Different types of PAP machines

By SA Editor, Nov 23, 2017 | |
  1. SA Editor
    Sleep apnea is considered to be one of the most common types of sleep disorders, affecting more than 22 million Americans. Sleep apnea is characterized by a person having periodic pauses in breathing while they are asleep. An interruption in breathing does not last for more than three minutes, and their frequency can be anywhere from few disruptions to up to a hundred every hour.


    When a person has breathing pauses, they get partially awakened from their sleep since the brain gets pulled out from deep stages of sleep to make the body resume breathing. When the process is repeated several times during the night, sleep quality decreases, and many medical conditions start cropping up. Obstructive sleep apnea (OSA) is the most common form of sleep apnea. Central and mixed apneas are other types of sleep apnea.

    Treatment for Sleep Apnea

    One of the most common treatments for sleep apnea is Positive Airway Pressure (PAP) therapy. The PAP therapy works by forcing air through a person’s airways at a pressure which is high enough for preventing apneas. This type of treatment is prescribed for OSA and central sleep apnea.

    Types of PAP Therapy

    There are three types of PAP therapies namely:
    • Continuous Positive Airway Pressure (CPAP)
    • Automatic Positive Airway Pressure (APAP)
    • Bi-Level Positive Airway Pressure (Bi-PAP)

    Continuous Positive Airway Pressure (CPAP) Therapy

    CPAP therapy is the most common treatment option for sleep apnea, especially OSA. OSA patients experience stoppages in their breathing due to airway obstructions. This can last anywhere from few seconds to a few minutes. Depending on severity, a sleep apnea patient can have anywhere from a few interruptions to more than 100 disruptions in breathing every hour! These can result in the person developing various health problems such as heart disease, stroke, unrefreshed sleep and chronic daytime drowsiness among others.

    Working of A CPAP Device

    A CPAP machine gently blows pressurized air through a person’s airway at a steady pressure which ensures that the throat does not collapse. CPAP machines are uncomplicated machines and can be used by anybody. A CPAP device consists of three parts:

    CPAP motor – A CPAP motor is essentially a small compressor, which draws in room air and gently pressurizes the room air to deliver an appropriate amount of air needed to clear the obstruction. The portion from where the room air is drawn in has a replaceable filter which aids in keeping out impurities and particulates. A majority of the modern CPAP machines also comes equipped with a small water tank which helps in providing moisture to the air that a sleep apnea patient breathes. These humidifiers are handy for those patients who reside in arid or dry climates and often complain of dry nasal cavities, dry throat, and dry mouth. Modern CPAP motors are very powerful yet remarkably silent.

    CPAP Hoses – A CPAP hose is a delivery device which helps in transporting the pressurized air from CPAP motor to the user’s mask. The length of a CPAP hose averages around 6 feet; the diameter, on the other hand, varies depending on machines being used by the sleep apnea patient. With the advent of humidifiers, the problem of condensation in the hose and mask increased to a great extent. To address this issue, hose manufacturers have started introducing heated tube into the market.

    CPAP Mask-
    Since no two human faces are similar, the market is flooded with different shapes and sizes of CPAP masks. Though there are different shapes and sizes, typically, there are three mask variations which a CPAP user can choose from. These include full face masks, nasal masks, and nasal pillows. Finding an appropriate mask based on the comfort level of a CPAP user is extremely important as this has a direct bearing on the CPAP compliance.​

    Selecting A CPAP Device

    A polysomnogram or sleep study forms the first step for starting a CPAP therapy. This study is usually performed in a sleep clinic, and the results are conveyed to the sleep specialist who determines the severity of the sleep apnea condition as well as ways to treat it. If the sleep specialist decides that the person would be best served by a CPAP machine, then the person would have to undergo a sleep titration study.

    This study takes places in a sleep clinic where the person sleeps in the clinic overnight while undergoing trials with different types of CPAP machines and masks. The machines are specifically calibrated to the settings determined in the previous sleep study.

    Sometimes, due to several factors, a person might not be able to visit the sleep clinic to undergo the sleep study and sleep titration study. These people can undergo an HST (Home Sleep Test), which is issued to them after a pre-screening process. An HST is cheaper than a sleep study; however, if the HST fails to detect sleep apnea for three consecutive days, then the person would have to visit the sleep clinic to undertake the sleep study. Click here to know the difference between the two tests.

    Once the person decides the most appropriate CPAP machine for their use, they have to ensure that they USE IT REGULARLY to alleviate their OSA symptoms, since CPAP is a therapy for OSA and not a cure for it and discontinuation of the CPAP therapy can result in re-manifestation of OSA.

    CPAP Results

    People who use CPAP devices for treating their OSA tend to experience positive results with immediate effect. Some of these results include:
    • Elimination of problems associated with breathing
    • Improved quality of sleep during the night
    • Reversal or prevention of severe health ailments like stroke and cardiac disease
    • Maintenance of normal blood pressure during daytime as well as night
    • Increased daytime alertness
    • Significant reduction in daytime drowsiness

    Automatic Positive Airway Pressure (APAP) Therapy

    APAP therapy works on the similar principle of a CPAP therapy. Just like CPAP devices, the machine used in APAP therapy is a form of non-invasive treatment which works on delivering pressurized air to the person’s airway to prevent it from collapsing. The pressurized air performs the role of a splint, and prevents the person’s throat from collapsing, thereby allowing obstruction-free breathing during the entire night without any apneic episodes.

    Difference Between APAP and CPAP

    CPAP therapy has always been the go-to therapy for sleep apnea patients. However, one of the major limitations of a CPAP device is that the device can have only one air pressure setting, which makes it redundant for patients who require changes in the pressure setting based upon the conditions. In CPAP devices, the pressure setting remains the same regardless of the sleep stage and the sleep position of the sleep apnea patient.

    APAP devices, on the other hand, have two different settings, a low and high range setting. The APAP machine works between these two settings during the entire night as it adjusts automatically to the particular needs of a sleep apnea patient at a given point in time. APAP machines use algorithms that help in sensing subtle changes in the breathing pattern of the user and adjusts automatically to the most appropriate setting.

    Five Reasons Why APAP Machine Is the Best Bet

    • One of the distinct advantages of an APAP machine is that it can also function as a straight CPAP mode. If a person has an APAP machine but finds that the auto-adjusted air pressure does not suit them, then they can reset the machine at one constant pressure setting. This feature enables the user to experiment with APAP and CPAP modes as they work to find the best therapy for their sleep apnea.
    • An APAP machine can automatically adjust to various pressure settings between the machines’ predetermined low and high range settings. This functionality is essential since many people do not have same breathing requirements during the entire night. Compared to sleeping on the sides, most apneic events happen when the person is lying supine. The APAP machine lowers the air pressure when the person rolls onto their side and brings it back to normal when the person lies flat again, a function which is not possible in a CPAP device.
    • When a person is in REM sleep, their body becomes relaxed, and the throat muscles get weak, which increases the requirement for higher pressures, a need which can be easily achieved on an APAP machine. On the other hand, a CPAP machine is calibrated to meet requirements of REM sleep when the need for air pressure for keeping the person’s airway open is at the maximum. This results in the machine pumping at the same pressure even when the person does not need it at the said pressure, which can cause discomfiture in many users.
    • If a PAP machine user has cold, respiratory infections or seasonal allergies, then their airways can become congested and make the process of breathing even more difficult. Chances of increased apneic events are high during this period, and the user would need higher pressure than determined for reducing these events. This can be only achieved by using an APAP machine.
    • Over a period, the titration needs of a sleep apnea patient changes and factors such as increased age, illness, changes in weight can result in the patient either requiring low pressure or high-pressure setting than the one which is set now. If the patient is using CPAP machine, then they may have to schedule a new study for recalibrating the pressure settings. An APAP machine, on the other hand, can adjust to these changes automatically and the user need not undergo the sleep titration study again.

    Some Disadvantages of APAP Therapy

    • An APAP machine needs algorithms to adjust the pressure settings. However, every manufacturer has a different set of the algorithm, and this makes it a tad difficult for the sleep study specialist to prescribe the most appropriate machine. CPAP machines, on the other hand, are standardized to a great extent, and a sleep study specialist does not have difficulty in prescribing the required machine. However, a sleep technician who is well versed with various machines and has enough experience can help a person in selecting the most appropriate machine.
    • Sometimes, during an apneic event, pressure settings changes can kick in relatively slowly compared to the need for ideal pressure setting. Setting the optimal air pressure is the key to addressing this problem.
    • Cost-wise, CPAP machines are cheaper than APAP machines. Previously, an insurance company would only approve an APAP machine if the sleep apnea patient has failed CPAP therapy. However, with changing times, an increasing number of insurance companies have started to realize benefits of approving an APAP machine. Moreover, with compliance rate with APAP being greater than CPAP, insurance companies are increasingly willing to pay for the machine based upon sleep doctor’s recommendation.

    Bi-Level Positive Airway Pressure (Bi-PAP) Therapy

    The function and design of a Bi-PAP machine used in Bi-PAP or BPAP therapy are similar to the CPAP machine. The Bi-PAP machine, just like the CPAP machine, is the non-invasive type of therapy for sleep apnea patients. Both Bi-PAP and CPAP machines deliver pressurized air to the person’s airway utilizing a mask, thereby preventing the throat from collapsing.

    A Bi-PAP machine is prescribed for:
    • Sleep apnea patients who either need higher air pressure settings or have lower oxygen levels
    • Patient who have failed CPAP therapy
    • Patients having cardiopulmonary disorders, specific type of neuromuscular disorders or lung disorders

    Difference Between a Bi-PAP and CPAP

    For many OSA patients, CPAP therapy has been the go-to treatment. Once an OSA patient undergoes titration study, the sleep doctor and technician determines the pressure setting for the CPAP machine, thereby enabling the CPAP machine to deliver a continuous stream of pressurized air at the exact determined setting. However, a CPAP machine has the option of only one pressure setting which remains the same during the entire night, thereby resulting in a patient not getting appropriate benefits based on the conditions.

    To address this issue, CPAP manufacturers have come up with a ramp feature which initially starts at a lower pressure setting and slowly increasing to the desired setting. This feature ensures that a CPAP user does not have to face higher pressure at the outset.

    Despite these significant modifications, many CPAP users complain about difficulties in exhaling against a steady stream of pressurized air. A patient who needs higher air pressure strengths finds it difficult exhaling against a steady stream of incoming air, making them feel as if they have to force the breathing out.

    Bi-PAPs machines have a feature called breath timing which measures the exact amount of breaths taken by a person in one minute. If the gap between two breaths exceeds the time limit, then the Bi-PAP machine can forcefully make the person breath by increasing the air pressure, albeit temporarily.

    Thus, the most significant difference between a CPAP and a Bi-PAP machine is that while CPAP has one setting, the Bi-PAP machine has two pressure settings, a setting for inhalation (ipap) and one for exhalation (epap). These dual settings enable the OSA patient to breathe more steadily.

    Is CPAP C-Flex the Best Bet Against Bi-PAP?

    Just like a Bi-PAP machine, a CPAP machine with C-Flex feature provides pressure relief when the person exhales. However, the C-Flex feature can offer pressure relief for only 3 cm and is considered mainly as a comfort feature in the CPAP machine. The pressure relief in a Bi-PAP machine, on the other hand, starts at 4 cm and increases steadily. CPAP with C-Flex is suitable for only those people who require pressure relief at lower levels.

    One other significant difference between a Bi-PAP and CPAP machine with the C-flex feature is that C-flex does not offer pressure relief at a fixed constant rate and the chances of increased pressure variations are more. A Bi-PAP machine, on the other hand, offers a continuous prescribed air exhalation pressure.

    Consult The Doctor About Bi-PAP

    Based on the CPAP titration study results, the sleep doctor and the sleep technician would be able to determine whether a Bi-PAP machine would be suitable for the person. However, if the person has already used CPAP and find that the settings are not manageable, they should talk with their doctor and check whether they are suitable for a Bi-PAP machine.

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