CPAP Therapy Tips

CPAP Machine Settings: Pressure, Ramp, EPR, CFLEX, Auto-Start

CPAP machines can make a world of difference in the quality of sleep you receive each night if you’re a sleep apnea patient. You’ll receive optimal benefits from your sleep apnea therapy when your CPAP machine settings are where you need them to be to keep your airways clear and unobstructed throughout the night.

These are some of the CPAP settings you’ll want to become familiar with as you explore your CPAP machine and learn more about how it works for you.

What Does My CPAP Pressure Setting Mean?

The CPAP pressure setting indicates the amount of pressure behind the air being sent through your mask at night. The pressure reading is typically abbreviated as “cm of H2O” or “cm of CWP.” The lowest setting on most CPAP machines is four or five CWP with maximum settings as high as 25 or 30 CWP (depending on the type of machine you have.

Most CPAP users require more than the minimal CPAP pressure settings and less than the maximum settings. While many people believe that the pressure settings are determined by the severity of the sleep apnea, that isn’t necessarily the case. In fact, there are numerous factors that determine which setting is the most appropriate for individual CPAP users.

Though it is true, to some degree, that people with severe OSA often do require higher settings to maintain unobstructed airways while sleeping, other contributing factors play roles in determining this, including:

  • Nasal obstructions
  • Obesity
  • Medications
  • Sleeping positions
  • Allergies

Others may even need to consider varied pressures throughout the night, particularly those who shift sleeping positions and at different sleep stages.

What Does My CPAP Ramp Setting Mean?

CPAP machines deliver a fixed amount of pressure into your airways at night. One of the challenges for many CPAP wearers is exhaling against the continuous pressure stream. Breathing against this powerful stream of air, especially for people who have higher than average prescribed pressure settings, can be discouraging and may even affect compliance.

Enter the CPAP ramp feature. Since the actual purpose of the CPAP machine is to deliver a stream of air while you sleep, the ramp feature, as its name implies, serves as a ramp that starts out delivering a lower amount of pressure allowing wearers the opportunity to fall asleep before the higher pressure settings engage.

The CPAP ramp is most commonly used to increase the air pressure incrementally, every five minutes, over a 45 minute period of time. There are devices that provide different ramp settings to meet the needs of different CPAP wearers. Work with your sleep technician to identify the best choice for you.

What is EPR?

EPR stands for “expiratory pressure relief.” It is a feature on some CPAP machines that allows users to adjust between three different comfort settings to alleviate feelings of breathlessness some CPAP wearers complain about.

How does EPR work? The three settings allow CPAP wearers to reduce the pressure by one, two, or three pressure points when exhaling. If you choose an EPR or three, for instance, and your normal pressure setting is 10, the machine will automatically reduce the pressure to seven when you’re exhaling then return it to 10 when you inhale.

The feature essentially makes it more comfortable for CPAP users to use their devices throughout the night, improving compliance which offers better outcomes for CPAP patients.

What is CFLEX?

C-FLEX is similar to EPR and is used by different CPAP machine makers. The goal of C-FLEX is the same as the goal of EPR – to make wearing CPAP masks more comfortable for patients with obstructive sleep apnea (OSA). C-FLEX accomplishes this by reducing air pressure sent into the airways prior in exhalation and restoring them to the prescribed settings just prior to inhalation.

This means patients do not need to work as hard to breathe against the machine while maintaining the appropriate supply or air pressure coming in while inhaling. The machine adapts to meet the changing air pressure needs of CPAP wearers on a person by person basis rather than offering a one-size-fits-all approach to adjusting the airflow.

  • A-FLEX. Moving beyond the abilities of C-FLEX on CPAP machines, AFLEX offers more sophisticated analysis of breathing cycles and adjusts the pressure accordingly. This technology is only available on Auto CPAP devices, however.
  • Bi-FLEX. More closely mimics natural breathing patterns than C-FLEX making it feel more natural to CPAP wearers.
  • C-FLEX +. Only available on fixed pressure CPAP devices, this feature combines the intuitive adjustments of A-FLEX with the traditional C-FLEX therapy for a more comfortable transition from inhalation and exhalation pressures.

As you can see, CPAP makers that offer C-FLEX technology are constantly building on this technology to create even more natural feeling sleep experiences for CPAP wearers.

What Does Auto Start On My CPAP Do?

Auto start is a feature that allows the CPAP machine to automatically begin delivering air pressure when the wearer puts on his or her CPAP mask. This allows wearers to get comfortable in bed before turning on their machines and eliminates some of the discomfort associated with maneuvering hoses and switches when trying to settle in.

Anyone who has ever had a wrestling match with their hoses, sheets, blankets, and pillows knows the struggling of forgetting to turn the machine on before settling in. Auto start eliminates that struggle.

What Does Mask Leak / Mask Fit Alert Mean?

Unfortunately, CPAP masks don’t always have a snug seal, resulting in mask leaks. For examples, many CPAP machines, including some ResMed machines offer a “Leak Alert” which can be enabled or disabled, and many Respironics positive airway pressure machines also have “Mask Leak Alert” feature: “Mask Leak Alert”. Some of the ResMed machines also offer a “Mask Fitting Feature”.

These alerts notify CPAP wearers if there is an airflow leak in their mask reducing the air pressure that actually reaches wearers through the course of the night. The alert will not only improve CPAP outcomes, but will also help improve compliance as people sometimes give up on CPAP therapy because they aren’t receiving the full benefits they are meant to offer.

The better you understand the various CPAP settings on your machine, the greater your ability to make choices that benefit your needs best. Working with your sleep technologist or CPAP machine and mask specialist can help you get even more mileage from your CPAP experience to make it more comfortable and productive for you.

Reach out to our CPAP expert by calling 1-800-356-5221 or using our live chat feature to learn more about optimal CPAP machine settings.

David Repasky has been using CPAP treatment since 2017 and has first-hand experience with what it’s like to live with Sleep Apnea. He brings the patient’s perspective to the CPAP.com blog and has received formal training in CPAP machines, masks, and equipment.

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