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Infectious Diseases

Updated 26 May 2020

What the lungs of Covid-19 patients can tell us about the virus

Covid-19 is largely a respiratory disease, and a small study of the lungs of deceased Covid-19 patients revealed certain distinctive features.

Covid-19, just like influenza, largely infects the respiratory tract. Whether the symptoms of Covid-19 are mild or severe, laboured breathing is a common symptom.

While the lungs are affected similarly by the novel coronavirus and influenza, researchers found some characteristics that are unique to Covid-19, according to a news release

Severe blood vessel damage

A new study in this regard was published in the New England Journal of Medicine (NEJM), led by Dr Steven J Mentzer, a thoracic surgeon at Brigham and Woman’s Hospital.

Dr Mentzer and a team of international researchers examined lung specimens from the autopsy of seven deceased Covid-19 patients and compared them with seven specimens from patients who died from influenza-related pneumonia.

Researchers noticed that the specimen from the Covid-19 patients had damaged endothelial cells (cells in the inner lining of blood vessels) which caused severe damage to blood vessels. This may explain the prevalence of some skin conditions (so-called "Covid toe" and purple rashes) and strokes in Covid-19 patients.

Blood clotting throughout the lungs was also unique to the Covid-19 lung samples. Tissue hypoxia, where the lung tissue is deprived of oxygen, was a factor in both sets of lung tissue, but was much more severe in the Covid-19 set.

Growth and sprouting of new blood vessels were also observed  in the lungs. This is a response unique to Covid-19 patients, also known as intussusceptive angiogenesis (IA), where the body basically tries to compensate for the severe blood vessel damage by creating new vessels. 

What we can take from this study

Although the authors stated that the study had serious limitations due to the small sample size, these differences in Covid-19 lung samples were significant and could explain the several vascular complications seen in Covid-19 patients.

The study also emphasised the need for more research into the way the body compensates for the blood vessel damage caused by Covid-19.

Image credit: Robina Weermeijer, Unsplash