‘Fibrosis-like lung damage reverses in 80% of Covid patients’

In pulmonary fibrosis, the lung tissues are damaged with scarring and thickening, and the damage worsens over a period of time

Early this year, a 50-year-old IT engineer from Pune spent 10 days in a local hospital battling Covid-19. At the time of discharge, he underwent a second high-resolution CT (HRCT) scan of the chest that showed ground-glass opacity, reticulation shadow and traction bronchiectasis. In medical parlance, these were classic HRCT signs of pulmonary fibrosis — an irreversible condition that causes scarring and thickening of lung tissues, making it difficult to breathe. The IT engineer went back home with a diagnosis of “post-Covid fibrosis” and was advised pulmonary rehabilitation.

A study from China published in the PLOS One journal in March found that patients who had a severe clinical classification of Covid-19 had more extensive and severe lung inflammation as well as severe residual pulmonary fibrosis. (Reuters)

Three months down the line, his chest scan improved. The hazy grey areas labelled as ground-glass opacities had reduced, his diffused lungs appeared to be expanding and the cough had reduced too. By July, six months since his hospitalisation, the scan was normal, with no sign of fibrosis. In many Covid-19 patients like this IT engineer, the lung fibrosis or fibrosis-like changes that appeared on the scan, reversed over a period of time. In some patients, the improvement is fast, while others may take anywhere between three months to a year.

“When we said fibrosis, it meant that the condition is lifelong and irreversible,” said Dr Sundeep Salvi, director of Pune-based Pulmocare Research and Education Foundation, who treated the IT engineer. “But gradually, we started noticing the fibrosis-like changes that we saw in Covid patients resolved with time,” he said.

These observations have prompted discussions among the medical fraternity if they should label such diagnosis as post-Covid fibrosis at all. “Most of us are now resisting the term post-Covid fibrosis,” said Salvi. “Now, we identify the Covid-induced lung changes as post-Covid interstitial lung disease — a broader term used for a larger group of diseases that cause lung scarring. The term fibrosis is used only in cases where the lungs don’t improve and worsen further” he said.

A study from China published in the PLOS One journal in March found that patients who had a severe clinical classification of Covid-19 had more extensive and severe lung inflammation as well as severe residual pulmonary fibrosis. “In most of these patients, pulmonary fibrosis improved or even resolved within 90 days after discharge,” the study observed.

Dr Rahul Pandit, a critical care specialist at Fortis Hospital in Mumbai and a member of Maharashtra’s Covid-19 task force said with experience, doctors now prefer to wait and watch instead of labelling the lung changes as pulmonary fibrosis. “Since what we saw as fibrosis reversed over a period of time, we realised that most Covid patients may not have the true form of irreversible fibrosis,” said Pandit. “After the preliminary Covid treatment, we refer such patients to pulmonary experts for longer follow-ups,” he said.

Progressive fibrosis in 20% Covid patients

In pulmonary fibrosis, the lung tissues are damaged with scarring and thickening, and the damage worsens over a period of time. As the tissues thicken and become hard, the lungs don’t expand fully, making it difficult for the patients to breathe. Pulmonary fibrosis is known as a terminal illness. Pulmonary rehabilitation including breathing exercises and some anti-fibrotic medication may slow down the progress in some cases.

Doctors use a battery of tests and scans — complete pulmonary function tests, including the diffusing capacity of the lungs for carbon monoxide (DLCO); six-minute walk test, among other tests — to diagnose fibrosis.

Another classical sign to detect the condition is listening for velcro-crackles from the lungs. Velcro crackles sound similar to what we hear when a joined strip of velcro is separated.

According to Salvi, while 80% of Covid patients who may have shown “fibrosis-like” lung changes recover over a period of time, at least 20% suffer from the progressive form of fibrosis.

Mumbai-based chest physician Dr P Prabhudesai agreed. “Progressive fibrosis is the most concerning outcome of Covid,” he said.

“The 20% patients who develop a progressive form of fibrosis are generally those who have been on oxygen support for a longer period, have underlying lung diseases like Chronic Obstructive Pulmonary Disease (COPD), history of smoking, age and other related co-morbidities,” he said.

But Prabhudesai refrains from attaching the term “irreversible” to the progressive fibrosis seen in Covid-19 patients.

“We should wait at least for another six months before labelling these cases as irreversible,” he said, adding that it is not a simple black and white when it comes to following up on Covid-19 patients.

“In some cases, we may stop anti-fibrotic medication within four to six weeks as they start showing improvement, while in some patients we may have to add the anti-fibrotic drugs,” he said.

According to Prabhudesai, some amount of fibrosis was also seen during the H1N1 outbreak and many patients improved back then.

“The severity and spread of Covid-19 is definitely much more compared to H1N1. But we had seen cases of fibrosis that resolved over a period of time in H1N1 pneumonia,” he said.

The pandemic hit Maharashtra in March 2020. Doctors say that it is advisable to closely follow up with patients with lung damage for a longer period to understand the irreversibility factor.

However, a small percentage of Covid-19 patients have suffered from irreversible lung damage, which led to lung transplants.

In August 2020, doctors in Chennai performed a bilateral lung transplant on a 48-year-old patient who had suffered from severe lung damage due to Covid related fibrosis.

Last December, a 34-year-old marketing professional from Haryana who suffered from post Covid lung fibrosis underwent a double lung transplant at a Hyderabad hospital. Lung transplants on Covid patients in the United State have also seen a rise.