CPAP / APAP pressures
The treatment pressure required by the patient may vary due to changes in sleep state, body position and airway resistance. In AutoSet mode, the device provides only that amount of pressure required to maintain upper airway patency.
The device analyzes the state of the patient’s upper airway on a breath-by-breath basis and delivers pressure within the allowed range according to the degree of obstruction. The AutoSet algorithm adjusts treatment pressure as a function of three parameters: inspiratory flow limitation, snore, and apnea.
Normal airway
When the patient is breathing normally, the inspiratory flow measured by the device as a function of time shows a typically rounded curve for each breath.
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Flow limitation
As the upper airway begins to collapse, the shape of the inspiratory flow-time curve changes. The AirCurve 11 VPAP Tx recognizes and treats traditional as well as less common flow-limited breath wave forms.
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Snore
Snoring is sound generated by vibrations of the walls of the upper airway. It is often preceded by flow limitation or a partial obstruction of the airway.
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Apnea
The enhanced AutoSet algorithm detects both obstructive and central apneas. If an apnea occurs, the device responds appropriately.
Obstructive apnea
An obstructive apnea is when the upper airway becomes severely limited or completely obstructed. AutoSet generally prevents obstructive apneas from occurring by responding to flow limitation and snoring. If an obstructive apnea occurs, the device will respond by increasing pressure.
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Central apnea
During a central apnea, the airway will remain open, but there is no flow. When a central apnea is detected, the device responds appropriately by not increasing pressure.
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AutoSet for Her mode is based on key aspects of ResMed’s AutoSet algorithm and delivers therapeutic responses tailored to the characteristics of female OSA patients.
The AutoSet for Her is similar to ResMed’s AutoSet algorithm with the following modifications:
Reduced rate of pressure increments designed to help prevent arousals.
Slower pressure decays.
Treats apneas up to 12 cm H2O (12 hPa) and continues to respond to flow limitation and snore up to 20 cm H2O (20 hPa).
Minimum pressure (Min. Pressure) that adjusts according to the frequency of apneas:
If two apneas occur within a minute, the pressure reached in response to the second apnea will become the new minimum treatment pressure until the next treatment session.
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Patients who use AutoSet for Her will still get the benefits of ResMed's AutoSet technology including improved sensitivity to flow-limitation and Central Sleep Apnoea Detection with Forced Oscillation Technique.
In CPAP mode, a fixed pressure is delivered—with optional Expiratory Pressure Relief (EPR™).