How does a tourniquet affect venous pressure?

When a tourniquet is applied, it temporarily restricts blood flow through the veins. This restriction leads to an accumulation of blood in the veins, which increases venous pressure. The increase in pressure causes the veins to become engorged and more prominent, making them easier to locate and puncture during venipuncture for blood collection.

This physiological response is important because it allows healthcare providers to efficiently select suitable veins for blood draws, thereby facilitating the collection of blood specimens. Proper application of a tourniquet is crucial to creating this effect without causing discomfort or harm to the patient.

Understanding how venous pressure changes with a tourniquet is an essential part of the blood collection process, ensuring that procedures are both effective and safe.