Coronavirus disease-19 (COVID-19) is caused by the SARS-CoV-2 virus. The infection is transmitted through respiratory droplets and close contact. The major organs affected by COVID-19 include the lungs, the heart, kidneys, genitals, and liver.
Severe cases of COVID-19 include respiratory distress and have a relatively high rate of death. Even healthy individuals can experience severe COVID-19, however, the risk of critical illness and death increases with age.
Severe disease is also more common in men compared to women. The risk of severe disease is higher among certain ethnic groups, such as Black and Hispanic individuals in the United States. Additional risk factors for the development of severe COVID-19 include cardiovascular disease, diabetes mellitus, immunosuppression, and obesity.
What is severe COVID-19?
The most common initial symptoms of COVID-19 include fever, cough, fatigue, headaches, muscle pain, and diarrhea. Statistically, 5% of symptomatic patients will be critically ill, while 14% will experience severe illness. There are vast differences in the duration of symptoms and complications caused by COVID-19. Generally, severe illness begins one week after the onset of symptoms.
Dyspnea (shortness of breath) is the most common symptom of severe COVID-19 and is present in 40% of symptomatic patients. Specifically, severe COVID-19 is diagnosed when the patient is experiencing:
- A respiratory rate of at least 30 breaths per minute
- A blood oxygen saturation of 93% or less
- Oxygenation index of 300mmHg
- Infiltrates in more than 50% of the lung field in lung imaging tests
Dyspnea is usually accompanied by hypoxemia (low blood oxygen). Many patients with severe COVID-19 also have progressive respiratory failure, lymphopenia, thromboembolic complications, and disorders of the central or peripheral nervous system.
Severe COVID-19 can lead to acute cardiac, kidney, and liver injury. Other complications include shock, cardiac arrhythmias, rhabdomyolysis (rapid breakdown of damaged skeletal muscle), and coagulopathy (impaired ability to form blood clots). The main cause of death in patients with COVID-19 is respiratory failure, which is why the main treatment is respiratory support.
How is severe COVID-19 treated?
COVID-19 can be diagnosed using:
- The patients’ clinical history
- Detection of SARS-CoV-2 RNA in respiratory secretions
- Discovery of bilateral consolidations using chest radiographies
After diagnosis, the first step for the treatment of severe COVID-19 is hospitalisation for careful monitoring. Patients are monitored in the intensive care unit through direct observation and pulse oximetry (a non-invasive test that measures oxygen saturation levels). Oxygen supplementation using a nasal cannula or Venturi mask is vital in order to keep the oxygen saturation of hemoglobin at 90-96%.
Procedures that are currently used in the treatment of COVID-19 include endotracheal intubation, extubation, bronchoscopy, airway suctioning, nebulization of medication, the use of high-flow nasal cannulae, non-invasive ventilation, and manual ventilation with a bag-mask device. Patients being treated for severe COVID-19 require appropriate nutrition and care to prevent further injury.
According to current guidelines, clinicians are required to wear suitable personal protective equipment (PPE), including gloves, gowns, N95 masks, and eye protection, in the presence of patients with COVID-19. If possible, patients should also wear surgical masks to limit the spread of infectious droplets.
Deciding when a patient with severe COVID-19 should receive endotracheal intubation is an important part of care. Endotracheal intubation is performed by a skilled operator to insert a flexible plastic tube into the trachea of the patient to maintain an open and secure airway. The trachea (which is also referred to as the windpipe) is a large tube that allows for the passage of air.
Patients require lung-protective ventilation after intubation, with a plateau pressure of 30cm of water and tidal volumes based on the height of the patient. If patients do not require intubation but are hypoxemic, a high-flow nasal cannula may be used to improve oxygenation.
Medications, including sedatives and analgesics, are often used to prevent pain, distress, and dyspnea in patients with severe COVID-19. Dexamethasone is a steroid that is currently considered to be the standard of care for these patients. This drug reduces the rate of death in this group of patients who require oxygen, especially those receiving oxygen through mechanical ventilation. A large clinical trial showed that dexamethasone led to a 17% reduction in mortality of hospitalised patients with COVID-19 who required oxygen supplementation.
Although remdesivir has been approved by the Food and Drug Administration (FDA) for the treatment of Covid-19 in patients in hospital, more data is required to understand its function in treating severe COVID-19. Remdesivir seems to have an antiviral mechanism of action as it has been shown to reduce the time taken for patients to reach clinical recovery. The combined use of dexamethasone and remdesivir is being used more clinically, although its benefit requires more research from clinical trials. Other antiviral drugs are being tested for use against COVID-19, including lopinavir and ritonavir.
Patients with COVID-19 can only be discharged from the intensive care unit and transferred to a department for treatment once specific criteria have been met. These criteria include:
- An absence of fever for at least three days
- Major improvements in respiratory symptoms
- Chest scans showing reduced lesions
- No life-threatening damage to major organs
In order to control the high risk of complications from severe COVID-19, it is vital that all infection-control guidelines are followed and goals of care for each patient are established promptly.
Berlin, D., Gulick, R., and Martinez, F. (2020). Severe Covid-19. The New England Journal of Medicine, 383 (25), 2451-2460. Retrieved from: https://www.nejm.org/doi/full/10.1056/NEJMcp2009575?query=featured_home
Xie, P., et al. (2020). Severe Covid-19: a review of recent progress with a look toward the future. Frontiers in Public Health, 8, 189. Retrieved from: https://doi.org/10.3389/fpubh.2020.00189
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