What type of device is a tourniquet considered to be?

A tourniquet is classified as a compressing device because its primary function is to apply pressure to a limb in order to constrict blood flow, typically to facilitate venipuncture. By compressing the blood vessels, the tourniquet helps to engorge the veins, making them more prominent and easier to access for drawing blood. This action is crucial in phlebotomy, as it enhances visibility and access to the veins without causing injury or trauma to the patient.

The other types of devices listed serve very different purposes: measuring devices are used to quantify something, sampling devices are intended to collect specimens, and heating devices are meant to raise the temperature of a material. In contrast, the tourniquet's specific functionality is directly tied to its ability to compress and control blood flow, solidifying its classification as a compressing device in medical practice.