Positive Airway Pressure

Information for patients using positive airway pressure (CPAP, BILEVEL PAP, ADAPT SV, AUTO SV, AVAPS) treatments for sleep apnea

How do these devices work?

  • They all “blow the airway open” to prevent its collapse in sleep. Necessary pressure settings must be determined for each patient during sleep, so patient shouldn’t try to adjust these settings on their own.
  • Since they work by increasing airway pressure, significant leaks of air and air escape at the mouth can make them ineffective. Ensure your mask or nasal pillows (“puffs”) are snugly in place before sleep–but excessive tightening may cause leaks. Also, if a chinstrap is prescribed, be sure to wear it routinely! Many patients underestimate the importance of their chinstrap because they can’t know what happens while they sleep.

What kinds of machines are there?

  • CPAP: Continuous Positive Airway Pressure. Delivers continuous flow of air at a constant pressure.
  • Bilevel PAP: permits cycling between higher and lower pressures while the patient breathes in and out. Some patients find it makes exhalation easier, while others dislike the cycling and resulting increased noise.
  • Bilevel PAP with IMV (intermittent mandatory ventilation): The machine delivers burst of air to stimulate breathing in patients who have long pauses in breathing and don’t start breathing promptly on their own. The timed mode is a special feature of some bilevel machines which is used to increase length of time spent breathing in: to improve blood oxygen/ carbon dioxide levels.
  • Adaptive Servo-Ventilation (ASV): The most sophisticated technology available today, developed by the ResMed Company to address the vexing problem of central apneas (repeated failure to initiate efforts to breathe)–with or without additional elements of obstructive sleep apnea. Prior treatments were often ineffective. In fact, they sometimes made central apneas worse.

ASV continuously analyzes a patient’s breathing pattern on an ongoing basis: immediately sensing when breathing is becoming unstable. Then, it provides just enough support to ensure stable breathing–“backing out” when it no longer is needed. It is far more comfortable than prior treatments because it adjusts to the patient’s changing needs–rather than forcing the patient to try to adapt to it.

For example, bilevel PAP with intermittent mandatory ventilation responds to lack of breathing effort by delivery of bursts of pressurized air at a pre-set rate. Many patients feel that they cannot “get in synch” with these machines such that they find themselves unable to achieve restful sleep. Adapt SV tailors both the rate and magnitude of pressure support to the individual patient on an ongoing basis: a major reason why many patients find ASV far more comfortable.

ASV is of particular importance for two reasons:

    • The high prevalence of central sleep apnea in heart failure patients: a problem that can accelerate deterioration in heart function while rendering medical therapy for heart failure ineffective. Studies have clearly shown that ASV is far more effective than any other treatment for central sleep apneas in heart failure victims.
    • The fact that treatment of obstructive sleep apnea with conventional positive airway pressure units sometimes precipitates repeated central apneas–sometimes with worsening drops in blood oxygen levels, and with severely disrupted sleep that can render positive airway pressure intolerable. This phenomenon, recently termed “COMPLEX SLEEP APNEA” is one major cause of patients’ inability to comply with CPAP or bilevel PAP treatments.

Only certain masks can be used to deliver ASV, because significant leaks of air render ASV ineffective.
ASV is very new in the United States and it is not yet available at most sleep disorders centers.

  • Auto Servo-Ventilation (ASV): A new treatment approach developed by the Respironics Company that incorporates some features reminiscent of both adaptive servo-ventilation and bilevel positive airway pressure with IMV.
  • Average Volume Assured Pressure Support (AVAPS™): a revolutionary new approach for the treatment of patients who breathe too shallowly to maintain adequate oxygen levels and to eliminate carbon dioxide (a waste product that can depress breathing). It can help people afflicted with such problems as chronic lung disease (COPD), spine deformities such as kyphoscoliosis and patients with weakness of the respiratory muscles arising from conditions that include post-polio syndrome and muscular dystrophy.

Which machine is the best?

Whichever machine works for you and that you tolerate well.

  • For many patients, the first month of treatment is a difficult–but crucial–adjustment period. Some patients require a more sophisticated machine initially to help them get “over the hump”–after which, once accustomed to it, they might do fine on CPAP (the simplest, cheapest unit).
  • For example, the first time that patients who sleep lightly try sleeping with CPAP, they may experience arousals followed by breathing pauses (central sleep apneas) which in turn provoke yet other arousals-similar to a “slipping clutch”. A bilevel unit with IMV may help correct this, and once they’ve adjusted to using positive airway pressure and are sleeping sounder, it may be possible to convert them to treatment with a basic CPAP unit.
  • If a bilevel unit with IMV is either ineffective or poorly tolerated, adaptive servo-ventilation (ASV) will typically resolve both the patient’s central and obstructive apneas with superior comfort and acceptability to the patient.

Are these oxygen machines?

No. They simply use room air pressurized by a blower unit, much like a vacuum cleaner in reverse. Oxygen can be ‘piped into them’, though, for patients who require it. Supplemental oxygen is sometimes delivered via PAP to either treat low oxygen levels that persist following elimination of upper airway obstruction, or to stabilize breathing when central apneas are a problem (effective in some cases and ineffective in others).

Do these machines cure sleep apnea?

No. As is true for most medical treatments, they control sleep apnea, as long as they’re used consistently: thus protecting patients from sleep apnea complications and symptoms, and “buying time” for them to utilize for elimination of such aggravating factors as obesity.

Do CPAP/BILEVEL PAP/ADAPT AND AUTO SV treatments remain effective over the years?

Yes. Unless other factors (such as sedating drugs or new illnesses) make your sleep apnea worse. Also, sleep apnea can worsen with both age and weight. If you are significantly overweight, it is crucial that you promptly achieve steady, ongoing weight loss to counteract the deleterious effects of aging that could otherwise ultimately render your present machine inadequately effective.

It usually is safest to record patients once again after a number of years have passed to ensure that their originally prescribed pressure is still adequately effective, particularly if they are overweight and significant weight loss has not occurred. Also, most third party payors demand fresh proof that a patient’s sleep apnea did not “go away” before they will replace an old unit that no longer functions well.

How good is treatment with Positive Airway Pressure compared to the alternatives?

Much better: from the standpoint of both long-term effectiveness and safety. No other treatment, short of tracheostomy, is as reliably effective as eliminating airway obstruction in sleep. Since the problem is a vacuum suction-like collapse–much like sucking on a balloon–surgical widening of the airway at one level is often followed by collapse at yet another level.

For example, a patient undergoing palate surgery may continue to experience airway collapse “down river” behind the tongue base. In fact, only 18-33% of patients with excessive drops in oxygen levels during sleep respond adequately to palate surgeries, and many subsequently relapse and ultimately require CPAP. The advantage of CPAP/bilevel PAP is that they typically keep the entire airway open, irrespective of where the collapse might have occurred. While children with sleep apnea due to large tonsils and adenoids often seem to respond to surgical treatment, results in adults have been disappointing.

CPAP/Bilevel PAP/ASV are typically safe and immediately effective: without operative risks nor the need to wait for surgical healing before effectiveness can be determined. Also, unlike surgeries or oral appliances, they can be tried initially on a rental basis (which, in fact, is required by most insurance companies) and returned if things don’t work out.

What if I don’t use my machine?

Your sleep apnea will recur quickly, which in some patients can be dangerous.

Is “part-time use” enough for my treatment?

NO. One common, potentially serious mistake would be to wake up toward the end of the night, remove it and allow yourself to fall asleep again. Since we experience most of our REM sleep (the stage when most patients’ sleep apnea usually reaches its greatest severity) during the final hours of sleep, you will have removed it before you needed it more than ever.

Should I use my machine during naps?

Ideally, yes. How dangerous napping without it might be depends both upon individual patients’ sleep apnea severity and also, whether they have a history of heart trouble or strokes.

Should I take my machine with me when I travel?

YES. If you can’t find a way to leave your sleep apnea at home, “don’t leave home without it”! Traveling with these units is usually quite easy. Some travel tips–

  • Ensure you were given a carrying case, and ask your home care company for extra fuses to take with you.
  • For foreign or air travel, ask your physician for a letter to facilitate its transport through airport check-ins and customs. Carry it on with you: don’t check it with your luggage.
  • If you’re going overseas, talk with your home care company beforehand. While nearly all units are designated to operate on either 110 or 220 volts, one patient reported his machine was destroyed by British current, and an electric current converter may be advisable.
  • If you will be without access to electricity (ex. while camping/boating) ask your home care company if a battery or DC converter is available for your particular machine.
  • If you also require oxygen (which is difficult to transport), ask your home care company for assistance in arranging rental oxygen at your destination.

Are there patients who possibly should not be treated with these machines?

YES. Some examples:

  • Some patients with a history of spontaneous pneumothorax, or large bullae (“blebs”, similar to bubbles on a tire) that could rupture and cause lung collapse.
  • Some patients on high doses of steroids (ex. prednisone, Decadron®).
  • Some patients with increased pressure in the brain (ex. hydrocephalus, pseudotumor) or a past history of cerebrospinal fluid leaks.
  • Patients who cannot or will not use the equipment consistently as prescribed throughout sleep.

If you encounter problems what steps should you take?

Refer to our troubleshooting guide and try the recommendations listed for those specific problems you’re experiencing.

If you’ve tried those measures and if they didn’t resolve your difficulties, call your physician. Don’t allow significant problems to persist, and don’t allow yourself to go untreated and unable to use your equipment throughout sleep.

What about maintenance?

  • Clean your equipment regularly according to the manufacturer’s recommendations you will receive from your home care company.
  • Broken, defective or worn equipment must be repaired or replaced immediately.
  • You may wish to have your machine checked routinely and serviced once a year, even if it seems to be functioning well.
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