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General Discussion on any topic relating to CPAP and/or Sleep Apnea.
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jnk...
 
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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby jnk... on Thu Sep 01, 2016 10:27 am

To your question, the problem (as I see it as a civilian layman) is that many CV patients will have the symptoms of OSA whether caused by sleep-breathing or not, so a researcher has only AHI numbers to use for "diagnosis." That is a problem because, absent symptomology, there is no true, clear consensus on where to draw the line on who will benefit from PAP and who won't. There is only a line for when insurance will pay for it. So you choose an arbitrary line in the sand to say some CVD people on one side "have OSA and should be treated" and people on the other side don't and shouldn't. It is already a false construct to even create the categories themselves, scientifically, though not for the bean counters running clinical practice. Your "research" from that point on is research into the validity of your own construct, since it could be argued that many of the people "treated" with PAP didn't have OSA to start with--they only had a certain AHI, which is not really the same thing. Your comorbid condition has removed the ability to diagnose by symptoms, so you are really only researching the question of "at what AHI should the average CV patient definitely be put on PAP, since we have no idea how much of the symptomology is CVD and how much is SDB?" What gets confused is, Are you trying to treat OSA, which should theoretically help the CV too, or have you reduced your question to, Does PAP itself treat CVD? This is a distinction with a difference but without good working definitions available yet to address any of it. That is because trying to prove that a CV patient without OSA-related SDB is going to benefit from an OSA treatment is at its heart an odd thing to do, or at best involves a guess that will be wrong a good percentage of the time. Then, as is apparently the case in this study, they took away people with symptoms of OSA. Now the question is, At what AHI do you treat non-sleepy, non-tired CV patients? And what real-world category is THAT supposed to be? I believe that in clinical practice a CVD patient who does not feel any better on PAP and who has an AHI below 30 (or 25, or 20) might not even be encouraged by the average heart doc to continue PAP, since response-to-therapy did not prove the need for it.

Or maybe I have a deeply flawed understanding of ALL of it. That IS often the case with me.
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Pneumophile
 
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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Pneumophile on Thu Sep 01, 2016 10:47 am

Thanks for the response. As for the diagnosis of OSA in this population of CV patients: (from "Patients and Procedures")
The diagnosis of moderate-to-severe OSA, which was defined as an oxygen desaturation index (blah blah blah) of at least 12, was established with the use of a home sleep-study screening device (ApneaLink, ResMed) and was confirmed by review of the data at a central core sleep laboratory.

That seems reasonable to me but I'm no expert on ApneaLink.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby jnk... on Thu Sep 01, 2016 11:05 am

Pneumophile wrote:Thanks for the response. As for the diagnosis of OSA in this population of CV patients: (from "Patients and Procedures")
The diagnosis of moderate-to-severe OSA, which was defined as an oxygen desaturation index (blah blah blah) of at least 12, was established with the use of a home sleep-study screening device (ApneaLink, ResMed) and was confirmed by review of the data at a central core sleep laboratory.

That seems reasonable to me but I'm no expert on ApneaLink.

I am no expert on ANY of it. But it seems to me that O2 saturation in CV patients would be a suspect marker. When you use CPAP to treat OSA, you are not simply masking a symptom, you are preventing the problem entirely. With CVD, you could just be masking a symptom and calling it a treatment. Right?

I apologize if that is a silly question. Just trying to wrap my head around it.
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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Pneumophile on Thu Sep 01, 2016 12:42 pm

Not in the least a silly question. In fact it's a profound one but unfortunately there is no easy answer. IMO many treatments in the drug marketplace only treat "symptoms", in the sense that they do not effectively attack the underlying cause of the disease and indeed often only improve SOME of the set of symptoms in play. To be blunt about my own profession, we often THINK we know the cancer pathophysiology involved and THINK we know why and how an approved drug is working, only to have egg on our faces later when another hypothesis comes along that better explains the data. Such is life in pharma.

Is anyone in this forum knowledgeable about ApneaLink?

To me, based on my experience in oncology clinical trials over the years, the fact that they used a core (central) laboratory to run the analysis and make the OSA attributions tells me that it's a complicated matter that needs to be tightly controlled. They did their best given the great difficulties presented by the reality of such a vast,international multicenter trial. Core labs are very often used to categorize tumor patients into 'non-responder', partial responder' and 'complete responder' (from the raw CT or MRI scans) and in other ways - especially in large "registrational" oncology trials where FDA may approve (or not) the submission largely based on the data from that study.'The scans are collected from all the sites involved in the study, to a central location,and analyzed there. So-called "Investigator" data are also generated - the oncologist at the particular site does his/her own analysis - but the Core data are always considered superior. I used to analyze both sets of data (biomarker research on the clinical data), at least in some cases - electrons are cheap and you might learn something interesting.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby palerider on Thu Sep 01, 2016 1:39 pm

Pneumophile wrote:Is anyone in this forum knowledgeable about ApneaLink?

what info are you looking for?

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby jnk... on Thu Sep 01, 2016 2:53 pm

Personally, although I am still being cowardly in shielding my eyes from any stirred-up dust in the details, I'd still love to hear more observations and thoughts from Arlene1963 on this study.
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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Pneumophile on Thu Sep 01, 2016 5:46 pm

palerider wrote:
Pneumophile wrote:Is anyone in this forum knowledgeable about ApneaLink?

what info are you looking for?

I'm looking for detailed info on the merits and demerits of ApneaLink as a diagnostic tool for evaluating patients for possible OSA (false positives, false negatives, sensitivity - that type of thing), and for a comparison with polysomnography as the standard method. The paper doesn't go into any real detail other than mentioning an oxygen desaturation index of at least 12 (is that all there is to it? - surely not.). In fact I can't find a reference to an ApneaLink article in 'Patients and Procedures'. This is a bit weak - maybe all readers are supposed to be familiar with the device and its pros/cons, so much so that there's no need for a reference! Or maybe there's a reference buried somewhere in the epic, 80-page Supplementary Appendix.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby palerider on Thu Sep 01, 2016 6:31 pm

Pneumophile wrote:
palerider wrote:
Pneumophile wrote:Is anyone in this forum knowledgeable about ApneaLink?

what info are you looking for?

I'm looking for detailed info on the merits and demerits of ApneaLink as a diagnostic tool for evaluating patients for possible OSA (false positives, false negatives, sensitivity - that type of thing), and for a comparison with polysomnography as the standard method. The paper doesn't go into any real detail other than mentioning an oxygen desaturation index of at least 12 (is that all there is to it? - surely not.). In fact I can't find a reference to an ApneaLink article in 'Patients and Procedures'. This is a bit weak - maybe all readers are supposed to be familiar with the device and its pros/cons, so much so that there's no need for a reference! Or maybe there's a reference buried somewhere in the epic, 80-page Supplementary Appendix.


well, since the study was directed at people in the field... yeah, they're probably assumed to be familiar.

here's a start: https://www.google.com/search?client=ub ... 8&oe=utf-8

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Pneumophile on Thu Sep 01, 2016 9:42 pm

It is always a judgment call as to how much you describe the methods used. This paper is of great interest to cardiovascular docs for obvious reasons and indeed was presented at a CV conference; I doubt many of these types are all that familiar with the finer points of ApneaLink. Most of them are probably as clueless as I was until recently. Sleep docs reading the paper will obviously know more about it. As for general readers, I don't think that knowledge of ApneaLink should be presumed.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby palerider on Thu Sep 01, 2016 9:52 pm

Pneumophile wrote:It is always a judgment call as to how much you describe the methods used. This paper is of great interest to cardiovascular docs for obvious reasons and indeed was presented at a CV conference; I doubt many of these types are all that familiar with the finer points of ApneaLink. Most of them are probably as clueless as I was until recently. Sleep docs reading the paper will obviously know more about it. As for general readers, I don't think that knowledge of ApneaLink should be presumed.

perhaps they presume the readers ability to tell their assistant to dig up some info on it.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Pneumophile on Thu Sep 01, 2016 9:59 pm

That would be a strange assumption for an author to make. Personally I assumed it to be reasonably well validated which it seems to be. Why they just mention oxygen desaturations in the methods section is unclear.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Greendirt on Fri Sep 02, 2016 6:35 pm

jnk wrote...

...the problem (as I see it as a civilian layman) is that many CV patients will have the symptoms of OSA whether caused by sleep-breathing or not, so a researcher has only AHI numbers to use for "diagnosis." ...it could be argued that many of the people "treated" with PAP didn't have OSA to start with--they only had a certain AHI, which is not really the same thing. Your comorbid condition has removed the ability to diagnose by symptoms ... trying to prove that a CV patient without OSA-related SDB is going to benefit from an OSA treatment is at its heart an odd thing to do...


OSA symptoms and high AHIs are not 100% indicative of OSA. Cardiac issues can present similarly.

For what it's worth I had an AHI of over 50 (99% hypopnia, 1% apnea) and started CPAP. I felt better: which is hardly surprising as I wasn't breathing well as the high rate of hypopnia demonstrated.

Then I got a pacemaker which resolved regular periods of bradycardia and occasional periods of asystole. My AHI dropped to 0 and all my OSA symptoms disappeared immediately. I am otherwise fit and healthy. I conclude that CPAP didn't resolve my heart issue. It couldn't. I had symptoms of OSA, but didn't have OSA. But I did feel better while on CPAP (as it was giving me extra air, I suppose) until I got the pacemaker which addressed the actual cause.

While some (many?) people may have both CVD and OSA and which came first may be unclear, not all will have both. But evidently CPAP can help CV symptoms, maybe via increasing the amount of air reaching the lungs so that reduced cardiac efficiency is somewhat compensated for.

But cardiac issues will need a cardiac intervention, not an air pump, even if pumped air happens to make a CVD sufferer feel better.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Greendirt on Fri Sep 02, 2016 6:42 pm

jnk also wrote:

When you use CPAP to treat OSA, you are not simply masking a symptom, you are preventing the problem entirely. With CVD, you could just be masking a symptom and calling it a treatment. Right?


Right. Correct. Spot on. Bravo. Exactly.

Let CPAP treat OSA. Let CPAP help CVD sufferers feel better. Let cardiac symptoms be identified, diagnosed and treated.

Don't let an internet forum orthodoxy that high AHI = OSA = CPAP for life for everyone cloud the reality CPAP is really great for a whole lot of people with airways that obstruct, but might be a temporary band-aid for a few who breathe badly for other reasons.
Last edited by Greendirt on Fri Sep 02, 2016 6:57 pm, edited 1 time in total.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Pneumophile on Fri Sep 02, 2016 6:56 pm

You would certainly not be treating the root causes of CV diseases, clearly, but the hope is that some of the cardiovascular consequences of chronic intermittent hypoxia in CV + OSA patients might be ameliorated by CPAP therapy. That was the whole premise of the study. Sadly this massive piece of work failed to address the hypothesis in an effective way.

Many therapies on the market that have clinical utility and are approved by FDA do not "treat root causes" but they are definitely worth having - many anticancer agents for one thing.

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Re: Study: "CPAP machines do not reduce heart attack, strokes"

Postby Greendirt on Fri Sep 02, 2016 7:05 pm

Pneumophile wrote:You would certainly not be treating the root causes of CV diseases, clearly, but the hope is that some of the cardiovascular consequences of chronic intermittent hypoxia in CV + OSA patients might be ameliorated by CPAP therapy. That was the whole premise of the study.


Yes. Naturally we can hope for amelioration.

I guess that either this study isn't the final word, or there's something more complicated going on that means more than CPAP (as used by the study group) is needed.

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