NOT listed as a cause of Mediastinal Emphysema?

• A. Running fast on the surface
• B. Breath holding during ascent
• C. Positive pressure breathing
• D. Drown proofing

Answer: (A)

Mediastinal emphysema in divers comes from rupture of the lung tissue due to pressure changes and forced air entry into the chest, typically from breath-holding during ascent or from breathing with positive pressure. Holding your breath during ascent lets expanding air inside the lungs push outward against the delicate alveoli as ambient pressure falls, increasing intrapulmonary pressure and risking rupture. Positive pressure breathing—using equipment that delivers air at positive pressure—also raises the air pressure in the lungs, making alveolar rupture more likely. Drown proofing involves extended breath-holds and submersion techniques that can produce similar barotrauma risks through air trapping and rapid pressure changes. Running fast on the surface, however, does not create the pressure dynamics or breath-hold scenarios that cause pulmonary barotrauma, so it’s not listed as a cause.