CPAPtalk.com

pbriggs wrote:what about a "stress test" - is this not where you exercise to induce stress by working harder and to lower the oxygen levels in the blood to see how the heart reacts to it?
https://www.nhlbi.nih.gov/health/health ... cs/stress/

I get a stress test every other year. I suppoe I could ask them what my pulse ox levels are during the test.

Start with this.

http://www.mayoclinic.org/symptoms/hypo ... m-20050930

Then contact the Mayo Clinic and ask them why they mentioned 90% as being low. Then discuss this with your doctor and see what information you can find there. Then find a doctor or nurse that works in the emergency room and check with them. Then visit a medical school and see why they get concerned with low oxygen levels. Then do the same at a birthing clinic.

You can also do a search on hypoxemia and hypoxia and study the various articles and studies that come up. The problem is that you get a lot of information but may not be able to put context around it to understand it. At this point you go back to your medical professionals and ask them to put context around what you have found.

Another place to find information is to visit a Vet.

http://www.petmd.com/dog/conditions/car ... _hypoxemia

You may also be able to strike up a conversation with Max Costa and see if he can offer some insight...

http://molpharm.aspetjournals.org/conte ... /1469.full

pikov22 wrote:

LSAT wrote:Use of the CPAP will help keep your O2 levels above 90%...if you don't think that is important, you can stop using the CPAP.

Completely irrelevant! Read my original question, kindly.

I think your question is completely irrelevant!

B Strong,
As you can see you get a lot of comments, but not answers to your question.

You asked a specific question as to how the SpO2 90% limit is set asking for a scientific study.

I don't know where it comes from either, but in CpapTalk there isn't a comprehension of the idea of a scientific study. Things are just repeated from secondary sources. You can ask what are the studies supporting "sleep hygiene and no one knows or they refer to a secondary source and there isn't a comprehension of the idea of an evidentiary based study.

You see your got some hostile responses also when you persisted on trying to get an answer to your question.

I purchased "Sleep Apnea: Current Diagnosis and Treatment," Krager, a bound volume of "Progress in Respiratory Research." It was expensive.

If you go to your local public university you can usually get online in the library as a guest and search online sources. I am thinking it is probably the library for the medical school, but you might be able to get access at any of the university libraries. Each university's policies vary. However, you can usually search journals by key words. I do it off and on when I am doing engineering research or as an author. The university libraries pay fees to get access to huge online databases of articles.

LSAT wrote:

pikov22 wrote:

LSAT wrote:Use of the CPAP will help keep your O2 levels above 90%...if you don't think that is important, you can stop using the CPAP.

Completely irrelevant! Read my original question, kindly.

I think your question is completely irrelevant!

LOL. So why did you respond? LOLLOLLOL!!

sleepy1235 wrote:B Strong,
As you can see you get a lot of comments, but not answers to your question.

You asked a specific question as to how the SpO2 90% limit is set asking for a scientific study.

I don't know where it comes from either, but in CpapTalk there isn't a comprehension of the idea of a scientific study..

Sludge often references studies that support his views. In fact he did just this for me last week. I guess we need more sludge around here. (Not sure about the sanitary problems that might cause.)

Regarding the original questions about data supporting diagnosis and treatment recommendations for 02 desats, I believe Too Tall on this forum has been seeking the same info. Maybe he found some answers.

Kennerly wrote:I guess we need more sludge around here.

One simply can't have enough sludge!

pikov22 wrote:They tell us that pulse O2 levels should not be allowed to drop below 90% (I think).

What is the science behind that?

That's easy!

It does not really start with oxygen saturation-- that methodology swamps the countryside because it is cheap and easy to measure.

Rather, the important measure is the gas tension of oxygen, or pO2. It is that driving pressure that puts the oxygen molecules on the hemoglobin to saturate it (and it can only be 100%, 75%, 50%, 25% or 0% saturated (a key concept, more on that later)).

Because of the behavior of hemoglobin, 90% saturation is critical because that's the precipice of The Cliff:



The driving force of pO2 is not important over a huge range of tensions until it approaches The Cliff-- you can be sitting in a hyperbaric chamber with a pO2 of 1520 mmHg, then put a plastic bag over head and be fine while the pO2 drops 1460 mmHg (actually you wouldn't, but for other reasons...)

At pO2 60mmg, O2 sat is still 90%, so the body is still OK.

However, if you drop just 20 mmHg more, your O2 saturation is now 75% and you are poking the GR with a stick...

...because of another hemoglobin concept. Each hemoglobin molecule has 4 receptor sites, so individually it can only have one of the 5 possibilities of saturation noted above. If all 4 sites are saturated, the Hb freely gives and takes oxygen molecules.

However, at 75%, the Hb becomes REAL stingy about surrendering another one (because what he REALLY wants to do is go looking for another molecule, and it needs to be in "grabby" mode to go do that).

However2, the body compensates for oxygen supply issues (over a period of time) by a few mechanisms, like polycythemia, hypertension, dead, etc.

Further, target organs do not extract oxygen equally. Specifically, the heart and brain pull most of the oxygen off of the Hb they see. Consequently, they are more susceptible to lower O2 saturations.

Then you can add in other risk factors, like coronary artery narrowing from a steady diet of bacon double cheeseburgers which reduces blood flow (the other critical concept in Oxygen Delivery) to target organs, and even mild desaturations can result in crushing substernal chest pain (a REAL bad sign)(or a real GOOD sign if your goal is to be in the Express Lane of the Life Checkout Line...).

Sludge wrote:Further, target organs do not extract oxygen equally. Specifically, the heart and brain pull most of the oxygen off of the Hb they see. Consequently, they are more susceptible to lower O2 saturations.

Then you can add in other risk factors, like coronary artery narrowing from a steady diet of bacon double cheeseburgers which reduces blood flow (the other critical concept in Oxygen Delivery) to target organs, and even mild desaturations can result in crushing substernal chest pain (a REAL bad sign)(or a real GOOD sign if your goal is to be in the Express Lane of the Life Checkout Line...).

Thanks for the detailed report. I can't say that I understood it all -- too many abbreviations, for one thing -- but I do appreciate your effort.

FWIW, I was just looking at my pre-treatment polysomnogram and a titration study after treatment began. The poly report said,

"Respiratory monitoring is most notable for sustained hypoxemia in REM. In addition, frequent obstructive hypopneas (73) as well as obstructive and mixed apneas (20) are identified in all sleep stages, most prominently in REM. ... These apneas and
hypopneas range in duration from 13 to53 secondi and are associated with arousal from sleep as well as recurrent oxygen desaturation to as low as 77%. In addition, sustained oxygen desaturation to the low 70s was identified in REM, and to the high 80s in non-REM,
independent of clear-cut respiratory irregularities. Cumulative oximetry monitoring shows the patient spent nearly half his sleep time with an
oxygen saturation below 90%"

I suspect that that was occurring for a period of months, perhaps years. Is it a miracle that I did not have a stroke or a heart attack?

The titration study report concluded with "Cumulative oximetry monitoring further shows that percentage of the night spent with oxygen saturation below 90% has decreased from nearly half the night on the diagnostic study, to less than 4% of the night of the treatment
study."

pikov22 wrote:I can't say that I understood it all -- too many abbreviations...

Which abbreviations did you not understand?

pikov22 wrote:I suspect that that was occurring for a period of months, perhaps years. Is it a miracle that I did not have a stroke or a heart attack?

Well, I would not call that a "miracle", per se, cause actually the odds are (were) with you that you would get this far:



OTOH, since the stakes are (were) your life, if you want (wanted) to gamble, IIW(W)Y I'd (have) stick (stuck) to buying Powerball tickets.

Sludge, thanks. The curve is really good.

Sludge wrote:

pikov22 wrote:I suspect that that was occurring for a period of months, perhaps years. Is it a miracle that I did not have a stroke or a heart attack?

Well, I would not call that a "miracle", per se, cause actually the odds are (were) with you that you would get this far:



OTOH, since the stakes are (were) your life, if you want (wanted) to gamble, IIW(W)Y I'd (have) stick (stuck) to buying Powerball tickets.

What is the source of that graph?

That is a very interesting study...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2542952/

With an average of 50 it appears that you can actually survive a little over 12 years with a high AHI before you drop off the cliff. It is amazing that the body can handle that much punishment before the accumulated damage finally ends in demise.

HoseCrusher wrote:That is a very interesting study...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2542952/

With an average of 50 it appears that you can actually survive a little over 12 years with a high AHI before you drop off the cliff. It is amazing that the body can handle that much punishment before the accumulated damage finally ends in demise.

When you say "survive .. over 12 years...", I ask "when does that start?". Is it 12 years from the time that SDB was diagnosed? The participants were a random sample of a community. Presumably, many did not have SDB.

And, I found this in it:

"Consequently, our data cannot establish how CPAP contributes to lower death rates."

Also, it's difficult to apply their results to any individual.

Pertaining to that figure, they wrote "Kaplan-Meier survival curves (Figure 1) illustrate the decrease in survival with increasing SDB category in the total sample of 1522 participants (Panel A) and in the sample after excluding participants (n = 126) who had reported CPAP use (Panel B). The decrease in survival with SDB not treated with CPAP was markedly greater. [Emphasis added.] It would have interesting to see Panel C, only those who reported using CPAP.

I was diagnosed with OSA at age 77. So if I discontinue my CPAP, I have a 50/50 chance of living until say age 87. Considering what else is wrong with me (COPD and myopathy), I probably have less than 50/50 chance reaching 87 even if I continue CPAP. Something for me to think about.

Thanks for the science, Very much appreciated!