Which prevention practice is recommended to reduce risk of mediastinal emphysema during ascent?

• A. Hold breath during ascent
• B. Exhale continuously during ascent
• C. Pause at depth
• D. Breathe normally upon ascent

Answer: (D)

Ascent safety hinges on how your lungs handle expanding gas as ambient pressure drops. When you ascend, air inside your lungs tends to expand. If you hold your breath or pause at depth, that trapped air can push on delicate lung tissue and lead to alveolar rupture, allowing air to move into the mediastinum. Breathing normally during ascent keeps ventilation steady and lets the lungs expand gradually with the changing pressure, reducing the risk of air escaping into the mediastinal space.

Holding breath is risky because it traps expanding air. Pausing at depth delays venting of the expanding gas, increasing the chance of barotrauma. Exhaling continuously during ascent isn’t the standard safeguard; it’s best to maintain normal, relaxed breathing, which is why breathing normally upon ascent is the recommended practice.