Central Sleep Apnea; Sleep Quality; Ramp - ResMed S9 VPAP Series Clinical Manual

Central sleep apnea

In VAuto or CPAP mode, these VPAP devices detect both obstructive and central sleep apneas (CSA).
CSA detection uses the Forced Oscillation Technique (FOT) to determine the state of the patient's airway
during an apnea. When an apnea has been detected, small oscillations in pressure (1 cm H
peak at 4 Hz) are added to the current device pressure. The CSA algorithm uses the resulting flow and
pressure (determined at the mask) to measure the airway patency.
Respiratory flow

Sleep quality

Designed to promote compliance, the Sleep Quality indicator allows the patient to actively engage in
their own therapy by identifying leak, usage and AHI information. This information can be set to:
• Usage—where only usage hours are displayed
• On—where usage, leak and AHI information are displayed.

Ramp

Ramp is designed to make the beginning of treatment more comfortable.
In CPAP mode during ramp time, the pressure increases from a low pressure to the prescribed treatment
pressure.
In S, ST and T modes, ramp time defines the period during which the pressure gradually increases from a
low start pressure (referred to as Start EPAP) to the prescribed treatment pressure (EPAP).
IPAP
EPAP
Start EPAP
0
Ramp time
10 sec
4 sec 6 sec
delay
CSA detector
(expiratory
begins
pauses)
O peak-to-
2
Apnoea type
detected -
Central or
Obstructive
Time
9
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