Flow Limit Control (Flc) State - Respironics BiPAP Vision Service Manual

Chapter 6
Troubleshooting
6-6
6.2.4

Flow Limit Control (FLC) State

The ventilator enters the flow limit control (FLC) state when a disconnect
alarm occurs.
Detecting a disconnect condition:
The device determines that a patient is not connected to the circuit based on
flow for a given pressure (as defined in a lookup table that includes a flow
entry for every generated pressure). The range of flows is 95 to 180 LPM, with
180 LPM the low limit for any pressure above 9 cmH
flow greater than the threshold at any given pressure for more than 10 seconds
(3 seconds in for software versions earlier than 13.2), it enters the FLC state.
In the FLC state, the ventilator attempts to limit the flow from the mask to
make putting the mask back on the patient easier and more comfortable for
the patient. The oxygen valve closes to discontinue oxygen delivery. Pressing
the Standby key also causes the ventilator to enter the FLC state, regardless of
the flow at the time.
During FLC the ventilator drops the pressure to 4 cmH
a flap that closes the patient circuit and opens the mask to atmosphere upon
loss of flow and pressure. The 4-cmH
FLC to avoid occluding the patient circuit. When the ventilator detects that the
patient is reconnected, it slowly increases pressure to maintain a the flow of
160-170 LPM. Circuit pressure is limited to 10 cmH
and 11.3) or 15 cmH O (software version 11.3a and higher), regardless of how
2
much flow is generated. This means that the ventilator delivers 160-170 LPM
within the specified pressure range, or is limited to a lower flow at 10 or 15
cmH O (depending on the software version).
2
Terminating the FLC state:
FLC terminates if the ventilator detects negative flow (that is, the patient
breathes back into the device) as pressure increases from 4 cmH
maximum of 10 or 15 cmH
For software versions earlier than 13.2, this pressure increase takes about 10
to 12 seconds (¼ cmH O per 40 ms), depending on how soon the flow set
2
point is reached. The ventilator increases pressure more quickly (1 cmH
40 ms) for software versions 13.2 and later.
For software versions earlier than 13.2, when pressure drops to 4 cmH
the flow is above 160-170 LPM, the flow limit algorithm decreases the
pressure to reduce the flow to 160-170 LPM. For software versions 13.2 and
later, FLC terminates immediately pressure drops to 4 cmH
above 160-170 LPM.
BiPAP Vision Service Manual © Respironics, Inc.
O pressure keeps the flap open during
2
O (depending on software version).
2
O. If the unit detects
2
O. A full face mask has
2
O (software version 11.2
2
O to its
2
O per
2
O and
2
O and the flow is
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