My son has tried many masks, which your vendor RT will bring when they come to set up. Your son should be able to pick 2 or 3 to try. My son loves his nose mask "Mirage Vista" by Res-med. Unfortunately I hear they are going to discontinue it, so hopefully the replacement will be just as comfortable. My son usually starts the night with nasal pillows and switches to Mirage about 3 a.m. Your vendor RT is the person to ask about any bi-pap supplies. Ask him/her how many you will be allowed. Medicaid is very generous. Also ask about bi- versus v-pap. Actually it is better to ask your pulmonologist. It is also good to find out what your pulmonologist thinks of non-invasive ventilation. Here is a video link for that: http://www.uwtv.org/programs/displayevent.aspx?rID=4123
Karen, the bi- or volume pap will help exchange of gases so your son doesn't build up to a dangerous CO2 level. Too many of our guys have also been given straight oxygen, and as they cannot breathe out well after a certain age(different for each) their CO2 levels rise. High CO2 signals the brain not to breathe.
We are just getting our second v-pap, as my son is 29. He uses a "sip vent" during the day. Bless whoever invented these machines!