Heated humidity is the most important factor in CPAP and bilevel compliance.  Positive pressure devices like CPAP and bilevel decrease the amount of relative humidity found naturally in the nasal and oral airways.  Inadequate humidity can cause the following problems:

• Nasal congestion
• Nasal bleeding
• Sinus pressure, ear pain and runny nose
• Dry mouth

Inadequate humidity and mouth leak go hand in hand. The following graphic explains this relationship:

Sealing the mouth with the correct mask system coupled with adequate humidification gives the patient the best opportunity for success.