Chest Medicine Made Easy-Dr Deepu

COVID 19 Pathology

By Dr Deepu Changappa Cheriamane

Etiology

On 9 January 2020, the World Health Organization (WHO) confirmed that SARS-CoV-2 was the cause of COVID-19 (2019-nCoV was the name of the virus at that time). It is one of the two strains of the SARS-CoV species known to cause human disease, the other being the original severe acute respiratory syndrome coronavirus (SARS-CoV), the cause of SARS. It is a member of the Betacoronavirus genus, one of the genera of the Coronaviridae family of viruses. Coronaviruses are enveloped single-stranded RNA viruses that are found in humans, mammals and birds. These viruses are responsible for pulmonary, hepatic, CNS, and intestinal disease.

As with many human infections, SARS-CoV-2 is zoonotic. The closest animal coronavirus by genetic sequence is a bat coronavirus, and this is the likely ultimate origin of the virus. The disease can also be transmitted by snakes.

Six coronaviruses are known to cause human disease. Two are zoonoses: the severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), both of which may sometimes be fatal. The remaining four viruses all cause the common cold.

Pathophysiology

COVID19 Complications

By Dr Deepu Changappa Cheriamane

Complications of COVID 19

In one of the largest studies of hospitalized patients, reviewing 1,099 individuals across China, the admission rate to the intensive care unit (ICU) was 5%.

In this same study, 6% of all patients required ventilation, whether invasive or non-invasive.

ICU patients tend to be older with more comorbidities.

Commonly reported sequelae are:

acute respiratory distress syndrome (ARDS): ~22.5% (range 17-29%)

acute thromboembolic disease

pulmonary embolism

deep vein thrombosis (DVT)

acute cardiac injury:

elevated troponin levels

myocardial ischemia

cardiac arrest

myocarditis

CNS

delirium

viral encephalitis

diffuse leukoencephalopathy

microhemorrhage (seen in juxtacortical white matter and corpus callosum particularly of the splenium)

stroke: cryptogenic/ischemic

higher mortality and greater severity of stroke in context of COVID-19

secondary infections, e.g. bacterial pneumonia

sepsis

acute kidney injury (AKI)

coagulopathy

disseminated intravascular coagulation (DIC)

multiorgan failure

In a small subgroup of severe ICU cases:

secondary hemophagocytic lymphohistiocytosis (a cytokine storm syndrome)

Risk factors for pulmonary embolism

In a multivariate analysis, an elevated risk of developing PE was associated with:

obesity

elevated D-dimer

elevated CRP

rising D-dimer over time

Pediatric complications

In April 2020, reports started to appear of critically-ill children presenting with a multisystem inflammatory state which bore some resemblance to Kawasaki disease and toxic shock syndrome. Typically abdominal pain and other GI symptoms were present and often evidence of a myocarditis. The presentations necessitated ICU admission and fatalities have been reported.

Pathology

COVID 19 Other investigations

By Dr Deepu Changappa Cheriamane

Laboratory tests

The most common ancillary laboratory findings in a study of 138 hospitalized patients were the following.

lymphopenia

increased prothrombin time (PT)

increased lactate dehydrogenase

Other commonly identified abnormalities include:

mild elevated inflammatory markers (CRP 89 and ESR)

elevated D-dimer

mildly elevated serum amylase: 17% patients (study of 52 cases)

frank acute pancreatitis has not been reported

mildly deranged liver function tests are common, primarily elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST)

bilirubin rise is generally mild

alkaline phosphatase (AKP) and gamma‐glutamyl transferase (GGT) levels remain normal

Complications

COVID Radiology investigation

By Dr Deepu Changappa Cheriamane

Chest X ray

It doesn't have any sensitivity or specificity in diagnosing COVID, but can lead to diagnosis with strong suspicion and further referral for PCR.

HRCT Thorax

Multiple radiological organizations and learned societies have stated that CT should not be relied upon as a diagnostic/screening tool for COVID-19. On 16 March 2020, an American-Singaporean panel published that CT findings were not part of the diagnostic criteria for COVID-19. However, CT findings have been used controversially as a surrogate diagnostic test by some.

Other investigations

COVID19 Diagnostic tests

By Dr Deepu Changappa Cheriamane

RT-PCR

The definitive test for SARS-CoV-2 is the real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test. It is believed to be highly specific, but with sensitivity reported as low as 60-70% and as high as 95-97%. Meta-analysis has reported the pooled sensitivity of RT-PCR to be 89%. Thus, false negatives are a real clinical problem, and several negative tests might be required in a single case to be confident about excluding the disease.

Its sensitivity is predicated on time since exposure to SARS-CoV-2, with a false negative rate of 100% on the first day after exposure, dropping to 67% on the fourth day. On the day of symptom onset (~4 days after exposure) the false negative rate remains at 38%, and it reaches its nadir of 20% three days after symptoms begin (8 days post exposure). From this point on, the false negative rate starts to climb again reaching 66% on day 21 after exposure.

Radiology investigations

COVID clinical presentation

By Dr Deepu Changappa Cheriamane

Clinical presentation

COVID-19 typically presents with systemic and/or respiratory manifestations. Some individuals infected with SARS-CoV-2 are asymptomatic and can act as carriers. Some also experience mild gastrointestinal or cardiovascular symptoms, although these are much less common.

The full spectrum of clinical manifestation of COVID-19 remains to be determined. Symptoms and signs are non-specific:

Common

fever (85-90%)

cough (65-70%)

disturbed taste and smell (40-50%)

fatigue (35-40%)

sputum production (30-35%)

shortness of breath (15-20%)

Less common

myalgia/arthralgia (10-15%)

headaches (10-36%)

sore throat (10-15%)

chills (10-12%)

pleuritic pain

Rare

nausea, vomiting, nasal congestion (<10%), diarrhea (<5%)

palpitations, chest tightness

hemoptysis (<5%)

confusion, seizures, paraesthesia, altered consciousness

stroke(most commonly cryptogenic)

COVID-19 sufferers have reported high rates of disturbances of smell and taste, including anosmia, hyposmia, ageusia, and dysgeusia. The numbers of patients affected vary and current evidence points more towards a neurological than a conductive cause of the olfactory dysfunction.

Various reports suggest patients with the disease may have symptoms of conjunctivitis, and those affected, may have positive viral PCR in their conjunctival fluid. However a meta-analysis of over 1,100 patients found that conjunctivitis was only present in 1.1% cases. A small case series found conjunctivitis to be the only clinical manifestation in some patients with COVID-19.

Cutaneous lesions may also be seen, similar to many other viral infections. In a cohort of 88 patients, 20% developed skin disease, most commonly an erythematous rash. Most of the skin abnormalities were self-limited, resolving in a few days.

Pediatric

In the main, the clinical presentation in children with COVID-19 is milder than in adults. Symptoms are similar to any acute chest infection, encompassing most commonly pyrexia, dry cough, sore throat, sneezing, myalgia and lethargy. Wheezing has also been noted. Other less common (<10%) symptoms in children included diarrhea, lethargy, rhinorrhea and vomiting.

Diagnostic tests

COVID - Epidemiology

By Dr Deepu Changappa Cheriamane

Epidemiology

As of July 2020, the number of cases of confirmed COVID-19 globally is over 11 million affecting virtually every territory, other than isolated South Pacific island states and Antarctica, according to an online virus tracker created by the medical journal, The Lancet, and hosted by Johns Hopkins University. As of June 2020, the United States had more than two million cases, Brazil more than one million, with Russia and India with >500,000 cases.

The R0 (basic reproduction number) of SARS-CoV-2 has been estimated between 2.2 and 3.28 in a non-lockdown population, that is each infected individual, on average, causes between 2-3 new infections.

The incubation period for COVID-19 was initially calculated to be about five days, which was based on 10 patients only. An American group performed an epidemiological analysis of 181 cases, for which days of exposure and symptom onset could be estimated accurately. They calculated a median incubation period of 5.1 days, that 97.5% became symptomatic within 11.5 days (CI 8.2 to 15.6 days) of being infected, and that extending the cohort to the 99th percentile results in almost all cases developing symptoms in 14 days after exposure to SARS-CoV-2.

As of June 2020 the number of deaths from COVID-19 passed half a million globally. The case fatality rate is ~2-3%. It is speculated that the true case fatality rate is lower than this because many mild/asymptomatic cases are not being tested, which thus skews the apparent death rate upwards.

A paper published by the Chinese Center for Disease Control and Prevention (CCDC) analyzed all 44,672 cases diagnosed up to 11 February 2020. Of these, ~1% were asymptomatic, and ~80% were classed as "mild".

Another study looked at clinical characteristics in COVID-19 positively tested close contacts of COVID-19 patients. Approximately 30% of those COVID-19 positive close contacts never developed any symptoms or changes on chest CT scans. The remainder showed changes in CT, but ~20% reportedly developed symptoms during their hospital course, none of them developed severe disease. This suggests that a high percentage of COVID-19 carriers are asymptomatic.

In the Chinese population, 55-60%% of COVID-19 patients were male; the median age has been reported between 47 and 59 years.

Pediatric

Children seem to be relatively unaffected by this virus, or indeed other closely-related coronaviruses.with large cohort studies reporting that 1-2% of COVID-19 patients are children. However, there have been cases of critically-ill children with infants under 12 months likely to be more seriously affected. A very low number of pediatric deaths has been reported . In children, male gender does not seem to be a risk factor. The incubation period has been reported to be shorter than in adults, at about two days.

Read..

Clinical presentation

Terminology

By Dr Deepu Changappa Cheriamane

The World Health Organization originally called this illness "novel coronavirus-infected pneumonia (NCIP)", and the virus itself had been provisionally named "2019 novel coronavirus (2019-nCoV)" .

On 11 February 2020, the WHO officially renamed the clinical condition COVID-19 (a shortening of COronaVIrus Disease-19) 15. Coincidentally, on the same day, the Coronavirus Study Group of the International Committee on Taxonomy of Viruses renamed the virus "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2). The names of both the disease and the virus should be fully capitalized, except for the 'o' in the viral name, which is in lowercase.

The official virus name is similar to SARS-CoV-1, the virus strain that caused epidemic severe acute respiratory syndrome (SARS) in 2002-2004, potentially causing confusion 38. The WHO has stated it will use "COVID-19 virus" or the "virus that causes COVID-19" instead of its official name, SARS-CoV-2 when communicating with the public.

Epidemiology

COVID 19

By Dr Deepu Changappa Cheriamane

Introduction

COVID-19 (coronavirus disease 2019) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a strain of coronavirus. The first cases were seen in Wuhan, China, in December 2019 before spreading globally, with more than 11 million cases now confirmed. The current outbreak was officially recognized as a pandemic by the World Health Organization (WHO) on 11 March 2020.

Terminology

Bandana Face Covering (no sew method) Materials

By Dr Deepu

• Bandana (or square cotton cloth approximately 20”x20”)
• Rubber bands (or hair ties)
• Scissors (if you are cutting your own cloth)
Tutorial

Quick Cut T-shirt Face Covering (no sew method)

By Dr Deepu

Materials
• T-shirt
• Scissors
Tutorial

Learn

1. How to make see mask

2. How to make bandana Mask

Sewn Cloth Face Covering

By Dr Deepu

Materials
• Two 10”x6” rectangles of cotton fabric
• Two 6” pieces of elastic (or rubber bands, string, cloth strips, or hair ties)
• Needle and thread (or bobby pin)
• Scissors
• Sewing machine
Tutorial
1. Cut out two 10-by-6-inch rectangles of cotton fabric. Use tightly woven cotton, such as quilting fabric or cotton sheets. T-shirt fabric will work in a pinch. Stack the two rectangles; you will sew the mask as if it was a single piece of fabric.

2. Fold over the long sides ¼ inch and hem. Then fold the double layer of fabric over ½ inch along the short sides and stitch down.

3. Run a 6-inch length of 1/8-inch wide elastic through the wider hem on each side of the mask. These will be the ear loops. Use a large needle or a bobby pin to thread it through. Tie the ends tight.
Don’t have elastic? Use hair ties or elastic head bands. If you only have string, you can make the ties longer and tie the mask behind your head.

4. Gently pull on the elastic so that the knots are tucked inside the hem. Gather the sides of the mask on the elastic and adjust so the mask fits your face. Then securely stitch the elastic in place to keep it from slipping.

Learn how to make non sewn face mask in next post

How to Wear a Cloth Face Covering

By Dr Deepu

Cloth face coverings should—

fit snugly but comfortably against the side of the face
be secured with ties or ear loops
include multiple layers of fabric
allow for breathing without restriction
be able to be laundered and machine dried without damage or change to shape

CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies), especially in areas of significant community-based transmission.
CDC also advises the use of simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others. Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure.

Cloth face coverings should not be placed on young children under age 2, anyone who has trouble breathing, or is unconscious, incapacitated or otherwise unable to remove the mask without assistance.
The cloth face coverings recommended are not surgical masks or N-95 respirators. Those are critical supplies that must continue to be reserved for healthcare workers and other medical first responders, as recommended by current CDC guidance.

Should cloth face coverings be washed or otherwise cleaned regularly? How regularly?
Yes. They should be routinely washed depending on the frequency of use.

How does one safely sterilize/clean a cloth face covering?
A washing machine should suffice in properly washing a face covering.

How does one safely remove a used cloth face covering?
Individuals should be careful not to touch their eyes, nose, and mouth when removing their face covering and wash hands immediately after removing.

Read the next article on how to prepare face mask at home

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