Home » Understanding the Fixed Pressure CPAP Machine: A Comprehensive Guide

Understanding the Fixed Pressure CPAP Machine: A Comprehensive Guide

Continuous Positive Airway Pressure (CPAP) machines are one of the most common treatments for obstructive sleep apnea. Obstructive sleep apnea is a disorder where the airway collapses during sleep, causing interrupted breathing. CPAP machines work by delivering constant air pressure to keep the airway open. Fixed pressure CPAP machines provide one set of pressure throughout the night.

How Does a Fixed Pressure CPAP Machine Work?

A fixed-pressure CPAP machine comprises three main parts – the motor, the mask, and the hose.

The Motor

The motor unit draws in room air, pressurises it, and delivers it through the hose. The motor contains a filter to remove allergens and pollutants from the air. It also includes a humidifier to add moisture to the air, preventing irritation and dryness.

The Mask

The pressurised air is delivered through a hose to a mask worn over the nose and mouth. The mask creates a seal so the pressurised air does not escape. Many types of masks are available, including nasal, full-face, and nasal pillow masks.

The Hose

The hose connects the mask to the CPAP machine’s motor. Standard CPAP hoses are 6 feet long, allowing flexibility in CPAP machine placement. Heated hoses are also available to warm the air before it enters the mask for additional comfort.

As the motor unit continuously delivers pressurised air through the mask, it splints the airway open, preventing apneas, snoring, and airflow limitations.

What Pressure Level is Used?

The fixed pressure CPAP provides a constant, prescribed level of pressurised air. The optimal pressure level is determined during an overnight sleep study called a titration study.

During the titration study, your sleep is monitored, and different air pressures are trialled until the apneas are effectively eliminated. Factors like the severity of your apnea, body size, and sleeping position are considered when determining the fixed pressure setting.

The prescribed pressure generally ranges between 6-15 cm of water but can go higher if needed. Your sleep doctor will set your specific prescribed pressure.

Benefits of Fixed Pressure CPAP Therapy

Using fixed-pressure CPAP therapy has many benefits for obstructive sleep apnea patients, including:

Eliminates Apneas and Improves Oxygen Levels

The pressurised air from the CPAP prevents the airway from collapsing, effectively treating the apneas. This eliminates oxygen drops and fragmented sleep patterns.

Reduces Daytime Sleepiness

Untreated sleep apnea can make you chronically tired. Using CPAP therapy helps restore healthy sleep cycles so you feel refreshed and alert during the day.

Lowers Blood Pressure

Obstructive sleep apnea is related to hypertension. CPAP therapy helps normalise blood pressure levels.

Improves Heart Health

By treating sleep apnea, CPAP machines reduce strain on the heart. CPAP can help improve cardiovascular health.

Enhances Quality of Life

With improved sleep and increased energy levels, CPAP therapy enhances day-to-day life. Mood, cognition, performance, and safety are all improved.

Considerations of Fixed Pressure CPAP

While fixed pressure CPAP is an effective sleep apnea treatment, there are some things to keep in mind:

Requires Nightly Use

CPAP therapy must be used every night during sleep to gain the full benefits. Some adjustment is required to incorporate this into your bedtime routine.

Air Pressure Stays the Same

The air pressure does not adjust throughout the night based on your changing sleep stages and positions. The set fixed pressure may feel too high or too low in certain conditions.

Can Take Time to Get Used To

Most patients adjust to fixed-pressure CPAP within 2-4 weeks of consistent use. However, getting accustomed to sleeping with the mask and air pressure takes time.

Side Effects May Occur

Some people experience side effects from fixed-pressure CPAP devices, including nasal congestion, dry mouth, bloating, mask discomfort, and skin irritation. Proper mask fitting and settings adjustments can minimise side effects.

Doesn’t Treat Central Sleep Apnea

Fixed pressure CPAP only treats obstructive events. It does not treat central sleep apnea, where the airway is open, but no breathing effort is made.


Fixed pressure CPAP is an effective and commonly used treatment for obstructive sleep apnea. The machine pumps pressurised room air through a sealed mask to splint the airway open during sleep. This eliminates apneas, low oxygen, and fragmented sleep. With consistent use, fixed-pressure CPAP can help you feel more alert and improve your health and quality of life. While there are some downsides, like nightly use and potential side effects, patients often adjust quickly to the therapy. Work closely with your sleep doctor to find the optimal settings, mask, and pressures for your fixed-pressure CPAP, such as the Resmed Airsense 10 Elite.

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Jack Reuben Fletcher

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