How does NMES facilitate edema reduction?

• A. By heating tissue to increase blood flow.
• B. By delivering continuous stimulation to cause tissue compression only at electrode sites.
• C. By reducing lymphatic function.
• D. By producing rhythmic muscle contractions that activate the muscle pump, promoting venous and lymphatic return and reducing interstitial fluid.

Answer: (D)

The main idea is that NMES reduces edema by triggering rhythmic muscle contractions that act as a functional muscle pump. When the stimulated muscles contract, they squeeze nearby veins and lymphatic vessels, creating pressure waves that push venous blood and interstitial fluid back toward the heart and promote lymphatic drainage. The alternating contraction and relaxation phases help overcome gravity and reduce fluid stasis, which decreases swelling in the limb.

The other options don’t fit this mechanism. Heating tissue may increase local blood flow but it doesn’t mobilize interstitial fluid through a muscle pump. Continuous stimulation that only compresses tissue at the electrode sites wouldn’t generate the coordinated, whole-muscle pump action needed to move fluid effectively. Reducing lymphatic function would worsen edema, not alleviate it.