What Are Blood Oxygen Levels? Normal, High, and Low

Blood oxygen levels can get low due to any of the problems that include:

• Low air oxygen levels: Atmospheric oxygen becomes extremely low at high altitudes such as mountainous regions.
• Decreased capacity of the body to take in oxygen: This can be caused by lung conditions that include:
  • Asthma
  • Emphysema (damage of the air sacs in the lung)
  • Bronchitis
  • Pneumonia
  • Pneumothorax (leaking of air in the space between the lung and chest wall)
  • Acute respiratory distress syndrome (ARDS)
  • Pulmonary edema (the lung swells due to build-up of fluid)
  • Pulmonary fibrosis (scarring of the lungs)
  • Interstitial lung disease (a large group of lung disorders that generally cause progressive scarring of the lungs)
  • Viral infections such as COVID-19
• Other conditions include:
  • Anemia
  • Sleep apnea (temporary cessation of breathing during sleep)
  • Smoking
• Decreased capacity of the heart to supply the oxygenated blood back to the lungs: The most common causes are congenital heart diseases (heart defects present by birth).

Blood oxygen levels can be checked by withdrawing blood from your artery present in the wrist, elbow, or groin. You may feel a sharp pain when the needle enters the artery. The blood will be put in an ABG machine (blood gas analyzer) that provides your blood oxygen levels in the form of the partial pressure of oxygen (PaO2).

A pulse oximeter is a small, mobile, and handy medical device. It is most commonly used when doctors want to know your blood oxygen levels quickly. It is also used to monitor the response of your body to certain medications or supplemental oxygen. Blood oxygen levels are indicated as SpO2, which is the percent saturation of oxygen in the blood.

The test that measures blood oxygen levels using a pulse oximeter is known as pulse oximetry. The procedure is very simple and requires only clipping the pulse oximeter in between any of the fingers for a few seconds. The reading appears on the pulse oximeter screen. This test may be slightly less accurate than ABG but is easier to perform than ABG tests when needed quickly.

• The brain gets affected when the SpO2 level falls below 80-85%.
• Cyanosis develops when the SpO2 level drops below 65%.
• The normal oxygen levels in a pulse oximeter usually range from 95% to 100%.  Note: Normal levels may vary if you have lung disorders. Your doctor can tell what levels are normal for you.

Hypoxemia can give rise to many signs and symptoms depending on its severity. These signs and symptoms include:

• Headache (mild to severe)
• Shortness of breath
• Dizziness
• Coughing
• Wheezing (breathing with a whistling or rattling sound in the chest)
• Confusion
• Rapid heartbeat
• Cyanosis (bluish color in the skin, fingernails, and lips)

Not having enough blood oxygen levels results in inadequate oxygen supply to the organs and tissues of the body. Severe hypoxemia can become dangerous. If left untreated for a long time, it can end up affecting the brain or heart.

Treating hypoxemia involves measures that increase the levels of oxygen in the blood. This is achieved by

• Treating underlying conditions: Treating the cause of hypoxemia is the most important part of the therapy that gives long-lasting effects. Many times, medications are given through an inhaler that quickly enables you to breathe the medicine into your lungs.
• Oxygen therapy: You are given supplemental oxygen through an oxygen cylinder (which can be portable). The pressure of delivered oxygen can be controlled.

You can maintain your normal blood oxygen levels after you recover from hypoxemia.

Here are a few lifestyle steps you can take to help prevent hypoxemia:

• Deep breathing exercises
• Mild exercise such as walking or as advised by your doctor
• Yoga
• Eat a healthy, well-balanced diet
• Drink water adequately
• Quit smoking