How relaiable is pulse oximeter and what does it do?

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How relaiable is pulse oximeter and what does it do?

Postby Chattabob » Tue May 03, 2011 8:23 am

Hi all,

Just called the sleep lab to get my results from the pulse oximeter test and they advise the results are normal :(

From what I'm told this is a basic test to identify sleep apnea (So I guess I do not have sleep apnea or at least not severe)

I've now got to get wired up for another sleep test on my chest, legs ect... and sleep at home again... What are the chances of this highlighting something this time? How more in deph and accurate is it? I know my sleep is not normal and I really do not want to here another "it's normal" again

13 hours sleep per day
Dark circles under my eyes
Tired during the day
Poor concerntration
Pale face

Among many others listed on the forum, I know this is not normal and god forbid I have kids in the future... If I can't cope with 13 hours sleep per night what will I be like with kids.

I read in another thread that I shoul;d ask for the results of the test... Is this worth it for this type of test?

I think I just need someone here who's been through this to give me some hope
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Postby CrohnieToo » Tue May 03, 2011 10:24 am

By all means do request a copy of that overnight oximetry report. An overnight oximetry alone is NOT a sufficient indicator of sleep apnea and certainly not an indicator of any other sleep disorder you may or may not have.

These at-home sleep apnea tests are relatively new and not as accurate as a full in-lab PSG sleep study for detecting anything but sleep apnea but they are pretty good at detecting obstructive sleep apnea. IF it is determined from the at-home sleep test that you do have sleep apnea then they will most likely provide you w/an auto-titrating PAP (an APAP) to determine your PAP pressure need(s). IF the at-home test doesn't detect sleep apnea then a full in-lab sleep evaluation PSG study would be warranted. There are some 80 or so sleep disorders w/sleep apnea just being the most common and easiest to diagnose.

And do be sure to ask for and get copies of any and all sleep tests done, at-home or in-lab.
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Postby CrohnieToo » Tue May 03, 2011 10:29 am

Ooops. What does an overnight oximetry do? It provides a record of your blood oxygen levels and heart rate all thru the night. There can be drops in oxygen saturation that go below 90% for various periods of time. If not low enough or not long enough these drops in oxygen saturation are considered "normal". What the overnight oximetry can NOT do is indicate whether the drops in saturation and increased heart rate due to the drops are causing "arousals", driving you from a deeper stage of sleep to a lighter stage of sleep or even waking you to awareness.
ResScan 3.10 - Resmed S8 ResLink & oximeter
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Postby DougVK » Wed May 04, 2011 2:33 am

How can someone like this say with high certainty that a drop in oxygen is caused by sleep apnea? Atleast with the same certainty as a full in lab sleep study.
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Postby Daniel » Wed May 04, 2011 3:13 am

DougVK wrote:How can someone like this say with high certainty that a drop in oxygen is caused by sleep apnea? Atleast with the same certainty as a full in lab sleep study.


Many do say it..............BUT they shouldn't, because it is incorrect.

Many apnoea sufferers do not desaturate.

Daniel.
The untreated Sleep Apnoea sufferer died quietly in his sleep..
Unlike his three passengers who died screaming !


The first 40 years of childhood are by far the hardest
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Re: How relaiable is pulse oximeter and what does it do?

Postby Sleepynight » Sat Apr 14, 2012 6:09 am

Hi Daniel,

Could you please explain why so many apnea sufferers do not desaturate? I would appreciate a scientific approach to your explanation. Can you also provide a link from a clinical study which proves your statement?

Thank you.
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Re: How relaiable is pulse oximeter and what does it do?

Postby Daniel » Sat Apr 14, 2012 11:43 am

Sleepynight wrote:Hi Daniel,

Could you please explain why so many apnea sufferers do not desaturate? I would appreciate a scientific approach to your explanation. Can you also provide a link from a clinical study which proves your statement?

Thank you.


I'm not a scientist or a doctor, and don't have time to look up clinical studies at this time....but if you look at the definitions of 'apnoea events' it states that for an event to count as an apnoea event, breathing cessation must be for a minimum of 10 seconds or longer, it may or may not be accompanied by an oxygen desaturation. An hypopnoea event is a partial closing of the airway and is accompanied by a desaturation of 4% or greater.

Many people who have posted here reported that they did not experience oxygen desaturations during their diagnostic sleep studies, and this is backed up by copies of their sleep study reports. Typically someone who sugffers from purely apnoea events may not desaturate, while someone who sufferers from a mix of apnoeas and hypopnoeas will probably show desaturations. There are also those who suffer from hypopnoeas only....they would normally show desaturations.

If you go to the 'pubmed' site http://www.ncbi.nlm.nih.gov, and type in your search words there are many studies to back this up.

Daniel.
The untreated Sleep Apnoea sufferer died quietly in his sleep..
Unlike his three passengers who died screaming !


The first 40 years of childhood are by far the hardest
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Re: How relaiable is pulse oximeter and what does it do?

Postby Sleepynight » Sat May 05, 2012 4:41 pm

It took me a while to find some time to write here. But I did some research these days and here are my results:

I found a lot of clinical studies in favor for using oximetry as an effective way to diagnose and monitor sleep apnea, and I didn't find any study who can sustain your observation "Many apnoea sufferers do not desaturate. "

It is pointless to post here all the links from these studies, because no one will have so much time to read them all. But if someone insists...I saved most of them in a document.

However, I will post one study about the effectiveness of oximetry for sleep apnea diagnosis: http://www.ncbi.nlm.nih.gov/pubmed/17283346

TITLE: Diagnosis and initial management of obstructive sleep apnea without polysomnography: a randomized validation study.

ABOUT: Polysomnography (PSG), despite limited availability and high cost, is currently recommended for diagnosis of obstructive sleep apnea and titration of effective continuous positive airway pressure (CPAP).

68 patients with a high pretest probability of moderate to severe obstructive sleep apnea (apnea-hypopnea index [AHI] >15 episodes/h) identified by sequential application of the Epworth Sleepiness Scale (ESS) score, Sleep Apnea Clinical Score, and overnight oximetry.

RESULTS: In the initial management of patients with a high probability of obstructive sleep apnea, PSG confers no advantage over the ambulatory approach in terms of diagnosis and CPAP titration. The ambulatory approach may improve adherence to treatment. When access to PSG is inadequate, the ambulatory approach can be used to expedite management of patients most in need of treatment.

Tens of clinical studies come to the same conclusion. As for the remark with "Many apnoea sufferers do not desaturate", a study says that using unstandardized oximeters can influence the interpretation of sleep apnea severity. So it might be less, or more. It depends on the oximeter's quality, user's knowledge, etc... This study is on my list, so if you really want to read it, please let me know. I forgot which one it is, so I have to test each link.

This investigation took me almost 2 hours, but I hope it's worth it.
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