The poor condition of veins after multiple venepunctures or prolonged intravenous infusion is a common phenomenon. In addition to the possibility of vein rupture, phlebitis, pain, and bruising, one group, Vein Access Technologies, has proposed that each time the tourniquet is applied, the vein will distend and thin resulting in venous system leakage into the subcutaneous tissues. The result of this can be falsely elevated blood components due to hemoconcentration. Their theory is that when intravenous pressure exceeds 20mm Hg (which happens each time a tourniquet is applied ) there is an immediate extravasation of intravascular fluids out of the venous system and into the extravascular tissue. The group has responded to this by developing a device called the Venicuff which could replace the tourniquet. It works similarly to a blood pressure cuff but limits the amount of pressure to 20mm Hg. It is always placed halfway between the shoulder and the antecubital line. The cuff portion of the device is disposable.
