Lung Pathology – Sri Lankan Experience of COVID-19
By Dilanthi Jayamanne
“Sri Lanka is one of few countries which has performed post mortem examinations in deaths due to COVID-19 infection. The office of the Judicial Medical Officer of National Institute of Infectious Diseases (NIID) have performed over 40 post mortem examinations on bodies, that were positive for COVID-19 by PCR testing performed before or after death. They include both natural and unnatural deaths of which majority fell into the former category,” says Judicial Medical Officer (JMO) of the Colombo East, JMO Complex, Dr. Channa Perera.
Nearly 90 to 95 percent of infected persons with COVID-19 can be given home care which has to be monitored by the medical services in the locality that he or she resides in. They can be provided with the necessary medical advice over the telephone remaining in their homes.
Out of the percentage of hospital admissions, currently it is observed that about 15 – 20 percent may require oxygen therapy. These percentages of persons requiring hospital admission and treatment may vary depending on the number of diagnosed cases within the community following PCR test.
Those who are vulnerable to this condition are the elderly, debilitated people, immune-compromised persons of different nature including those who are infected with the human immunodeficiency virus (HIV), persons with cancer, persons undergoing chemotherapy, radio therapy, and are undergoing treatment following transplantation, etc. Also, persons with comorbidities such as hypertension, diabetes, bronchial asthma and heart disease who are in the vulnerable bracket. Pregnant mothers are also included in this vulnerable group.
Having received approval from the Director General of health Services Dr. Perera has conducted over 40 autopsies on COVID-19 dead. The 1st of it was performed on 4 May 2020, over a year ago and was the 1st ever post mortem examination of a COVID-19 death performed in Sri Lanka. The article focuses on his pathological and mainly histological findings and would undoubtedly assist clinicians and COVID-19 care providers to enhance their quality of treatment.
Once a person contacts the disease, or the virus it infects the upper respiratory passage of the patient which comprises the nose, pharynx, sinuses, throat etc., which results in the condition appearing clinically as any other flu condition. But the outcome of this particular condition could cause dangerous consequences unlike in a normal flu.
Majority of persons get only the symptoms of upper respiratory infection such as a fever, sneezing, dry cough and body aches etc. Some of them don’t show even these symptoms. Therefore, one would get to know if he or she has the coronavirus only with a PCR test. A large number of persons in society who are actually infected don’t even notice that they have contacted the coronavirus, he explained.
However, a small percentage of patients could develop lower respiratory symptoms, which is a disease complication should it get to that.
Acute viral pneumonitis in COVID-19 infection
The lower respiratory infection occurs mainly in two stages. Since this is a viral infection, it may affect the alveoli of lungs. The two types of cells that form this wall (alveolar basement membrane) are Type I pneumocytes which is a squamous cell and type II pneumocytes which are cuboidal cells. Type II pneumocytes produce a substance called surfactant that keeps the surface tension of the alveoli which prevent the alveoli being collapsed. A condition called “Acute viral pneumonitis is caused at the initial stage of lower respiratory symptoms,” he said. This is the inflammation of the cell wall caused by the virus. This phenomenon was observed in histological sections of the lung in post mortems performed by him. However, this condition in COVID-19 has not been reported yet in literature, Dr. Perera explained.
“But the danger of SARS CoV-2 virus causing pneumonitis is that apart from the inflammation it severely disrupts the alveoli wall which is known as Defused Alveoli Damage (DAD),”, he said. “It can also cause a phenomenon called hyaline membrane formation inside this wall. At this stage there could be formation of micro thrombi in Pulmonary Vasculature (blood vessels of the lung), too.
Defused alveoli Damage (DAD)
Is caused due to acute interstitial pneumonitis caused by the destruction of the alveoli wall due to toxic effects of the virus. You may develop difficulty in breathing due to compromised transfer of oxygen from the alveolar spaces through the alveolar wall into blood vessels. Damage to type II pneumocytes may cause alveolar collapse due to reduced production of surfactant which is important for the stability of alveolar wall. The difficulty increases as oxygen transportation from the alveoli wall to the blood vessels is compromised even more.
If the patient is PCR positive with a difficulty in breathing, then they must seek medical advice at that stage immediately.
Type II pneumocytes have the ability to regenerate themselves whereas type I pneumocytes does not have the ability to regenerate. Therefore, regeneration of type II pneumocytes reconstruct damaged alveolar wall. The initial stage of DAD is a reversible condition which should not be neglected so that it could goes to the irreversible stage.
A model autopsy performed last year on a schizophrenic patient who had severe dyspnoea (shortness of breath - SOB), with a cough who was pronounced dead on arrival to hospital. He may have been neglected because of his mental condition. It is possible that he may have contracted the virus seven to ten days before death. He was diagnosed with the disease following a post mortem PCR. He had sought treatment from his general practitioner (GP) seven days before death. It is not clear from where he had contracted the infection. However, his GP was also diagnosed positive for the virus.
What was unique about the deceased was that he was never treated in a hospital. Most of the dead bodies of the patients that the office of the JMO receives are of those who have been undergoing treatment for COVID-19 at the time of death. Therefore, their classical picture is altered by treatment. The medication, ventilation in a machine, oxygen therapy etc. This was a classical picture uninterrupted by the physician. The Post mortem PCR tested positive. He had all features of acute viral pneumonitis, Hyaline membrane formation and Micro thrombin formation in lungs. This helped us to diagnose the phenomenon of Acute Viral Pneumonitis (AVP) which has not been reported before in COVID-19.
This has been taken as a model because with it we were able to decide how the patients who were treated, have altered features and how the treatment modifies these features. For instance, Hyaline membrane formation (HMF) can occur due to early lung complication of COVID-19 as a result of the cytopathic COVID-19 virus induced injury or as a latter complication due to conditions such as ARDS (Adult Respiratory Distress Syndrome), severe secondary bacterial pneumonia , Oxygen toxicity due to inappropriate oxygen therapy, sepsis etc. It can occur as a result of overly prolonged ventilated patients on a ventilator, too. “We continually talk about giving oxygen to the patient but it is extremely important to calculate the amount and speed of oxygen therapy at different stages of the illness” he observed.
Dr. Perera identified these as the early stages of lower respiratory complications of Corona patients suffering with lung complications of COVID-19 which could occur at the end of 1st week to the second week of infection. However, the dating of these complications need more studies.
If the patient is not cured at these stages, they may develop secondary bacterial pneumonia.
The patient develops secondary bacterial pneumonia when the viral infection advances towards DAD. Therefore COVID-19 pneumonitis occurs as a result of cytopathic injury to the lung induced by the virus but the secondary pneumonia is mainly of bacterial origin since the bacteria can grow well in the damaged lung caused by DAD. It is only precipitated by the virus. The pneumonia also has several stages. It has the acute stage and resolving stage if the patient is improving. Unfortunately it may transform into an organizing pneumonia stage which could be difficult to treat successfully.
One of the other complications micro-thrombi formation and systemic thrombosis due to Hyper-Coagulatory state (increasing clotting ability of blood). In systemic Hyper-coagulatory state blood clots form in the deep veins of the lower limbs, upper limbs and pelvis most commonly. The COVID-19 virus has the ability to increase the clotting ability of blood and that could occur at any stage of the illness. It is even possible to persist after discharge of patients since we have seen such cased even 3 to 5 weeks after acquiring the illness. The blood clot that are formed in the veins that carry deoxygenated blood get dislodged and travels back to the heart. It goes into the right atrium and right ventricle of the heart and moves into the lungs which re-oxygenates the blood to purify it. At this point the clot cannot go beyond lung and gets wedged in the lungs. This is known as pulmonary thrombi embolism. People who die as a result of this may or may not have pneumonia.
Choosing whom to hospitalise
Since 90 to 95% with no symptoms or very mild symptoms can be treated at home since hospitals are overwhelmed, they should be under the purview of a medical practitioner and not take medication on their own. Proper hydration and rest during home based treatment is important.
However, there are instances where people can get heart attacks aggravated due to the coronavirus. Also, they can get a rare condition called, myocarditis.
Therefore, even these patients need close monitoring even at homes.
The five to ten percent with complications must be hospitalised. “My recommendation is that health authorities should pick the needy ones and hospitalise them. They are the ones who should be under the supervision of a physician.
The take home message
It is a disease that is best prevented. People followed the regulations and guidelines during the first and second waves.
The only way to achieve that is by keeping your face clean, wearing a clean mask, maintaining hand hygiene, refrain from touching the face or the mask without cleansing the hands. Also, maintain social distancing. “We have to touch money and various surfaces. Therefore, the hands should always be thoroughly cleansed.”
Explaining further the JMO said: “You may have had contact with a person who has COVID-19. If you wear your mask on your chin or neck, he or she may have given some viruses to the mask which will not infect you. But the virus may touch your body - the common area being the neck. So, when the masked is pulled down to the neck when you are not in society and pull it back on when you enter a crowded area the viruses that are on the neck could easily enter the nostrils and the mouth.”
If everyone living in Sri Lanka follows these basic principles, for a period of one or 1 ½ months there would be no need for quarantine or lockdown.
Those who get infected should make every effort not to get into the second phase of the disease but stop it at the upper respiratory level of the infection.
Even middle aged and young people may develop complications without having any of the conditions that were mentioned earlier. There are new strains which are more virulent and more damaging.
“Also based on our findings I hope that physicians would work on the treatment methods. Treatment varies according the stages of the disease. For instance, in AVP and systemic thrombosis the treatment is totally different. It calls for enhancement and modification of treatment methods,” he explained.
Therefore, more than criticising the lack of oxygen and absence of ventilators and ICU beds, it’s better to take precautions and stop this deadly disease from spreading and increasing the number of cases in the country and the number of deaths that occur on a daily basis, he appealed.