Transcript IPPB: Bennett valve tutorial - Kingwood Application Server

IPPB: Bennett valve tutorial
By Elizabeth Kelley Buzbee AAS,
RRT-NPS, RCP
The PRII
• Pneumatically powered, pneumatically
controlled
• Time* or pressure, manually triggered on
• In Air-mix has a descending pressure
ramp
• Flow or time* cycled off.
*when used as a mechanical ventilator
The Bennett valve
• This valve works on the balancing of gas
flow and gravity. The valve at rest is
closed due to gravity, when inspiratory
flow exceeds the force of gravity, the valve
stays open and the breath continues.
Once the flow drops off as the pressure
rises, then gravity starts to close the valve
and the breath is over.
The Bennett
In A, the valvevalve
drum is at rest because
the off-center Weight holds it closed.
• This valve works on
the balancing of gas
There is high pressure Above the valve
and below
the valve
[to patient]
flow and gravity. The
valve
at
rest
is
There is zero pressure [ambient]
closed due to gravity, when inspiratory
The pressure inside the rotating drum
flow exceeds the force
of togravity,
thethisvalve
was Vented
ambient during
so that it is at ambient pressure.
stays open and thephase
breath
continues.
The pressure
just
below
the valve
Once the flow drops
off
as
the
pressure
will be read on the SYSTEM PRESSURE
rises, then gravity manometer.
starts to close the valve
and the breath is over.
The pressure just above the valve will
be read on the PRESSURE monometer
While there is no gas pressure inside the drum
there is no gas flow down the exhalation drive l
In B, as the patient inhales on the
The Bennett
valve
circuit. The pressure drops in the
Mainline and in the area just
under the drum
• This valve works on the balancing of gas
Once the pressure exceeds the
flow and gravity. The valve
resttheisvane on
force ofat
gravity
the side of the drum is pulled
closed due to gravity, when
inspiratory
toward the
patient and the
begins to open toward both
flow exceeds the force Drum
of
gravity,
the
valve
The patient [bottom] and the
gas inlet
[top].
stays open and the breath
continues.
Once the flow drops offGasasstarts
theto pressure
flow from above
The valve to the patient circuit.
rises, then gravity starts to close the valve
pressure seen on the
and the breath is over. The
SYSTEM PRESSURE manometer
will rise As the pressure
downstream from the drum rises.
In C during inspiration the drum is still open to both
the high Pressure coming from the Dilutor regulator
and the patient circuit.
The Bennett valve
Pressure rises in the
patient circuit and the exhalation
valve is shut so that the gas goes
to the Patient.
During the breath,
the SYSTEM
PRESSURE
monometer
drops and the
PRESSURE
monometer rises
until it reaches the
same pressure
As the SYSTEM
PRESSURE
• This valve works on the balancing of gas
flow
and
gravity.
The
valve
at
rest
is
As long as there is a
pressure
closed due to gravity, when inspiratory
Gradient between
flow
exceeds the force of gravity, the valve
the two
areas
There is flow, but as
stays open and the breath continues.
the pressure
Downstream
starts
toflow drops off as the pressure
Once
the
rise, the flow
Starts
to slow then
down
rises,
gravity starts to close the valve
and the breath is over.
The Bennett valve
The flow continues to
Slow down and once it
Is only 1- 3lpm, the
force of gravity is stronger
Than the gas flow and
The drum swings shut
• This valve works on the balancing of gas
flow and gravity. The valve at rest is
closed due to gravity, when inspiratory
flow exceeds
the force of gravity, the valve
The breath is over
staysThe
open
and the breath continues.
drive line to the
valvedrops
is no longer
OnceExhalation
the
flow
off as the pressure
Charged with pressure so
exhalation
valve starts to close the valve
rises,the
then
gravity
opens for exhaled Vt to exit
and the
breath is over.
The patient.
PRESSURE monometer now
Reads Zero while the SYSTEM
PRESSURE reads the high
pressure