why is less than 5 AHIs the magic number?

idamtnboy · Post by **idamtnboy** » Thu Nov 04, 2010 8:49 am

jlk wrote:Hey, are we talking 5 per hour or 5 per night?

5 average per hr. If you sleep 8 hrs and have 8 apneas during one particular hr your avg is 1/ hr. If that's the only apneas you have during the night there probably is something unusual happening during that one hr. Probably nothing to be concerned about unless there is a repeating pattern. As long as the apneas are random and average less than 5, or whatever lower # leaves you feeling refreshed in the morning, you have nothing to worry about.

Gerald · Post by **Gerald** » Thu Nov 04, 2010 9:31 am

Evan.....

Apnea and Hypopnea is sort of like the torture "Waterboarding".....which is really slow motion "suffocation".

"Suffocation" means that our blood saturation level of O2 is dropping below where it should be for good health.

Through experimentation, I've found that I have to keep my AHI below 2.5 or I don't get enough O2 in my bloodstream.

So now.....what is the correct O2 level supposed to be?

The general consensus seems to be that the O2 saturation level should be 93% or above....measured by an Oximeter.

Many of us use Recording Oximeters to check the effectiveness of our CPAP machines....rather than depend on "feel".

Remember......your O2 saturation level while sleeping is the real problem......measure it......and keep it at 93% or above while sleeping.

Here's a link to the Recording Oximeter I use. It's a good tool....and the software that comes with it is good too!

http://www.turnermedical.com/SPO_PulseO ... imeter.htm

Gerald

HoseCrusher · Post by **HoseCrusher** » Thu Nov 04, 2010 10:29 am

I am not sure what the relationship is between what the xPAP machine reports as AHI and O2 saturation.

For example, last night I had an O2 level of 97% with desaturations down to 92% and a reported AHI of 10.1. Go figure...

AHI determined during a sleep study has significance. AHI reported by the machine is only based upon one parameter, air flow, and is interesting and is a way to trend what is going on, but I am not sure how significant it is.

DHC · Post by **DHC** » Thu Nov 04, 2010 2:21 pm

HoseCrusher wrote:I am not sure what the relationship is between what the xPAP machine reports as AHI and O2 saturation.

For example, last night I had an O2 level of 97% with desaturations down to 92% and a reported AHI of 10.1. Go figure...

AHI determined during a sleep study has significance. AHI reported by the machine is only based upon one parameter, air flow, and is interesting and is a way to trend what is going on, but I am not sure how significant it is.

>>AHI determined during a sleep study has significance. AHI reported by the machine is only based upon one parameter, air flow, and is interesting and is a way to trend what is going on, but I am not sure how significant it is.<<

Given that the manufacturers are not terribly (or at all) forthcoming with their AHI scoring algorithms, and that ResMed clearly manipulates its algorithm from one generation of machine (S8) to the next (S9) to achieve LOWER AHI scores, it seems fair to conclude that home-based AHI scores are; (a) not comparable from one manufacturer's machine to another (i.e. ResMed to Respironics), (b) in some cases not comparable from one generation of machines to another for the same manufacturer (ResMed S8 to S9), and (c) probably not comparable to the scores produced in a PSG.

As you stated, the only real value of the home-based AHI is for trending.

idamtnboy · Post by **idamtnboy** » Thu Nov 04, 2010 3:02 pm

Gerald wrote: Remember......your O2 saturation level while sleeping is the real problem......measure it......and keep it at 93% or above while sleeping.

Unequivocally? I wonder. My first step in the diagnosis process was to use an oxygen monitor for one night during sleep. As I recall my O2 level didn't drop below 93%, if even that low. I remember thinking something along the lines of, "Hmm, my oxygen level seems to be pretty good. Why does the doc think the sleep study is needed?" The reason the Dr. said to go for the sleep study, I think, is because my O2 level fluctuated, not because it dropped low. But I could be wrong. I didn't ask for a copy of the results to bring home, and I wasn't offered one. The sleep study showed I had 35+ events/hr and never went into deep sleep. My understanding is there are other consequences from apnea events, not just low O2, that can be dangerous or fatal.

All I know is I don't have near the sleepy feeling during the day or early evening that I used to have. Mid day naps are only half as long, and I can actually get along quite well without them!

rested gal · Post by **rested gal** » Sun Jan 09, 2011 1:53 am

viewtopic.php?p=511023#p511023

On page 3 of that topic:

-SWS wrote:This excerpt from Promise of Sleep describes how Stanford sleep medicine pioneers William Dement and Christian Guilleminault devised an AHI-of-5 as the original apnea/hypopnea clinical cut off in 1973:
William C Dement in [i]PROMISE OF SLEEP[/i] wrote:In 1973 Christian Guilleminault and I proposed the measure that is still used for the clinical definition of sleep apnea and for rating its severity. We called it the Apnea/Hypopnea Index (AHI). Hypopnea is the term we use when the throat doesn't quite close entirely, but air flow is reduced sufficiently to lower oxygen and cause an arousal. The AHI score represents the average number of Apnea and Hypopnea episodes that a patient has during an hour of sleep. We decided that an AHI of 5 should be the lower limit for making a diagnosis of apnea, so a score of less than 5 (breathing stops fewer than 5 times per hour) is considered too low for clinical diagnosis and doesn't require treatment. However treatment may be necessary if a patient has an AHI of 5 to 10 with other signs or symptoms of apnea such as daytime fatigue or high blood pressure. Although not all my colleagues agree, I feel strongly that people with an AHI of 10 to 20 should definitely consider treatment, even if they are not feeling sleepy during the day. In my opinion, anyone with a score over 20 should always be treated - they will soon have a serious, life-threatening problem."
Sleep medicine and Medicare still adhere to Dement's and Guilleminault's AHI-of-5 as clinical cut-off criterion to this day.

Below is a recap of one classic debate between doctors Sullivan and Rapoport, two sleep medicine legends in their own right. They argue AHI's usefulness as an apnea/hypopnea severity marker in the year 2002: http://www.pulmonaryreviews.com/sep02/p ... Index.html

why is less than 5 AHIs the magic number?

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