I get a machine with a 15 ml flow.  Some places won't give you a regulator to that point without the perscription calling for it.  There are other ways to get it without perscription, but I'm not familiar with it.  I've always gone through my Neuro and a local distributor.  My insurance use to cover it, but now it costs about $20 a month.

I find that it works best with actual attacks and I haven't had as much luck with the shadows, but I usually don't have the oxygen until things start getting bad, since I have a long remission period.

You'll get lots of great advice on O2.  Just keep checking.

My understanding of how O2 works is that when the brain thinks that it's getting waaaay too much oxygen, it responds by constricting the blood vessels. Since a cluster headache is caused by a swollen blood vessel putting pressure on the trigeminal nerve, this effectively aborts the attack.

(More accurately, it's the lack of CO2 in the bloodstream that causes the constriction, but you get the general idea. There's also other mechanisms at work which I won't go into, unless you want me to of course.)

For oxygen to work, you need to supply the brain with waaaay too much of it. And that's why you need to ensure:

• The oxygen is as close to 100% pure as you can get.
• The flow rate is sufficient - 15 litres per minute is good, 25 is even better.
• The mask or equipment you use doesn't allow the oxygen to get diluted with air. Use a non-rebreating mask, or stick the whole pipe into your mouth and breath out through your nose.

The flow rate + purity + non-rebreathing mask is considered too extreme by many hospitals and doctors who have never encountered CH before and it's possible that they will consider you a lunatic if you ask for it (as indeed happened to me).

Where I am, the purest oxygen I can get is 93% and I can only get up to 15 lpm for the valve. With a non rebreathing mask, I can abort a Kip 8 in about 10 minutes, but may require two attempts at 15 minutes each to abort a Kip 10.

Oh, keep breathing the O2 for 5 minutes after the pain goes away to make sure the attack stays aborted. You can turn down the flow rate at that point if you like.