What is the purpose of using a tourniquet during a blood draw?

Using a tourniquet during a blood draw serves the primary purpose of restricting blood flow temporarily, which helps to engorge the veins and make them more visible and palpable. When blood circulation is reduced in the area below the tourniquet, the veins become fuller and more pronounced, facilitating easier access for the needle. This visibility is crucial for successful venipuncture, especially in patients with smaller or deeper veins.

While increasing patient comfort, preventing fainting, and ensuring stable blood pressure are important considerations in phlebotomy practice, they are not the primary function of the tourniquet. Instead, the tourniquet is specifically designed to aid in the visibility of veins, ensuring a more efficient and accurate blood draw.