During the last 20 years, the world has seen several endemic and epidemic viral infections. Some of these viral infections had caused upper respiratory tract infection resulting in mild to moderate breathing difficulties. In most of these pandemic diseases, respiratory breathing problems were less severe than what is observed in cases of COVID-19 viral infection.
COVID-19 coronavirus is a single-stranded RNA virus that had caused severe coronavirus infection in 2019. As of April 11, 2020, the number of people infected across the world is approximately 1,8 million, and 108,800 individuals died. Similarly, in the USA, over 0.5 million were diagnosed with COVID-19 infection, and approximately 20,500 individuals died. The data suggests around 2.5 to 3% of people who were infected died in the USA. Mortality percentages varied in different states in the USA from 1.5% to 3.4.
During the initial phase, about 20% of patients admitted in the hospital were found suffering from upper respiratory tract infection and breathing difficulties needing intensive Care admission. The blood oxygen saturation in most of these patients was not responding to nasal oxygen and facial mask, delivering oxygen. Few of the coronavirus patients were incubated and put on Ventilator to support breathing and improve blood oxygen saturation.
Following recent pandemic viral diseases that had caused mild to moderate, severe breathing difficulties. Ventilator breathing treatment was not needed in most of the patients suffering from these diseases.
SARS Resulting In Breathing Difficulties
In the year 2002, SARS coronavirus epidemics originated in China and spread rapidly around the world to become a pandemic infection. The infection was named as “Severe Acute Respiratory Syndrome” (SARS). Symptoms observed were sore throat, running nose, cough, and fever. Few patients had breathing difficulties but were treated with nasal oxygen and conservative treatment. Pandemic SARS-CoV (the severe acute respiratory syndrome coronavirus) was observed during the years 2002 and 2003. SARS was identified in 29 countries in 2003, and 8096 individuals were affected by the disease. The fatality was low and published data suggests 774 patients died from SARS-CoV infection.1
H1N1 Resulting In Breathing Difficulties
Seasonal influenza became a pandemic infection in 2009, and lab study found the infection was caused by the H1N1 Influenza A virus. The infection was first detected in Mexico and followed by the USA. The symptoms were sore throat, cough, and fever. Few patients had breathing difficulties. Most patients suffering from breathing difficulties were treated with conservative treatment, nasal oxygen, and oxygen mask. Very few needed Ventilator for breathing difficulties. The H1N1 influenza virus affected 60.8 million individuals across the globe. The infection resulted in 274,304 hospitalizations (range: 195,086-402,719), and 12,469 deaths (range: 8868-18,306) in the United States.2
The Middle East Respiratory Syndrome Resulting In Breathing Difficulties
The Middle East respiratory syndrome caused by a coronavirus (MERS-CoV) was first seen in Saudi Arabia in 2012.(3) The virus was identified as MERS-CoV. The MERS virus was transmitted from camel to human. Human to human transmission was promoted by touch and air droplets. Most of the cases were observed in the Arabian Peninsula; later in 2015, several cases were treated at the Republican of Korea. The symptoms observed in most cases were cough, running nose, sore throat, and fever. Few patients developed pneumonia. Patients suffering from pre-existing conditions experienced serious life-threatening complications and died during treatment.
Physiology of Normal Breathing
It is necessary to understand the physiology of normal breathing and oxygen exchange in alveoli (lungs) to know why is ventilator therapy needed. Severe breathing difficulties cause low blood oxygen level that results in inadequate oxygen supply to vital organs like heart, liver, and kidney. The condition is known as hypoxia. Hypoxia can cause life-threatening damage to the heart, liver, and kidney. Such hypoxic patients are considered for breathing support with Ventilator.
Normal breathing involves inspiration and expiration. Breathing air in, through the nose or mouth, is known as inspiration. Inspiration carries air from the atmosphere to the lungs. Breathing out air through air passage like bronchi, trachea, and nose is known as expiration.
Inspiration- Air is breathed in mostly from the nose and occasionally from the mouth. The air then passes into the trachea through the mouth and throat (pharynx). The air in the trachea then passes through right and left bronchi into bronchioles. Bronchioles branches into smaller bronchiole. The smaller bronchiole ends into multiple terminal branches known as terminal bronchiole. The diameter of the terminal bronchiole is 0.4 to 0.5 mm.
Oxygen and Carbon Dioxide Exchange In Alveoli- Terminal bronchiole opens into several alveoli. Alveoli is also known as the air sac. The diameter of the alveoli is 0.2 mm. Twenty-one percentage of air volume contains oxygen. The oxygen in air passes through the extremely thin membrane and diffuses into capillaries. Capillaries lie in the wall of the alveolar wall. Hemoglobin within the red blood cells that lie in capillaries picks up the oxygen molecules. The hemoglobin within red blood cells delivers the oxygen molecules to all the organs and tissue in the human body. Similarly, carbon dioxide passes from tissues and organs into the blood and attaches to hemoglobin. The carbon dioxide then gets transferred from capillaries into the alveolar sac. The exchange of oxygen from alveolar sac to blood and carbon dioxide from blood capillaries to alveoli is critical to maintaining healthy blood oxygen and carbon dioxide level.
Expiration- Expiration is a physiological process that causes air from alveoli exhaled out.
Average Normal Oxygen Blood Level- Normal blood oxygen partial pressure in arterial blood ranges from 75 mm Hg and 100 mm Hg. Similarly, the venous blood oxygen level is between 30 mm Hg and 40 mm Hg. Blood oxygen level is also measured as oxygen saturation.4 The measured oxygen saturation suggests saturated hemoglobin. The normal oxygen saturation is between 95% to 100%.
COVID-19 Coronavirus Infection
The press release and literature published suggests the outbreak of coronavirus disease-19 (COVID-19) infection originated in Wuhan, China. The illness was initially diagnosed as a respiratory infection of unknown origin. The COVID-19 infection was different than any other endemic or epidemic infection. The endemic COVID-19 infection located in Wuhan rapidly turned into an epidemic infection within China. The disease spread throughout the entire globe and became pandemic. The rapid spread of viral infections affected over a million people in 8 to 10 weeks. The pandemic COVID-19 blindfolded almost all experts, CDC, and WHO organization.
The initial symptoms observed are running nose, cough, throat pain, and mild breathing difficulties. The life threatening respiratory complications were observed in high risk patients. Patient suffering with conditions like obesity, diabetes, high blood pressure, chronic obstructive lung diseases, asthma, emphysema, and congestive heart failure were considered high risk patients.
What Causes Cyanosis And A Drop In Oxygen Saturation in COVID-19 Patients?
The COVID-19 infection causes severe inflammation of the respiratory tract from the nose to terminal bronchioles and alveoli. Inflammation triggers swelling of the mucosal gland and dilatation of blood vessels that lie within the mucosal membrane of terminal bronchioles and alveoli. In addition, the connective tissue that forms the mucosal layer retains water and swells. Mucosal membrane and gland secrete abundant volume of mucosal fluid in the nasal cavity, pharynx, trachea, bronchi, and alveoli. Mucosal fluid accumulates in the nasal passage that causes a running nose and sneezing. The secretions within the trachea, bronchi, and alveoli cause cough. The wall of bronchi, bronchioles, and alveoli swells up because of inflammation, increase diameter of capillaries, retention of fluid, and increase the size of mucosal glands. The swelling causes the narrowing of respiratory passage that includes bronchi, terminal bronchioles, and alveoli. Besides, the lumen is filled with mucosal secretion and causes partial or complete obstruction. Such a condition prevents air passing to alveoli and results in less oxygen transfer into blood. Such condition results in cyanosis and a drop in oxygen saturation below 93%, as well as an increased level of carbon dioxide in the blood. The pneumonia and pulmonary edema was more often seen in high risk patients.
When is Ventilator Used?
The patient suffering from symptoms of running nose, sore throat and cough are advised to get blood examination to diagnose the cause of infection. Those who were suffering with mild coronavirus infection were either admitted in hospital or sent home with strict guidelines to be in quarantine for 2 weeks. All symptomatic patients were treated with conservative treatment. Conservative treatment advised were rest, fluids and tylenol for fever and body aches. Those who were admitted and had breathing difficulties were closely observed for cyanosis and decreased oxygen saturation. Patients showing signs of cyanosis like bluish discoloration of lips, tongue, nailbed, conjunctiva, and fingertips were transferred to ICU. The patients were closely monitored in ICU for blood oxygen saturation. Some were considered for ventilator therapy when blood oxygen saturation dropped below 93%.
Is Ventilator Treatment Helpful To Improve The Outcome of Covid-19 Infection?
The data is not available to make any prediction regarding a favorable treatment option of ventilation therapy to treat COVID-19 infection. The COVID-19 disease seems to be causing severe rapid deterioration of health in infected individuals of all ages. Several medications are tried in different countries. Some of these medications were in use for the last several years. The medicines that had favorable outcomes are Remdesivir, hydrochlorothiazide, and azithromycin.5
The heated debate about prescribing these medications among physicians, press representatives, and politician gives a mixed message. Some experts encourage the use of these medications and others discourage the use of these medications. The 4 to 5 % of the patients suffering with severe respiratory symptoms resulting in hypoxia with peripheral oxygen saturation less than 93% are treated with ventilator to support breathing and improve oxygenation.
In the meantime, report published in news media confirms that city officials had mentioned 80% or more of coronavirus patients placed on the ventilators in New York City have died during treatment.6 Most physicians preferred to try conservative treatment and other medication instead of ventilator therapy.
- CENTER FOR DISEASE CONTROL & PREVENTION SARS after 10 Years https://www.cdc.gov/dotw/sars/index.html
- CENTER FOR DISEASE CONTROL & PREVENTION 2009 H1N1 Pandemic (H1N1pdm09 virus). https://www.cdc.gov/flu/pandemic-resources/2009-h1n1-pandemic.html
- Middle East respiratory syndrome coronavirus (MERS-CoV)December 20 2019 | Q&A World Health Organization https://www.who.int/news-room/q-a-detail/middle-east-respiratory-syndrome-coronavirus-(mers-cov)
- Oxygen Saturation Brant B. Hafen; Sandeep Sharma. https://www.ncbi.nlm.nih.gov/books/NBK525974/
- COVID-19-associated ARDS Treated With Dexamethasone: Alliance Covid-19 Brasil III (CODEX) Sponsor: Luiz F. L. Reis, Ph.D. Collaborators: Hospital Israelita Albert Einstein, Hospital do Coracao, Brazilian Research In Intensive Care Network and Ache LaboratoriosFarmaceuticos S.A. https://www.health.harvard.edu/diseases-and-conditions/treatments-for-covid-19
- 80% of NYC’s coronavirus patients who are put on ventilators ultimately die, and some doctors are trying to stop using them https://www.businessinsider.com/coronavirus-ventilators-some-doctors-try-reduce-use-new-york-death-rate-2020-4
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