Barotrauma/Decompression Sickness Causes

Two different phenomena cause barotrauma:

• The inability to equalize pressures
  
  
• The effect of pressure on an enclosed volume

• Decompression sickness is caused by the elevated pressures of the gas mixture inhaled underwater that diffuse into the body tissues, and then the inadequate diffusion of the gas from the tissues if the diver surfaces too quickly.
  
  
• Middle ear squeezes occur because of obstruction of the eustachian tube.
  
  
  • The most common cause is an upper respiratory infection (cold), creating congestion.
    
    
  • Other causes of obstruction include congestion caused by allergies or smoking, mucosal polyps, excessively aggressive Valsalva attempts, or previous facial injuries.

• Factors that trigger sinus squeezes include a cold, sinusitis, or nasal polyps.

• Contributing factors to aerogastralgia (swallowing air) include performing Valsalva maneuvers with the head down (which allows air swallowing), consuming carbonated beverages or heavy meals prior to diving, or chewing gum while diving.

• Pulmonary barotrauma occurs from the diver holding their breath during ascent, which allows pressure to rise in the lungs.
  
  
  • The pressure increase results in rupture.
    
    
  • Air also may penetrate into the tissue around the lungs.

• The classic description of a dive causing an air embolism is rapidly ascending to the surface because of panic.

• Failure to make recommended decompression stops during ascent usually causes decompression sickness. Stops are based on diving tables or charts, which factor into account the depth, duration of the dive, and previous dives completed and give you guidelines on the proper rate of ascent.