Can You Reverse Lung Damage?

From Covid-19 to wildfires, 2020 has been an assault on the lungs

Written by – Tara Santora

Image: wildpixel/Getty Images

The year 2020 has been an assault on the lungs. On top of normal-year issues such as air pollution and influenza, many people’s pulmonary systems must now deal with one or two added stressors: Covid-19 and wildfires. In the short term, both can cause respiratory symptoms such as coughing and shortness of breath. But data is lacking about how often these irritants damage the respiratory system in the long term. What pulmonologists do know is that they can cause irreversible lung injury, but that injury may not destroy a person’s ability to live an active life, says Panagis Galiatsatos, MD, a pulmonary and critical care physician at Johns Hopkins University School of Medicine.

The damage Covid-19 and wildfire smoke trigger varies from temporary, mild inflammation to permanent scarring and loss of function. And although virus and smoke particles are very different — one group is considered biological and the other is not — they share similar mechanisms of causing lung damage. In both cases, it’s not the invading particles that cause the damage. It’s the immune system.

Covid-19 can scar the lungs for life

The coronavirus hijacks lung cells to replicate its own genetic material, but it does not benefit from permanently injuring the lungs. In fact, it’s not the direct cause of lung damage at all, Galiatsatos says. Instead, immune cells are the culprit. The primary goal of these cells is to fight off the virus, but lung cells suffer collateral damage during the battle. Luckily, the lungs have strategies to limit that damage.

The first defense priority of the lungs is to keep viruses like the coronavirus at bay. To do so, secretions and mucus in the airway trap the virus so the infected person can cough it up and out. Next, the airway becomes inflamed as immune cells charge into the area. This is where some lung cells are caught in the crossfire. Those that have been damaged by the virus aren’t salvageable and are killed by the immune system.

It’s not the invading particles that cause the damage. It’s the immune system.

Once the immune system has fended off the virus it rights its wrongs by cleaning up dead lung cells and helping to regenerate new ones. This last step doesn’t always happen though. “If cleaning up is going to be too hard to do, then the lungs will just make a permanent scar and move on,” Galiatsatos says. When the airway scars, forming a condition called bronchiectasis, bacteria and mucus can build up and make the lungs vulnerable to infections and blockages. When lung tissue scars, called pulmonary fibrosis, the tissue can’t fulfill its normal role of exchanging carbon dioxide for oxygen. In other words, it can’t help with breathing.

CBD Inhalers to help fight Inflammation

Cleaning up dead lung cells can be particularly difficult with Covid-19 because the immune system often goes overboard when defending against the disease and is too aggressive at attacking the body’s own cells. The ramping up of the immune system is a core feature of the second phase of the illness, says Gabriel Lockhart, MD, a pulmonologist at National Jewish Health. Although theories abound, no one knows what provokes this overreaction.

Once a scar in the lungs finishes forming, it’s there for the long haul. But the virus hasn’t been around long enough for experts to confidently say how often scars develop, Galiatsatos says. “We definitely are seeing in a lot of our survivors ongoing lung consequences on imaging that may result in fibrosis or some level of permanent damage,” he adds. One of the other types of damage that may show up is airway remodeling, which, like scarring, occurs after faulty repair of lung tissue. It features changes in the structure of the airway, such as thickening of the airway walls, which can cause coughing for months after infection.

Lung scarring only appears to occur in a small fraction of people with Covid-19, and it usually develops in those with the most severe cases, such as those who develop acute respiratory distress syndrome (ARDS). In rare instances, Covid-19 patients have needed lung transplants because they haven’t been able to recover from ARDS. But some doctors, including Lockhart, are hopeful that permanent lung damage may not be as widespread as they had originally feared.

At the beginning of the pandemic, mortality rates were high. Covid-19 patients with ARDS needed to be on a ventilator longer than patients with typical ARDS, and experts expected the worst. But now mortality rates have dipped and hospitalized patients are faring better. One study of 86 patients with severe Covid-19 found that 88% had lung damage when they were discharged from the hospital, but that number dropped to 56% of patients after 12 weeks. “They’re not going to return back to 100% of where they were before,” says Lockhart, who was not involved with the study. “But we’re hopeful that some of these patients may not have had as much scar tissue lay down and may have had some recovery of lung tissue.”

Fine particles from wildfire smoke dig deep into the lungs

Although the lung injuries experts expect from Covid-19 and wildfire smoke are similar, how they induce that damage differs. The main danger of wildfire smoke is the fine particles it carries. Fine particles are two and a half micrometers or less in size — 24 times less than the diameter of a human hair. Because they’re so small, they can work their way deep into the lungs. “We think they’re the cause of a lot of the hazardous effects we see from air pollution and from wildfire smoke,” says Coralynn Sack, MD, a pulmonologist and critical care specialist at University of Washington School of Medicine.

The lungs are always producing mucus, but they increase levels of these secretions when exposed to fine particles, similar to the Covid-19 coughing response. The airway also constricts in an effort to prevent fine particles from burrowing into the lungs, and that can make breathing difficult. Particles can still make it through, however, and some people cough for weeks after exposure to wildfire smoke. If they can’t cough out the particles after about six months, scarring may occur, Galiatsatos says.

Although risk of long-term lung complications probably increases with exposure to wildfire smoke, experts are unsure how commonly it occurs. Most research focuses on short-term effects of exposure, Sack says, such as how it can aggravate preexisting lung conditions such as asthma and COPD. “Wildfire events are really pretty new, that we’ve had such extreme and severe events over a prolonged period of time and that are recurring year after year,” she says. “So our knowledge of those longer-term effects is still emerging.”

There have been no studies to date on the long-term effects of wildfire smoke inhalation, although researchers have studied the cumulative effect of firefighters’ repeated short-term exposures. That evidence points to a decline in lung function over the wildfire season. However, firefighters are exposed to more smoke than the average person, all while they are physically exerting themselves, so the same damage may not occur in those who stay home.

“The best way to approach any concern for a disease is the healthier you are going into it, the more likely you are to recover.”

Rehabilitation can make the lungs nearly good as new

Injury from Covid-19 or wildfires can impair lung function, but it doesn’t have to be “endgame,” Galiatsatos says. “You can get lung scarring and still be awesome by exercising, through pulmonary rehabilitation and strengthening the other parts of the lungs.”

Pulmonary rehabilitation, which was developed primarily to treat people with COPD, is a program that includes breathing exercises and guided exercise to aid in recovery. The lungs detect that the damaged tissue isn’t exchanging gases effectively and shunt blood away from it to healthy areas of the organ. In turn, those areas can grow bigger and compensate for the injury. Pulmonary rehabilitation can also relieve shortness of breath, preserve lung function, and improve quality of life, among other benefits. Rehabilitation is much more common with Covid-19 patients than in people exposed to wildfires. All hospitalized Covid-19 patients are evaluated for rehabilitation, Galiatsatos says, and he refers those with obvious lung injury or symptoms such as shortness of breath. Rehabilitation may be used on an individual basis for people whose underlying lung conditions were exacerbated by wildfire smoke — after the smoke has passed.

Formal rehabilitation includes a combination of aerobic exercises such as walking and anaerobic exercises such as weight training to get the blood pumping. There isn’t a magic set of exercises that return a patient back to normal; each regimen is tailored to the patient based on what they can tolerate and what they will be able to do at home once they leave the program. Rehabilitation usually takes six weeks, Galiatsatos says. Resistance and exercise duration are increased as the person begins to recover. Those who don’t qualify for formal rehabilitation should do aerobic and anaerobic exercises on their own to aid in physical recovery (but should check with their physician about what would be safest and most helpful).

Rehabilitation doesn’t prevent lung injury, but a new class of medications may be able to do so. Drugs called antifibrotics are approved to treat idiopathic pulmonary fibrosis, or scarring of the lungs for unknown reasons. Two antifibrotic medications are available in the United States: nintedanib and pirfenidone. Some doctors are proposing that research look into whether these medications can prevent scarring of the lungs and slow lung function decline in patients with severe Covid-19. However, using these drugs with Covid-19 is controversial. Some experts argue that effort and money is better spent researching antiviral therapies. And Gailatsatos worries that antifibrotics could interfere with natural recovery. “You could be disrupting the healing process for someone who would not have permanent damage,” he says. “I would need to see much more robust basic science investigations into why [antifibrotic therapy] seems plausible.”

Like with antifibrotic drugs, experts don’t yet know how effective pulmonary rehabilitation is for Covid-19 because the disease is so new. However, there is much more reason to believe the rehabilitation is effective. “For other pulmonary conditions, it’s awesome,” Galiatsatos says. “There is 30 years of data to support pulmonary rehabilitation for patients with chronic obstructive pulmonary disease, emphysema, cystic fibrosis, you name it.” Although experts don’t have the data to say for sure that rehabilitation will lead to the same outcomes in those recovering from Covid-19, Galiatsatos expects them to be similar. “We don’t see why it wouldn’t. I mean, lungs are lungs.”

People who were healthy before they were infected with the coronavirus are likely to experience better results from rehabilitation. “The best way to approach any concern for a disease is the healthier you are going into it, the more likely you are to recover,” Galiatsatos says. For example, quitting smoking is beneficial because long-term smoking increases the risk of developing COPD, among other lung conditions. “Try to stay as healthy as you can because you never know where you might get exposed to either a wildfire or to a viral pandemic.”

Original Story can be found on Medium