APAP - Auto Adjusting Positive Airway Pressure

APAP - Auto Adjusting Positive Airway Pressure

APAP is the acronym for Auto adjusting positive airway pressure.

APAP devices are increasingly used in the treatment of obstructive sleep apnea (OSA).

Pressure adjustments are made throughout the night with these “smart” CPAP machines.

Purpose Of APAP Usage

Different pressures are needed for different levels of sleep and positions. The purpose of APAP is to have the lowest possible pressure for each position or sleep level.

At a given pressure, the machine adjusts the pressure higher until the occurrences are controlled, if a person starts to have an apnea or hypopnea. The pressure is decreased, if a person is in a sleep level or position that doesn’t need a higher pressure.

The advantage is when a lower pressure is all that is required; the machine is not stuck at the highest pressure needed. The down side is, a person can be stuck at a lower pressure having apnea episodes, if the machine does not adjust.

With auto adjusting positive airway pressure (APAP), the mean pressure throughout the night is lower, and 2/3 of the night is spent below the set CPAP pressure. The machine can also adjust for the changes in pressure that are needed to overcome the effects of weight gain and alcohol or narcotic use.

Disadvantages Of APAP

The disadvantages of auto adjusting positive airway pressure (APAP) are that leaks may underrate pressure or airflow. Each corporation has a different algorithm for adjusting the pressure and adjusting for leaks.

The Three Measure Employed By APAP

  • Pressure is low when there are no problems but is raised gradually when they are detected.
  • Pressure is gradually increased and lowered in response to problems or their absence. In addition, the device can change depending on problems within single breaths.
  • Overall pressure is kept low until a specific problem is detected. At that time the pressure is automatically raised rapidly.

These devices are higher in price than those that provide continuous airflow. And, in general, the pressure exerted using APAP devices is lower than with standard CPAP and there is little difference in effectiveness.

These devices may improve compliance, however, in patients who find the steady flow of air from standard devices irritating or who require varying levels of pressure due to other conditions, such as seasonal allergies.

APAP devices are not currently suggested for all patients, however, including those with congestive heart failure or serious lung disease. They are also proving to be very useful as home diagnostic tools for sleep apnea.

It is unsure whether these devices are equally effective in controlling sleep-disordered breathing as different measurements of upper airway obstruction are applied.

Advantages of APAP over fixed pressure CPAP:

  • Detects adverse mask conditions.
  • Ultra-sensitive snoring detection capabilities.
  • Eliminates the necessity for CPAP calibration every night
  • Improves CPAP compliance since the pressure rises and falls to deliver the minimum pressure required keeping the airway patent and hence there are lower mean pressures throughout the night.


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