Vasal dilation is exactly what this technique is all about:

Dr. Wright’s Circulatory Technique

What follows is a technique learned from a neurologist:
I am not sure what mechanism is triggered by this but whatever it is, at least indirectly helps kill the pain. I do know that this technique has nothing to do with meditation, relaxation, or psychic ability. It is entirely physical and takes some work. It involves concentrating on trying to redirect a little circulation to the arms, hands, or legs. It can described as a conscious circulatory flexing. Increased circulation will result in a reddening and warming of the hands. Try to think of it as filling your hands with redirected blood. The important and difficult part is that it has to be done without interruption through the pain. Do not give up in frustration. It may not work on the first try. Every now and then it will work almost immediately. I lived for those moments. Try experimenting between attacks. You will find that it gets easier with practice.

I was given less than five minutes instruction in the use of method. The doctor, while placing his arm on his desk, showed me that he could slightly increase his arm and hand circulation. After several attempts, I was able to repeat this procedure and use it successfully. I have had about a 75% success rate shortening these attacks. My 20 minute attacks were often reduced to 10 minutes or less. Once proven that I had a chance to effectively deal with this horror, I always gave it a try as I had nothing to lose but pain.

Perhaps it will help if you think of it as trying to fill the arm as if it is were an empty vessel. I used to try to imagine I was pushing blood away from my head into my arm. Use your imagination. There is one man who wrote that his standing barefoot on a concrete floor shortened his attacks. This may be similar as it draws some circulation away from the head. Cold water, exercise, or anything affecting circulation, seems to be worth a try. My suggestion is to not let up immediately when the pain goes. Waiting a minute is probably a good idea. So long as you do not slack off, this has a chance of working.

This technique is very useful while waiting for medication to take effect or when none is available. It costs nothing, is non-invasive, and can be used just about anywhere. It is not a miracle but it helped me deal with this horror. It can be a bit exhausting but the success rate was good enough for me and a cluster headache sufferer will do just about anything to end the pain. It gives us a fighting chance.

I hope this technique is helpful and I wish you the best of luck

Charlie