I started sleeping with a Contec CMS50F several years ago, it broke and i did not replace it since my SPO2 barely changes during sleep and was ok. Recently i got curious about Perfusion Index with sleep (PI) and purchased this upgraded model from china on ebay (~$120): CMS50I Fingertip Pulse Oximeter,Wrist,Sound,PI,Pulse oxygen saturation,PulseRate …
it generates csv files but so far i have been unable to translate the PI column into percent based data. It allows logging ~4-5 nights of sleep before the memory fills, but i typically offload and charge via USB every morning. You can learn more at: http://www.cpaptalk.com/CPAP-Sleep-Apnea-Forum.html