What is SpO2?

The body usually maintains healthy SpO2 levels by breathing. The lungs take oxygen and bind it to hemoglobin then travels throughout the body. During physiological stress and at higher altitudes, the body adapts to these increases provided that they are not too extreme.

  • In a normal healthy individual, the SpO2 levels should be ≥ 94%
  • Normal – COPD the SpO2 levels should be 88% – 92%
  • In Hypoxic condition, the SpO2 levels should be 85% – 93%
  • In severely Hypoxic condition the SpO2 levels should be < 85%
  • A drop of 3% or more SpO2, even within normal saturations, indicates the first evidence of an acute illness.

Conditions that cause blood oxygen levels to become low – SpO2?

  • Asthma 
  • Bronchitis
  • Acute respiratory distress syndrome
  • Emphysema
  • Pneumothorax
  • Pulmonary edema
  • Interstitial lung disease
  • Pulmonary fibrosis
  • Smoking
  • Sleep Apnea
  • Anemia

Signs and symptoms of Hypoxia:

  • Darker complexion
  • Hallucinations
  • Twitches
  • Pallor
  • Disorientation
  • Irregular heartbeat
  • Shortness of breath
  • High blood pressure
  • Depression and other mood disorders
  • secondary polycythemia

SpO2 levels can be measured with two different tests:

Arterial blood gas:

It’s a blood test that measures the pH, acidity and levels of oxygen (O2) and carbon dioxide (CO2) from an artery. The test is used to check the patient’s lungs and how well they are able to move oxygen into the blood and remove carbon dioxide.

For people who use supplemental oxygen, it can be detected on an ABG.

Pulse oximeter:

Pulse oximeters are medical devices that indicate the oxygen levels present in the blood that flows through the arteries in the body. These devices are essential in measuring oxygen and carbon dioxide levels before they enter body tissues.

The body needs a certain level of oxygen in the blood for metabolism but the brain and heart are sensitive to lack of oxygen. The shortage of oxygen in the body is called hypoxia and there will be a visible effect on the skin, known as cyanosis due to the blue tint it takes on.

Steps that help to prevent Hypoxia are: 

  • Deep breathing exercises
  • Mild exercise such as walking
  • Yoga
  • Eat healthy and well-balanced diet
  • Drink water adequately
  • Quit smoking

Blood oxygen levels pulse oximeter:

  • 95-100% – Normal blood oxygen levels
  • 91-95% – Concerning blood oxygen levels
  • ≥ 90% – low blood oxygen levels
  • 80-85% – When low oxygen saturation affects your brain
  • 67% – Cyanosis


people with health problems that cause low oxygen need to regularly monitor their blood oxygen level.  The pulse oximetry method is useful than an invasive ABG.