Poll: What is worse - AHI, or the lowest recorded oxygen level?
AHI - Higher Apnea Hypopnea Index (number of apneas and hypopneas per hour)
Lowest recorded Oxygen level (O2)
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What's Worse -O2 Level, or AHI?
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Krull Offline

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Post: #1
What's Worse -O2 Level, or AHI?
I understand that apnea is classified mild moderate or severe based on the number of events. However, my doctor told me I was moderate based on events (22.6/hr) and severe based on O2 level dropping below 80 (lowest level was 77 during the study). So he classified me as "severe". And I was prescribed BIPAP, with a 15/10 setting.

I posted that on a forum, and someone mentioned they had not heard of the O2 level rating making it severe.

Anyhow, since my mother has severe sleep apnea based on her events (33/hr) I recommended my older sister get checked. She did, and she was worse - at 49 events/hr, so she was classified as severe as well.

HOWEVER, both my mother and sister's lowest O2 level was 89, and they only need 8psi setting CPAP.

So that made me want to better understand - which situation is really worse, and why? Is it worse to have more events per hour, but perhaps they don't last very long (which means the O2 level doesn't drop much), or is it worse to have less events but the ones you do have last longer and therefore your O2 level drops a lot? Hypoxia is a dangerous condition. Without oxygen, your brain, liver, and other organs can be damaged just minutes after symptoms start.

To me, it would seem like O2 level would be a hugely important factor in determine whether one has mild, moderate or severe sleep apnea. Going down to 77 would seem a lot worse from a health impact perspective than dropping to 89.

Any thoughts? Any supported studies to back them up?

If anyone knows how to add a Poll, please add it to this - it would be interesting to know what everyone thinks.
10-17-2015 07:10 AM
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drgrimes Offline

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Post: #2
RE: What's Worse -O2 Level, or AHI?
Krull, i'm not the expert but i would tend to agree with you. Seems like all of this cpap stuff has a purpose of providing oxygen to your brain. Looks to me like having the lowest O2 level of 89 is barely a factor. Isn't anything below 88% supposed to be the redline?

I purchased one of those recording O2 devices. Have experimented with it several times to really verify if cpap was making a difference. Recently i tried a couple of nights with no cpap, then with cpap, and using the O2 recoreder. It was obvious that cpap was keeping me up in the 90s. Without, i was dropping down into the lower 80s.

I think there is, or should be a direct correlation between AHI and O2, but to me, the O2 level is the ultimate goal of cpap.

Truth be known, i would wager that a very high percentage of "normal" people have O2 levels that fluctuate a bit below the 88%.

I have noticed some on this forum have self diagnosed OSA due to not having insurance. Seems like the O2 recorder would be an easy and inexpensive way to verify the problem for people who cannot afford the sleep study.
(This post was last modified: 10-17-2015 09:43 AM by drgrimes.)
10-17-2015 09:40 AM
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OpalRose Offline

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Post: #3
RE: What's Worse -O2 Level, or AHI?
I'm not sure how to answer your poll. Some folk never have a drop in Oxygen levels during their sleep study.

My levels did drop to 69% with an AHI of 33, which explains why I was so foggy all the time.

One is not worse than the other unless you go untreated. Once on successful CPAP therapy, your oxygen levels should be ok during sleep. If not, your doctor should add oxygen therapy.

Occasionally, I use an overnight finger oximeter to make sure all is well.

Being oxygen deprived is serious, and that's why I don't understand some who fight this therapy and give up.







OpalRose
10-17-2015 11:27 AM
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PoolQ Offline

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Post: #4
RE: What's Worse -O2 Level, or AHI?
My first test was 29 events and O2 not below 92. The number of events alone can do damage and really mess up your sleep. I have had two low points: one was only sleeping 2 hours a night and the other was not sleeping longer than 30 minutes at a time all night-O2 was always fine. Believe me that this type of sleeping is quite bad and has a major impact on your life.

On the other hand, having low O2 is quite bad also.

Sleep Apnea is complex and can get very complex. Everybody reacts differently to different levels of apnea. Some people you could hit with a hammer while they sleep and they would not notice, others like me have to get used to a fan blowing on them at night.
10-17-2015 01:31 PM
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kaiasgram Offline

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Post: #5
RE: What's Worse -O2 Level, or AHI?
(10-17-2015 07:10 AM)Krull Wrote:  If anyone knows how to add a Poll, please add it to this - it would be interesting to know what everyone thinks.

A meaningful discussion has more value than a poll.

And, you're asking an "either/or" question which forces an artificial and unhelpful distinction between O2 sats and AHI.

I think most of us, including your wise doctor, already understand that even though the official accepted diagnostic criteria for severity is AHI, to understand the real impact of sleep-disordered breathing both O2 sats and frequency of events -- and for that matter even sleep fragmentation due to increased respiratory effort -- must be factored in to get a complete picture of severity.
(This post was last modified: 10-17-2015 02:40 PM by kaiasgram.)
10-17-2015 02:38 PM
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Sprig Offline

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Post: #6
RE: What's Worse -O2 Level, or AHI?
I am a former medical consultant in the life insurance industry and osa has been a hot topic for several years. I have a certain amount of expertise with this subject. I don't think you can say if ahi or 02 desat is worse. The bottom line osa increases mortality. In assessing mortality risk we look primarily at both ahi and O2 desat. although numerous other factors may be involved. I have never recommend declining a risk based solely on ahi but I have recommended declining risks based on low O2 desat. I am not aware of any data comparing ahi vs. O2 desat. and mortality. If you treat osa and reduce ahi your O2 desat should be reduced thus improving mortality unless you are diagnosed with other pulmonary disease in addition to osa. We do know that the lower the O2 desat whether associated with osa or other pulmonary disease the higher the mortality. I would recommend declining a life insurance applicant with a desat below 60.
If you are being treated for osa and are concerned about O2 desat ask your physician to order a nocturnal oximetry. This is often offered without cost by companies that provide supplemental oxygen to patients.
10-17-2015 04:03 PM
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zonk Offline

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Post: #7
RE: What's Worse -O2 Level, or AHI?
(10-17-2015 04:03 PM)Sprig Wrote:  I am a former medical consultant in the life insurance industry and osa has been a hot topic for several years.

Welcome
10-17-2015 04:08 PM
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PaytonA Offline
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Post: #8
RE: What's Worse -O2 Level, or AHI?
My answer to the question, "What's Worse -O2 Level, or AHI?" is BOTH!!! and lots-o-coffee
10-17-2015 07:43 PM
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DocWils Offline

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Post: #9
RE: What's Worse -O2 Level, or AHI?
The diagnosis of sleep apnoea is made by looking at a number of factors in combination, and anyone who has been tested either in the lab or in a home test will notice that oxymetry is combined with a variety or other monitors to arrive at a conclusion and treatment option. AHi is not sO2sat and vice-versa, and although one is dependant on the other, the level of desaturation is not directly related on a one-to-one basis with the number of hypopnoea events. Rather the severity of an individual event and length of event will determine the O2 desaturation. As such, two people, one with a higher AHI than the other, may find that the pressure settings on the higher AHI to be lower than the other person's, due to the severity of the desaturations of the lower AHI patient. In short, your throat may close more (if you have OSA) even at low AHI levels and thus require higher pressures to keep it open - it all depends on what is driving your SA. This is not something to poll about - it is a simple bit of medical science.

In the case of OSA, to make a simple illustration, you may have a looser or fattier flap in the back of your throat that causes a greater air restriction and as such even though you have fewer events than another person, the events are more severe and your loss of available oxygen is greater than someone who has more events, but lighter events, with only partial closures and more flow limitations but fewer anoxia events, due to greater throat tone.

The mistake people make is to associate AHI solely with anoxia events, when in fact it is a more complex calculation looking at hypopnoeas, flow limitations, length of each, and other factors. As such, numbers can be lower or higher and independent of the severity of individual serum oxygen desaturations. One hypopnoea is not like another.
(This post was last modified: 10-18-2015 05:00 AM by DocWils.)
10-18-2015 04:58 AM
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