CPAP Machines vs APAP Machines

When it comes to positive airway pressure treatments for sleep apnea, most patients and physicians simply refer to them as CPAPs. Unfortunately, that’s not entirely accurate and tends to be the source of confusion for many. You may have heard your doctor say things like bilevel, AutoPAP, or APAP only to then refer to it as CPAP again. Even here on the site, where we focus on APAP as the best form of CPAP treatment, we often refer to all sleep apnea treatments as CPAP, as that is what is most familiar. But, are these really all the same thing or are they something completely different?

The thing is, while all options are positive airway pressure devices, each one is very different and provides different benefits. Knowing what each machine is, how they work, and the way they benefit the user can help you better talk to your doctor and determine which machine will offer you the most benefits.

What is CPAP?

Continuous positive airway pressure (CPAP) machines are the most prescribed sleep apnea treatment and are the most basic flow generator, also meaning the least expensive. For this reason, many insurance companies require it to be the first treatment method for sleep apnea.

CPAP is just what it says. It provides a constant and continuous flow of air that is delivered to the patient through a mask. This air stays at a continuous pressure throughout the night, keeping your airway open and allowing for uninterrupted breathing.

With a CPAP, the air flow is always at the same pressure. This can be a challenge for many, especially when they require higher air pressure. While the high pressure keeps your airway open so you can breathe, you also have to try and exhale over that same air pressure. This can become overwhelming and is often the reason people give up on CPAP treatments.

In an effort to combat this continuous air pressure, some CPAP manufacturers have developed sensors that sense exhalation and allow the pressure to drop to 3cm H2O. While this can help for some, that small of a change may not be enough for patients that require higher air pressures. For example, a CPAP typically caps out at 20cm H2O, which is a strong pressure. Dropping that down by 3cm H2O still leaves you at 17cm H2O and very strong air pressure to try and exhale against.

This is where the APAP really makes a bigger difference and becomes the better treatment option.

What is an APAP?

An APAP, or AutoPAP, are both the same thing and refer to automatic titrating continuous positive airway pressure. So, as you can see, technically, CPAP is still in the name, so you might see the confusion. APAPs work in the same way that CPAPs do. A patient wears a mask and a continuous supply of pressurized air is delivered. The difference with APAP is that the pressure rates do not remain constant but change as sensors detect different needs.

An APAP machine is set with an air pressure range that is determined by your doctor. This range can be anywhere from 4cm H2O to 20cm H2O. Typically, your physician will set or recommend a tighter range, but the idea is that your pressure rates will adjust as needed.

As you sleep, your pressure needs adjust. For example, you may experience more obstructive sleep apnea episodes when you sleep on your back. An APAP machine will note this and increase the pressure when it senses you are on your back. Other things, such as allergies, medications, alcohol, or a cold can affect how we sleep and the rate of apnea episodes. An APAP is able to sense changes in your breathing and adjust the pressure accordingly.

It even adjusts for exhalation. Remember above when we talked about some CPAPs being able to adjust 3cm H2O for exhalation? Well, the benefit of APAP is it is not limited by that small window. When a person requires 20 cm H2O for inhalation, the air pressure can drop much more than 3cm H2O for breathing out, making it much easier for new patients to get used to and comply with. After all, positive airway pressure only works when you wear the mask.

What is BiLevel?

While you may or may not have heard of BiLevel machines, they are a more complex machine designed for patients that require more pressure than a standard CPAP or APAP. Where they typically cap out at 20 cm H2O, a BiLevel has higher settings up 25 cm H2O. As you can imagine, exhaling over 25 cm H2O would be near impossible as would it be limiting with only a 3 cm H2O drop, so BiLevel machines produce one pressure for inhalation and one pressure for exhalation.

CPAP vs APAP is all About What Makes You Comfortable

Your insurance may require you to try a traditional CPAP machine because of their low cost and effectiveness. While this works for many people, others never quite feel comfortable on a CPAP and often just give up treatment. If you speak with your doctor and your insurance company and let them know that the CPAP just isn’t working for you, chances are good that they will prescribe an APAP that will give you a bit more comfort in your breathing while still helping to prevent apnea episodes. If you have shown that you have tried a traditional CPAP, chances are good that your insurance may cover the APAP machine.  After all, the CPAP machine won’t do you any good if you don’t wear it and making sure you are breathing and sleeping well is the goal of everyone.