APAP vs CPAP
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If you are wondering what the difference between an APAP and CPAP machine is, you or someone close to you has likely been diagnosed with sleep apnea. Sleep apnea is a potentially serious disorder that causes the body to repeatedly stop breathing during sleep. There are three types:
- Obstructive Sleep Apnea (OSA): The muscles in the throat relax during sleep, in general or in a specific sleeping position, blocking the airway.
- Central Sleep Apnea (CSA): The brain doesn’t send the proper signals to the muscles that control breathing during sleep.
- Complex Sleep Apnea Syndrome: Sleepers experience a combination of obstructive sleep apnea and central sleep apnea.
Apneas, or pauses in breathing during sleep, often cause microarousals from sleep. Frequent waking from sleep, even if only for a small amount of time, can prevent a person from getting the healthy, restorative sleep that they need.
Sleep apnea affects approximately 2% to 9% of adults. Millions of Americans have been diagnosed with sleep apnea and are actively seeking treatment, while others may have undiagnosed or untreated sleep apnea.
If left untreated, sleep apnea can cause short-term symptoms such as intrusive snoring, morning headaches, sore throats, daytime fatigue, irritability, and disordered sleep patterns. It can also lead to long-term negative health outcomes such as an increased risk of cardiovascular disease, metabolic syndrome, type 2 diabetes, and liver disease, as well as potential surgery complications.
Once a doctor establishes that you are suffering from sleep apnea, they may initially suggest lifestyle changes, such as losing weight, quitting smoking, or discontinuing the use of alcohol or certain sleep medications. They may also treat underlying conditions like allergies. In addition to these potential changes, a doctor will usually prescribe the use of a device that can help open the airway during sleep. In some cases, other interventions, such as surgery, are necessary.
In the majority of sleep apnea cases, treatment usually includes one of two devices: a continuous positive airway pressure (CPAP) machine, or an automatic positive airway pressure (APAP) machine. There are similarities between CPAP and APAP machines, as both devices are designed to promote airflow to help relieve symptoms of sleep apnea. A CPAP machine is the standard treatment option in most cases, but some sleepers may respond better to an APAP machine.
What Is the Difference Between CPAP and APAP?
The main difference between a CPAP and an APAP machine is that an APAP machine automatically adjusts its settings as you sleep. This allows it to meet changing pressure needs throughout the night.
A CPAP machine is adjusted to one setting, usually during a PAP titration study at home or in a sleep study center, or by trial and error while using the machine. If the pressure is too high and causes exhalation discomfort, the CPAP can be manually adjusted to a new setting, but it will not adjust automatically.
Understanding the differences between these two machines can help sleep apnea sufferers work with a medical professional to find the right fit.
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CPAP Basics
CPAP machines are the most commonly prescribed treatment for sleep apnea, and have been in use since the 1980s. CPAP machines, which stands for continuous positive airway pressure machines, work by pushing a steady stream of pressurized air through the nostrils, opening up the muscles that improperly relax in people with sleep apnea.
The machine takes in air through a filter, often passing it through a heated humidifier so that it’s easier on the nose and throat. It then uses a built-in motor to push the filtered, humidified air through a tube attached to the machine. At the end of the tube is a CPAP mask that is worn over the nose and affixed to the head with straps.
When the mask is placed over the nose, the steady stream of air goes into the upper airway, essentially creating a cushion or air splint that prevents the throat muscles and tissues from relaxing and collapsing the airway. The continuous airflow also helps keep the soft palate, the uvula, and the tongue from blocking the airway. This helps prevent the pauses in breathing that cause many sleep apnea sufferers to wake up throughout the night.
For people with mild to moderate sleep apnea, particularly OSA, the CPAP can have immediate benefits. Studies have shown that CPAP machines can be effective for many people in reducing or eliminating the risk of both short-term symptoms and long-term health complications.
That said, there are several factors that may impede someone’s ability to benefit from a CPAP machine. Since the air continues to flow in a steady stream, it can cause an uncomfortable choking feeling when users try to exhale. If this happens, the machine can be set to a lower pressure.
Additionally, some users find it hard to get comfortable enough to fall asleep or stay asleep while wearing the mask. In many cases, this is because the mask has not been sized or adjusted to fit them properly. This can cause discomfort, in addition to air leaks, which may decrease the machine’s overall effectiveness. Users should find the best CPAP machine for them because an improperly fitting CPAP mask can cause other complications, such as irritation and pressure sores where the mask is rubbing against the skin.


APAP Basics
An APAP is an automatic positive airway pressure machine. Like CPAP machines, APAP machines work by taking in air through a filter (often with heating and humidification), and then using a motor to push the air through a tube that is connected to a face mask. APAP machines create an air splint by cushioning the airway and propping it open, while keeping the soft palate, uvula, and tongue from obstructing or collapsing the airway.
While a CPAP has one continuous setting, an APAP is able to respond to changing pressure needs by constantly measuring how much resistance is present in your breathing. The technology in an APAP machine allows it to remain on a low setting until a change in breathing is detected and more airflow is needed.
APAP machines are often prescribed to people who do not get the desired results from a CPAP machine, or to those who have specific issues with the CPAP’s unchanging pressure level. They may be prescribed before CPAP machines in specific instances, such as sleep apnea that is comorbid with other sleep disorders, or sleep apnea that only occurs when the body shifts into a specific position. APAPs may work better for those who are prone to allergies, colds, or other temporary airway blockages, as they can adjust pressure as needed and then return to a lower setting when the flare-up has passed.
Additionally, APAP machines can be set to perform like a CPAP by setting the machine to a continuous mode.
APAP machines do have some drawbacks that should be considered. Like CPAP machines, they may cause skin irritation, especially if the mask is not properly fitted. They are not recommended for people with CSA, chronic heart failure, COPD, or obesity hypoventilation syndrome, nor are they recommended for use in people who have sleep apnea related to opioid use.
APAP vs CPAP: Which is Best for You?
When it comes to choosing between a CPAP and an APAP, you can start by performing an at-home sleep study or consulting with a sleep specialist or doctor to find the right machine for you. In many cases, finding the right PAP machine is a matter of trial and error. Many people start with a CPAP machine as prescribed by a doctor, but may switch to an APAP if they are not getting the desired results. Others may find that neither PAP machine is the right choice for them, and go with an alternative treatment. Discussing your symptoms and needs with your doctor will help you determine the best treatment plan for your individual case.
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