Compartment Syndrome

Balloon in a Rigid Box

Imagine blowing air into a balloon trapped inside a rigid plastic box that does not stretch. At first, the balloon expands normally—air flows in through a tube (like an artery) and deflates through a valve (like a vein). But if you keep blowing, pressure inside the box rises because the box cannot give. Soon the pressure squeezes the valve shut first (veins collapse), trapping stale air inside. Keep blowing and the pressure crushes the inlet tube too (arteries collapse), so no fresh air can enter. The balloon (muscle and nerve) is now suffocating in a sealed, pressurized box. The only fix is to crack open the box (fasciotomy) to release the pressure instantly—waiting just makes the balloon tissue die faster. This is exactly what happens when blood or fluid swells inside a muscle compartment wrapped by non-stretchy fascia.