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• Barotrauma

  Any injury caused by abnormal pressure of air
• Barotrauma

  • Usually associated with scuba diving but can happen anywhere where there is a sudden drop or change in pressure
• Buoyancy

  Dependent on the object's density relative to the liquid which can either lead to the object to sink or float
• Neutral buoyancy

  An object that neither floats or sinks
• Boyle's law

  P1V1 = P2V2 and PV = constant (P = Patm +⍴gh)
• SCUBA

  Self contained underwater breathing apparatus
• SCUBA

  • Delivers ambient pressure to the diver
  • Contains a dive regulator, mask, and wetsuit
• Divers breathe in high pressured air that is greater than atmospheric air and will experience abnormally high pN2 and pO2 as well as high gas solubilities in blood and tissues
• Dalton's law

  Ptotal is the sum of all partial pressures (P1 + P2 + P3)
• Henry's law

  The amount of gas that is dissolved in a liquid is directly proportional to the partial pressure of that gas
• The further a diver descends, the more the gasses become soluble in the blood
• Compression (descent)

  • Also known as squeeze injuries where as the diver descends the pressure increase and the air spaces become compressed which leads to the divers lungs not being able to function anymore
• There is a potential for a squeeze to occur whenever there is an airspace on or around the body. This usually occurs when the pressure inside the air space is different than the pressure outside the airspace
• During descent, the barotrauma injuries usually effect freedivers (divers holding their breath) as the effects of pressure on the lungs of breath holders compared to breathing compressed air is reduced as breath holding can reduce the lung capacity ¼ of the normal volume
• Ear squeeze

  • When the pressure is not equalized and due to the pressure difference this can cause the eardrum to rupture
• Vertigo

  Dizziness that is due to water being present in the middle ear disrupting the semicircular canals
• Sinus squeeze

  • Occurs when a person dives with a cold or the membrane lining the sinus is irritated which cannot therefore clear the sinuses
• An indication of this trauma is blood on the mask during ascent
• Mask squeeze

  • When the air inside the mask is compressed, this causes the mask to suck to the face causing bruising and results in 2 black eyes
• Masks are equalized by exhaling into them
• Oxygen toxicity


  Oxygen can affect the central nervous system by causing convulsions and seizures when above atmospheric pressure
• Oxygen can be toxic when the pO2 is greater than 1.6 atm which is considered fatal underwater due to convulsions as a consequence
• Nitrogen narcosis

  Results due to the solubility of nitrogen in the blood and tissues as the diver descends and the partial pressure of nitrogen increases
• Nitrogen narcosis can have an intoxicating effect (drunk) - (pN2 > 3.2 atm) and is a frequent cause of fatalities
• Decompression

  • On ascent, decompression sickness and air embolism can occur
• If a diver is at depth for too long, the body tissue may become saturated with nitrogen which can they not be excreted/removed at a fast enough rate during ascent
• During ascent, the pressure increases causing the nitrogen in the blood to form microbubbles
• Decompression sickness (the bends)

  The bubbles actually start to form in the CSF, joints, muscle, capillary bed - everywhere, leading to involuntary spasms that causes the victim to go into a fetal position
• To prevent 'the bends' to occurs, immediate administration of oxygen is needed and the patient needs to be rushed to the nearest hyperbaric/recompression chamber
• DCS (decompression sickness) victims are more susceptible to further attacks and are prohibited from diving and DCS is not only a condition due to scuba diving it can also be due to the loss of cabin pressure which is why it is important to get masks on ASAP to prevent DCS and hypoxia
• DCS is also a risk during spacewalks as the suits only work at one third of atmospheric pressure. They must decompress slowly over 2 hours before spacewalking
• Air embolism

  Caused by breath holding on ascent. When the air expands the lungs, this leads to the alveoli membranes and capillaries to rupture, allowing air bubbles to enter the bloodstream
• Air embolism leads to the blood vessels being blocked in the brain, heart and various parts of the body and when not treated quickly, this causes certain parts of the body to die leading to permanent damage
• Barotrauma injuries during ascents

  • Thoracic trauma (chest injury)
  • Pneumothorax (lung collapsing)
  • Haemothorax (blood collection in pleural space)
  • Subcutaneous emphysema (chronic obstructive pulmonary disease)
  • Air embolism
• Barotrauma injuries

  • Pneumocardium (air in the sac around the heart)
  • Subcutaneous emphysema (air under the skin - like bubble wrap)
  • Mediastinal emphysema (air enters the space where the great blood vessels lie as well as the heart, lungs and trachea)
  • Pneumothorax (air between lung and chest wall may cause lungs to collapse)
  • Cerebral embolism (blockage of air in blood vessels supplied to the brain)
• Descent squeezes

  • Ears
  • Sinuses
  • Mask
  • Thoracic
  • Teeth
  • Stomach/intestines
  • Suit
• Ascent squeezes

  • Air embolism
  • Pneumothorax
  • Mediastinal emphysema
  • Subcutaneous emphysema
• In breath holder divers such as snorkeling, spearfishing and free-diving, shallow water blackout can occur
• Before diving, the divers hyperventilate to increase the depth and rate of breathing to maximize the oxygen volume in the lungs. This also blows off the carbon dioxide so when diving, it is at an abnormally low pCO2 level