Radial artery puncture
Radial artery puncture is a medical procedure that is performed in order to obtain arterial blood sampling for gas analysis. A needle is inserted into the radial artery and spontaneously fills with blood. The syringe that is used is either prepacked with a small amount of heparin, to prevent coagulation, or needs to be heparinised, by drawing up a small amount of heparin and squirting it out again. Most commonly radial artery puncture is performed in order to obtain arterial blood sampling for gas analysis. The partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) and the pH of arterial blood are important in assessing pulmonary function, since these data indicate the status of gas exchange between the lungs and the blood.
- Cellulitis or other infections over the radial artery
- Absence of palpable radial artery pulse
- Positive Allen test (see below), indicating that only one artery supplies the hand
- Coagulation defects (relative)
It is very important to perform Allen Test to confirm the patency of the ulnar artery, because in case there is no collateral flow through the ulnar artery, radial artery puncture is contraindicated since it can result in a gangrenous finger or loss of the hand from spasm or clotting of the radial artery. The Allen Test is performed with the patient sit with her hands supinated on her knees. Then stand at the patient's side with your fingers around her wrist; compress the tissue over both radial and ulnar arteries. Allow a few minutes for the blood to drain from the hand while the patient opens and closes her hands several times. Release the pressure on the ulnar artery while keeping the radial artery occluded. normal skin color should return to the ulnar side of the palm in 1-2 seconds, followed by quick restoration of normal color to the entire palm. A hand that remains white indicates either absence or occlusion of the ulnar artery, and radial artery puncture is contraindicated.
The radial artery runs along the lateral aspect of the volar forearm deep to the superficial fascia. The artery runs between the styloid process of the radius and the flexor carpi radialis tendon. The point of maximum pulsation of the radial artery can usually be palpated just proximal to the wrist.