Which of the following is NOT a prerequisite for a squeeze?

• A. Gas filled space
• B. Vascular penetration (allows blood to be forced into the space)
• C. Enclosed space
• D. Ambient pressure change

Answer: (B)

A squeeze happens when a gas-filled space in the body is subjected to a change in ambient pressure that cannot be equalized, causing the space to compress or overexpand and injure surrounding tissues. For this to occur, three conditions are typically present: a gas-filled space, an enclosed space that traps that gas, and a change in ambient pressure (as you descend or ascend).

Vascular penetration is not required for a squeeze. Gas entering the blood vessels is a different injury mechanism (gas embolism) and can occur via other pathways, but the squeeze itself relies on a gas-filled space, enclosure, and a pressure change to cause injury.