When a diver’s airway is shut on ascent the expanding air in the lungs can provoke a rupture of the alveoli, thereby causing air to move into the arteries. The expression arterial gas embolism (AGE) better describes the action than the general term air embolism, and is pulmonary barotrauma following voluntary breath holding, or a closure of an airway. It also can result from gas being trapped in the air passages due to diseases, such as a chest cold. When gas enters the arterial circulation it is distributed to all organs of the body. The organs most susceptible to AGE are the heart and brain (CNS), because of this it advances to a life threatening condition.

For the same reason a diver should never dive with a cold, he should also never dive with a cough or chest congestion. When mucus arises in the lung it can entrap air. As the diver ascends this trapped air expands and lung rupture may take place. Never dive with any chest congestion, cough (productive or not), or chest pain. A diver should wait at least one week before doing any dive operations after all symptoms of chest cold have passed. Air embolism must be diagnosed swiftly and accurately. The blood supply to the brain is virtually always involved. Unless treatment is initiated promptly, by recompression, AGE is apt to result in unalterable CNS harm or death. Brain involvement transpires so swiftly, well-defined symptoms show up almost as soon as surfacing. Any CNS symptom that shows up later than 10 minutes after surfacing, other than unconsciousness, is seldom the result of air embolism. Any diver who has been breathing compressed air and is unconscious, or loses consciousness within ten minutes after surfacing must be concluded to have air embolism and re-compressed as having such. A major factor to consider in determining AGE is that its benchmark is sudden onset. It often arises seconds after surfacing, or before.

Signs and symptoms consist of dizziness, paralysis or weakness in the extremities, large areas of abnormal sensation, blurring vision, or convulsions. During ascent the diver may have undergone a sensation of a blow to the chest. The victim may become unconscious or stop breathing without warning. Some of these symptoms also may be the same as someone suffering from decompression sickness. If the dive has been less than 40 feet decompression sickness is unlikely and AGE must be assumed. If the sensation is only pain, and decompression sickness is unlikely, then other over inflation disorders should be considered. Some symptoms can be masked be environmental factors. Pain from any origin might divert attention from other symptoms. A diver who is coughing up blood may be showing signs of a ruptured lung or sinus squeeze, symptoms may improve without treatment spontaneously, and even if this occurs treat as if they were still existing.

Sometimes it may be perplexing to discern air embolism from decompression sickness, so when in doubt treat as AGE. Treatments pertaining to air embolism are longer, and deeper, but are satisfactory for decompression sickness even without air embolism. If there is any doubt as to which is which, presume AGE and treat as such.

Signs and Symptoms of Air Embolism
(usually appear IMMEDIATELY upon surfacing)

Dizziness
Visual Blurring
Bloody Froth From Mouth
Paralysis or Weakness
Convulsions
Unconsciousness
Pulmonary Arrest
Cardiac Arrest