Complex sentence: Distilled water is also used in Constant Positive Airway Pressure (CPAP) machines to humidify the air entering the user's nasal cavity, mouth, and throat.
Split into simpler sentences: Distilled water is also used in Constant Positive Airway Pressure (CPAP) machines. The water is used to humidify the air entering the user's nasal cavity, mouth, and throat.