- Hypoxia is low levels of oxygen in the body’s tissues. Hypoxemia is low levels of oxygen in the blood.
- While both hypoxia and hypoxemia can occur separately, they often occur together because if there is low blood oxygen, the blood does not deliver enough oxygen to the body’s tissues. The term hypoxia is often used to describe both low oxygen in the body’s tissues as well as low blood oxygen.
- Silent hypoxia is a condition caused by COVID-19 (coronavirus disease 2019) in which patients have low levels of oxygen but no difficulty breathing or shortness of breath, which are common symptoms of hypoxia.
- Silent hypoxia is not usually an early symptom of COVID-19. By the time silent hypoxia occurs, patients may come to a hospital’s emergency room for other COVID-19 symptoms that are already present, such as muscle aches, fatigue, fever, and cough, and patients may be in critical condition.
Signs that may indicate you could have silent hypoxia include:
- Mild symptoms of COVID-19 for a couple of days before a dramatic tightening of the chest
- Inability to take deep breaths because of the pain caused by inhalation
- Profuse sweating for no reason
- Blue lips or a change of color in the skin, ranging from cherry red to blue
The American Lung Association does not advise that patients monitor blood oxygen levels as a form of self-detection for COVID-19. If you have any signs of COVID-19, see a doctor immediately and do not rely on a home pulse oximeter reading.
Look for other signs and symptoms of COVID-19 such as fever, cough, gastrointestinal symptoms, muscle soreness, fatigue, and changes in taste and smell.
Typical symptoms of hypoxia include:
- Shortness of breath
- Difficulty breathing
- Rapid breathing
- Changes in skin color, ranging from blue to cherry red
- Blue skin, lips, and fingernails
- Fast heart rate
- Slow heart rate
Hypoxia is a medical emergency. If you think you are experiencing symptoms of hypoxia, call 911 and get to a hospital’s emergency department.
What Causes Silent Hypoxia?
Silent hypoxia is caused by COVID-19 but the reason this occurs is unknown. There are some theories as to why this occurs with COVID-19 infection:
- The virus may affect the airways of the lungs and the blood vessels flowing through the lungs, disrupting this normal matching of blood flow and airflow, but this interference may not be enough for a person to sense a feeling of shortness of breath.
- COVID-19 may not be affecting the lungs’ ability to get rid of carbon dioxide. Normally, when carbon dioxide levels rise, there is an urge to increase breathing and patients will sense some shortness of breath.
- COVID-19 may be directly affecting the body’s oxygen sensing mechanism or the nervous system, so it becomes less sensitive to the effects of low oxygen levels.
Risk factors for developing silent hypoxia include COVID-19 patients who are:
- Have diabetes
How Is Silent Hypoxia Diagnosed?
Silent hypoxia is diagnosed with a physical examination, where a doctor will listen to the heart and lungs, and also check to see if the skin, lips, or fingernails have a bluish color.
If COVID-19 is suspected, tests used to diagnose the virus include:
- PCR tests (genetic or molecular test)
- Antigen test
Tests used to check oxygen levels include:
- Pulse oximetry
- A small device with a sensor that clips to the finger and measures the amount of oxygen in the blood
- Normal readings are about 94% to 99% oxygen saturation levels
- Arterial blood gas test
- A blood sample is taken from an artery to measure levels of oxygen in the blood
- Pulmonary function tests
- 6-min walking test (6MWT)
- Oxygen saturation level is measured after six minutes of taking walks
What Is the Treatment for Silent Hypoxia?
Hypoxia is a medical emergency and treatment for hypoxia involves the administration of oxygen in a hospital.
- Oxygen is typically supplied via a nasal canula or a mask that covers the nose and mouth.
- In some cases, asthma medications or an inhaler may be used to help patients breathe.
- Steroids may be used to help reduce inflammation.
- Antibiotics may be given to treat underlying infection.
- In severe cases, patients may need oxygen in a hyperbaric chamber, and others will require mechanical ventilation (intubation).
Patients will also require treatment for other COVID-19 symptoms, which may include:
- Monoclonal antibodies
- Antiviral therapy with remdesivir
- Dexamethasone is preferred
- Prednisone, methylprednisolone, or hydrocortisone may be used if dexamethasone is not available
- Convalescent plasma
- Immunoglobulin products
- Interleukin inhibitors
- Kinase inhibitors
- Antithrombotic therapy — anticoagulants and antiplatelet therapy
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