Ramírez-Lorca, Fernando Cala, José L Labandeira-García, Mariano Esteban, Juan J Toledo-Aral, and José López-Barneo, November 23, 2020, Function.DOI: 10.1093/function/zqaa032.