Auto EPAP algorithm reaction time for Aircurve ASV

[Sleeprider]

I am going to use this thread as a placeholder for some material I plan to add to the Wiki

Resmed ASV uses a three minute moving average to monitor and determine an appropriate target minute ventilation, set to 90% of their most recent minute ventilation. This target threshold prevents under and over ventilation by dynamically increasing (for hypopneas) or decreasing (for hyperpneas) inspiratory pressure support (IPS) as needed. Together with a back-up respiratory rate 758 Journal of Clinical Sleep Medicine, Vol. 12, No. 5, 2016RN Aurora, SR Bista, KR Casey et al. Adaptive Servo-Ventilation Recommendations (set dynamically at 15 breaths/min), when a patient’s minute ventilation falls below the set target, ResMed’s ASV automatically adjusts the inspiratory pressure support to provide the ventilation needed. As breathing stabilizes, the pressure delivered is rapidly reduced back towards the minimum required. ResMed’s newest ASV device, AirCurve 10 ASV, has a maximum pressure of 25 cmH2O and can be set to an IPS of 0 to 20 cmH2O.

The Philips Respironics ASV (BiPAP autoSV Advanced System One) utilizes inspiratory flow as the primary variable to identify and respond to sleep-related breathing disorders (SRBD). In the absence of SRBD, EPAP is automatically determined based on the REMstar Auto algorithm. The algorithm identifies and responds to obstructive sleep disordered breathing events as they occur. During periods of airway stability, the algorithm will proactively assess the airway to minimize pressure while optimizing airway patency. The maximum inspiratory positive airway pressure is 30 cmH2O with a mini-mum EPAP of 4 cmH2O. The Philips Respironics ASV devices are also capable of withdrawing IPS entirely during periods of normal breathing. All Respironics ASV devices have two methods of setting a backup rate: a fixed rate determined by the operator, or an auto mode that synchronize with the patient’s intrinsic rate.

Source: https://aasm.org/resources/practiceparameters/asv.pdf
Updated Adaptive Servo-Ventilation Recommendations for the 2012 AASM Guideline: “The Treatment of Central Sleep Apnea Syndromes in Adults: Practice Parameters with an Evidence-Based Literature Review and Meta-Analyses”

[Michaely6]

Thans for the clarification and sounds good to me!

[Sleeprider]

The new wiki will reside here http://www.apneaboard.com/wiki/index.php...tion_(ASV)

I want to find relevant articles, posts and information to include in the wiki, and anyone that wants to contribute ideas on how to improve that information is encouraged to contribute their thoughts.

[Michaely6]

The new wiki will reside here http://www.apneaboard.com/wiki/index.php...tion_(ASV)

I want to find relevant articles, posts and information to include in the wiki, and anyone that wants to contribute ideas on how to improve that information is encouraged to contribute their thoughts.

Do you have the link to the original post of the ASV example image that was posted on your optimizing ASV section? I wanted to see the entire image and all of the numbers.

[WillSleep]

Thanks. I figured that I rises slowly just like the vauto and airsense. I watched Lanky lefty's video about ASV which prompted me to make this post because I definitely do no agree with his take regarding the epap on the ASV. He stated that their is no reason to have the EPAP set to anything above 4 due to the sophistication of the machine but I believe it is still best to set the EPAP  to a setting where it will eliminate all or most of obstructive apneas. Any thoughts?

LankyLefty is a great guy.  Everyone should support him.  

"..no reason to have the EPAP set to anything above 4 due to the sophistication of the machine."  I think he got this one wrong, which is Ok, because he gets many right. 

To answer your original question:  I don't know for sure from an engineering documentation standpoint that ASVAuto EPAP rising/increasing responsiveness is far slower than the Autoset and VAuto but it sure seems that way.  And this would see to match the logic of using PS as the primary weapon to put down apenas.  

I can not remember seeing EPAP on an ASV move more than 2-4 cm H2O in a session and I have seen people configure ASVAuto at Min PS 5-9cmH2O.  

With other machines we titriate (adjust up) first.   For ASVAuto I  (my opinion only)personally like adjusting EPAP & PS as a interacting pair during the MIDDLE to the END of the titration process. 

Sort of like start with the bottom half of the page for the ResMed titration guide for the ASV, and then starting in the middle of the tritration process sprinkle in a mix of the top half of the page as well.

... Remembering that from the Middle to the End sometimes you change just EPAP or PS and sometimes the changes offsetting (you increase one by the ~~same amount you decrease the other).    

WillSleep

[Michaely6]

Thanks. I figured that I rises slowly just like the vauto and airsense. I watched Lanky lefty's video about ASV which prompted me to make this post because I definitely do no agree with his take regarding the epap on the ASV. He stated that their is no reason to have the EPAP set to anything above 4 due to the sophistication of the machine but I believe it is still best to set the EPAP  to a setting where it will eliminate all or most of obstructive apneas. Any thoughts?

LankyLefty is a great guy.  Everyone should support him.  

"..no reason to have the EPAP set to anything above 4 due to the sophistication of the machine."  I think he got this one wrong, which is Ok, because he gets many right. 

To answer your original question:  I don't know for sure from an engineering documentation standpoint that ASVAuto EPAP rising/increasing responsiveness is far slower than the Autoset and VAuto but it sure seems that way.  And this would see to match the logic of using PS as the primary weapon to put down apenas.  

I can not remember seeing EPAP on an ASV move more than 2-4 cm H2O in a session and I have seen people configure ASVAuto at Min PS 5-9cmH2O.  

With other machines we titriate (adjust up) first.   For ASVAuto I  (my opinion only)personally like adjusting EPAP & PS as a interacting pair during the MIDDLE to the END of the titration process. 

Sort of like start with the bottom half of the page for the ResMed titration guide for the ASV, and then starting in the middle of the tritration process sprinkle in a mix of the top half of the page as well.

... Remembering that from the Middle to the End sometimes you change just EPAP or PS and sometimes the changes offsetting (you increase one by the ~~same amount you decrease the other).    

WillSleep

I agree with your post and have the same thinking because no matter where I set my EPAP min on my ASV, it almost never goes past 1-2 cmH20 no matter what my EPAP needs are on other machines like the VAuto. I never could figure out why which is why I thought that PS was doing the heavy lifting for apneas. If I set my EPAP min to 5 on the ASV and fall asleep, my MED will only go up to maybe 6 or 6.5. If I use the same EPAP min on my VAuto, my med may end up being something like 10. I couldn't quite figure out why is that so if PS doesn't increase for apneas or prevent apneas. Kinda weird..

[WillSleep]

I agree with your post and have the same thinking because no matter where I set my EPAP min on my ASV, it almost never goes past 1-2 cmH20 no matter what my EPAP needs are on other machines like the VAuto. I never could figure out why which is why I thought that PS was doing the heavy lifting for apneas. If I set my EPAP min to 5 on the ASV and fall asleep, my MED will only go up to maybe 6 or 6.5. If I use the same EPAP min on my VAuto, my med may end up being something like 10. I couldn't quite figure out why is that so if PS doesn't increase for apneas or prevent apneas. Kinda weird..

Sounds like your ASV is functioning as I think they expected it to with regards to EPAP. 

EPAP is the Big Stick for the VAuto and many traditional ventilation strategies but high Pressure is the Big Stick in the "Low Tidal Volume Lung Protective Ventilation" strategy and in the ASV.    

Near as I can tell (opinion only) the ASV algos seem to be based in ARDSnet ventilation protocol to delploy a  "Low Tidal Volume Lung Protective Ventilation" strategy for people suffering ARDS, with the exception the ASVAuto focuses on Minute Volume rather than Tidal Volume.

   https://www.google.com/search?&q=Low+tid...%28LTVV%29 

   

I have seen Ventilation training and ER/ICU team process documentation that reads something like: 

"Low Tidal Volume Lung Protective Ventilation"

• Set EPAP to 5cm H20 
  
• Set PS to 15 or 20, climb to 30cm H2O as needed  (...now some discredit as too high) 
  
• Set Resp Rate from 15-20  (ASV seems to like 15-18 RR).
  
• Regardless of patient weight, set Tidal Volume to start at 8mL/kg of IBW or PWB (trauma victims need more air) and drive down to 6mL/k IBW or PWB and target 6-8 L/min Minute Volume within the first 2 hours.   
  
• Monitor each hour and adjust Tidal Volume, EPAP, Rise Time, Cycle, etc so that the ventilator achieves synchronicity with the patient (what we try to do through our nightly titration cycles, except the ASV does not give us access to most of those dials).  
  

Does that sound kind of like the ASV?   


WillSleep

Fun Fact for the day:  AHRQ seen here defining EPAP below 5.0cm H2O as "Zero End Expiration Pressure (ZEEP)."

[Michaely6]

I agree with your post and have the same thinking because no matter where I set my EPAP min on my ASV, it almost never goes past 1-2 cmH20 no matter what my EPAP needs are on other machines like the VAuto. I never could figure out why which is why I thought that PS was doing the heavy lifting for apneas. If I set my EPAP min to 5 on the ASV and fall asleep, my MED will only go up to maybe 6 or 6.5. If I use the same EPAP min on my VAuto, my med may end up being something like 10. I couldn't quite figure out why is that so if PS doesn't increase for apneas or prevent apneas. Kinda weird..

Sounds like your ASV is functioning as I think they expected it to with regards to EPAP. 

EPAP is the Big Stick for the VAuto and many traditional ventilation strategies but high Pressure is the Big Stick in the "Low Tidal Volume Lung Protective Ventilation" strategy and in the ASV.    

Near as I can tell (opinion only) the ASV algos seem to be based in ARDSnet ventilation protocol to delploy a  "Low Tidal Volume Lung Protective Ventilation" strategy for people suffering ARDS, with the exception the ASVAuto focuses on Minute Volume rather than Tidal Volume.

   https://www.google.com/search?&q=Low+tid...%28LTVV%29 



I have seen Ventilation training and ER/ICU team process documentation that reads something like: 

"Low Tidal Volume Lung Protective Ventilation"

• Set EPAP to 5cm H20 
  
• Set PS to 15 or 20, climb to 30cm H2O as needed  (...now some discredit as too high) 
  
• Set Resp Rate from 15-20  (ASV seems to like 15-18 RR).
  
• Regardless of patient weight, set Tidal Volume to start at 8mL/kg of IBW or PWB (trauma victims need more air) and drive down to 6mL/k IBW or PWB and target 6-8 L/min Minute Volume within the first 2 hours.   
  
• Monitor each hour and adjust Tidal Volume, EPAP, Rise Time, Cycle, etc so that the ventilator achieves synchronicity with the patient (what we try to do through our nightly titration cycles, except the ASV does not give us access to most of those dials).  
  

Does that sound kind of like the ASV?   


WillSleep

Fun Fact for the day:  AHRQ seen here defining EPAP below 5.0cm H2O as "Zero End Expiration Pressure (ZEEP)."

Interesting post! I really wish Resmed ASV let you increase PS min past 6 so that I can experience with a higher PS min on the ASV device. Recently, I seem to get better sleep with very high PS that the average PAP user wouldn't even dare to use.

[WillSleep]

Interesting post! I really wish Resmed ASV let you increase PS min past 6 so that I can experience with a higher PS min on the ASV device. Recently, I seem to get better sleep with very high PS that the average PAP user wouldn't even dare to use.

 I am personally a bigger fan of lower pressures but... 

I have not tried this.  

Does SmartStart work in ASVAuto Mode?  If not then in ASV mode?  If so maybe to see what a higher pressure start would be like run your ASV with your finger blocking enough of the tube or blocking vents on the mask just enough for the screen to show the 110-115% of the starting PS you want to try, run it just long enough to enable SmartStart at the desired pressure.  

WillSleep

[Sleeprider]

You might be thinking of Philip's where the 90% pressure of the previous session is used as the starting pressure. I think "Smartstart" is just the ability to start the machine when breathing is detected, and to turn off when the mask is removed.