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How a Bi-Level CPAP Machine Works

Working of the Bi-Level CPAP

A Bi-level CPAP machine as its name suggests, delivers two different positive pressure levels. This allows users to experience the benefits of using CPAP such as prevention of sleep apnea, hypopneas, snoring and also the benefits of not suffering from the side effects of using a high level pressure during exhalation.

The two separate air pressures which are delivered are:

  • IPAP or Inspiratory Positive Airway Pressure
  • EPAP or Expiratory Positive Airway Pressure

    A Bi-level CPAP at work

When the user exhales, the pressure of the air is lowered, subsequently when the user inhales, the pressure of the air is increased. This allows for easier breathing and exhaling with low pressure. This makes these CPAP machines more user friendly and easy to use when compared to traditional CPAP machines.

In a traditional CPAP, due to the excess pressure, it is very hard to breathe out. But due to the low pressure in the bi-level CPAP, this process becomes easier. This problem can easily be solved by using a Bi-level CPAP machine.

The Different IPAP and EPAP Settings

Usually three settings are present to change the pressure from IPAP to EPAP and vice-versa:

  • Timed Mode: This mode is completely independent, it depends only on time. When a pre-configured amount of time passes, the pressure level is controlled and changed mechanically.
  • Spontaneous: In this mode, the pressure level of the air is changed according to the changes in the users breathing. The machine will recognize ones inhalation and exhalation timings and control the IPAP and EPAP levels accordingly.
  • Timed/Spontaneous: In this mode, the pressure is adjusted based on the patients breathing, if and when the breathing stops, the level of pressure is changed to bring back normal breathing.

  These machines usually cost more than the traditional CPAP machines due to the use of sophisticated and advanced circuitry and machine parts. But it is worth your money, since it lowers all of the negatives of the traditional machine and produced superior and more comfortable results



  1. I really appreciate what you post. You have a new subscriber now.

  2. Nice and brief article on how bi-level CPAP works – thanks