Sleep apnea generally causes low oxygen levels in the blood, which can lead to all sorts of problems. When you're using your CPAP machine your oxygen saturation level should remain normal throughout the night, never dropping below 90%. You can use one of our easy-to-use pulse oximeters to view your oxygen saturation. An advanced pulse oximeter can be used to record an entire sleep session so that you can see the results in the morning. A pulse oximeter can allow you to check the effectiveness of your CPAP therapy, and it can also be used by people who don't use CPAP therapy as one indicator of general health.