The long answer
VAuto mode
In
VAuto mode, the AutoSet algorithm automatically adjusts pressure in response to flow limitation,
snore and obstructive apneas.
Min EPAP, Max IPAP and pressure support in VAuto mode
Pressure support allows you to set the difference between inspiratory and expiratory pressure and
is fixed throughout the night. Min EPAP and Max IPAP settings allow you to restrict the delivered
pressure ranges in which the AutoSet algorithm can operate.
The EPAP and IPAP will vary across the session according to the patient’s needs. It responds to
snoring, apneas and flow limitation of the patient’s flow curve.
Min EPAP and Max IPAP can be adjusted to limit the upper and lower delivered pressure limits.
Triggering and cycling
VAuto, S and ST modes only
The device has adjustable trigger/cycle sensitivity to optimize the sensing level according to patient
conditions.
Under normal conditions, the device triggers (initiates IPAP) and cycles (terminates IPAP and
changes to EPAP) as it senses the change in patient flow. Patient breath detection is enhanced by
ResMed's VSync automatic leak management.
TiControl - Inspiratory time control
VAuto, S and ST modes only
Unique to ResMed bilevel devices, TiControl™ allows the clinician to set minimum and maximum
limits on the time the device spends in IPAP. The minimum and maximum time limits are set at
either side of the patient’s ideal spontaneous inspiratory time, providing a ’window of opportunity’
for the patient to spontaneously cycle to EPAP.
The minimum time limit is set via the Ti Min parameter and the maximum time limit is set via the Ti
Max parameter.
TiControl’s Ti Max and Ti Min parameters play a significant role in maximizing synchronization by
effectively intervening to limit or prolong the inspiratory time when required. This ensures
synchronization even in the presence of significant mouth and/or mask leak.
The following table is a guide to selecting the Ti Max and Ti Min values that best correspond to the
patient’s respiratory rate and inspiration and expiration ratio, depending on the respiratory
conditions.
Examples:
- I:E = 1:1 – Ti Min prevents the premature cycling to EPAP for patients whose inspiratory effort is extremely weak.
- I:E = 1:3 – Ti Max limits the inspiration time for patients who require a longer expiration time.
The
Triggering and cycling and
TiControl - Inspiratory time control are not available in an AutoSet and apparently they cannot be disabled, only set up do do what they were designed to do, help trigger breathing for the user when needed and adjusted properly.
Fred