The arm is turned with the ventral surface up. Tie or attach a tourniquet or blood pressure cuff on the arm, approximately 3-5 inches above a potential venipuncture site. It should be attached tightly but not so that it is uncomfortable for the patient. A half-loop is tied so as to allow for rapid release with one hand. Never allow the tourniquet to remain on for more than 1-2 minutes as hemoconcentration may occur.
Site selection requires a technique known as palpation or feeling the vein.
Palpate for a viable vein first, then select equipment, put gloves on and then perform the venipuncture. The most common site selected for venipuncture is the antecubital area of the arm, where the basilic, cephalic and medial cubital veins are most prominent and usually near the surface of the skin. If Both left and right antecubital areas are evaluated and no veins can be located, move down the arms , toward the hands in an attempt to find a viable site. With no arm veins, attempt to locate one in the hand or wrist. Extend or bend the hand or foot to help hold the vein in place since they may tend to roll.