Final answer:
Venipuncture in the back of the hand requires the tourniquet to be placed just above the wrist, aiding in making veins more prominent. Understanding the veins draining the upper limbs, like the radial and ulnar veins, is crucial for this procedure. Blood collection works with gravity, positioning bags below the arm, while IV fluid administration requires bags to be above the entry point.
Step-by-step explanation:
Understanding Venipuncture and Blood Flow
When performing a venipuncture, particularly on the back of the hand, it is essential to make the veins more prominent for ease of needle insertion. This is commonly achieved by placing a tourniquet between the wrist and the puncture site. Venous blood collection often involves using gravity to assist in blood flow, where the collection bag is situated below the arm, in contrast to the administration of IV fluids where the IV bag is typically placed above the entry point into the arm to promote fluid entering. The vascular anatomy is significant in this process as well; understanding how veins draining the upper limbs function is key to performing effective venipuncture.
The digital veins in the fingers lead to the formation of the palmar venous arches which then form larger vessels including the radial, ulnar, and median antebrachial veins. These veins drain into the brachial vein, and eventually, the axillary vein. For venipuncture, the most common site is the median cubital vein located at the antecubital fossa. However, when access in this area is not viable, the superficial veins on the back of the hand can be used.