Operating Information; Bilevel Pressures; Modes Of Operation - ResMed VPAP ST Clinical Manual

Operating information

The VPAP device uses internal pressure and flow sensors in the air path to respond reliably to patient
flow rates even in the presence of most normal leaks in the patient circuit.

Bilevel pressures

The VPAP device assists spontaneous breathing by cycling between two pressures in response to the
patient flow or a preset fixed time.
The inspiratory positive airway pressure (IPAP , or the sum of EPAP and the pressure support level) assists
inspiration.
The lower expiratory positive airway pressure (EPAP) eliminates exhaled air through the mask exhaust
vent. This facilitates exhalation comfort while providing a splint to maintain an open upper airway.
The difference of the two pressures—pressure support (PS) level—contributes to improved patient
ventilation.

Modes of operation

The following table describes the operating modes available on the VPAP ST or VPAP S.
Mode
CPAP mode
A fixed pressure is delivered.
S (Spontaneous) mode
You may set two treatment pressures-–one for inspiration (IPAP) and
one for expiration (EPAP). The VPAP device senses when the patient
is inhaling and exhaling and supplies the appropriate pressures
accordingly. The difference between IPAP and EPAP levels helps
determine the tidal volume.
ST (Spontaneous/Timed) mode
The VPAP device augments any breath initiated by the patient, but will
also supply additional breaths should the patient breath rate fall below
the clinician's set "backup" breath rate.
T (Timed) mode
The fixed breath rate and the fixed inspiration/expiration time set by
the clinician is supplied regardless of patient effort.
4
Pressure
IPAP
Pressure
Support
EPAP
0
One breath cycle
Rise time
Time
VPAP ST VPAP S
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