ResMed VPAP III ST Algorithm

[dsm]

Color me confused. The manual says the RR and VT are a 5 minute moving window. There is no graph for RR and VT just median, 95th percentile and max. MV has a detailed graph and is the product of RR and VT. My "gap" is 5 (19 - 14)? There are settings of low, med and hi for Cycle and Trigger but the manual says nothing about them.

Also, there does seem to be a difference in the IPAP at the beginning and ending of the night and I took into consideration the mask leak test at the start.

Is there anything to be gained from tweaking things like Rise Time, IPAPmin, IPAPmax, ???

Roger,

What I believe the manual is saying is "The reported data is ..."
> 'RR and VT are a 5 minute moving window'
(as reported) so tidal Volume is calculated in a 5 min moving window as reported in the nightly data.
But, AFAIK this data does not change the behavior in any way, of the machine. It is merely a reported stat.

The settings of Low Medium & High for trigger & cycle are the sensitivity used by the machine as to when to trigger or cycle (trigger = epap to ipap, cycle = ipap to epap - note I corrected my refs to trigger & cycle in the earlier post as I occasionally reverse these in my mind & only realize later when rereading it).
The 3 settings effectively alter the point when trigger & cycle occur by changing the amount of measured airflow used to activate the triggering or cycling. This adjustment is only added to the newest version of the VPAP III (there will be a label 'ENHANCED' just near the words VPAP III on the front case) which clearly you have.

Just to restate, the Vpap III does nothing special to the epap & ipap pressures other than deliver them as previously set. But when in timed mode, will activate the triggering (epap to ipap) on its own if the RR drops below the preset backup rate RR.

Also if the machine is set to just T Mode (the modes are Cpap, S mode, ST mode & T mode), then it drives both triggering and cycling events (not just triggering).

S Mode is when the user alone spontaneously drives triggering & cycling (i.e. if the user breaths out & doesn't try to breathe in again the machine will stay in epap mode - that is why timed mode capable machines are essential for people with CA).

DSM

[dsm]

Color me confused. The manual says the RR and VT are a 5 minute moving window. There is no graph for RR and VT just median, 95th percentile and max. MV has a detailed graph and is the product of RR and VT. My "gap" is 5 (19 - 14)? There are settings of low, med and hi for Cycle and Trigger but the manual says nothing about them.

Also, there does seem to be a difference in the IPAP at the beginning and ending of the night and I took into consideration the mask leak test at the start.

Is there anything to be gained from tweaking things like Rise Time, IPAPmin, IPAPmax, ???

Rogelah,

Now I am getting confused

Where in your Vpap III are there settings for IpapMin & IpapMax ? - IIRC they *are* settings in a Vpap Auto but there is no ranging of IPAP in a Vpap III ?.
Again 'ranging' (varying in flight) of Ipap happens in a Vpap Auto & the ASV machines.

Cheers

DSM

[rogelah]

I finally got 4 nights of a leak with a flat line at zero except at 3 or 4 hours into sleep I wake up with the machine giving me a very high rate of BPM, usually 40 or more BPM. Last night when I woke up and noticed the high rate I looked at the clock and started counting puffs from the machine. I quit at 50. No problem I thought, the machine must be broken (read that as perhaps the software has a bug.) I have a followup appointment today and I'll tell them my observation. I printed out the nights detailed graph and sure enough just before I woke up the rate was at a high of 52. More good news; when they see the detailed graphs showing these abrupt forays into the Mount Everest region of the graph they'll know what to do.

First I go to a clerk who hooks up my machine after looking for 5 minutes for the cable and then proceeds to print only summary data. I ask if she is going to print detailed data too and she says no, they only use summary data. I show her where to change to all available data and she tells me that she checked for detailed data and there was none. DUH, if you tell it summary only how does it know to look for detailed data? She says tell the PA and she'll tell the doctor.

So, I talk with the PA and she is looking at the summary data and tells me I'm getting good volume and that's all they care about. I ask her to get the clerk to dump the detailed data. She takes the machine and disappears but is back too quickly and no detailed data. She gets the doctor. I explain all over again about high BPM and he agrees that should not happen. I ask him to print the detailed data for the last 4 days and he ignores me and says he wants to hook me up to the machine. He does and then looks at the settings.

Bottom line, they don't believe me. I think they don't know how to print out the detailed data or are so used to flat straight lines that they think it's useless.

I asked him what I should do if the same thing happens tonight. Call him. The only change he made was to put IPAPmin on 250ms (was 300ms) and change trigger and cycle to MED from LOW. Does he think that will prevent the mountain climbing expedition?

I have a followup in 2 weeks and next time I will take my notebook with the detailed reports or better yet email them.

I tell them about the headaches and the PA tells me that my mask is too tight. She gives me new mask mounting instructions: turn on the machine, put on the mask and then tighten the straps. I tell her I don't mind the fit; she says I have red marks on my face and that causes the headaches I experience several hours after removing the mask. I believe I am a reasonable person but hours after I am off the machine. I wonder if they know what hypercapnia is. I had these headaches when I would wake in the morning before I got involved in SDB.

[dsm]

I finally got 4 nights of a leak with a flat line at zero except at 3 or 4 hours into sleep I wake up with the machine giving me a very high rate of BPM, usually 40 or more BPM. Last night when I woke up and noticed the high rate I looked at the clock and started counting puffs from the machine. I quit at 50. No problem I thought, the machine must be broken (read that as perhaps the software has a bug.) I have a followup appointment today and I'll tell them my observation. I printed out the nights detailed graph and sure enough just before I woke up the rate was at a high of 52. More good news; when they see the detailed graphs showing these abrupt forays into the Mount Everest region of the graph they'll know what to do.

### Rogelah: The problem in this analysis is that the machine doesn't deliver that RR, it is following your breathing. It ONLY takes control when your RR drops below the backup rate. It is you that is hyperventilating. I hear what you are saying but I really doubt that the machine has gone haywire & is triggering/cycling at the speeds you mention. To do that the backup rate would have to be set at 40 or more which is not the case.

First I go to a clerk who hooks up my machine after looking for 5 minutes for the cable and then proceeds to print only summary data. I ask if she is going to print detailed data too and she says no, they only use summary data. I show her where to change to all available data and she tells me that she checked for detailed data and there was none. DUH, if you tell it summary only how does it know to look for detailed data? She says tell the PA and she'll tell the doctor.

So, I talk with the PA and she is looking at the summary data and tells me I'm getting good volume and that's all they care about. I ask her to get the clerk to dump the detailed data. She takes the machine and disappears but is back too quickly and no detailed data. She gets the doctor. I explain all over again about high BPM and he agrees that should not happen. I ask him to print the detailed data for the last 4 days and he ignores me and says he wants to hook me up to the machine. He does and then looks at the settings.

Bottom line, they don't believe me. I think they don't know how to print out the detailed data or are so used to flat straight lines that they think it's useless.

I asked him what I should do if the same thing happens tonight. Call him. The only change he made was to put IPAPmin on 250ms (was 300ms) and change trigger and cycle to MED from LOW. Does he think that will prevent the mountain climbing expedition?

I have a followup in 2 weeks and next time I will take my notebook with the detailed reports or better yet email them.

I tell them about the headaches and the PA tells me that my mask is too tight. She gives me new mask mounting instructions: turn on the machine, put on the mask and then tighten the straps. I tell her I don't mind the fit; she says I have red marks on my face and that causes the headaches I experience several hours after removing the mask. I believe I am a reasonable person but hours after I am off the machine. I wonder if they know what hypercapnia is. I had these headaches when I would wake in the morning before I got involved in SDB.

If it helps you, I used to get nights where my Vpap III & I went up to RR of 40+ but that is hyperventilation & usually caused by excessive CO2 build up. For some reason, this seems to be more likely to happen with a Vpap III but I have never quite come up with a sound theory as to why. I didn't ever get this high RR when using Bipap Pro II or Bipap S/T.

Cheers

DSM

[rogelah]

I know it wasn't me. I was having a problem trying to keep up and gave up. It was definitely the machine that was outputting puffs of air at a high rate. I can't breathe that fast when I am basically holding my breath while counting.

When I took several deep breaths it throttled back until I went back to my normal shallow breathing. Then it went back to a very high rate.

It was suggested that next time I turn it off and start over again.

I still think it is the machine. It already had 691 hours on it when I got it. The case does not fit tight where the h2i adapter fits against the blower; it is a little bit loose and there is bruise on the case as if it were dropped.

As for not going that high, I agree with you until it gets to the 3 or 4 hour mark (my guess is heat related) and then it goes up immediately (as viewed on the review screen). The instantaneous (or almost so) rise from around 12 to 15 BPM to 42 or 46 or like last night 52, leads me to believe mechanical failure. If I were the cause, it would be more random based upon my body's response to the therapy.

Another thing I noticed since I got the leaks under control is that the AHI components, AI and HI trade places from one day to the next. One day AI is high and HI low and the next HI is high and AI is low. One night there are several clusters spaced evenly over the night and the next, one cluster about 30 minutes after I was asleep and then one or two at the end and one night a couple in the middle third.

The only thing that is consistent is the inconsistency.

I am a biological entity with an out of whack breathing algorithm, hooked to a robot programmed to deliver air at a rate of 19 cm on inhale and drop to 14 cm to allow CO2 to exit. The robot is measuring my BPM spontaneously and if it falls below 15 it then nudges me with puffs of air at a rate of 15 BPM to hopefully get me back to 15 BPM. It has other parameters to tell it how long to wait for me to begin inhaling and another to tell how long I should be in inhalation. One to determine how quickly it should go from exhale to inhale and a set to determine how gently it should transition for inhale to exhale and exhale to inhale.

Have I got those correct?

[dsm]

I know it wasn't me. I was having a problem trying to keep up and gave up. It was definitely the machine that was outputting puffs of air at a high rate. I can't breathe that fast when I am basically holding my breath while counting.

When I took several deep breaths it throttled back until I went back to my normal shallow breathing. Then it went back to a very high rate.

It was suggested that next time I turn it off and start over again.

I still think it is the machine. It already had 691 hours on it when I got it. The case does not fit tight where the h2i adapter fits against the blower; it is a little bit loose and there is bruise on the case as if it were dropped.

As for not going that high, I agree with you until it gets to the 3 or 4 hour mark (my guess is heat related) and then it goes up immediately (as viewed on the review screen). The instantaneous (or almost so) rise from around 12 to 15 BPM to 42 or 46 or like last night 52, leads me to believe mechanical failure. If I were the cause, it would be more random based upon my body's response to the therapy.

Because of the design of the machine, it can only go to those RR numbers if triggered spontaneously (a leak may skew the triggering) or if falling below RR backup rate. So if you aren't triggering it something else is & that is a mystery. But, as mentioned, I have charts showing my Vpap III (S & S/T) doing what you describe. I always accepted it was me doing it.

Another thing I noticed since I got the leaks under control is that the AHI components, AI and HI trade places from one day to the next. One day AI is high and HI low and the next HI is high and AI is low. One night there are several clusters spaced evenly over the night and the next, one cluster about 30 minutes after I was asleep and then one or two at the end and one night a couple in the middle third.

I am inclined to think that your condition is the likely culprit here & also tends to lean me a bit towards thinking it is linked to the high RR you are experiencing.

The only thing that is consistent is the inconsistency.

I am a biological entity with an out of whack breathing algorithm, hooked to a robot programmed to deliver air at a rate of 19 cm on inhale and drop to 14 cm to allow CO2 to exit. The robot is measuring my BPM spontaneously and if it falls below 15 it then nudges me with puffs of air at a rate of 15 BPM to hopefully get me back to 15 BPM. It has other parameters to tell it how long to wait for me to begin inhaling and another to tell how long I should be in inhalation. One to determine how quickly it should go from exhale to inhale and a set to determine how gently it should transition for inhale to exhale and exhale to inhale.

That is a good summary of the intention of the Vpap III S/T. But the 'puffs' of air may not be an accurate description, what I think you are describing is the effect rather than the action. By this I mean that the switch from epap to ipap (when you drop below RR backup rate) feels like a puff but is in fact a mechanical shift from 14CMs to 19CMs & at a particular speed (rise time) for the duration of a breathing cycle and as divided up by the I:E ratio. 15 BPM means one full breath is 60/15 or 4 secs. The I:E ratio then splits this into the inhale vs exhale phases that the machine will stick to. The feeling of the speed of rise might make it feel like a puff. ASV machines *DO* put out distinctly short 'puffs' of air & we have discussed possible reasons for that some months back. Bilevels normally don't & the Vpap III S/T & Bipap S/T are normal Bilevels. But if you think about 40 BPM that is one breathing cycle each 1.5 secs with Ipap as a smaller proportion (see I:E ratio setting). Yes I guess that does feel like a puff, BUT, the triggering & cycling when above backup rate, are user driven & not machine driven in a machine where T (timed) is active.

Have I got those correct?

Yup -

Keep working on it

DSM

[-SWS]

Rogelah, sorry for getting to your latest VPAP party late...

I am wondering if the hyperventilation shown (when RR goes above say 25) is the cause of the highish tidal flow numbers.

Well, fast RR doesn't necessarily translate to hyperventilation. Recall that corresponding tidal volumes need to add up such that minute volumes are high in order for any given fast RR to translate to hyperventilation. So short-term respiratory rates and volumes both need to be analyzed (versus nightly averages, nightly highs, and nightly lows) to really know if hyperventilation is occurring.

However, in the case of neuromuscular disease, moments of fast RR are often paired with very shallow breathing. And that translates to typical hypoventilation associated with neuromuscular disease:

Patients with neuromuscular disorders have rapid shallow breathing secondary to severe muscle weakness or abnormal motor neuron function. The central respiratory drive is maintained in patients with neuromuscular disorders. Thus, hypoventilation is secondary to respiratory muscle weakness.

http://emedicine.medscape.com/article/304381-overview

Rogelah, unfortunately we can't see on your Resmed reports exactly what your tidal and minute volumes are up to during your moments of fast RR (we can only see nightly averages). However, since you have SDB related to neuromuscular disease, one very good question for your PSG clinicians would be whether your tidal and minute volumes are either low or high during your moments of fast respiration. Are you experiencing machine-induced hyperventilation or are you experiencing neuromuscular-disease related hypoventilation during those moments?

And as a side note, more primary hypoventilation can induce yet other forms of secondary central skew---such as central apneas and sometimes periodic breathing via counteractive hyperventilation.


Also, Ti min (instead of Ti max) is the parameter that Resmed considers more useful in managing restrictive neuromuscular disease. I haven't looked at the VPAP III S/T clinician's manual just yet, but the VPAP II S/T clinician's manual gives a nice, brief description of Ti min use relative to restrictive disorders. DSM, do you per chance have a link to a VPAP II S/T clinician's manual that Rogelah might print and show his clinicians relative to Ti min settings for neuromuscular disease?

Rogelah, the fact that your clinicians set up your VPAP III S/T with all default parameters (except IPAP and EPAP settings) for any neuromuscular-disease patient, inspires about as much confidence as them also initially prescribing ASV for shallow-breathing related to neuromuscular disease. I'd get a new clinical dog if it were me...

[-SWS]

A quick review of neuromuscular-disease related EPAP caveats for clinicians:

http://www.mda.org/publications/Quest/q152sleep.html

Weak respiratory muscles can lead to nocturnal hypoventilation

In the case of FSHD, neuromuscular-based hypoventilation is the primary respiratory issue, while central apneas are more secondary to that hypoventilation. Those central apneas can presumably be secondary to hypoventilation, as central timing or blood-gas related skew occurs because of FSHD's muscular-based hypoventilation.

Because ventilatory therapies for people with weak muscles are different than those used for obstructive apneas, it’s important that your physician is highly skilled at analyzing test results

Bach questions the usefulness of polysomnograms for people with muscle diseases because the test “interprets all abnormalities as central or obstructive apneas rather than muscle weakness,” he says — especially when read by physicians unfamiliar with neuromuscular disease.

That last statement probably translates to clinicians: 1) thinking upper-airway obstruction needs to be stented with a high EPAP, when restrictive neuromuscular weakness instead needs to be vented with a higher PS spread (via lower EPAP and higher IPAP to assist with Work of Breathing), and 2) attempting to prioritize and treat central apneas as if they were the primary problem, rather than first attempting to address the hypoventilatory component (alleviating secondary or incidental central skew).

In muscle diseases, the BiPAP “span,” or difference between the inhalation and exhalation airflow pressures, is typically high to provide greater assistance to the inspiratory muscles and little or no resistance during exhalation.

So if a doctor or PSG clinician spends most of their career analyzing upper-airway obstruction results, a similar PSG presentation via restrictive neuromuscular weakness can easily throw them off according to Bach.

Some clinicians may conceivably think their rare neuromuscular-disease patient needs either a high CPAP or high EPAP pressure to stent upper airway obstructions, when instead they need a high PS with low EPAP to vent (mechanically offload Work of Breathing).

And getting that primary restrictive-disorder properly vented can conceivably help avoid secondary central problems related to either hypoventilation or wrong machine settings.

[dsm]

SWS

As always, great to have your insightful precision analysis - very interesting. Re the Vpap II clin manual, looked through what I have but not that one.

Cheers

DSM

[-SWS]

Here are brief descriptions of Ti max and Ti min:
http://www.resmed.com/us/products/vpap_ ... s&sec=true

Note that Resmed sometimes refers to Ti max as IPAP max. And Resmed sometimes refers to Ti min as IPAP min.

But in that description, Resmed calls for the Ti min parameter ("IPAP min") to help with neuromuscular disease. Specifically, lengthening Ti min can help offset hypoventilation's rapid, shallow breathing cycles associated with neuromuscular disease.

IPAP Min ensures sufficient inspiratory time for patients who may cycle to EPAP too early. IPAP Min helps prevent premature cycling to EPAP and allows more consistent delivery of tidal and minute volumes, particularly for restrictive lung disease patients (eg, those with neuromuscular weakness, chest wall deformity, etc.)

[dsm]

Here are brief descriptions of Ti max and Ti min:
http://www.resmed.com/us/products/vpap_ ... s&sec=true

Note that Resmed sometimes refers to Ti max as IPAP max. And Resmed sometimes refers to Ti min as IPAP min.

But in that description, Resmed calls for the Ti min parameter ("IPAP min") to help with neuromuscular disease. Specifically, lengthening Ti min can help offset hypoventilation's rapid, shallow breathing cycles associated with neuromuscular disease.

IPAP Min ensures sufficient inspiratory time for patients who may cycle to EPAP too early. IPAP Min helps prevent premature cycling to EPAP and allows more consistent delivery of tidal and minute volumes, particularly for restrictive lung disease patients (eg, those with neuromuscular weakness, chest wall deformity, etc.)

SWS
Very good diag & yes those contradictory labels create quite a bit of confusion. Added to that I see Resmed has 'trademarked' the terms Ipap Min & Ipap Max. Seems an odd thing to try to trademark - appears unenforceable ?.

I have extracted the diag as a jpeg & it is shown below (thanks to SWS for the link).

DSM

[rogelah]

I have recently found some abstracts of papers regarding diaphragmatic paralysis (bilateral and unilateral) and diaphragm weakness in general as it relates to neuromuscular disease (NMD) in general and in some cases FSHD explicitly.

One of the interesting effects, said to be related to the intersection of NMD and SDB, occurs in REM. There is a precipitous spike in RR due to a weakened or paralyzed diaphragm.

Another interesting anecdotal tidbit, from the fshsociety blog mostly, is the ratio of inspiration to expiration during a breathing cycle which needs to be 1:2. Some (who use BIPAPs during parts of the day as well as all night) also say there is not enough difference between IPAP and EPAP. As one stated an IPAP of 22 and EPAP of 11 is preferred rather than 22 to 16,

My followup this week was the ordinary, automatically scheduled visit. It was for the R/T to download usage compliance and then a visit with a physician's assistant to ask me about any problems. When I asked why they had only extracted summary data she got the doctor (sleep specialist). I know he is seriously attempting to understand the symptoms and give me an effective therapy.

I have a follow-up in 2 weeks with the doctor (sleep specialist). At that time I will decide if he needs to call for backup. It is a large teaching and research facility with another similar facility in another state. Some of the abstracts I have read are by physicians at the sister facility.

[-SWS]

Good luck with that, Rogelah. Can I suggest that you let your RT and doctor know that VPAP III default values are unacceptable for a neuromuscular diseased patient with pulmonary restriction? Maybe this set-up information from the VPAP II S/T clinicians manual will help your doctor and RT with your settings:

Set-Up for Different Disease States:

Restrictive Lung Disorders (eg. chest wall deformity, neuromuscular diseases)

Setting TiControl's IPAP Min Time:
1) Measure respiratory rate during ventilation and at rest (see "Measuring Respiratory Rate" on page 59).
2) Refer to the column entitled Restrictive IPAP Min in "TiControl: IPAP Min and IPAP Max time Calculation Guide" on page 58.
3) Set IPAP Min to the value that corresponds to the resting respiratory rate from step 1.
4) If the patient complains that inspiratory time is too long or too short, verify the respiratory rate and IPAP Min setting
-or-
adjust the IPAP Min setting until the patient feels the inspiratory time is slightly too long.
5) Reduce the IPAP Min setting by 0.2 to 0.3 second from the setting in the previous step.


Setting TiControl's IPAP Max Time:
1) Measure respiratory rate during ventilation and at rest (see "Measuring Respiratory Rate" on page 59).
2) Refer to the column entitled Restrictive IPAP Max in "TiControl: IPAP Min and IPAP Max time Calculation Guide" on page 58.
3) Set IPAP Max to the value that corresponds to the resting respiratory rate from step 1.
4) If the patient complains that inspiratory time is too short, verify the respiratory rate and IPAP Max setting.



(my note: below are the table columns relevant to Restrictive disease)

Respiratory Frequency (BPM) / IPAP Max / IPAP Min:
------------------------------------------------------------------
30 / 1.0 / 0.5
29 / 1.0 / 0.5
28 / 1.1 / 0.5
27 / 1.1 / 0.6
26 / 1.2 / 0.6
25 / 1.2 / 0.6
24 / 1.3 / 0.6
23 / 1.3 / 0.7
22 / 1.4 / 0.7
21 / 1.4 / 0.7
20 / 1.5 / 0.8
19 / 1.6 / 0.8
18 / 1.7 / 0.8
17 / 1.8 / 0.9
16 / 1.9 / 0.9
15 / 2.0 / 1.0
14 / 2.1 / 1.1
13 / 2.3 / 1.2
12 / 2.5 / 1.3




Measuring Respiratory Rate:

Respiratory rate should be calculated with the patient ventilated and at rest when possible.

Measure the patient's resting respiratory rate during assisted ventilation. If you think the patient's respiratory rate will decrease during sleep and you are unable to measure it, then estimate the nocturnal respiratory rate and use this figure to determine the IPAP Max and IPAP Min setting. Refer to the section above that most appropriately matches the patient's condition. In some instances, recommended settings may need to be fine-tuned based on patient feedback and/or ongoing clinical assessment.

Very different then leaving the machine at default values...

[-SWS]

Rogelah, is that just a typo regarding the IPAPmin decimal in your tag line?

IPAP:19.0, EPAP:14.0, RR:15, RT:300ms, IPAPmax:2.0s, MAX I:E:1:2, IPAPmin:0.10s

Resmed's recommended range for IPAP min targeting restrictive disease is 0.5s to 1.3s. Again, good luck with your upcoming doctor visit.

[rogelah]

Rogelah, is that just a typo regarding the IPAPmin decimal in your tag line?

IPAP:19.0, EPAP:14.0, RR:15, RT:300ms, IPAPmax:2.0s, MAX I:E:1:2, IPAPmin:0.10s

Resmed's recommended range for IPAP min targeting restrictive disease is 0.5s to 1.3s. Again, good luck with your upcoming doctor visit.

It is not a typo; it is the default value. I'll change it to 1.0 tonight. The RT is 250ms. The doctor changed it at the followup.

I'm now having a problem with the mask slipping up on the right side below the lip. My left side is weakened. I am not able to don the mask myself and need assistance. I think the cause is uneven tension between the two sides, left is tighter than right; pops up on the right side. It ends up in the middle of my mouth.