ASV Titration Study

[ResearchMom]

My 17 year old son has struggled with OSA and UARS since 3 months old.  It persists after multiple surgeries and therapies over the years.  He was using Philips Respironics CPAP from 2015 to 2021 and currently uses Resmed AirCurve 10 ASV.  While he feels he sleeps better with ASV than without, he is still chronically tired mentally and physically all the time.  While past CPAP use has helped with emotional regulation, it has NEVER helped with fatigue.

I’m ready to experiment with his settings and have included his titration numbers below from his 2022 sleep study.  Would you mind reviewing and giving me feedback as a starting point?

Titration Numbers

BiLevel: 8/4/0 AHI/RDI: 14.6

BiLevel: 9/5/0 AHI/RDI: 6.2

ASV: 5/3/15 AHI/RDI: 14.2

ASV: 6/3/15 AHI/RDI: 13.8



BiLevel=IP/EP/Rate
ASV=EEP/MinPS/MaxPS 

BiLevel and ASV were tried for 3+ hours each.  Is it normal for AHI/RDI to still be that high during a Titration Study, over 13 for 3 of the settings?  I thought the purpose was to find a pressure that would bring his numbers in the normal range of less than 5.

His Titration lists EPAP pressure, Min Pressure Support and Max Pressure Support for ASV.  But ASV requires settings for both Min EPAP and Max EPAP, right?  Does this mean they used only one EPAP pressure the entire time?  Any reason why they wouldn't use or list both Min and Max EPAP? 

Although one of the BiLevel settings was the lowest at 6.2 AHI/RDI, they still recommended ASV because the “flow contours and sleep continuity appeared better.”  These are his current ASV settings from the doctor.

Min EPAP 6
Max EPAP 15
Min PS 3
Max PS 8

I will post OSCAR charts as soon as I figure that out!

Thanks for your help!  I’m learning so much here!

[SarcasticDave94]

Welcome to Apnea Board.

Others will address some other aspects. I can give a few pointers on using ASV as I have used it myself. Unfortunately, most titration results are the tech and doctors best guess and almost always will be a compromise, partly due to time limits in the test.

On this ResMed AirCurve 10 ASV, there's 3 operation modes, CPAP which is straight single pressure with no PS, ASV which is single EPAP and PS Min and Max, finally is ASV Auto with EPAP Min and Max plus PS Min and Max.

EPAP is the inhale pressure, PS or pressure support, is added on inhale giving the IPAP or inhale pressure.

EPAP mostly addresses obstructive apnea while PS combats the central apnea.

I'll suggest you try to reset the pressures to include ASV Auto mode, I would consider a redo of these pressures you list. High EPAP and low PS may not work. Try this EPAP 6-10 PS 3-13. This will still give IPAP of 9-23, but may be more comfortable and effective.

You as the patient, counts as parent and child like this as well, you don't need to have a new script to edit this.

How to edit the ASV? Facing the unit, push and hold both Home and the dial in simultaneously, holding for about 5 seconds. The display now shows the Clinical menu. And this is where settings are edited.

Use the dial to scroll to the various settings areas. Look at mode, and make sure ASV Auto has the dot next to it, indicating that's the active mode. Scroll to EPAP Min and Max, and edit those numbers as you intend. The machine allows a whole number and a single place even decimal (tenths). 6.0, 6.2, 6.4, etc.

Use the dial to roll through the number representing your pressures settings, and when it shows the correct number, click the dial to lock that number in making it active.

Repeat this step for 2 EPAP numbers, low and high, and then again in the PS section. IPAP is not a direct setting, but the sum of EPAP and PS at the moment.

After you're done with all edits, scroll to either an exit menu page or I think clicking home can escape the clinical menu also.

OSCAR is free, download to your computer, it will require an import of the SD card data that needs to have been on the left side of the ASV under the rubber side cover overnight to store info. In the morning, the SD card goes to your computer card reader to import the data to OSCAR. After the import, you can take a screenshot to create a file which can be included here in the attachment section to create an image in your reply.

[Sleeprider]

ResearchMom, the bilevel titrations only explored low EPAP pressures and with bilevel nothing above PS 4.  With ASV EPAP 5 and 6 were used, but without more detailed data on the nature of the vents, we have no ideal if pressures should have been higher.  I'll wait to see the Oscar charts to offer suggestions, but will provide the ASV titration protocol recommended by Resmed. As you can see, the titration barely scratched the surface of what might be needed.  Also, if your son does not experience central events, the default ASV pressure support range of 3-15 is often disruptive and unneeded.  So much more could have been accomplished with the bilevel titration as well by using EPAP to eliminate obstructive events, and pressure support to reduce or eliminate flow limitations.  From what I see, there were a lot of opportunities missed to learn what is effective.

[ResearchMom]

Sleeprider and SarcasticDave94--Thank you so much for replying!  I know I didn't give you enough details to really work with yet but wanted to start somewhere.  I agree, much more could have been accomplished at his sleep study.  I appreciate the ASV Titration Protocol and instructions on how to change settings.

I look forward to more feedback when I post OSCAR.

[ResearchMom]

I've attached two screenshots from OSCAR.  Please let me know if I need to do post these differently or if you need additional information.

We are concerned about Upper Airway Resistance Syndrome more than apnea.  His AHI is consistently below 5 with very little oxygen desaturation.  What feedback can you give about his Flow Rate in relation to this?

I don't think you can tell from these screenshots but his mask leaks are almost are close to 24 L/Min every night.  He uses the nasal Wisp mask with a mask liner.  The liner has really helped him keep the mask on longer but he also realizes it messes with the seal.  He feels a lot of air blowing and I think that wakes him up.  Any suggestions to reduce leaks?

He is using the ASV specifically for UARS, although he had a few centrals, obstructions and hypopneas on his sleep study.

Thanks for any help!

[Sleeprider]

Researchmom, how tall is your son? I ask so I can relate the relatively low tidal volume of 280 mL to his ideal which is based on height. Is there a physical reason his tidal volume is low for a 17 year old male?

The closeup charts don't show much of a problem however I would like to see the full night with flow rate, pressure, tidal volume, and minute vent. For settings, In the zoomed image, the first 3-breaths are paced by the machine with EPAP 6.5, IPAP 14.4 (PS 8.0). Spontaneous respiration increases to 18 bpm for the next 5-breaths, then there is some flow limit at 02:44:30 that slows inspiration time and resp rate and the ASV again picks up PS to increase tidal volume. There are 3-cycles of varying respiration rate and flow limitation with increased PS from the ASV before spontaneous respiration starts to stabilize at about 02:45:50. I think EPAP max can be reduced from 15 to 10.0 and PS min increased to 3.0 and PS max to 9.0. So EPAP min 3.0, EPAP max 10.0, PS min 3.0, PS max 9.0.

[ResearchMom]

My son is 5’ 8” and about 130 pounds.  I've been watching his tidal volume so I’m glad you noticed that.  Will you clarify the numbers for this on the side panel?  180 was his minimum for the night?  But I’m not sure what the other 3 values mean exactly.  Medium=280?  95%=420?  99.5%=620?

I’ve attached his full night charts for flow rate, pressure, tidal volume, and minute vent.  I’ve also included a separate chart for respiratory rate, insp. time, exp. time, mask pressure, and leak rate.  The values on most of the charts seem unstable with too much spiking up and down.

I’ve also attached a screenshot of his oxygen and heart rate from his Wellue wrist tracker.  It’s not the same night as the attached OSCAR reports (he doesn’t wear the tracker every night) but the info has been consistent every time he wears it.  His oxygen isn’t terrible but his heart rate feels too erratic.  It ranges from 46-100 with an average of 59.  I know you can’t correlate his heart rate with anything on OSCAR but regardless, it seems very abnormal.

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[Sleeprider]

I tend to track the median as the minimum is useless for tidal volume.  It would be nice if Oscar calculated the 5th percentile as the minimum.  These are statistics. The median is the most frequently reported breath volume and if the distribution of data is "normal" will be equal or close to the "mean" or average.  The graph below represents a normally distributed set of data and shows the relationship of percentiles to the mean and median in graphed data.  Another way to think of the 95th percentile is that it is the value equaled or exceeded only 5% of the time, while the mean, or in this case median, is approximately the value equaled or exceeded 50% of the time.

Without diving too deep on the respiratory graphs, the oximeter data shows his metabolic needs are met at this volume and his SpO2 is satisfactory. the spikes in the data are also normal, and what we see is when tidal volume spikes upward the respiration rate goes down due to higher inspiration time, and minute vent increases. Similarly when tidal volume is low, the respiration rate increases significantly and maintains a steady minute vent.  I would interpret this as meaning your son is mostly breathing spontaneously on his own. I'm a bit surprised his  titration resulted in a recommendation of ASV rather than the bilevel.

Going back to his titration, his best results were on bilevel with IPAP 9, EPAP 5 (PS 4.0), and the AHI/RDI was better than with ASV with EPAP 5 or 6 and PS min 3.  My conclusion is that your son might have better results with higher PS min. He is currently at 2.6 and I thing it would be interesting to try PS min 4.0 (PS max 9.0) and see if this has a stabilizing effect on the tidal volume and minute vent.  Increasing PS min to 4.0 is contingent on his tolerance.  Since we don't see any obstruction in his results, you can probably back off EPAP min to 6.0.  That appears to have been sufficient in the titration tests as well.  Higher PS min should show up as an increase in median tidal volume and more stable minute vent and may also reduce respiration rate a bit.

[gainerfull]

I know that in general w/ ASV you want to let the machine work it's magic but I'd recommend tightening the settings once you figure out if your son is feeling better with the therapy. Based upon the last data you posted you could consider capping the max ipap at around 18cmH20 to avoid the low probability of pneumothorax which requires an ER trip. Also, it looks like you may want to have him start taping his mouth or consider a soft cervical collar to keep his mouth closed at high pressures.

[Sleeprider]

Gainerfull, the max IPAP in ASV is determined from EPAP max and PS max. I agree with your observation that in this case, an EPAP max of 8 or 9 would be appropriate, and with IPAP max 9.0 that would fit your description. In fact with the current settings, the actual maximum IPAP is just about 15 cm.