Oximeters good indicators of probable apnea?

Is an oximeter a good indicator of probable apnea? I suspect my father has sleep apnea. I'm imagining he might be resistant if I mention it to him and suggest a sleep study. (Until I point out that he is especially vulnerable to stroke, at which point that very prudent man will probably move mountains to treat the apnea). I thought suggesting an oximeter would be a suggestion he'd be more likely to act on. A gentler way to start the conversation, without adding terror into the mix. A friend of mine was also asking if there was an easier and less expensive way than a sleep study to find out whether his daughter might have apnea. I'm wondering if the results of the oximeter indicate oxygen drop, then they would be more likely to pursue a sleep study and find out their AHI, etc.

Maybe he could fill out an Epworth quiz?

Oximeter would be a good screening too as long as the limits are understood.
If there are significant desats then obviously there is a strong likelihood of sleep apnea
BUT
Not everyone will have significant desats with sleep apnea so it could be a false negative thing.
It wouldn't necessarily mean no sleep apnea...it just means no significant desats.

I have a friend with an AHI of 66 prior to cpap... her lowest O2 desat was only 94%.

That's how I finally realized I had sleep apnea. I was in the hospital and they were shocked how low my oxygen went while sleeping. They ordered me to get a sleep study. Of course, if I had listened to my husband, I would have been diagnosed years ago and may have avoided the heart problem that sent me to the hospital.

Hi Napstress,
Another aspect that I just learned about is the pulse measurement. An apnea event that might not cause a desat might still cause a pulse rise adding sensitivity to your impromptu apnea screening.

One danger is that if you get a negative (which really proves nothing) it might be even harder to get that person into a sleep clinic. Depending on the personalities involved.
Cheers,
Jamis

I think your idea is good. A full sleep test would be better, of course, but an oximeter test is a lot better than nothing. While better for detecting moderate-severe OSA than mild-moderate OSA, an oximeter apparently will detect most OSA. A report on using oximetric data to determine OSA can be found at http://chestjournal.chestpubs.org/conte ... ull#ref-89.

The abstract of one of the studies cited in the above report is copied below.

Abstract

BACKGROUND Polysomnography (PSG) is currently the “gold standard” for the diagnosis of the sleep apnoea hypopnoea syndrome (SAHS). Nocturnal oximetry (NO) has been used with contradictory results. A prospective study was performed to determine the accuracy of NO as a diagnostic tool and to evaluate the reduction in the number of PSGs if the diagnosis of SAHS had been established by this method.

METHODS Two hundred and seventy five patients with a clinical suspicion of SAHS were admitted to undergo, in the same night, full PSG and NO. Desaturation was defined as a fall in the haemoglobin saturation level (Sao 2) to lower than 4% from the baseline level and an oxygen desaturation index per hour (ODI) was obtained in each patient with three cut off points: ≥5 (ODI-5), ≥10 (ODI-10), and ≥15 (ODI-15).

RESULTS SAHS was diagnosed in 216 patients (194 men). After withdrawing patients with abnormal lung function (forced expiratory volume in one second (FEV1) lower than 80% predicted), sensitivity (SE), specificity (SP), positive and negative predictive values (PPV and NPV) of NO were: ODI-5 (80%, 89%, 97%, 48%); ODI-10 (71%, 93%, 97%, 42%); ODI-15 (63%, 96%, 99%, 38%). The accuracy for each ODI was 0.81, 0.75, and 0.70, respectively. If NO had been considered as a diagnostic tool and PSG had been performed only in patients with a negative NO (false negative and true negative) and those with a positive NO and abnormal pulmonary function tests, 135/275 (ODI-5), 156/275 (ODI-10), and 170/275 (ODI-15) PSGs would have been performed, a reduction of 140, 119, and 105, respectively.

CONCLUSION Nocturnal oximetry in patients with suspected SAHS and normal spirometric values permits the institution of therapeutic measures in most patients.

Thanks for your responses, all.

Pugsy wrote:Not everyone will have significant desats with sleep apnea so it could be a false negative thing.
It wouldn't necessarily mean no sleep apnea...it just means no significant desats.

I have a friend with an AHI of 66 prior to cpap... her lowest O2 desat was only 94%.

But isn't the 02 desats the main problem? Is it the microarousals or the resulting 02 drops that lead to stroke, heart attacks, etc.? If the oximeter shows no significant desats, then there's no problem, right?

Hi Napstress,

But isn't the 02 desats the main problem? Is it the microarousals or the resulting 02 drops that lead to stroke, heart attacks, etc.? If the oximeter shows no significant desats, then there's no problem, right?

It is the desats that causes much of the organ damage. But it's the arousals that interrupt sleep and prevent a person from getting good restorative sleep. No rem sleep makes people behave strangely. Car accidents from nodding off, poor memory and focus, and on and on. Many things can go awry even w/o desats. Both issues are important.

The study that was posted above makes it clear that oximetry doesn't pick up all OSA cases and sleep study is needed beyond that. In short arousals can occur w/o visible desats.

Sorry if that was meant for Pugsy...so does that explain it?
Jamis

Ditto to what Jamis said and let me add this.

Just because the oxygen levels in the blood stream don't drop dramatically doesn't mean that stress is not occurring to all the major organs.

If that was the only criteria then there would be no need for PSG sleep studies.. we could all wear a little oximeter and be diagnosed with that alone.

My friend that has an AHI of 66....that is more than one a minute average...her O2 levels only went from a baseline of 97 or 98 down to 94...trust me she feels just as crappy as I did when mine went to 73%. She still had to get up and pee 5 or 6 times a night...that tells me the heart was stressed and producing that stress hormone which tells the kidneys to go into over drive.

There is much more to sleep apnea than oxygen levels alone.

napstress wrote:But isn't the 02 desats the main problem? Is it the microarousals or the resulting 02 drops that lead to stroke, heart attacks, etc.? If the oximeter shows no significant desats, then there's no problem, right?

Good question, what else does apnea do?

Apnea can disturb your sleep, which might cause lots of problems. Even if you don't wake up, you may not sleep deeply enough, or not get the right kind of sleep.

There's a lot of stress when you can't breathe in your sleep. I assume an apnea will make your heart race, cause you to pump out adrenaline, etc. I think it does a lot of things to your body chemistry. There might be some brain effects from the stress, too.

It can cause GERD as your lungs and diaphragm try to force some air past your throat.

What other things can apnea without desaturation cause?

Thanks, everyone. Your responses make a lot of sense and have been really helpful.

An aside to archangle: Is your new avatar the offspring of your previous one? And is that a tortilla the puppy is wrapped up in?

Nope, not an offspring, just a cute picture I saw on ihasahotdog.com or squee.icanhascheezburger.com/.

Yes, I presume it's a tortilla.

Anyone else remember "Pup N Taco" restaurants?