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Silent Hypoxemia in COVID-19 Patients
COVID-19 Airborne Transmission?
Silent Hypoxemia in COVID-19 Patients
Written By: Pimtawan Jatupornpakdee
Researchers made a new finding suggesting that the phenomenon of “happy” hypoxia or silent hypoxemia found in people with COVID-19 could be explained by the principles of respiratory science. Hypoxemia is a condition when arterial oxygen tension is below average, while hypoxia is a failure of oxygenation. These two terms can be used interchangeably. The risks from a decrease in blood oxygen include dyspnea, or shortness of breath, and shutdown of organs leading to life-threatening issues.
COVID-19 is a pandemic disease involving respiratory issues. Patients with severe cases can possibly diminish the amount of oxygen their lungs can absorb. Therefore, the oxygen level in some COVID-19 patients is surprisingly low. However, many media sources have reported that patients with low blood oxygen continue to function without consequential issues and no sign of dyspnea.
Many physicians, including the authors of the present research, found this case to be “especially bewildering” and “is considered as defying basic biology.” Dr. Martin J. Tobin, the lead author of the study and a professor of pulmonary and critical care medicine at the Loyola University Medical Center in Maywood, talks about his experience with his patient. His patient was completely comfortable to the point of using a phone while the physician was going to insert a breathing tube and connect a mechanical ventilator to the patient. Although this is a lifesaving process, there are still risks while performing it.
To solve this curiosity, Dr. Tobin and his colleagues conducted an informal survey of 58 healthcare workers. The survey asked whether the healthcare workers had confronted patients with silent hypoxemia, or happy hypoxia. There were only 22 responses that were practical. The team analyzed those data and concluded that the explanation for many cases of silent hypoxemia is conventional respiratory science.
An example would be the use of a pulse oximeter to measure oxygen levels. Dr. Tobin points out the fact that the pulse oximeter may be accurate when oxygen readings are high, but it over exaggerates the information when the readings are low. He also stated that the brain may not realize about the reduction of blood oxygen immediately, therefore it would not respond until oxygen decreases to very low levels to the point of patients experiencing dyspnea. Another piece of information is how more than half of the patients with silent hypoxemia are reported to have low carbon dioxide levels. Dr. Tobin believes that low carbon dioxide levels can lead to the reduction of the effect of low blood oxygen levels.
COVID-19 is still considered a new outbreak throughout the world. Clinicians have limited knowledge about the disease to determine effective treatments because of its sudden appearance. Every real-world data gathered would be helpful in the future, including this information relating to conventional respiratory science. According to Dr. Tobin, this new information can help prevent the risks from endotracheal intubation and mechanical ventilation when the second wave of COVID-19 is much anticipated.
COVID-19 Airborne Transmission?
Written By: Kandharika Bamrungketudom
Up until now, the World Health Organization (WHO) has insisted that the COVID-19 disease can only be transmitted via large droplets produced by spit or mucus from people’s coughs and sneezes. However, 239 scientists from 32 countries do not agree, and recently wrote an open letter to the WHO to revise its recommendations, suggesting otherwise — that the disease is airborne.
The current belief of the transmission of COVID-19 is that it can only spread through large droplets. To clarify, these so-called “large droplets” measure to be around a millimeter in diameter. These large droplets that the WHO believes COVID-19 to be transmitted by can only stay in the air for a short period of time and don’t usually travel further than 6 feet (thus the distance of social distancing).
If the disease is airborne, however, it means that the disease can be spread through coughing, sneezing, as well as talking and exhaling. An airborne disease is spread through droplets that are small enough (less than 5 microns) to stay suspended in the air for a longer period of time. These air suspensions are generally referred to as “aerosols.” The aerosols left by an infected person can spread further than the large droplets, since they stay in the air longer. Furthermore, the small droplets have the ability to linger in the air of a room even after the person who produced it has left.
There is also much evidence pointing to the fact that the disease might be airborne, such as in many cases that involve a “superspreader,” where a single person infects many people standing farther than six feet from the spreader. Examples include the event of the spreading at a choir practice in Mount Vermont, where a single person infected 45 other people, or the event of one of the first spreadings at Guangzhou, where 9 people could trace their infection back to a single person. Curiously, the nine people infected received no direct contact with the infected person, but analysis of airflow patterns suggests that the air conditioning unit might have spread the virus from the infected person to the other nine diners. Evidence from the laboratory also shows that the SARS-CoV-2 virus can be aerosolized and survive up to four hours in this form.
During a press conference on the Tuesday after the letter from the scientists was published, the WHO stated that it acknowledges the possibility of the disease being airborne, but is still collecting more evidence.
A reason as to why the WHO has not adjusted its regulations yet may also be due to the fact that not every country has the resources to increase the level of protection, therefore it is looking for more definite proofs first.
If the disease is indeed airborne, it raises many concerns towards not only the healthcare workers, but also the general public as well, as the disease could potentially be transmitted through air currents and possibly air conditioning units as well. Many regulations concerning the prevention of disease spread would have to be adjusted accordingly if the disease is airborne, such as allowing more ventilation in areas where people densely congregate indoors.
Meanwhile, the general public should not panic over this, but follow the current guideline that the WHO has created of washing hands, wearing masks and retaining social distancing, as this also reduces the chance of contracting the disease.
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