Divers exhale during an ascent to accommodate the air that expands inside the lungs. This is the best way to avoid the hazards of pulmonary barotrauma.
This help guide explains the leading cause of pulmonary overinflation syndrome (POIS) and the common signs and symptoms of lung barotrauma injury in scuba diving and freediving.
What is Pulmonary Barotrauma Definition?
A pulmonary barotrauma in diving refers to a pressure-related injury of the lungs, such as a burst lung or over-expansion.
What Causes Pulmonary Barotrauma in Scuba or Freediving
Holding your breath during an ascent or a descent.
Making a rapid ascent with inadequate or improper exhalation.
Monitor the diver's responsiveness, airway, and breathing (begin cardiopulmonary resuscitation if necessary).
Lay the injured diver down and maintain an open airway. A diver who is nauseated, vomiting, or not fully conscious, should be placed on their side - known as the recovery position.
Important: The short tutorial video [4:55 seconds] presented by DAN contains safety tips for beginners about preventing barotraumas in the ears and sinuses.