 What come to nursing school explain in this video on the Allen test which checks the patency of the arteries that feed the hand at the wrist and the Allen test is usually used for drawing arterial blood gases because we want to make sure that the artery where we're actually going to draw that blood from is Patent and doesn't have any kind of problems because if we cause additional problems that might Eventually cause some problems with the blood flow to the patient's hand So the Allen test will help us determine if the artery is patent and most Commonly we will use the radio artery for that test, but we can also use the opposite the ulnar artery So let's take a look at that So for the Allen test, we are going to compress both the patient's radial and Ulnar arteries which then will basically Cause a little bit of ischemia or lack of blood flow in the hand Which you will see by the changing of the color of the hand and then I let go of the radio or the ulnar side first And see how fast the color returns back to the patient's hands and that lets me know that their artery is patent and Ready to go for a arterial blood gas test Typically we use the radio artery. So that's what we are going to demonstrate here today So first I find the radio artery and then I find the ulnar artery and I use Good pressure to constrict them both and pay attention to the patient's hand It's going to turn a little bit pale because by the compressing the arteries limiting the blood flow that allows The blood to flow into the patient's hand So now that the hand turns kind of pale and I keep my pressure on the ulnar artery But let go of the radial artery and watch what happens to the hand in terms of color So my hind is still on the ulnar artery So right now most of the blood supply is coming from the radial artery meaning that the artery is patent There is no obstruction no problems with that and I would be okay to use that for an arterial stick or an arterial line Thanks for watching nursing school explained Please also check out the other videos about my skill different skills in my skills playlist. Thanks for watching