Headaches

I am getting horrible headaches for @ 2 weeks using a nasal canula. Does anyone else get this? Is this caused by breathing in CO2?

Can you please give more detail - what machine, what pressure settings, what mask, why the cannula, etc. etc?

I use a ResMed- setting 11- tried face mask years ago and felt claustrophobic.

Which particular Resmed do you have? There are several models (see cpap.com for some of the most common ones), and some DMEs will try and unload old models because they think that you don't know any better. After reading a bit/lot on here, you may know more than many technicians at the DME. Is 11 your starting pressure? Is the cannula delivering extra oxygen? If not, why are you using that? A good, properly fit, mask can deliver the important therapy for most people, and a cannula can be added to deliver extra oxygen. If your pressure is set up correctly, and the mask adjusted properly, you should not be getting headaches. If the pressure is too low, or the straps are too tight, that may be a cause. However, post more information and you may get better answers.

Or are you mis-using the term cannula and mean your mask is one with the nasal prongs?

And saying you tried a 'face' mask (do you mean 'full face'?) years ago does not say what you're using now... we need some info to try and help you. And yes, Resmed makes very many machines, different series, different years, different types, and lots of model #'s.

I have a 7 year old S8 HumidAire 3i model-using nasal pillows-11 is the initial setting prescribed by ENT doctor

Do you ever check your overnight progress with software? The S8 machine is one in a series made by Resmed. Humidaire is the manufacturer of the attached humidifier. And if you believe you're re-breathing CO2, you need to make sure the vent is not covered by bedding overnight. But that's unlikely to cause serious headaches... which might be caused by lack of adequate therapy. The answer however, is not raise your pressure, but to first question whether you might be mouth breathing once asleep, losing therapy air that way and not being effectively treated. If you think it's a possibility, you might want to look into wearing a 'full face' mask that will also cover your mouth and keep the Cpap air from being lost.

Otherwise, check with your doctor about the headaches - not everything is related to OSA or Cpap, and you could have e.g. a blood pressure problem, some neurological problem, many, many other things and getting checked out for them would be a good idea.