What's The Difference Between CPAP, AutoPAP, and BiLevel?

These are the different treatment options which are delivered through different machines:

  • Continuous positive airway pressure (CPAP) provides one constant air pressure all through the night
  • Automatic positive airway pressure (APAP) therapy automatically varies the pressure all through the night and from night to night. It actively responds to the continuous changes in your upper airway
  • Bilevel therapy provides a higher pressure when you breathe in, and a lower pressure when you breathe out


Successful CPAP users report improvements in:

  • Vitality and motivation
  • Job performance
  • Mood
  • Sexual drive and performance
  • Alertness while driving
  • Quality of life
  • Quality of sleep

A failure to use CPAP therapy may increase your risk for conditions linked to untreated OSA:

  • Hypertension (OSA increases your risk of hypertension by up to five times)
  • Stroke
  • Congestive heart failure (CHF)

CPAP equipment

  • Machine
    A flow generator that pushes air through a filter and provides a set air pressure through a mask system to the patient
  • Mask
    Seals over the face to deliver the treatment pressure to the upper airway
    A mask system (nasal pillows, nasal or full face) includes:
  • Mask or pillows
  • Air tubing
  • Humidifier
    Moistens the delivered air to relieve nasal irritation and dryness that can result from constant airflow, especially at higher treatment pressures

CPAP therapy will work for many people with OSA, but sometimes a different type of treatment is prescribed. Automatic positive airway pressure (APAP) therapy automatically varies the pressure all through the night and from night to night. It actively responds to the continuous changes in your upper airway.



  • Short for "automatic positive airway pressure"
  • Device used in the treatment of obstructive sleep apnea (OSA)
  • Automatically adjusts, on a breath-by-breath basis, to deliver the minimum pressure needed to keep the upper airway open during sleep. This allows the device provide you with your ideal pressure over the entire night
  • Tend to be more advanced and contain more features than CPAP devices
  • May also be known as:
  • Auto-adjusting CPAP
  • Auto-titrating CPAP
  • Self-adjusting CPAP
  • Auto PAP
  • Automatic CPAP
  • Auto

AutoSetâ„¢ technology

Third-party clinical trials have found that ResMed's AutoSetâ„¢ autotitration devices prevent more apneas and hypopneas and operate at lower average pressures than fixed pressure devices. Lower pressure means greater comfort for you.

Most devices only adjust pressure after an event (an apnea, hypopnea, or snore) has occurred, but AutoSet devices actually prevent most events. AutoSet devices respond preemptively to apneas and hypopneas by monitoring the user's inspiratory flow-time curve. Changes in this curve indicate the likely occurrence of an apnea, hypopnea or snore.

Some apneas will occur without any precursor, and in these situations, the AutoSet device responds to the severity of the apnea, not providing too much additional pressure and not providing too little, as opposed todevices with arbitrary incremental increases.

Are all APAP devices the same?

No. Although these machines use complex algorithms, each manufacturer's device uses a different — usually patented — algorithm that responds to different signs of snoring, flow limitation, hypopneas and apneas.

The algorithm largely determines the quality and comfort of treatment, so if you are prescribed an autotitration system, please check with the manufacturer to see that the device has been clinically validated to provide the treatment it promises.


Bilevel devices can provide therapy:

  • For people with Obstructive Sleep Apnea (OSA) if they have found continuous positive airway pressure (CPAP) therapy too difficult
  • Provide noninvasive positive pressure ventilation (NPPV) for people with respiratory disorders or other forms of Sleep-Disordered Breathing (SDB)

Bilevel therapy works by delivering two different levels of positive air pressure:

  • A higher level of pressure when you breathe in
  • A lower level of pressure when you breathe out

Although both are non-invasive, Bilevel and CPAP therapy differ in two significant ways:

  1. Bilevel devices deliver two levels of air pressure that are set to coincide with the patient's inspiratory and expiratory efforts
  2. Bilevel therapy can be used to treat conditions other than sleep apnea (OSA) and is the first line of treatment for a wide-range of respiratory disorders

Frequently Treated Conditions

Physicians may use bilevel therapy to treat a broad range of conditions, including:

  • Nocturnal hypoventilation
  • Respiratory insufficiency
  • Neuromuscular disease
  • Respiratory failure
  • Chest wall deformity
  • Chronic obstructive pulmonary disease (COPD)
  • ALS or Lou Gehrig's disease
  • OSA*

*Bilevel therapy is not typically prescribed for OSA patients; however, OSA patients who require high treatment pressures or have another respiratory condition are often candidates for bilevel therapy.

Why Shop with Us?