Confused about diagnosis

[Txracer]

According to my sleep study results my AHI was 3.4, RDI was 44.8 and arousal index is 74.5.

Sleep efficiency is 25%. 35% of sleep time in N1, 58% in N2, 7% in N3, and 0% in REM sleep. SpO2 only dropped to 91%.

Diagnosis is severe OSA and periodic limb movements of sleep. Can anyone explain a low AHI but a diagnosis of severe OSA?

[reolhlains]

Hey Txracer
Your results are pretty similar to mine - my AHI was below 5, my RDI was 23.5 I think. What it's saying (I think, and I am new and there are people here with a lot more knowledge than me) is 23.5 events triggered, not quite long enough for an aponea event, but a restricted breathing event none the less.
Have a look at what your AHI was specifically in REM sleep if you have that - you might find that pushes you above an AHI of 5 during that phase.
I tried various things for 18 mths or so after my sleep study - it was only when I tried CPAP that my life literally changed.
Good luck with it all - I'm sure you'll get plenty of advice here (that'll no doubt shut down my comments!).

[BlackSpinner]

RDI was 44.8

The diagnosis is about MORE then AHI.
AHI is just one of the criteria.

That is why it is now called "sleep disordered breathing"

[Txracer]

Ok. That makes sense. I was just looking at AHI because that's all I see people measuring and discussing on here.

[Pugsy]

RobySue goes into the arousal index explanation a bit in her blog about the sleep study results.
It may help clarify things for you.
http://adventures-in-hosehead-land.blog ... -test.html
So there's a lot more to all this stuff than just AHI but AHI is what we can accurately measure on our machines to help us evaluate our therapy. So we tend to talk about it more.

If AHI was all there was to it this whole cpap therapy would fix all of us easily but unfortunately there's so much more to sleep sleep disordered breathing than just plain Obstructive Sleep Apnea with nice easy to fix AHI numbers. The best AHI in the world doesn't guarantee feeling great.
I wish it were that easy because it's relatively easy to get "good numbers"...but not so easy to feel those "good numbers".

When you get your machine (and make sure to get a full efficacy data machine) your AHI isn't going to be a good marker to evaluate effectiveness because it is already low. Unfortunately these machines can't really measure arousals all that accurately but some will at least try with RERA flagging (respiratory event related arousal). You are going to need to realize how you feel is going to be real important and that's going to be difficult to measure by conventional numbers. It make take a bit of trial and error to get you feeling good because the usual markers for effective therapy aren't going to help you much. It can be done though and it's well worth it.

[kteague]

What kind of numbers did they give you on those periodic limb movements and their arousals? If your limb movement arousals are significant they can mask apnea events, possibly mean your OSA events are underrepresented in the study.

[greatunclebill]

What kind of numbers did they give you on those periodic limb movements and their arousals? If your limb movement arousals are significant they can mask apnea events, possibly mean your OSA events are underrepresented in the study.

exactly right. if the apnea is questionable, they should get the leg thing under control, then retest for the apnea.

[OkyDoky]

AHI includes apneas and hypopneas. Apneas can be either obstructive or central. Apneas are defined as air flow stopping or significantly decreased for at least 10 seconds. Hypopneas are a 40 = 50% reduction in air flow.

RDI (Respiratory Disturbance Index) includes apneas, hypopneas and RERAS. RERAS are:
Respiratory Event Related Arousal... a sequence of breaths characterized by increasing respiratory effort leading to an arousal from sleep, but which does not meet criteria for an apnea or hypopnea.”

RERA Detection in the Respironics System One data..Respiratory effort-related arousal..defined as an arousal from sleep that follows a 10 second or longer sequence of breaths that are characterized by increasing respiratory effort, but which does not meet criteria for an apena or hypopnea. Snoring, though usually associated with this condition need not be present. The RERA algorithm monitors for a sequence of breaths that exhibit both a subtle reduction in airflow and progressive flow limitation. If this breath sequence is terminated by a sudden increase in airflow along with the absence of flow limitation, and the event does not meet the conditions for an apnea or hypopnea, a RERA is indicated.


Respiratory Disturbance Index is a better indicator of overall sleep disturbance and some look to it as a better indicator for treatment need. Yet most insurances and medicare may still use the AHI only. This is a quote from the following linked article:
No universal consensus exists on whether the AHI or the RDI should be the standard index used to determine treatment by specialists and insurance carriers, with Medicare being the most confusing as it varies by region as to whether AHI and RDI can be used. This needs to be resolved as soon as possible. One study found that 30% of symptomatic patients would have been left untreated if the AHI were used rather the RDI. http://emedicine.medscape.com/article/2 ... fferential
Here is a link to a Sleep disorder Glossary. http://sleepyhead.sourceforge.net/wiki/ ... r_Glossary

I also agree that the PLM's may be masking your apneas. The bottom line is you do need treatment.