4. Components of DAT
A. Recognizes and compensates for system leaks
1. Leak Tolerance
B. Provides 2 methods of inspiratory Trigger
2. Volume Trigger
3. Shape Trigger
C. Provides 4 methods of expiratory cycling
4. Spontaneous Expiratory Threshold (SET)
5. Shape Trigger/Cycle
6. Flow Reversal
7. Maximum IPAP time
5. 1. Leak Tolerance
2
1
1 = Increase in flow & stabilizes most part of the inspiratory phase
2 = Decrease in flow & stabilizes most part of the expiratory phase
= Original Baseline/Beginning of inspiration/End of expiratory cycle
= Change in leakage flow/New Baseline Flow
12. 4. Spontaneous Expiratory Threshold
Actual Flow
The slope of the SET is calculated at the beginning of the breath
and signal rises in proportion to the inspiratory flow rate of
each breath
13. When the SET signal crosses the flow signal, EPAP is triggered
14. 5. Shape Trigger/Cycle
The shape signal also functions as a “sensitivity threshold” for
Expiration, when patient flow crosses the shape signal , it cycles
into EPAP
15. 6. Flow Reversal
During flow reversal, the unit in the
process Of cycling into EPAP when
the leak occurs
16. Flow reversal does not allow trigger to IPAP without
returning to EPAP. This keeps “breath stacking” from
occurring
19. DAT Components Modes
1. Leak Tolerance All Modes
2. Volume Trigger All Modes (except T & CV)
3. Shape Trigger All Modes (except T and CV
4. SET All Modes (except T, CV, AC & SIMV)
5. Shape Cycle All Modes (except T and CV)
6. Flow Reversal All Modes
7. IPAP Time S, S/T, T, PC
20. Bottom line!!!The DAT detects and
compensates for unintentional leaks in
the system and automatically adjusts
trigger and cycle algorithms to maintain
optimum performance in the presence
of leaks
22. Sensitive Auto-Trak is an enhancement
to the DAT algorithm that improves
patient and machine synchrony for
patients with minimal respiratory
effort. DAT refines the baseline trigger
and cycle sensitivity thresholds.
24. What are hybrid modes?
Pressure Support Ventilation modes
with targeted volume delivery
25. What is AVAPS?
• Average Volume Assured Pressure Support
• Available in S, S/T, PC, and T modes (Not a
standalone mode!!!)
• It maintains tidal volume (VT) equal to or
greater than the target volume setting by
automatically controlling the PS
26. AVAPS rate
• Allows the adjustment of the maximum rate at
which PS automatically changes to achieve the
target volume
27. AVAPS Speed per Device
Fixed 2.5
cmH2O / min
0.5 to 5
cmH2O / min
1 to 5
cmH2O / min
28. How does AVAPS Work?
AVAPS automatically adapts pressure support to patient needs to
guarantee an average tidal volume.
Target Vt
EPAP
IPAP
± 1 to 3 cmH2O
over 1 min
IPAP min
IPAP max
29. Main Settings:
• Can be accessed in S, S/T, PC and T modes
• AVAPS (set based on IBW 6-8ml/kg)
• IPAP max
• IPAP min
• EPAP
• RR
• Ti
31. What is AVAPS-AE?
AVAPS-AE is a auto-titration mode of
noninvasive ventilation designed to better treat
respiratory insufficiency patients (OHS, COPD
and NMD) in the hospital and homecare
environments
36. Popt – Optimal Pressure Search
(High Pressure Search)
EPAP
P therapy
P therapy
Critical Pressure Searches
(Low Pressure Search)
P
therapy
EPAP
P therapy
Popt
Pcrit
Auto EPAP Proactive Analysis
P
ther
P
opt
Pressure
Resistance
P
crit
3
6
37. SET BR
Used for the rest of the night
AVAPS-AE
Auto Backup rate
12
1
2
3
4
56
7
8
9
10
11
1st
hour
50 breaths Sliding
window
BR continually
Updates
1h
BR set
15
30
45
5
60
BR=Actual Rate
minus 2
37
38. Auto backup rate
Movingbreathrate
Minimum auto
backup rate
Spontaneous breaths
Time 50 breaths
10
Calculated
spontaneous rate
Target auto
backup rate
Targeted auto backup rate is 2
bpm below avg. spontaneous
rate
3
8
Bpm
39. Auto backup rate
Spontaneous Breaths
Timed Breaths
Target auto
backup rate
10 Auto backup rate
buffer zone
The auto backup rate is buffered by
spontaneous triggers to promote synchrony
with the device
• The buffer is reduced or eliminated by timed
triggers.
• The patient will be guided back to the
targeted backup rate
3
9
Bpm
Movingbreathrate
Time (Night time session)
40. Bottom line: AVAPS-AE is an “auto-
titrating” BIPAP mode that will
respond to:
1) Hypoventilation (AVAPS)
2) Airway Closure (AE)
3) Inconsistent Respiration and /or
Apnea (Auto RR)
Editor's Notes
After the expiratory phase, there remains some positive air flow, called “Baseline Flow.”. This baseline flow is present because of leaks in the system. During subsequent breaths, changes could occur, causing more or less leakage in the system. DAT detects a new baseline flow, and bases subsequent calculations of this new baseline. No New manual adjustments are necessary. Leak tolerance is done in 2 ways:
Average and Parabolic: the average leak is computed using the conservation of mass algorithm to compute the average leak for a given PS relationship; the parabolic leak is proportional to the square of the patient pressure; therefore the leak is correlated to the patient pressure
Patient Flow = Total Flow-Circuit leak; the patient flow is imputed into the triggering and cycling mechanism
The volume trigger is one of the method used to trigger inspiration during spontaneous breathing except in T and CV. The DAT sensitivity system monitors the baseline flow. When a change in flow is detected, the system calculates the resulting volume of air that this change produces. When the accumulated patient inspiratory volume reaches 6cc, IPAP is triggered.
Available in all modes except in T and CV.The shape trigger continuously tracks patient inspiratory and expiratory flow and adjusts the spontaneous trigger threshold for optimum sensitivity. The shape trigger is created by offsetting the signal from the actual patient flow by 15L/min and delaying by 300ms period. The intentional delay causes the shape signal to be slightly behind the patient’s flow rate.
Available in all modes except in T, AC, CV & SIMV
When the SET signal crosses the flow signal, EPAP is triggered
DAT monitors how long the IPAP remains in the inspiratory phase
It uses the patient set Ti for in mandatory and assisted breaths
Is a safety mechanism to limit the amount of time spent on IPAP level during spontaneous breathing in S and S/T modes
Total Leak = Intentional leak + Unintentional leak
When being ventilated, a spontaneous change in the patient condition can decrease or increase the tidal volume. AVAPS will then adjust the IPAP progressively (within a pre-set window between IPAP Min and IPAP max) until the pre-set tidal volume is reached.
What does AVAPS do for the clinician?
It is like sending a skilled therapist into the patient’s room with orders to titrate the pressure support for a specific tidal volume.
At some point the therapist will have to leave the room and when they do you can’t be sure what tidal volumes are going to be delivered.
But in this case the therapist never takes their hand off of the pressure support knob.
They never leave!
This illustrates the proactive nature of our auto EPAP algorithm.
The device will proactively increase EPAP pressure to evaluate the impact the increase has on the airway.
This AVAPS-AE is seeking the optimum pressure or conducting a Popt search.
AVAPS-AE will do this until the pressure changes have no improvement on the airway.
At that point, AVAPS-AE will restore the pressure to the level prior to the last change and it will then search downward on the next cycle.
This is called a critical pressure search or Pcrit.
The Pcrit search will lower pressure gradually until the airway patency starts to decrease.
At that point the device will reverse the last pressure decrease and then repeat the process by conducting a Popt search next.
This method allows the algorithm to anticipate the changing EPAP pressure needs before an obstructive event occurs.
The auto backup rate for AVAPS-AE will average the breath times over a 50 spontaneous breath rolling window (Array) over the 1st hour and use the highest 50 average value of spontaneous breaths to calculate the patient’s spontaneous rate.
The algorithm will continue to monitor the spontaneous breath times after the first 50 breaths and if the spontaneous rate increases during the 1st hour of use each night, then the rate will be updated to the higher rate. Lower spontaneous rates will not update the rate
Once a spontaneous rate has been determined, the unit will update the backup rate to 2 bpm less than the spontaneous rate.
The lowest auto backup rate is approximately 10 and the highest is 20, however the patient can breath more than 20 breaths per minute.
If a higher rate than 20 or rate less than 10 is required, then the clinician can turn off the auto function and set a desired rate or turn off any machine-delivered rate.
Once the auto backup rate has been determined by AVAPS-AE with 50 spontaneous breaths it will then maintain the patient near this rate for the remainder of the night (the patient can always go higher than this rate).
So, as seen here in the first few breaths, the rate is delivering the auto backup rate because the patient is not triggering breaths. If the patient starts to trigger breaths above the auto backup rate, the algorithm will promote synchrony with the vent by allowing some flexibility with the rate.
As the patient continues to trigger more spontaneous breaths, the rate may be suppressed by as much as 25% of the targeted rate. It may be easier to think of this not as a rate, but as an interval between breaths, e.g., if the target rate is 15 bpm, that would mean an interval of 4 seconds between triggers.
If the patient were to breath enough above the rate, the algorithm could allow the interval between breaths to be extended as long as 5 seconds, or 12 bpm. If the patient were to go as long as 5 seconds, a backup breath would be delivered. If the patient continues to receive timed breaths, the rate will slowly be guided back to the targeted rate and the process would start over again.
