Top 9 Things to Consider when buying a new Auto CPAP machine.

August 31, 2016 | By Peter Stanza | Filed in: Buyers Guide, CPAP Advice.


Buying a new Auto CPAP machine can be overwhelming. Each manufacturer seems to be trying to outdo each other, and they seem to have different names for effectively the same features. This article assumes you have decided an Auto machine is right for you.

Here I have compiled a quick list of items that is worth considering and comparing when looking at a new Auto CPAP machine.

1. The Auto Machine Algorithm… Does it do as it says?

Some manufacturers have also got better AutoSet algorithms than others. Some have more advanced algorithms, but this doesn’t necessarily mean better. Bench testing is one way in which CPAP machines can be compared. All Auto CPAP machines that I have researched achieve good treatment of obstructive sleep apnea. This is despite seemingly negative results for the Weinmann  and DeVilbiss auto algorithms, which was actually caused by the inability of the bench test to appropriately simulate Obstructive Pressure Peak, vital to the workings of these manufacturers algorithms.

A good Auto algorithm will treat the obstructive sleep apnea without ramping up the pressure too much. Manufacturers that appear to do this the best include:
– ResMed
– Respironics
– DeVilbiss
– Weinmann
– Fisher and Paykel
– Curative
– Sefam

Apex, Breas, and Transcend appear to treat OSA well, but seem to use a higher pressure than other devices. The Auto algorithms from these brands might need some fine tuning and don’t seem as effective as the other manufacturers.

2. Ramp

Most machines come with some sort of ramp these days, including the cheaper ones. This comfort feature benefits the new CPAP user more than experienced users by starting therapy at a more tolerable, lower pressure than the treatment pressure. Now, with many manufacturers implementing an Automatic Ramp feature, starting CPAP therapy is even easier.

Instead of working on a preset timer, automatic ramps detect when you fall asleep, and automatically increase the pressure to the treatment pressure only then.

Obviously, if you can afford a machine with the AutoRamp feature, it is a worthwhile investment for the quickest pressure response after you fall asleep. Auto machines with this feature include Respironics DreamStation Auto, ResMed AirSense 10 AutoSet, and the Weinmann Prisma20A Auto machines.

Most other models have a timed Ramp function, which ramps up the pressure over a determined time frame; usually between 5 to 40 minutes.

3. Expiratory pressure relief.

Most CPAP machines come standard with this option now; except for Fisher and Paykel. They all call it something different, and they all have a slightly different way of doing it.

Devices normally fit into two categories here. Some start the pressure relief when expiration is detected, and others anticipate the expiratory phase and start dropping the pressure prior to expiration. Some people prefer one style, where some prefer the other.

My research suggest that ResMed and Weinmann (for example) don’t start to drop the pressure until you start breathing out. Respironics machines, on the other hand start to drop the pressure at the end of the inspiratory phase, ready for expiration. Some patients note feeling rushed into taking a breath by the Respironics machines, whereas some feel more comfortable when the machine anticipates expiration.

4. Heated tube humidifier.

Now, this is sometimes a personal preference; but most patients prefer a humidifier; and they work better (mostly) with a heated tube. Using effective heated humidification helps prevent drying of the airways due to CPAP airflow. In addition, it can reduce the treatment pressure required by Auto set machines by reducing the resistance to airflow.

For most people, especially those new to CPAP, heated tube humidification is a must.

5. Noise

Simple. You want the quietest machine available. It’s not only important for you, but important for the person who is sleeping next to you. It is worthwhile comparing the noise levels of the different machines prior to choosing your new APAP. Most have similar noise levels, and most are below 30 dB these days.

photo credit: Too Loud via photopin (license)

photo credit: Too Loud via photopin (license)

Remember, sound energy doubles every 3dB. So a CPAP machine rated at 30dB will produce double the noise energy that a machine that operates at 27dB does.

There are a few Auto machines that operate at a noise level of under 27dB when operating at 10cmH2O. These include:
– Respironics DreamStation Auto
– ResMed AirSense 10 AutoSet
– DeVilbiss AutoAdjust 2
– Human Design Medical Z1 Auto Travel CPAP

6. Data

We seem to be moving to an increased reliance on the ability of APAP machines to reliably record and report on patients sleep apnea therapy.

With the increasing reliance on CPAP machine reports for measuring treatment efficacy, the quality and accuracy of the data collected and reported is important. There are two parts to this; whether the CPAP accurately records the information, and how easy it is to access this information. Recognizing that CPAP users are taking control of their therapy, with less influence from sleep professionals, newer models aim to make the information more accessible to you, the CPAP user.

Wireless data transfer has been a recent addition to CPAP therapy. It allows you, and sleep professionals to access select pieces of data from your CPAP machine without the need of cables or SD cards. Two solutions exist for this.

A few of the leading manufacturers have introduced bluetooth technology to their devices. Respironics, DeVilbiss, and Human Design Medical have developed smart phone apps that connect via bluetooth to their newest machine range. With the respective apps, you can see a breakdown of your CPAP therapy, as well as being able to change some of the comfort settings.

ResMed instead relies on an active internet connection and transfers the information to a database which is accessible online on a web browser application. This makes it very easy for health professionals to access the data from your machine and make any appropriate changes.

7. Warranty and reliability

We all hope that nothing goes wrong with your machine, and choosing a reliable machine is important to reduce the chances of this. From personal experience, I have found the ResMed, Respironics, DeVilbiss and Weinmann machines to be the most reliable. This is reflected in their warranty terms, which are generally 3 years. Other brands tend to have a 2 year standard warranty.

8. Travel

Whether you travel for work, or have joined the tribe of gray nomads a machine that is easy to travel with is vital. Look at things like how easily it connects to 12V power, how easily the water chamber is filled and emptied, and how compact the machine is. From purely an ease-of-travel standpoint, my recommendation is ResMed’s AirSense 10 Auto if you need a heated tube humidifier; or the humans Design Medical Z1 Auto CPAP if you don’t. This isn’t taking financial considerations into account.

9. Price

Let’s be honest. This is important. Not all of us can afford the Rolls Royce of CPAP machines.

The reason I have included this last, is that you should look at all of the features that are important to you. The reason I have not suggested setting a budget first is:

    1. You might find you need to up your price range when you discover that none of the machines in your price range have the features you desire
    2. You might find a CPAP machine at a lower price point that meets all of your treatment requirements

My advice is that you should invest in the best quality CPAP machine that you can afford that meets you ‘features list’.


There are many things to consider when buying a new CPAP machine, and this is by no means an exhaustive list. Greater importance is placed upon different features by different individuals, however this represents, I believe the most common features you should take into consideration when buying a new CPAP machine.

Cheers, Pete.


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