APAP Therapy: How it Works And Who Might Benefit From It

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If you have had a Home Sleep Test (HST) to diagnose your symptoms of sleep apnea, you will most likely be prescribed an APAP device to help alleviate your nightly apnea events.

But what exactly is an APAP device, why would you not be prescribed a CPAP machine, and what is the difference between the two? What are the pros and cons of using an APAP device?

APAP stands for Automatic Positive Airway Pressure and is similar in function and design to the more traditional CPAP (continuous positive airway pressure) device.

Here we aim to answer these important questions in a full breakdown of everything you need to know about APAP therapy.


What is an APAP Machine and How is APAP Similar to CPAP?

All PAP devices work on a similar principle: To deliver a prescribed air pressure into a patient’s airways that acts as a splint by keeping the airways from collapsing. The air delivered is just enough to push past any potential obstructions while maintaining a level of air flow that feels as close to natural breathing as possible.

PAP machines are comprised of three parts:

  1. The Motor, which acts as a miniature compressor. It works by drawing in air from the room, which it then pressurizes to the prescribed amount and is then delivered to the patient via a mask and hose. Most newer PAP devices come stock with a heated humidification water chamber that helps keep the air being delivered moist to maximize comfort and reduce symptoms of dry mouth and nasal passages.
  2. The hose is simply the delivery system that transports the pressurized air from the motor to the mask. Most hoses are 6 foot in length making storing the device on a nearby nightstand easy.
  3. PAP masks come in a variety of styles, shapes, and sizes. Finding the right mask is one of the most critical components of quality PAP therapy as well as user compliance, which is why there are so many different choices for masks.

How is an APAP Machine Different than a CPAP Machine?

Buy CPAP Machine devices are titrated to a single set pressure setting by a sleep specialist after a CPAP titration study. The titration study is conducted after a traditional in-lab polysomnogram test and is meant to find the exact pressure needed to set the machine to eliminate apnea events during the night.

The problem with CPAP devices is that the single set pressure may be difficult to tolerate (especially at higher settings), and doesn’t adjust to varying pressure needs throughout the night.

APAP therapy solves this problem by having 2 pressure settings: a low range pressure setting (which is the minimum amount of pressure required to prevent apnea events), and a high range pressure setting.

APAP machines have a complex algorithm that detects on a breath-by-breath basis what pressure the patient needs at that moment to prevent apnea events. Never straying below the low-pressure setting nor above the high-pressure setting, the APAP device finds the ideal pressure for any given moment.

What are the Advantages of APAP Therapy?advantages of apap and cpap treatment

More and more often APAP devices are being prescribed in lieu of CPAP devices because of their versatility and ability to adapt to patient needs throughout the night. Here are some of the reasons why you might want an APAP device over a CPAP device:

  • APAPs can also be set to a single pressure. If for some reason APAP therapy isn’t working out for a patient, there isn’t any need for them to get a different machine. APAPs can be set to a straight CPAP mode. CPAP devices on the other hand cannot be adjusted to have multiple pressure settings. So if you’re going from CPAP to APAP, you will need to get a new machine.
  • APAP machines are great for those that toss and turn throughout the night. When you lay on your back (supine position) you are more likely to need a higher pressure setting than if you lie on your side. Why? Because gravity. Laying on your back allows the soft tissues in your throat to collapse into the airways more readily than when lying on your side. If you only slept in one position throughout the night, a CPAP device might be a good bet, but most people tend to move in their sleep and adjust their sleep positions throughout the night, which can call for different pressure needs when sleeping. APAP devices solve this by changing pressure settings when you change positions.
  • APAP machines can adjust pressure settings depending on stages of sleep. Your body is most relaxed during REM sleep, which is when your airways collapse the most readily. CPAP devices are callibrated to the pressure when you are at your worst for having apnea events. This means that even when you are in lighter stages of sleep, which would require less pressure, the CPAP device would still be giving you the highest pressure you could possibly need. APAP devices on the other hand will deliver higher pressures during this deep stage of sleep when needed, but then back off on pressure during the lighter stages of sleep making therapy more comfortable.
  • If you have seasonal allergies or contract an upper airway respiratory infection, your breathing needs at night will change as you become more congested. APAP machines will be able to increase the pressure to get past the normal amount of blockage as well as the added congestion blockage when you need it.
  • CPAP devices don’t allow for your physical changes. What happens if you decide to change your lifestyle and you lose a bunch of weight? There will be less fatty tissues in your throat to cause blockage, which often means you wouldn’t need as high of pressure as you would have before. If the opposite is true and you gain weight you would more than likely need higher pressure. Rather than having to get a new CPAP titration study to find your new pressure settings, the APAP device can change pressures to adjust to your new needs.
  • APAP devices help eliminate the need for expensive in-lab sleep tests. When you get a Home Sleep Test (HST) you will most likely be prescribed an APAP device. The main reason is that HSTs can’t determine which stages of sleep you are in. As previously discussed, CPAP devices are callibrated for breathing needs when you’re at your worst (during REM sleep). HSTs score your breathing needs over the whole course of the night during which it determines your range of needs. This range can later be fine tuned with remote monitoring by a registered sleep technologist as they check to see how well you’re performing with your equipment.
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