Good article comparing APAP's algorithms

Paul B · Post by **Paul B** » Tue Jun 06, 2006 8:39 am

This is taken from this month's Sleep Review magazine. For the full report, click on the pdf at the end of the article. Good stuff.

http://www.sleepreviewmag.com/article.p ... 006/05&p=9

ozij · Post by **ozij** » Tue Jun 06, 2006 9:16 am

Very interesting stuff. Thanks for the link!

I can vouch for PB's hypopnea comment: , "In fact, our algorithm is designed not to respond to hypopneas without flow limitation".

I've been using a PB420E for more than a year. Have probably had thousands of hypopneas unaccompanied by flow limitation during that time - not once did the pressure rise in response to those hypopnea events.

(I check the details screen practically every morning).

We discussed it about a year ago on the forum:

Good Knight 420E and hypopneas: Discussion with -SWS and others

O.

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CPAPopedia Keywords Contained In This Post (Click For Definition): 420E, Hypopnea

-SWS · Post by **-SWS** » Tue Jun 06, 2006 10:39 am

If I can ever get "unbacklogged" with work I'd like to come back and discuss it again... this time in relation to a possible CSDB consideration.

GoofyUT · Post by **GoofyUT** » Tue Jun 06, 2006 6:30 pm

Thank you so much for the posting is this very informative and useful article!!!

I'm very grateful for your bringing it to my attention.

Chuck

john5757 · Post by **john5757** » Tue Jun 06, 2006 8:26 pm

there was some information in the article but I wonder why they turn off the 420E flow limitation detection off. I was interested in how the 420E will compared to the Spirit but since the flow limitation detection was turn of makes the comparison invalid. There is another matter in how they get the machine to response to hypopneas without flow limitation? The Spirit is like the GoodKnight 420E in the fact that they do not response to hypopneas without flow limitation. Only the comparison between the ResMed machine and the Respironics was there some useful data. The article does confirm that the ResMed responded to flow limitation much quicker and at the start of the flow limitation event and starts to drop as soon the event passes as.
The charts is showing that the Respironics taking over 30 minutes before it will decrease the pressure after the flow limitation event passes. The apena curve makes no sense at all since it shows the Spirit going pass the 10cm mark. I wish they program the GoodKnight 420E correctly.

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CPAPopedia Keywords Contained In This Post (Click For Definition): 420E, respironics, resmed

Guest · Post by **Guest** » Tue Jun 06, 2006 10:09 pm

Hi John,

I was surprised at this also, but for some reason, they mention on Page 14 of the 23 page full PDF report that the manufacturer, Puritan-Bennett, recommended that they turn off this capability, so they did.

Paul B · Post by **Paul B** » Tue Jun 06, 2006 10:11 pm

Sorry, that last post was from me.

ozij · Post by **ozij** » Tue Jun 06, 2006 11:52 pm

However, in the 2005 study on the 420E, the flow-limitation feature was not turned on as recommended by the manufacturer.

I was surprised when I read this sentence, and then thought it might also be interpreted as: "the flow-limitation feature was not turned on despite the fact that that is the manufacturers default". This interpretation fits with PBs reaction to the results. "The flow limitation graph seems to suggest that the Puritan Bennett GoodKnight® 420E CPAP device does not respond to flow limitations. In fact, the GoodKnight 420E offers clinicians two options: the ability to program the machine either to detect and react to flow limitation, or detect but not react to flow limitation. This allows the clinician to tailor the machine to individual patient needs. We believe that the GoodKnight 420E auto-adjusting device used in this study was inadvertently programmed not to react to flow limitation. Had the machine been properly programmed, the GoodKnight 420E device would have properly responded to flow-limited breaths" (My emphasis).

"FL: on" is the way the machine comes from the factory. Turning it off and then testing the machine is very strange.

It is also worth noticing that in the PDF that they don't mention the clinician controled options in any of the PB machines tested. Reading their reporting on the older 418A and P models, you'ld never guess that the following apears in the SilverLining manual for those machines:

The Algorithm box tells you that
• The device is being controlled automatically for the GK4 1 8A on the events “Apnea” and “Acoustical Vibrations” and for the GK418P on the events “Apnea,” “Acoustical Vibrations,” and “Flow Limitation.”
• the events “Hypopnea” and “Apnea with CArdiac oscillations” can be controlled for the GK4 1 8P as required. In order to activate or deactivate automatic control for these two events, click the appropriate boxes or leave them blank. The function “Command on apnea with CArdiac oscillations” is only available on the P model.
The second box sets
• the maximum automatic pressure to be applied after an “apnea”. The automatic pressure used after an event that has been detected cannot exceed the Max pressure for command on Apnea that has been set. This value is set using the slider to select a value between Pmin and Pmax.
• the pressure increase to be applied after a “Flow Limitation” event. The pressure step can be set using the slider between 0,1 and 0,3 cmH2O.
Click OK to confirm your selections, or click Cancel if you want to keep the original parameters.

By the way, 420E gives you less control of the algorithm.

Comparing the present study with Abendi's study ("Bench testing of auto-adjusting positive airway pressure devices") is worth while for those interested in how such studies should be done, reported and analysed.

I honestly wonder if the persent machine testers ever used monitoring software, or read the manuals...

O.

Snoredog · Post by **Snoredog** » Wed Jun 07, 2006 3:01 am

Good article....

-SWS are you the SWS from TAS of years gone back? If so, do make time bud, ....it's been a while.

Darth Vader Look · Post by **Darth Vader Look** » Fri Jun 09, 2006 2:36 am

Here is the link to the pdf file.

http://www.sleepreviewmag.com/pdf/AA_Report.pdf

This is very interesting and will be good information when dealing with recent talks about this.

rested gal · Post by **rested gal** » Fri Jun 09, 2006 3:10 am

Snoredog wrote:Good article....

-SWS are you the SWS from TAS of years gone back? If so, do make time bud, ....it's been a while.

Yes, that's the same -SWS. Ain't it grand?!!

Which reminds me, Snoredog...are you the person who used to post as a Guest nicknamed "dizzy" on TAS, until they started requiring registration to post?

Machine

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Good article comparing APAP's algorithms

Good article comparing APAP's algorithms

Thank you so much!!!