Humidification in CPAP Therapy

The following information is provided by: Fisher & Paykel Healthcare

Mouth Leak and the Vicious Cycle

Mouth Leak

When a patient is receiving CPAP therapy, exhaling against the force of the constant pressure can be difficult. Often patients will open their mouths slightly when they sleep or even begin to breathe through their mouths. In doing this, a proportion of the incoming air travels in through the nose and straight out the patient's mouth. This is known as unidirectional flow.

The Vicious Cycle

The vicious cycle describes the situation which often occurs as a result of mouth leak. When the patient falls asleep while using CPAP therapy, mouth leak may occur. Because incoming air is able to travel directly out through the patient's mouth without first going to the lungs, unidirectional airflow occurs. The increased flow of cold dry air through the nasal passages causes mucosal drying and rebound congestion. The swelling that occurs in rebound congestion results in a decrease in nasal airway diameter and as a result, increased nasal airway resistance occurs. An increase in nasal airway resistance leads to an increase in mouth leak as the patient begins to mouth breathe, and so the vicious cycle continues.

Previous | Next

• The Role Of Humidification in CPAP Therapy
• What is Humidity?
• How the Human Body Humidifies Air
• CPAP Therapy Potential Problems
• Mouth leak and the Vicious Cycle
• Increase in Nasal Resistance
• Compliance With CPAP Therapy
• Frequently Asked Questions
• References