Which of the following is an example of mechanical DVT prophylaxis?

Mechanical DVT prophylaxis refers to methods that physically prevent the formation of deep vein thrombosis (DVT) without the use of medications. Intermittent pneumatic compression devices are a prime example of this approach. These devices apply rhythmic pressure to the legs, enhancing venous return and facilitating blood flow, which helps to prevent the stagnation of blood in the veins that can lead to clot formation.

In contrast, the other options you provided involve pharmacological methods that work through anticoagulation and blood thinning. Low molecular weight heparins, aspirin therapy, and direct oral anticoagulants all belong to the category of chemical DVT prophylaxis and rely on modifying the blood properties to reduce the risk of clotting. Hence, while these are effective in preventing DVT, they do not qualify as mechanical methods.