Context: Many medical practitioners have reported a condition called ‘silent’ or ‘happy’ hypoxia among the Covid patients in which people have extremely low blood oxygen levels, yet do not show signs of breathlessness.

More on the news:

  • Covid pneumonia — a serious medical condition found in severe Covid-19 patients — is preceded by ‘silent hypoxia’, a form of oxygen deprivation that is harder to detect than regular hypoxia.
  • The condition has puzzled medical practitioners, and many are now advocating for its early detection as a means to avoid a fatal illness called Covid pneumonia.

About Hypoxia and Silent Hypoxia:

  • Hypoxia is a condition wherein there is not enough oxygen available to the blood and body tissues. 
  • Hypoxia can either be generalised i.e affecting the whole body, or local i.e affecting a particular region of the body.
  • Normal arterial oxygen is approximately 75 to 100 millimetres of mercury (mm Hg), and normal pulse oximeter readings usually range from 95 to 100 percent. Values under 90 per cent are considered low.
    • When levels fall below 90 per cent, patients could begin experiencing lethargy, confusion, or mental disruptions because of insufficient quantities of oxygen reaching the brain. 
    • Levels below 80 per cent can result in damage to vital organs.
  • In ‘silent’ or ‘happy’ hypoxia, patients appear to be less in distress
    • Many Covid-19 patients, despite having oxygen levels below 80 per cent, look fairly at ease and alert, according to multiple reports.
    • In many cases, Covid-19 patients with silent hypoxia did not exhibit symptoms such as shortness of breath or coughing until their oxygen fell to acutely low levels, at which point there was a risk of acute respiratory distress (ARDS) and organ failure.

Why Covid 19 Patients Don’t exhibit Symptoms of Silent Hypoxia ?

  • According to a report in The Guardian, the reason why people are left feeling breathless is not because of the fall in oxygen levels itself, but due to the rise in carbon dioxide levels that occur at the same time, when lungs are not able to expel this gas efficiently. 
    • As per the report this response does not appear to be kicking in in some Covid-19 patients, the report says.
  • According to other experts, this happens because in patients with Covid pneumonia, the virus causes air sacs to fall, leading to a reduction in levels of oxygen. 
    • However, the lungs initially do not become stiff or heavy with fluid, and remain “compliant” — being able to expel carbon dioxide and avoiding its buildup. 
    • Thus, patients do not feel short of breath.

Way Ahead:

  • Experts suggest that a medical device called a pulse oximeter – used to detect oxygen level in the blood – could help in the early detection of silent hypoxia.
    • Using the device, those who have Covid-19 or those suspected of having it, can check their oxygen levels early on. 
    • A fall in oxygen levels, caused by the silent hypoxia, can serve as a signal for seeking additional treatment immediately, and not wait for a coronavirus test.
  • Others have expressed concern against this, saying that frequent use of the device would only lead to increased anxiety among many.

Pulse Oximeter:

  • Pulse oximetry is a test used to measure the oxygen level (oxygen saturation) of the blood.
  • The device measures the saturation of oxygen in red blood cells, and can be attached to a person’s fingers, toes, nose, feet, ears, or forehead. It can be reused or disposed of after use.
  • It is an easy, painless measure of how well oxygen is being sent to parts of your body furthest from your heart, such as the arms and legs.
  • Based on the information from the blood oximeter, a healthcare provider can take a decision about whether a person needs extra oxygen.
  • The device is generally used to check the health of patients who have known conditions that affect blood oxygen levels, such as heart and lung conditions, and for those who show symptoms such as shortness of breath.



Image Source: Economic Times