How low can your oxygen level go before you die?

Oxygen is vital for life. It is the principal element needed for life to be sustained. It is needed for the human body cells to produce energy for its daily use. While all the organs in the body need oxygen to optimally perform, it is particularly important for some cells in the body like the brain, the heart muscles, the immune system among others. The oxygen in the air is inhaled and absorbed into the blood in the tiny air sacs or alveoli in the lung. Once in the blood, the oxygen is bound to another molecule called hemoglobin in red blood cells, then taken through the bigger blood vessels to the heart, and then to the rest of the body.

Most body cells begin to die off after a particular period of time without oxygen. While there are varying figures for each cell, the Brain cells are known to start dying after 3 minutes of no oxygen (a state called hypoxia), the Kidneys and liver cells start dying off after about 15-20 min of hypoxia, for the Skeletal muscles, it is about 60-90 minutes, the smooth muscles of the blood vessels can tolerate about 24-72 hours of hypoxia, while the hair and nails can stay several days in a state of hypoxia.

How do we measure the oxygen level in the blood?

Oxygen level is measured in the blood through some methods like:

  • pulse oximetry
  • blood gas test
  • long term oxygen therapy (LTOT) assessment
  • hypoxic challenge (fitness-to-fly) test

The most popular and easiest method is the use of the pulse oximeter.

What is the normal oxygen level for a healthy human?

An oxygen level of 96 to 100% is regarded as normal.

A value of 95%, is considered acceptable

A value of 93 to 94% is borderline and not regarded as normal, there may be need to seek a doctor’s advice if the oxygen level remains at this level

Any oxygen level less than 93% is bad and should seek immediate evaluation by the doctor

What causes low oxygen level in the body?

For the body to maintain a normal oxygen level, several factors are needed to continuously supply the cells and tissues in with oxygen:

  • There must be enough oxygen in the inhaled air
  • The lungs must be able to inhale the oxygen-containing air and exhale carbon dioxide, so it can inhale oxygen again. This means the airways have to be functioning to get the inhaled oxygen to the lungs.
  • The bloodstream must be able to circulate blood to the lungs, take up the oxygen and carry it throughout the body.

If there is any problem with any of the above pathway, the oxygen level becomes low. Common conditions that cause a disruption in any part of this pathway causing low blood oxygen or hypoxemia are:

High altitudes where the oxygen supply is reduced, Anemia, ARDS (Acute respiratory distress syndrome), Asthma, Congenital heart defects in children and heart diseases in children and adults, COPD (chronic obstructive pulmonary disease) exacerbation, Emphysema, Interstitial lung disease, Medications that depress breathing, Pneumonia, Pneumothorax (collapsed lung), Pulmonary edema (excess fluid in the lungs), Pulmonary embolism (blood clot in an artery in the lung), Pulmonary fibrosis (scarred and damaged lungs), and Sleep apnea.

How does the body respond to low oxygen level?

When the oxygen level in the blood is low, the body cannot function properly and the cells cannot have enough energy to maintain their functions. This condition can produce symptoms such as

  • shortness of breath.
  • headaches.
  • restlessness.
  • dizziness.
  • rapid breathing.
  • chest pain.
  • confusion.
  • high blood pressure.
  • Fast heartbeat
  • Coughing
  • Wheezing
  • Bluish color in skin, fingernails, and lips
  • Coma and
  • Eventually death if the low oxygen persists

How low can your oxygen level get low before you die?

A reliably measured SpO2 of 92% is considered the lowest clinically acceptable level by established norms of clinical practice at any age, with an exception of 88% as the lowest in chronic lung disease. Death can occur due to hypoxemia at any level less than this. The BTS guidelines agrees with the above values and recommends people whose oxygen saturation are below these levels be placed at alert as emergency and life threatening.

In children however, values can be as low as 90% which could quickly lead to a serious deterioration in status, and values under 70% are life-threatening and can easily lead to death.

Death can however occur at any oxygen saturation less than the normal value of 94% depending on several factors like the speed of drop of oxygen saturation, the underlying cause, and the general condition of the person.

Severe hypoxemia usually leads to death when the brain cells die off due to inability to function properly. The death of the cells in the vital centers of the brain due to lack of oxygen will cause loss of signals to important organs like the heart, lungs, which will make the individual to stop breathing, and the heart to stop pumping. These processes eventually lead to death.

If you know anybody with a low oxygen level, do not wait for it to get to the dangerous level. Consult your doctor urgently to save a life.