What are the common causes of hypoxia?

Effects of HypoxiaHypoxia occurs when there is a lack of oxygen in the blood. There are many different causes of hypoxia and it is important for first aiders and first responders to know the common causes of hypoxia. 

The easiest way to remember the common causes of hypoxia is to split them into categories:

Outside the body

Environmental changes can cause hypoxia if the amount of oxygen in the air is reduced:

  • Smoke
  • Gas / Carbon Monxoide
  • High altitude
  • Deep sea
  • Mine shafts
  • Tunnels
  • Depressurised aircraft

Obstruction of the upper airway

Patients who have a reduced level of consciousness are particularly vulnerable to upper airway obstruction.

  • Tongue – this is the most common cause! 
  • External blockage (eg plastic bag) 
  • External pressure on the neck
  • Drowning
  • Blood / vomit
  • Inhaled objects (eg food)
  • Facial / neck injuries
  • Internal swelling of the throat – stings (Anaphylaxis) / burns

Chest or lung trauma

  • External compression – crowds, sand, damaged vehicle
  • Rib fractures
  • Blast injuries
  • Pneumothorax (air in the thoracic cavity)

Paralysis of respiratory nerves and muscles:

  • Electrocution
  • Head and/or spinal injuries
  • Stroke
  • Drugs
  • Chronic muscular diseases
  • Some poisons such as weed killers and nerve gases

Internal lung problems:

  • Chronic Obstructive Pulmonary Disease (COPD)
  • Pneumonia / Lower Respiratory Tract Infections
  • Asthma

John Furst

JOHN FURST is an experienced emergency medical technician and qualified first aid and CPR instructor. John is passionate about first aid and believes everyone should have the skills and confidence to take action in an emergency situation.

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