AVEA
Enhanced Pulmonary
Mechanics
Advanced Settings
User Interface Module
Advanced
Settings
Feature
Accessing Advanced Features
Press “Adv Settings”
hard key on left side
panel of the Avea
monitor to access the
Advanced Settings
Window
Advanced Settings Window
Yellow triangle
indicates this
parameter has
Advanced Settings
Activating an Advanced
Setting
Press the desired parameter. The parameter will
then be high-lighted with a blue background.
The Advanced Settings features will
then appear in the window above
for the parameter
Advanced Settings
Universal Features:
Sensitivity & Pressure Support
Sensitivity: Flow & Pressure
Flow Trigger Advanced Settings
Bias Flow
Pressure Trigger
Sensitivity
Sensitivity
• “Bias Flow”
– Bias Flow enables Flow Triggering
– To have adequate Flow Triggering, the Bias Flow
should be set 0.5 liters above the Flow Trigger setting
• Example: Bias Flow set at 2.0 litres, Flow Trigger should be
set no higher than 1.5 litres
• “Pressure Trigger”
– The Avea has both a pressure and a flow trigger
active at the same time. Whichever signal (flow or
pressure) is triggered first, the ventilator will then
cycle into inspiration
Pressure Support Ventilation
PSV Setting has 4 Advanced Settings
Max
Inspiratory
Time
Volume
Limit
Rise Flow
Time Cycle
%
Pressure Support Ventilation
• “Volume Limit”
– Every pressure type breath on the Avea has “Volume Limit” as
an Advanced Setting feature
– The clinician can enter a maximum volume limit. Once the
ventilator has reached this limit during the delivery of the
breath, it will then cycle the breath to exhalation using volume
as the cycle criteria
– When the volume limit is reached, a visual display appears in
the alarm area. The display remains illuminated as long as the
volume limit is active
• “PSV Rise Time”
– Setting range is from 1 to 9, 1 being fastest and 9 slowest.
– Allows the clinician to adjust the speed at which flow is
delivered to the patient during a Pressure Support breath
Pressure Support Ventilation
• “PSV Flow Cycle %”
– The Flow Cycle works as a percentage of the peak flow of the
PSV breath
– The Flow Cycle can be set in increments of 5% up to 45%
• Example: If the flow cycle is set at 10% and the peak flow for the
PSV breath is 60 lpm, the breath will cycle when the decelerating
inspiratory flow curve decays to 6 lpm
• “PSV Tmax”
– The PSV Maximum Inspiratory Time setting allows for an
adjustable back up inspiratory time setting in circumstances
where flow cycling is unreliable (i.e. endotracheal tube leaks)
– PSV Tmax should be set at 1.5-2 X the set Inspiratory Time for
Control breaths
– The PSV Tmax is adjustable from 0.2 to 5.0 seconds
Advanced Settings
Pressure Control Ventilation PCV
PCV - Pressure Control
Inspiratory
Pressure
Inspiratory
Time
Flow
Trigger
Inspiratory Pressure in PCV
Touch
Insp Pres
and these
settings
become
available
Machine Volume Inspiratory
Volume Limit
Rise Time
Advanced Settings
Inspiratory Pressure in PCV
• “Mach Vol” (Machine Volume)
– This feature allows the clinician to set a target tidal
volume during a Pressure Control breath
– When Machine Volume is active, the “Mach Vol” icon
appears in the modes display window
Machine Volume icon
Machine Volume
• Is a Dual Control Mode; Ventilator delivers
Volume Controlled Flow signal and
Pressure Control signal to gas delivery
system simultaneously.
– Sets the minimum tidal volume delivered
from the ventilator in a pressure control
breath.
– Always used with the time cycling
criterion in pressure control ventilation.
– Circuit compliance compensated in adult
and pediatric applications.
Machine Volume
• Allows for the
maintenance of
traditional Volume
Control Ventilation
while allowing the
ventilator to vary peak
flow to meet the
patient’s inspiratory
flow demands
• Incorporates a
decelerating/ variable
inspiratory flow
waveform
• Can be thought of as
a variable flowvolume ventilation
Machine Volume
• Ventilator calculates the decelerating inspiratory flow
required to deliver the Machine Volume (Minimum Tidal
Volume) in the set inspiratory time.
• When Peak Flow decelerates to this calculated peak
inspiratory flow
– If Machine Volume has not been delivered
• transition to a continuous flow until the Machine
Volume has been delivered
– Inspiratory Time will remain constant
» maximum
Peak
Inspiratory
Pressure
is
determined by the High Peak Pressure alarm
setting
– If the Machine Volume is met or exceeded during delivery
of the pressure control breath, the ventilator will complete
the breath as a normal Pressure Control breath.
Pressure Control- Volume Control
Transition
Pressure is increased
within the breath
The constant, square wave flow
continues until the pre-set tidal
volume is delivered
Pressure Control Adjustments with
Machine Volume Guarantee
• Pressure Control
– Decreased
Compliance
• Lung
• Chest Wall
– Neuromuscular
Blockers
– Increased AW
Resistance
•
•
Mucous
Bonchospasm
• Pressure Control
– Increased
Compliance
•
•
Lung
Chest Wall
– Spontaneous Breathing
– Decreased AW
Resistance
•
•
Post Suctioning
Post Bronchodilators
Machine Volume
Note Inspiratory Pressure set at zero, breath is
decelerating flow pressure controlled breath. (Set Mach
Volume 350cc) Inspiratory time is constant
Machine Volume
Note transitions in flow between Pressure Control and
Volume Control flow waveforms
Machine Volume Vs. PRVC
Machine Volume can respond to changes in compliance within
2-4 msec. PRVC will update on next breath.
Compliance decreases ventilator
responds within the breath
Compliance increases ventilator
responds within the breath
Inspiratory Pressure in PCV
• “Vol Limit” (Volume Limit)
– This feature allows the clinician to set a maximum volume
limit that cannot be exceeded during a Pressure Control
breath
– When the volume limit is reached, a visual display appears
in the alarm area. The display remains illuminated as long
as the volume limit is active
• “Insp Rise” (Inspiratory Rise Time)
– Setting range from 1 to 9, 1 being fastest and 9 slowest.
– Allows the clinician to adjust the speed at which flow is
delivered to the patient during a Pressure Control breath
Volume Limit
• Active in:
– Pressure,
– PRVC
– Vsync
– TCPL
– PSV breaths only.
– Neonatal applications
Volume LimitTM requires
the use of a wye flow
sensor.
– If a proximal flow sensor
is used
• Volume Limit is activated
by the inspiratory tidal
volume measured by the
wye flow sensor.
• If Volume Limit threshold
has been reached:
– Alarm status indicator will
change to yellow and
display the words
Volume Limit.
– Cannot be reset until the
ventilator has delivered a
breath, which does not
meet the Volume Limit
threshold.
– To reset the alarm status
window use the alarmreset button
– Do not use with leaky ET
tube
Volume limit with Neonatal Flow Sensor
2 KG
Inspiratory VT limit 16 ml
=
8 cc/kg
Volume limit can be used in conjunction with Machine volume to allow volume
bracketing in Pressure Control. Machine volume is the minimum volume guarantee
and Volume Limit will terminate the breath based on a maximum inspiratory tidal
volume threshold. When used with only PCV, as compliance improves, so will
volume. Patient will be protected from inadvertent volutrauma. Volume Limit may
limit gas flow during hiccups or during increased flow demands of the patient.
Inspiratory Time in PCV
“Flow Cycle”
is the only
Advanced
Setting feature
for Inspiratory
Time.
Inspiratory Time in PCV
• “Flow Cycle”
– In addition to time cycling in PCV, the Avea allows the
clinician the ability to add flow cycling to the
inspiratory cycle criteria of the PCV breath
– The Flow Cycle works as a percentage of the peak
flow of the PCV breath (mimicking a Pressure
Support Breath)
– When a Flow Cycle percentage is set, the PCV breath
can either be cycled into expiration by the percentage
of Flow Cycle or Inspiratory Time depending on which
criteria is met first
Flow Cycle
• The default setting is 0 (off)
– Can be set in increments of 5% to 45%
100
Breath termination at 45%
50
Breath termination at 5%
–Flow cycle can be more comfortable for
spontaneously breathing patients
–It can reduce mean airway pressure and VT
Flow Cycle
• Allows patient to determine their own Itime by terminating the breath once a
certain percentage of the peak inspiratory
flow is met
• May improve preload and eliminate V/Q
mismatching
• Improves patient/ventilator dsy-synchrony
• May tremendously improve oxygenation
and ventilation in spontaneously breathing
patients
Expiratory Flow Cycling
Peak Inspiratory
Flow
V
40%
20%
5%
T
Fixed Inspiratory Time
No Flow Cycle
Flow Cycle On
Flow Cycled
Breath
Flow Cycle
Volume
Cycled Breath
Flow Cycled
Breath
If Flow Cycle is set with Machine Volume the breath
will not Flow Cycle unless the Machine Volume
(Minimum Tidal Volume) has been delivered
Patient Comfort
• Dial in a Flow Cycle %
– May apply Flow Cycle transiently to measure
pt’s true I time and set IT accordingly
– Flow Cycling can only occur if target tidal
volume has been reached in PRVC and
Machine Volume
– Should only be used with patients that have
low FiO2 requirements because by limiting IT
Mean Airway Pressure may be affected
Breath Termination Hierarchy
Alarm
Supercedes all other criteria
Volume Limit
If set, supercedes all lesser
criteria
Flow Cycle
*In volume targeted and controlled
modes only after set volume is achieved
Time / Volume Cycled
If no other criteria intercede
Advanced Settings
Volume Control Ventilation - VCV
VCV - Volume Control
Volume Peak Flow
PSV
Flow Trigger
Volume Parameter in VCV
Vsync
Vsync
On/Off Rise Time
Sigh Select
Volume Parameter in VCV
When Vsync is selected, Volume Limit becomes
apparent and the Vsync icon appears on screen.
0=Off
1=On
Advanced Settings
Vsync
• Vsync operates similar to PRVC
– Flow is only difference
• Set in Vsync
• Automatic in PRVC
• The maximum step change between two
consecutive breaths is 3 cm H2O.
Volume Limit
• This feature allows the clinician to set a
maximum volume limit that cannot be exceeded
during a Vsync breath.
• When the volume limit is reached, a visual
display appears in the alarm area. The display
remains illuminated as long as the volume limit is
active
Advanced Settings
Volume Parameter in VCV
• “Vsync Rise Time”
– Setting range from 1 to 9, 1 being fastest and 9
slowest.
– With Vsync active, this control allows the clinician to
adjust the speed at which flow is delivered to the
patient.
• “Sigh”
– A sigh volume breath is delivered every 100th breath
in place of the next normal volume breath.
– The sigh volume breath is 1.5 times the set tidal
volume
Advanced Settings
Peak Flow in VCV
Demand Flow
On/Off
Waveform Type
0 = Square
1 = Ramp
Intra-Breath Demand Flow
• Peak Inspiratory Pressure (Ppeak) every 2 milliseconds
throughout the breath cycle
• “Virtual” Pressure Support Target of the greater of:
– PEEP + 2 cmH2O or
– Ppeak – 2 cmH2O
• Maximum PEEP x 2
• Ppeak decrease by 2 cmH2O
– “switch over” to Pressure Support at virtual PSV Target.
• Once Tidal volume has been delivered
– “looks” at the inspiratory flow
• Inspiratory Flow > set peak flow
– flow cycled at 25% of peak inspiratory flow
• Inspiratory Flow = set flow
– ends as Volume Control breath
Intra-Breath Demand Flow in VCV
Note augmented flow to meet patients
inspiratory demand. Demand ends
before set volume has been delivered.
Demand continues through end of breath. Breath
is FLOW CYCLED at 25% of PIFR.
Intra-Breath Demand Flow ON / OFF
Double cycling in periods of high demand
PSV & Flow Trigger in VCV
These Advanced Settings are the same for all modes and
types of ventilation
Advanced Settings
Pressure Regulated Volume Control PRVC
PRVC – Pressure Regulated Volume
Control
Volume
Inspiratory
Time
Flow
Trigger
Volume Parameter in PRVC
Similar settings to PCV since
PRVC is a hybrid of PCV
PRVC / Vsync
• Logic controlled Volume TARGETED breath
– Decelerating flow, VC test breath with a 40 msec pause
– End inspiratory pressure is Target Pressure for the first pressure
control breath
– Subsequent breaths are delivered as pressure control breaths
based on the dynamic compliance of the previous breath.
• Inspiratory pressure is adjusted automatically by the ventilator to
maintain the target volume.
• Maximum step change between two consecutive breaths is 3 cmH2O.
• Maximum tidal volume delivered in a single breath is determined by
the Volume Limit setting.
– Vsync NOTE:
• The Peak Flow control sets the flow rate, which is used by the
ventilator for the test breath only. The ventilator uses the Peak Flow
setting and Inspiratory Pause to determine the maximum inspiratory
time during Vsync ventilation.
– Flow Cycling can only occur if target tidal volume has been
reached
PRVC / Vsync
• This test breath sequence is initiated in the event any of the
following occur:
–
–
–
–
–
Entering the Mode (PRVC or Vsync)
Changing the set tidal volume while in PRVC or Vsync
Reaching the Volume Limit setting
Delivered tidal volume > 1.5 times the set volume
Flow termination of the test breath
• Intrabreath demand system is active for all test breaths
– Exiting Standby
– Activation of any of the following alarms
•
•
•
•
•
•
High Peak Pressure Alarm
Low Peak Alarm
Low PEEP Alarm
Patient Circuit Disconnect Alarm
I-Time Limit
I:E Limit
– Flow Cycling can only occur if target tidal volume has been reached
Advanced Settings
Airway Pressure Release Ventilation APRV
APRV
• Patient breathes spontaneously at a
CPAP level
• Periodically “released” to a lower CPAP
level to flush CO2 from the FRC
P
Question:
What two features would make this type of ventilation
better?
APRV – Airway Pressure Release
Ventilation
Answer: Synchronize the changes and add PSV
That’s what these Advanced Settings do.
Advanced Settings
Time High in APRV
APRV
• Allows spontaneous breathing over a high mean
airway pressure.
• High mean airway pressure may improve lung
recruitment.
• Pressure support available .
• Apnea back-up parameters available.
APRV
Advanced settings
• Time high sync period-allows the operator to
allow a period in which the ventilator will
synchronize (during expiration) from high to low
pressure phase.
– Adjustable from 0-50% of Time high.
• Time high PSV-on or off-allows the user to have
pressure support on or off during the time high
phase.
• Time low sync- allows the operator to allow a
period in which the ventilator will synchronize
(during inspiration) from 0-50%
– Adjustable from 0-50% of Time high
APRV
Proposed Benefits
•
•
•
•
•
•
•
•
•
•
1. Lower Paw for a given tidal volume compared
with volume-targeted modes, e.g., AC, SIMV
2. Lower minute ventilation, i.e., less dead space
ventilation
3. Limited adverse effects on cardio-circulatory
function
4. Spontaneous breathing possible throughout
entire ventilatory cycle
5. Decreased sedation use
6. Near elimination of neuromuscular blockade
APRV
Spontaneous
breaths
Pressure
Time High
Time Low
Advanced Settings
Time High in APRV
• “Time High Sync %”
– Synchronizes transition from Pressure High to
Pressure Low
– Occurs with the first end of inspiration detected after
the Time High Sync % window opens.
– The Time High Sync %window is adjustable from 0 to
50%, in 5% increments of set Time High.
– The default setting for Time High Sync % is 0 (off)
Advanced Settings
Time High in APRV
• “Time High PSV”
– Time High PSV is either turned on (position 1) or off (position 0)
– The PSV is delivered above the current phase baseline
pressure.
– If Time High PSV is activated as Time High
Advanced Setting, the ventilator will deliver the same PSV level
for both Pressure High and Pressure Low.
• Example: If Plow= 5cmH2O and Phigh= 25cmH2O, then a PSV breath
set at 5 cmH2O will result in a Plow increase to 10cmH2O and Phigh
increase to 30cmH2O
Advanced Settings
Time Low in APRV
Advanced Settings
Time Low in APRV
• “Time Low Sync %”
– The ventilator synchronizes the change from
Pressure Low to Pressure High with the
detection of inspiratory flow or the first
inspiratory effort detected within the Time Low
Sync % window.
– The Time Low Sync % window is adjustable
from 0 to 50%, in 5% increments of set Time
Low.
– The default setting for Time Low is 0 (off)
Synchronization Window
Gives a range of
possible I-times if
Sync is activated
• Actual Time High or Time Low can change if
Sync is activated
• Depends on when the patient triggers to go
from High to Low or Low to High
PSV & Flow Trigger in APRV
Both PSV & Flow Trigger Advanced Settings in VCV function
as previously discussed on earlier slides
Automatic Airway Compensation (AAC)
• AAC when applied, will supplement spontaneous pressure support or
or pressure control flow cycled breaths based on calculated
endotracheal tube resistance.
• Has no role in other pressure control or volume breath types.
• To activate, select “AAC On” and dial in tube size and length. An
indicator saying “AAC” will appear in the mode bar.
How Does Tube
Compensation Work?
• Positive pressure added based on the
inspired flow and tube curvature, diameter,
and length
• Patient doesn’t have to experience the
resistive work due to the artificial airway
AAC
• Calculation based on:
– ETT Size
• 2.0 to 10.0
• Length
– flow
– pharyngeal curvature
– FiO2 / gas density
– transitions from turbulent to laminar flow
• Only ventilator with AAC available for controlled breaths
AAC
(length) x (viscosity)
(radius4)
This equation is used during periods of laminar flow
where resistance is primarily determined by gas
viscosity.
(density 0.75) x (viscosity .025) x (flow 1.75) x (length)
(radius 4.75)
This equation is used during periods of turbulent flow
where resistance is primarily determined by gas
density.
What The Ventilator Circuit
Sees
Circuit Pressure
• Flow triggering can be
effective in minimizing
imposed work
Pa
w
What The Carina Sees
Circuit pressure
Lower pressure at the carina
Paw
What the Carina Sees
Higher circuit pressure
• AAC adds appropriate pressure
to keep carina pressure at
preset inspiratory pressure
No decrease in
pressure at carina
Paw
Considerations when using AAC
• Monitor pressure support level to achieve
desired volumes. Supported breaths may
be augmented above pressure support, so
less pressure support may be needed.
• Compensatory support varies with many
factors, and will vary with patient effort and
other factors.
• Monitor volumes and pressures carefully,
with special considerations with neonates.
Set-up for Patient Use (cont)
Automatic Airway Compensation-suggested
reading:
Wrigge H, Zinerling J, Hering R,Swafenberg N, Stuber F, et al,
Cardiopulmonary effects of automatic tubing compensation during
airway pressure release ventilation in patients with acute lung injury
Anesthesia 2001 Aug;95(2)382-9
Guttmann J, Haberthur C, Mols G.Related Articles
Automatic tube compensation.Respir Care Clin N Am. 2001
Sep;7(3):475-501
AutoPEEP Airway
AutoPEEP Airway
AutoPEEPaw is the airway pressure at the end of exhalation
immediately prior to the beginning of the next mandatory inspiration.
AutoPEEP Airway Timing
The ventilator will establish the AutoPEEP measurement when the
system pressure reaches equilibration, at the next mandatory breath
interval or 6 seconds whichever is shorter.
AutoPEEP Airway Gas Trapping
Normal: 0 cm H2O above the applied PEEP
Note:
Requires a passive patient and a cuffed endotracheal tube.
Occurs when either insufficient expiratory time is present or in dynamic flow
limitation conditions such as asthma or severe COPD. This results in gas
trapping in the lungs.
MIP / P100 Maneuver
MIP Maneuver
The MIP (Maximum Inspiratory Pressure) / P100 maneuver measures
the negative deflection in the pressure tracing during the patient’s active
effort to demand a breath.
MIP Maneuver
Maximum Inspiratory Pressure (MIP), is the maximum negative airway
pressure that is achieved by the patient, during an expiratory hold
maneuver.
MIP Maneuver
Normal:
Adults < -70 to -100 cm H2O
Pediatrics < -20 to -100 cm H2O
Readiness for extubation < -20 cm H2O
Note:
Patient effort variable.
Indicator of inspiratory muscle strength.
Useful in weaning and progression of neuromuscular
disease.
Will be decreased in conditions such as
kyphoscoliosis, advanced age, COPD and
neuromuscular disease.
.
P100 Maneuver
Respiratory Drive (P100), is the negative pressure that occurs 100 ms
after an inspiratory effort has been detected.
P100 Maneuver
Normal:
-1 to -4 cm H2O Adults
-0.5 to -4 cm H2O Pediatrics
Note:
The pressure that occurs 100 milliseconds (ms) after the onset of
inspiration while the inspiratory valve remains closed. Because it
normally takes at least 300 ms for the patient to become aware of the
occluded airway this is a good test of the respiratory center output.
There is no change in lung volume or airflow during this initial 300 ms,
therefore abnormalities in lung mechanics have no effect on the
measurement.
Values in excess of -5 cm H2O may indicate a high respiratory drive that
may result in increased work of breathing and subsequent fatigue.