I would like feedback on my sleep study results - am due to go back next week for CPAP titration:

TIB Minutes: 429.5
TST Minutes: 393
Sleep Efficiency: 91%
Apneas: Count 158, Index 24.1 (know this means I'm trying/working hard to breathe)
Hypopneas: Count 366, Index 55.9 (is this what my doctor means, I stop breathing roughly 1x/minute?)
AHI Index: 80
RDI Index: 80
Ar + Aw: Count 552, Index 84.3 (not sure what this is)
Min SpO2: 77

Total event classification breakdown:
Central: Apneas 17 (NREM)
Mixed: Apneas 17 (NREM), 1 (REM)
Obstructive: Apneas 96 (NREM), 27 (REM); Hypopneas 334 (NREM), 32 (REM)

Event statistics:
Apneas 158, Hypopneas 366, Total events 524



Thank you!

Addition to above statistics:

Minutes %TST (393)
Stage I: 2.5 .6
Stage II: 154.5 39.3
Stage III: 149.5 38.0
REM: 86.5 22.0

REM Latency 96.5 minutes

I'm no pro, just a patient, but as best I understand things:

TIB Minutes: 429.5 Time in Bed 429.5 minutes = 7 hrs & 9 1/2 minutes
TST Minutes: 393 Total sleep time 393 minutes = 6 hrs and 33 minutes
Sleep Efficiency: 91% Surprisingly good given your breathing indexes
Apneas: Count 158, Index 24.1 (know this means I'm trying/working hard to breathe)
Hypopneas: Count 366, Index 55.9 (is this what my doctor means, I stop breathing roughly 1x/minute?) Yup
AHI Index: 80 Number of apneas and hypopneas per hour
RDI Index: 80 Respiratory disturbance index - index means per hour
Ar + Aw: Count 552, Index 84.3 (not sure what this is) I THINK this is Arousals plus Awakenings but am not sure
Min SpO2: 77 Your oxygen supply in your blood went as low as 77% at some point during your sleep study

Total event classification breakdown:
Central: Apneas 17 (NREM) NREM means non-REM sleep, Central apneas occur when your brain "forgets" to tell you to breathe, usually due to the CO2 level in your blood/lungs
Mixed: Apneas 17 (NREM), 1 (REM) REM = rapid eye movement sleep, mixed apneas = apneas that start out as central apneas and become obstructive apneas
Obstructive: Apneas 96 (NREM), 27 (REM); Hypopneas 334 (NREM), 32 (REM) Apneas are a cessation of breathing for a specified length of time or longer, hypopneas are a reduced breathing due to partial obstruction of the airway for a specified length of time or longer

Event statistics:
Apneas 158, Hypopneas 366, Total events 524

Minutes %TST (393) TST = total sleep time
Stage I: 2.5 .6
Stage II: 154.5 39.3
Stage III: 149.5 38.0
REM: 86.5 22.0

REM Latency 96.5 minutes Latency = length of time to achieve

sanctuary57 wrote:I would like feedback on my sleep study results - am due to go back next week for CPAP titration:

TIB Minutes: 429.5
TST Minutes: 393
Sleep Efficiency: 91%

You spent a total of 429.5 minutes physically "in bed" and a total of 393 minutes asleep. The Sleep Efficiency is just the percentage of time you were asleep:

Sleep efficiency = (TST/TIB) * 100%

Apneas: Count 158, Index 24.1 (know this means I'm trying/working hard to breathe)
Hypopneas: Count 366, Index 55.9 (is this what my doctor means, I stop breathing roughly 1x/minute?)
AHI Index: 80
RDI Index: 80

In the 393 minutes you were asleep, you had 158 apneas---you quit breathing for at least 10 seconds 158 times. You also had 366 hypopneas during the night. A hypopnea is where you "almost" stop breathing: The flow of air into your lungs drops significantly for at least 10 seconds (how much depends on the particular lab's scoring rules---there are two common sets of rules that are used) and there is either an associated drop in O2 saturation or an arousal or both.

The AI index (24.1) is the number of apneas divided by the time asleep in hours: 158/6.55 = 24.1 Note: 393 minutes is equal to 6.55 hours since 393/60 = 6.55. The AI is the average number of apneas per hour you had during the night.

The HI index (55.9) is the number of hypopneas divided by the time asleep in hours: 366/6.55 = 55.9 The HI is the average number of hypopneas per hour you had during the night.

The AHI Index is the sum of the AI and the HI: 24.1+55.9 = 80. It represents the average number of apneas and hypopneas per hour you had during the night. Your AHI = 80 means that ON AVERAGE, you stopped breathing (an apnea) or came close to stopping breathing (a hypopnea) about 80 times each hour. That works out to having an apnea or a hypopnea on average about every 45 seconds. [And remember---each apnea and each hypopnea lasts at least 10 seconds---so that means on average there's mightly little time left over for normal breathing going on.]

Ar + Aw: Count 552, Index 84.3 (not sure what this is)

Ar most likely means "arousal" and Aw most likely means "awakening". An arousal is any sudden EEG change from a deeper sleep stage to a lighter sleep stage. It may be related to an apnea, a hypopnea, a leg movement, or it may just be labeled "spontaneous" meaning there was nothing that it was clearly related to. An awakening is a sudden EEG change from any sleep stage all the way to WAKE (if I recall correctly). But most people do NOT remember awakenings unless they are awake for at least 5 minutes or so. Awakenings that are shorter than that are usually not consciously remembered.

So you had 552 arousals and awakenings during the 6.55 hours you were "asleep". The Arousal/Awakening Index is just the number of arousals and awakenings divided by the total sleep time:

arousal/awakening index = (552/6.55) = 84.3

This number means that you were arousing or awakening (going from a deeper sleep state to a lighter one or all the way to WAKE) about 84 times an hour on average. That means that on average you were "arousing" or "waking up" about every 45 seconds. Most of these arousals and awakenings are due to the apneas and hypopneas you had.

Min SpO2: 77

Your minimum oxygen saturation dropped to 77%. Anything less than 90% is a concern.

Total event classification breakdown:
Central: Apneas 17 (NREM)
Mixed: Apneas 17 (NREM), 1 (REM)
Obstructive: Apneas 96 (NREM), 27 (REM); Hypopneas 334 (NREM), 32 (REM)

This is the breakdown of your 158 apneas and 366 hypopneas into types (obstructive, central, mixed) and into when they occurred (REM vs. NREM sleep).

First, a quick clarification: REM sleep is rapid-eye-movement sleep, which is when the most vivid dreaming occurs. NREM (non-REM) sleep consists of Stage 1 (transitional), Stage 2 (light), and Stage 3/4 (deep or slow wave) sleep. Most people have higher AHI numbers in REM than non-REM, but not everybody does. Note that the number of events in REM vs. NREM does NOT indicate which kind of sleep has the higher AHI---you need to know exactly how much sleep time occurs in REM and NREM before you can compute the REM AHI and the NREM AHI.

Central: Apneas 17 (NREM)
So you had a total of 17 central apneas in non-REM sleep and 0 central apnea in REM. A central apnea is when you are NOT breathing for at least 10 seconds AND there is no EFFORT to breath for at least 10 seconds---in other words, there's no air flowing into the lungs AND the belts around your chest and abdomen measure no effort to breath. Hence the upper airway is NOT necessarily blocked in a central apnea. The problem is your brain forgot to send the signal to your diaphragm to "breathe"

Mixed: Apneas 17 (NREM), 1 (REM)
You had a 17 mixed apneas 17 in non-REM sleep and 1 mixed apnea in REM. A mixed apnea is an apnea that has characteristics of both central and obstructive apneas. If I recall correctly, the event starts off looking like a central apnea (no effort to breathe), but at some point the belts start to measure an effort to breath, but there's still no air going into your lungs---indicating the airway is blocked by the time your body is trying to inhale.

Obstructive: Apneas 96 (NREM), 27 (REM); Hypopneas 334 (NREM), 32 (REM)
You had a total of 96 obstructive apneas in non-REM sleep and 27 in REM. An obstructive apnea is when you are attempting to breathe (there is effort to breathe as measured by the belts), but the air flow into your lungs has dropped to essentially 0 for at least 10 seconds. In other words, you've stopped getting air into your lungs because your upper airway has collapsed and is blocked, but your diaphragm continues to try to inhale air through the now blocked upper airway.

You had 334 obstructive hypopneas in non-REM sleep and 32 in REM. An obstructive hypopnea is when you are attempting to breathe (there is effort to breathe as measured by the belts) but the air flow is significantly lower than it should be for at least 10 seconds (it's less than 1/2 of what your "baseline" air flow is if I recall correctly). The diminished air flow with the continued breathing effort is caused by a partial collapse of your upper airway. It's often described as like trying to breathe through a very small straw.

Thanks to both of you, VERY helpful!

Robysue - you said:

First, a quick clarification: REM sleep is rapid-eye-movement sleep, which is when the most vivid dreaming occurs. NREM (non-REM) sleep consists of Stage 1 (transitional), Stage 2 (light), and Stage 3/4 (deep or slow wave) sleep. Most people have higher AHI numbers in REM than non-REM, but not everybody does. Note that the number of events in REM vs. NREM does NOT indicate which kind of sleep has the higher AHI---you need to know exactly how much sleep time occurs in REM and NREM before you can compute the REM AHI and the NREM AHI.

Looking at my report, this is how my event classifications are summarized:

CENTRAL
Count Mean Dur Range Dur
Apneas, NREM 17 17 11-22
Apneas, REM 0 0 0
Apneas, Total 17 17 11-22
Hypopneas, NREM 0 0 0
Hypopneas, REM 0 0 0
Hypopneas, Total 0 0 0

MIXED
Count Mean Dur Range Dur
Apneas, NREM 17 19 11-30
Apneas, REM 1 22 22-22
Apneas, Total 18 19 11-30
Hypopneas, NREM 0 0 0
Hypopneas, REM 0 0 0
Hypopneas, Total 0 0 0

OBSTRUCTIVE
Count Mean Dur Range Dur
Apneas, NREM 96 19 11-50
Apneas, REM 27 27 10-57
Apneas, Total 123 21 10-57
Hypopneas, NREM 334 19 11-56
Hypopneas, REM 32 39 18-109
Hypopneas, Total 366 21 18-109

I'm not sure how to interpret Mean Duration and Range Duration for the above.

Thanks for your help.

I never have been able to explain or even truly understand the difference between "mean" and "average" but they are NOT the same thing.

Range duration would be the highest and the lowest.

sanctuary57,

As CrohnieToo hinted at in her answer, there are different kinds of averages. Let me see if I can explain the meaning of the two "averages" that are listed in your sleep report.

I've already explained the indices. Recall, the AHI is the computed as follows:

AHI = (total number of apneas and hypopneas you experienced)/(time you slept)

So the AHI represents the average number of apneas and hypopneas you were experiencing per hour while you were asleep. It's important to realize that your body doesn't have a little stop watch that says "45 seconds---time to have another apnea/hypopnea!" Instead---it's likely that at some points in the night you had several minutes between apneas and at other points you had an apnea and five seconds later you had another apnea right on top of the first one.

So average in the sense of the AHI is in the context of the average rate---it answers the question: How many events per hour on average?

Now in your last post, you add data that was at the end of your sleep report and it contains the mathematical word mean, which also means "average" if you look it up in a dictionary. The data you add includes data about mean duration of events.

The mathematical mean of any set of data is found the same way:

Mean = (Sum of all the data values)/(number of data values in the set)

You may recognize this formula as what you (as a typical non-math person) thinks of as "average" for things like computing the "average test score" a class earned on a particular (math) test for example.

Since the data we are looking at is the length of each apnea and hypopnea, we compute the mean duration as follows:

mean duration = (Sum of the lengths of events of given type)/(number of events of the given type)

And the meaning of the numerical value of mean duration is the "average length" of the an event of the given type. In other words, mean duration answers the question, How long does each event last on average?

So now lets actually look at YOUR number and see how this works in practice.

Looking at my report, this is how my event classifications are summarized:

CENTRAL
Count Mean Dur Range Dur
Apneas, NREM 17 17 11-22
Apneas, REM 0 0 0
Apneas, Total 17 17 11-22
Hypopneas, NREM 0 0 0
Hypopneas, REM 0 0 0
Hypopneas, Total 0 0 0

Of the 17 central apneas you had during the sleep study, all of them occured in NREM and they lasted from 11 seconds long to 22 seconds long---that's the info in the Range Dur---short for "duration"---column

The mean duration of those central apneas was 17 seconds in length. Now mean here means "average" in one of the mathematical meanings of average. To compute the mean duration of the central apneas, this is what the lab did:

Add together the lengths of ALL 17 central apneas and then divide by 17-the number of data points.


Continuing on:

MIXED
Count Mean Dur Range Dur
Apneas, NREM 17 19 11-30
Apneas, REM 1 22 22-22
Apneas, Total 18 19 11-30
Hypopneas, NREM 0 0 0
Hypopneas, REM 0 0 0
Hypopneas, Total 0 0 0

Of the 18 mixed apneas, 17 occurred in NREM and 1 occurred in REM. The 17 NREM mixed apneas ranged in length from 11 seconds to 30 seconds long. The mean length was 19 seconds. Remember:

mean = (Sum of the lengths of the NREM mixed apneas)/(number of NREM mixed apneas) = 19 seconds long.

So the "average" length of a NREM mixed apnea was 19 seconds.

The one REM apnea lasted 22 seconds. Note the "mean" equals the length here because the mean is computed as follows:

mean = (Sum of the lengths of REM mixed apneas)/(number of REM mixed apneas) = 22/1 = 22.

And here's the Obstructive data:

OBSTRUCTIVE
Count Mean Dur Range Dur
Apneas, NREM 96 19 11-50
Apneas, REM 27 27 10-57
Apneas, Total 123 21 10-57
Hypopneas, NREM 334 19 11-56
Hypopneas, REM 32 39 18-109
Hypopneas, Total 366 21 18-109

We'll pick this one apart one line at a time, but at this point you may be able to do it for yourself. (TRY!)

Apneas, NREM 96 19 11-50
Number of NREM OAs is 96 and their lengths range from 11 seconds to 50 seconds. The mean (or average) length of the NREM OAs is 19 seconds. In other words,

(Sum of the lengths of the OAs)/(number of OAs) = Sum of the lengths of the OAs)/96 = 19 seconds.

Apneas, REM 27 27 10-57
Number of REM OAs is 27 and their lengths range fro 10 seconds to 57 seconds. The mean (or average) length of the REM OAs is 27 seconds.

Hypopneas, NREM 334 19 11-56
Number of NREM hypopneas is 334 and their lengths range from 11 seconds to 56 seconds. The mean (or average) length of the NREM hypopneas is 19 seconds. Remember that the way that mean was computed was by adding together the lengths of all 334 individual NREM hypopneas and then dividing by 334.

Hypopneas, REM 32 39 18-109
Number of REM hypopneas is 32 and their lengths range from 18 seconds to a whoppig 109 seconds (that's almost two minutes). The mean length of the REM hypopneas is 39 seconds.

Does that help clear stuff up?

robysue, your friendly math prof

Thanks CronieToo and friendly math prof Robiesue (I sucked at math K-12, picked up on it later in life). You've explained things clearly.

What is truly amazing is my sleep efficiency figure being at 91% with such severe apnea/hypopnea. I suppose this is due to the fact whenever I am aroused or awakened, I get right back to sleep.

Sanctuary57

sanctuary57 wrote:Thanks CronieToo and friendly math prof Robiesue (I sucked at math K-12, picked up on it later in life). You've explained things clearly.

You are welcome!

What is truly amazing is my sleep efficiency figure being at 91% with such severe apnea/hypopnea. I suppose this is due to the fact whenever I am aroused or awakened, I get right back to sleep.

Could be. It could also be that most of the time you "aroused" to Stage 1 sleep, which is still SLEEP and not WAKE.

What brings that sleep efficiency figure down fast is STAYING AWAKE when you are awake. Long latency to sleep brings it down. As do any extended WASO (Wake After Sleep Onset) periods. I had a really bad bout of insomnia show up in sleep study three. My sleep efficiency figure was a whopping 28% on that test.

Hi Robysue -

Thanks for the explanation.

Had CPAP titration last Thursday, which included BiPAP testing. Didn't like the latter, turns out CPAP is more suited for me. Don't know the results yet, but did feel TONS better in the morning - as if my brain finally got the oxygen it needed.

Turns out a "full face" (nose/mouth coverage) mask is what I need, and what they had on hand wasn't quite comfortable - both kept pinching the upper bridge of my nose cuz of air leakage, as I have deep-set eyes. Tech recommended I look into the new ResMed Quattro FX which makes sense as I normally do not get headaches and I've had several of these so far cuz of that nose-pinching....

Now it's wait several days for the results and discussion with pulmonary dr. Am SO anxious to get set up equipment-wise!

Sanctuary57

Well, don't be so anxious to get your equipment that you will accept just anything the local DME provider offers you. Be sure to read up NOW on what YOU SHOULD be doing BEFORE you even talk to the first local DME provider so that you get the best equipment for YOU.

1] check w/your insurance what local DME providers they are contracted with. Hopefully you will have the option of more than one
2] shop your various local DME options to see which one you are most comfortable with, has a lenient mask exchange policy, will provide a fully data capable CPAP (provides at least Leak, AHI and AI data) at no extra charge.
3] educate yourself as to which brands and models of CPAP are fully data capable
4] if you see your sleep doctore BEFORE your equipment order is scripted ask him or her to include "access to Leak, AHI and AI data" and "full face, nasal cushion, nasal pillows or oro-nasal mask of patient's choice"
5] request that your equipment order script be given to you so you can shop your DME provider options
6] request a copy of the sleep doctor's dictated results report (1-2 pages) from each of your in-lab PSGs
7] request a copy of the full scored data summary report w/condensed graphs (5+ pages) from each of your in-lab PSGs

CrohnieToo -

Thanks for the detailed guidance, very helpful.

I do have my 1st PSG report - it is four pages with graphs, waiting now for 2nd PSG (CPAP titration) report - expect to talk with my doctor by Wednesday or thereabouts (when we both have the 2nd study report in hand)

Also I've been researching ResMed products online cuz my husband has a S8 Escape, so think I'll request the S9 Elite with all the bells and whistles. Have all the product and HCPCS codes for the device/supplies as well as Quattro FX full face mask et al (assuming I do like it).

Lincare is the DME my husband uses (we are both under Aetna), so suspect my doctor will direct me to them.....

Sanctuary57

Is your husband satisfied w/Lincare? Lincare doesn't always have the best reputation, second only to Apria for being problematic. But there are exceptions w/in individual branches. Why not visit Lincare ahead of time and see just how comfortable you are w/their staff and how helpful it seems they will be before committing yourself?? If you can find another provider who is better, more helpful and more encouraging your husband can always stay w/Lincare or switch, whichever he feels inclined to do.

Hi CrohnieToo -

Thanks for telling me about Lincare/Apria. I'm medically oriented, do my homework, ask questions galore, etc. whereas my husband is not. I know cuz I had to badger him to get a smaller CPAP machine some years ago, insisting he was eligible (he blew up his gigantic monster in Spain by forgetting to change the voltage, ha!). Even told him he was eligible to get parts replacements quite easily. Never mind about him, I'm more concerned about my set-up, smile.

There are three Lincare offices where I live, one is nearby. There are other DMEs accepted by Aetna (not Apria) in my home area however these seem smaller. Will check them out, for sure. One I looked at doesn't even have the Resmed S9 Elite. Makes me wonder about their currency with respect to the latest products and services.

Sanctuary57

Me again....

I've been experiencing tension - all over - headaches since my first PSG and more so since last Thursday's CPAP titration study (haven't gotten the results/talked to my doctor yet) partly because of the upper nose pinch by the first full face mask.

At first I waved off these headaches which occur at all hours of the day. They've worsened and I've not been sleeping well either. I normally do not get headaches (in fact almost never do), so this is strange.

Thoughts, advice?

Sanctuary57