Which of the following is NOT listed as a POIS type?

• A. Arterial Gas Embolism
• B. Mediastinal Emphysema
• C. Subcutaneous Emphysema
• D. Inner ear barotrauma

Answer: (D)

This question tests understanding of what injuries fall under POIS—pulmonary over‑inflation injuries that arise from lung overexpansion during ascent. When a diver ascends with a closed airway (for example, by holding breath), the expanding air can rupture alveoli. That rupture can send air into different spaces: into the arterial circulation, causing an arterial gas embolism; into the mediastinum, causing mediastinal emphysema; or into the subcutaneous tissues, causing subcutaneous emphysema. These are classic POIS presentations because they all originate from pulmonary over‑inflation and subsequent air leakage from the lungs.

Inner ear barotrauma, in contrast, results from pressure changes affecting the middle and inner ear and is not caused by alveolar rupture or pulmonary air leak. It’s a different mechanism of barotrauma and isn’t categorized as a POIS type, which is why it isn’t listed among POIS injuries.