The big problem is that the oximeters do not use a standard Bluetooth Low Energy profile. Therefore, I guess only the ones using the same chipset will be compatible.
The best solution would be devices that support the relatively new profile https://www.bluetooth.org/DocMan/handlers/DownloadDoc.ashx?doc_id=304923 from Bluetooth Special Interest group. But you won't find the required information in the specs so it's hard to tell which devices support the profile. Most devices will work only with their own apps.
What specs does the oxymeter need to meet besides Bluetooth?
Thanks for your fast response!
Because the availability of this pulse oxymeter is in a very limited amount of webshops I would like to know what specs it needs to meet besides Bluetooth? Then I will look if I can find a suitable (beter available) one.