They tried two different facemasks on me with the bi-pap at high pressure of 10/18. Neither worked as they continuously leaked, so they have given me a device that places two soft rubber pieces into my nostrils. This works much better and is much more comfortable. The only problem is, you absolutely cannot open your mouth while sleeping. At least I can sleep on my side with this device. I know of no medicine that can control central sleep apnea as it is neurological. My myasthenia gravis has spread, now affecting both eyes. In addition to the Mestinon I take, they have now prescribed prednisone which I regularly take with no side effects yet.