Hypoxia

Hypoxia - What is it ?
Hypoxia is a condition arising from a deficiency in the amount of oxygen in the blood which results in damage to the organs and tissues of the body.

(Note : Hypoxia and Hypoxemia are terms which are often used interchangeably)

To understand this more fully, we need to have an understanding of how this deficiency may arise.

The only way for oxygen to reach your liver, brain, muscles, etc, is by travelling there through your circulatory system - your arteries, veins  and capillaries.  You breath in air, 21% of which is oxygen, and this oxygen is tranferred into bloodstream, in your lungs, through the alveoli, the endpoint, if you like, of your respiratory system.  The alveoli exchanges the 'new' oxygen you have just breathed in for the carbon dioxide in the bloodstream.

This carbon dioxide is a by-product of the process of cell respiration, as is water. In this process, energy is produced in the mitochondria of cells. This energy is our physical "life force". Both oxygen and glucose (produced by the liver) are required for this. Glucose contains carbon. That's where the carbon in the carbon dioxide comes from. Glucose plus oxygen produces carbon dioxide, water and energy. When this process stops, the cell dies.  (adapted from https://tinyurl.com/y2fd659u)

This 'energy' is what keeps is alive.  Without the right balance of oxygen and glucose, our organs and tissues will start to shut down, and this can, ultimately, result in death.

So ... Hypoxia is a condition arising from a deficiency in the amount of oxygen in the blood which results in damage to the organs and tissues of the body.

Hypoxia can kill if the oxygen deficiency is severe enough that organs start to shut down.

What Causes Hypoxia ? 
There are a number of causes of hypoxia.  Now that you know what hypoxia is, it isn't too difficult to work out what might cause it.
Basically, anything which impedes the supply of oxygen to the lungs, or which impedes the flow of oxygen enriched blood to the organs and tissues of the body will result in hypoxia.

Impaired oxygen supply could be caused by ... 
  • Strangulation
  • Choking (or 'throttling')
  • Suffocation
  • Smoke inhalation
  • Swollen airway (for example, from an allergic reaction)
  • Asthma
  • Lung damage (like a collapsed lung) or chest wall injury
  • Crushing of the chest
  • Drowning
  • High Altitude
  • Poisoning
Note that 'asphyxia' is defined as the cutting off of the oxygen supply to the lungs, and so many of the things listed above could result in asphyxia.

Impaired blood flow could be caused by ...
  • Heart attack
  • Angina
  • Blood loss
  • Seizure

Hypoxia could also be brought on by a spinal cord injury or a head injury.

Signs and Symptoms of Hypoxia
Signs and symptoms of Hypoxia could be ... 

  • Air hunger - because the casualties body will be desperate for oxygen.
  • Clammy skin
  • Cyanosis - the development of a 'blue' tinge to lips, nostrils and earlobes (because the oxygen depleted blood is close to the surface of the skin at these points, and so the colour change in the blood becomes apparent)
  • Increased breathing and pulse rates - the body tries to compensate for the low blood oxygen by taking in more air (faster breathing) and increasing the heart rate to try to get more blood to where it needs to be.
  • Lowered consciousness - as the brain starts to experience low blood oxygen, brain function will deteriorate.
  • nausea - feeling sick, and inclined to vomit.
  • Thirst
  • Weak pulse - it may be going faster, but as tissue damage commences due to insufficient levels of oxygen, the functioning of the heart may be impaired.
Treatment of Hypoxia
Hypoxia, unless you can remove or treat the cause, will require immediate assistance from medical professionals. Remember ... this could be a life threatening situation.

As a first aider, then, you role is to ...
  • Maintain an open airway
  • Remove or treat the cause
  • Do not allow the casualty to eat or drink anything until they have been checked over (they may require further intervention such as surgery depending on the cause of the hypoxia)
Once you have stabilised the casualty, transport them to the nearest hospital for further checks.  You can do this in your own car or by calling an ambulance.  You need to use your discretion.  If the 'incident' was very brief and you were able to sort things out quickly, it will probably be fine to transport them yourself, but if the casualty was hypoxic for anything more than a few minutes, or appeared/appears to be in any way cognitively impaired as a result of the incident, it would be appropriate to call an ambulance.  Remember that tissue or organ damage may not be apparent to you as a first aider.

For more information on Hypoxia, please refer to pages 20 of your course reader.
© Copyright Simon Watson