Using a pressure sensor, this device can detect ​breathing patterns of the user.  The pressure sensor detects negative pressure when the user is inhaling, and oxygen is delivered at this time.  The pressure sensor detects positive pressure when the user is exhaling, and oxygen delivery is shut off at this time.  If the pressure sensor detects neutral pressure, the system will test whether the cannula is inserted in the user's nostrils.  If the cannula has fallen out or been removed, the system will display a low-oxygen warning.  If the cannula is still inserted in the user's nostrils, the system will display a warning indicating the user has stopped breathing and will sound an alarm.