I was put on the Trilogy recently after using a CPAP for years. I was recently diagnosed with COPD with CO2 retention. I almost passed into the afterlife after having kidney failure and septic shock. After two hospital stays in 2 months I started using the Trilogy. I found it easy to adjust to vs. CPAP. Because it most resembles your normal breathing pattern. The machine eliminates the CO2 build up by venting thru the upper mask. I also use oxygen hooked to it at night. I this machine will keep me alive and out of the hospital. That is worth the cost alone. It is pricey but I was able to get multiple cost breaks. I highly recommend it and advocate for its use. Every pulmonary dr. Has praised its technology.