For how long should a tourniquet not remain on a patient during blood collection?

A tourniquet should not remain on a patient for longer than 2 minutes during blood collection to minimize the risk of complications. Extended application of a tourniquet can lead to several issues, including hemoconcentration, which affects the results of laboratory tests by altering the concentration of cellular components in a blood sample. Hemoconcentration can cause falsely elevated levels of certain analytes, impacting the accuracy of test results.

Moreover, leaving a tourniquet on for too long can cause discomfort or even pain for the patient, and can potentially lead to the formation of hematomas if the blood is drawn after the tourniquet has been on for an extended period. Therefore, the standard practice is to apply the tourniquet just long enough to engorge the veins—typically not exceeding 1 to 2 minutes—to facilitate a successful blood draw while maintaining the quality of the specimen and patient comfort.

In summary, adhering to the guideline of keeping the tourniquet on for less than 2 minutes ensures optimal conditions for blood collection and accurate laboratory results.