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What is Apnea pressure, and how does it occurs.

This discussion is about Apnea and pressure. When I talk pressure it IS NOT xPAP pressure, but the pressure from an apnea and the harms this can do to your health.

xPAP pressure is measured in cmH2O, and pressure inside your body (Blood pressure, intracranial pressure, pressure in your inner ear etc.) is measured in mmHG. In fact the pressure from an xPAP is very small, compared to pressures inside the body.

Let me give an example. A couple of members in another forum have asked if the xPAP pressure could go through the Eustachian Tube to the middle ear. To open the Eustachian Tube the pressure needs to be about 45 mmHG, which is about 61 cmH2O, so an xPAP pressure (at max 20 cmH2O) can’t open the Eustachian Tube. (Except from very few people, who have a dysfunction with an open Eustachian Tube)

In my first post I will explain what happens when an apnea occurs. It is important to understand this, before my next post where I will describe my story about my Menieres diagnosis, and how I got it treated.

Everyone have very much focus on the O2 level in the blood, but in fact there is a condition with SA which is a little overlooked, but can be as severe as the low O2 level in the blood, maybe even worse.

When an apnea occurs then it gives a pressure in the esophageal. With a normal apnea (inspiratory apnea) it will give a negative pressure in the esophageal (Müllers maneuver). This pressure will affect both the BP and the intracranial pressure in the brain (the pattern is the same). In the first place the pressure in the BP and the brain will decrease, and after a few seconds and especially in the end of an apnea, it will increase extremely. Some call it a tsunami effect. The pressure in the brain can increase as much as 70 – 80 mmHG depending on the length of the apnea. The normal pressure in the brain is about 15 mmHG.

Here is a link to an article proving this. This article is made by a Danish scientist. He is a neurologist and also a sleep specialist (maybe the best in the country). He has made a lot of international sleep studies. This article is an older one, but still the one used as a reference in a lot of other international studies (Maybe because the CSF pressure was measured via a lumbar cannula, and I think there today are some ethical rules that don’t allow this, because of the risk.) He is also one who helped me a lot when I need answers, and today he is my new sleep specialist.

Intracranial pressure and obstructive sleep apnea:

http://chestjournal.org/cgi/content/abstract/95/2/279

Most articles about sleep apnea and intracranial pressure only describes the inspiratory apnea. But in fact there are several studies which describe expiratory apneas. This kind of apneas is very common. In fact about 40% of all SA sufferers have this kind of apneas. Most of these expiratory apneas are following just after an inspiratory apnea, but some also have stand alone expiratory apneas.

The main difference between inspiratory and expiratory apneas is that an expiratory apnea gives a positive pressure in the esophageal (Valsalva maneuver). This positive pressure also affect the BP and the intracranial pressure, but much quicker. The increase in the BP and the brain happens in a second or so. There is not a decrease before. The pressure in the brain can increase with up to 90 mmHG.

But another thing about this Valsalva maneuver is that our body is going into a “battle” mode. This is used in the sport medicine. By performing a Valsalva maneuver the body can make up to 70% more force. (It is better than EPO). But the effect is only for a short period. For example in weightlifting they have measured BP up to 400/300, and the brain pressure will increase extremely. This is probably also one reason why we sometimes have seen a young sportsman who gets a stroke.

But in fact we perform this Valsalva maneuver a lot without knowing it. For example we can’t lift heavy things without holding our breath and press. We also perform Valsalva maneuvers when straining, bending over, with forceful nose blowing, in high speed elevators, and even when we are on the toilet and need to press.

We also use this Valsalva maneuver if we have to equalize our ears, for example in a flight. Then we can close our nose with our fingers, and press so the pressure in our middle ears is equalized (popping the ears).

But why is this important – we are all in treatment with xPAP?

Because sometimes just a single or a few apneas can make harms to our body. So when we are talking apnea and pressure, IMHO the AHI index is not a good measurement to the severity. We also need to know the length of the apneas. A few long apneas can be more severe than a lot of short apneas.

Unlike the O2 level where Hypopneas can be as severe as apneas, then it is only apnea’s that is important when we talk pressure. I haven’t documentation for that, but I haven’t found any studies about Hypopneas and pressure. Also in my own experience it’s also Apneas alone which it’s important.

As mentioned my next post will describe how I got a Menieres diagnosis (after I started my xPAP treatment), and how I got it treated.

I did a lot of research to figure this out, and I also found some other relations between apnea pressure and other conditions. I will describe this in some later posts.

Henning

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My story about Menieres and my treatment.

Before I tell my story, I will give one more link. This link is to a lot of articles about illness in the inner ear. This is articles written by an American Professor of Neurology, Otolaryngology Timothy C. Hain. He is also known as “The dizzy doctor”. There are a lot of articles about Dizziness, Imbalance and Hearing Disorders.

http://www.dizziness-and-balance.com/disorders/index.html

I will mention a couple of these articles later on.

In fact his articles are known all over the world. My own ear specialist uses his articles a lot. (He is an ENT specialized in the inner and outer ear, and a surgeon – I don’t know what his title is). He is also educated in diver’s medicine and in flight medicine. He has also made a lot of international studies especially in the diver’s and flight medicine. He is known as “The dizzy doctor” here in the country. He is another one who helped me with information’s.

First I can tell that I since my teens have had problems with my nose and sinuses. If we look at the sticky in the top of this forum, and a lot of other treads/post I think that nose and sinus problems is the most single standing problem for compliance. Maybe even more than mask problems. It is also well known, that the use of xPAP can worsen this a lot, and can give Eustachian Tube dysfunction.

After I started my xPAP treatment my blood pressure normalized within 2 weeks. But in fact there were many other positive things. I was suddenly fresh in the mornings, I was not tired during the day, and I began to lose weight, in fact I reached my ideal weight.

It gave me a mental surplus. I stopped smoking; I started to run again, so all in all a real success story. I think this is what a lot of new xPAP users have experienced. The only negative was that my nose and sinus problems became worse and worse.

After 3 month on xPAP I had a follow up at my sleep center, and the conclusion was that I was very well treated.

But suddenly one month later, I stood up from bed, and the whole world was turning around and I could not stand on my feet. I came at the hospital at once, and got some examinations. They told me that I had something with my balance (I certainly was fully aware of that). I got some medicine, and they told me that it could be some “virus on my balance nerve”. IMO this is not a real diagnosis, this is more a “wait and see for 3 month, perhaps it goes away by itself”.

Then I contacted a private hospital, and the ear specialist mentioned above. He made a lot of examinations on me (balance tests, hearing tests, nystagmus tests (eye movements), and a lot of other things, and finally an MRI scanning. He also sends me to a neurologist). After 6 months and all tests taken 3 times to see if there were any changes, he found that I had great problems with my balance nerve, Vertigo, nystagmus and tinnitus (ringing in the ears), and I got a Menieres diagnosis. (In my right ear).

A Menieres diagnosis is an exclusion diagnosis, but normally there will be Vertigo, dizziness, tinnitus and in most cases hearing loss. I had it all except from hearing loss. There is an article about Menieres at the link above.

At that time I could not work at all, and he offered me a reference to early retirement. I am self-employed, so I would then be forced to sell my business, which I did not want to, so I refused.

At this time I began to think of it had something to do with my SA, especially because my vertigo always came when I stood out of bed. My dizziness was there all the time, and my balance was very poor, and my tinnitus got worse and worse.

I made a few searches, and found in an hour or so an interesting article from Dr. Hain. This is an article about Perilymph Fistula (PLF). In this article I found this passage:

“A closely related condition is "alternobaric vertigo". Here dizziness is associated with a difference in pressure between ears. This condition remains difficult to document. Some patients with sleep apnea on CPAP may have vertigo due to this mechanism.”

I could not get contact to this doctor, so I started to read about “alternobaric vertigo”. This is not an illness but more a phenomenon. This phenomenon is very known by divers, and occurs when you have one blocked Eustachian tube. (This is a tube from the back in your nose to the middle ear. This tube is used to equalize the pressure in the middle ear to the pressure outside your body). But if the pressure difference between the two ears (the middle ear) exceeds 45mmHG then this phenomenon occur.

This can happen when you are diving with a blocked Eustachian tube. So NO divers will go and dive if they have a Eustachian tube dysfunction. Some divers are drowned because of this phenomenon. But I found out that it was easy to test. I could just perform a forced Valsalva maneuver, and if there is a blocked Eustachian tube this phenomenon will occur.

I tried that, and I immediately got a Vertigo attack, I could not stand on my feet. There was absolutely no doubt, this was what I have experienced. (But take care, if you try this, because if the pressure is too high it can give a Perilymph Fistula (a leakage in the two windows between the inner ear and the middle ear).

So I made a new appointment with my ear specialist. He knows this phenomenon very well, and in fact at my first meeting with him, he had asked me if I had dived.

But he could not see any connection between SA/CPAP and alternobaric vertigo (he don’t know anything about SA), but he recognized that the symptoms could be alternobaric vertigo, and furthermore he told me that a total blocked Eustachian tube can give a high negative pressure in the middle ear and give ear pain and dizziness.

So he/we decided to put an ear tube into my ear drum. Within an hour the half of my dizziness disappeared, and I have never experienced Vertigo attacks since.

I had a new balance test done, and my balance was still very poor, and I was still dizzy. My tinnitus was the same, but my Vertigo was gone. He then changed my diagnosis to “Atypically Menieres”.

I could now work a little, but from here my searching for an answer took a very long time, so I will just give the conclusions.

What was happened is that I have expiratory apneas (probably single standing). This kind of apneas my AUTO CPAP can’t manage, because there is no snoring or change in airflow before these apneas. So when an apnea occur the CPAP machine is just waiting until the apnea release, and then it will set up the pressure. This increased pressure stay for about 20 minutes before the machine set down the pressure again. It opens up for 3 apneas / hours. But my AI was not 3.0 (Normally less than 1.0), so it was probably only when I was sleeping on my back.

In the link to Dr. Hain there is an article about “Pressure sensitivity of the ear”, and here I found my finally answers.

There are two of the mentioned conditions of pressure sensitivity to the ear which is interesting here:

“An example of dizziness induced by inner ear pressure changes might be dizziness associated with the Valsalva maneuver. This is a straining maneuver that increases pressure in the spinal fluid and inner ear Perilymph space.”

“An example of dizziness induced by middle ear pressure fluctuation is "alternobaric vertigo" -- such as occurs in people who can "clear" one ear, but not the other.”

As mentioned in my first post of this topic, an expiratory apnea gives a Valsalva maneuver, and can give a very high pressure to the spinal fluid and from there through the Cochlear Canal to the Perilymph space. There are some very individual delays, depending on the opening in the Cochlear Canal, and the length of the apnea. With these repetitive changes of the pressure in the inner ear, the inner ear can be very sensitive. But this is probably also very individual. So here is also an explanation of why not all get into this condition.

The Valsalva maneuver can also give a big pressure to the middle ear and give alternobaric vertigo (IF the obstruction is above the Eustachian tube, AND you have a Eustachian tube dysfunction).

My problem was that only a few apneas could affect my ears.

So when I had realized this, the solution was straightforward. I set up my minimum pressure of my AUTO CPAP, and within a week my dizziness was completely gone, and my balance was normalized. (Maybe this is also a good reason to decrease the window when on AUTO CPAP. But I think that a lot of users on AUTO CPAP have a large open window at 4 – 20 cmH20).

Two month later I had a new balance test done, and it shows that my inner ear was completely normal. Today my tinnitus is also disappeared (It took a long time).

But now I got another problem. My nose could not tolerate this higher pressure, so it swells up, and I have to set my minimum pressure at a higher level again. I was in a vicious circle. I made a temporarily solution by fixating me on my left side when sleeping, so I could set down my minimum pressure. But this solution was not optimal. Just a few apneas a night and I got dizzy.

Furthermore it took a long time to find an ENT surgeon that understood my problems, or even would listen to me. When I started to talk about intracranial pressure they seem “to look at the moon”. But they had very much focus on my uvula and my soft palate. But I knew that my obstruction had to be above my Eustachian tube.

But after a long time I found an ENT surgeon who knows a lot about SA, and had the time to listen to me. She even told me that it was my nose there was my problem. (After she has looked into my nose and throat). She is also one of the few in the country that performs coblation on the turbinate’s. So I think I was lucky to find this surgeon. I got a sinus surgery and a coblation on my turbinate’s.

Today my expiratory apneas are disappeared, and I will have a new sleep study done in January.

So in fact if I had got my nose "opened up" from the beginning, I would have avoided all these problems.

This story shows how a combination of several things wide across several medical specialties can develop into a serious situation.

It also shows that we need, that various medical specialties can work together on a common solution for the patient. And sometimes the solution can be very simple.

Occasionally I still think that today I could sit here as retired, because of a lack of knowledge.

Henning
I have a friend that suffers from Menieres. I am going to share your info with her.
SA and vestibular (inner ear) disorders in general.

As you probably have noticed, I have a lot of focus on expiratory Apneas (because of the Valsalva effect).

But actually inspiratory Apneas (Normally apneas) can give dizziness and other disorders in the inner ear as well.

This requires only that the Apneas last longer.

If you read my second post in this discussion, you can find a link to an article about "Pressure sensitivity of the ear." Here you can read about how the intracranial pressure can give a very sensitive effect to the inner ear.

There are some factors that can influence on this, such as the delay in the Cochlear Canal. There is no way to measure this. But there is a single study" (on pigs), who demonstrated that there is a delay of approximately 10 seconds. But it is very individual. As mentioned in my first post there is also a delay before the intracranial pressure increases. Finally there is probably great individually differences in the sensitivity of the inner ear.

From my search I found a small study from the Pacific Sleep Program. This is a study about Perilymph Fistula PLF (leak in the two windows between the inner and the middle ear). PLF disorders are often initially treated with bed rest, minimizing the pressure fluctuations that may prevent spontaneous closure.

But in some cases the PLF will not close spontaneous, and then operative closure may be a solution, often with a poor outcome.

In the discussion area of this study I found two very interesting passages:

“F. Owen Black, MD, a local neuro-otologist with a special interest and expertise in PLF syndrome, has concluded that one important reason for the failure of spontaneous closure or operative intervention is sleep apnea syndrome. The association is so strong that individuals with this vestibular disorder, and in whom sleep apnea is also suspected, undergo expedited evaluation and treatment for their sleep apnea before primary, corrective vestibular intervention.”


“It is important to add vestibular disorders to the growing list of medical conditions affected by sleep apnea syndrome. A growing number of patients are being seen by the Pacific Sleep Program who has other vestibular disorders, particularly Menieres syndrome. When they also have sleep apnea, its correction has been followed by improvement in the vestibular disorder. This suggests a broader impact of obstructive apnea on vestibular function and disorders. In addition, it is important that both sleep medicine professionals and clinicians providing care to patients primarily for their vestibular disorder recognize the importance of this relationship.”

Here is a link to this study:
http://www.sleepreviewmag.com/issues/articles/2001-07_08.asp

I think we will see more studies showing this correlation in the future.

Henning
SA and eye disorders.

A high pressure tends to find the weakest point, just asks your plumber.

From the brain, there are two obvious places to where an elevated intracranial pressure can influence. To the inner ear and to the eyes. In rare cases, it may also cause a leak to the nose.

I found a recent article from ENToday (2007), where they describe correlations between OSA, increased intracranial pressure and eye diseases such as glaucoma, nonarteritic anterior ischemic, optic neuropathy, visual field defects, papilledema, and more.

They suggest further investigations.

In the end of the article you can read:

“But it is possible that otolaryngologists and ophthalmologists may find themselves working together a bit more in the future.”

Link to this article:
http://www.entoday.com/pt/re/entoday/fulltext.01265117-200706000-00...!-234910483!181195629!8091!-1?index=1&database=ppvovft&results=1&count=10&searchid=1&nav=search

From this link, you can choose the full article in PDF

Here is a link to another article. This is an article from November issue of Mayo Clinic. Here at least Papilledema is associated with OSA and increased intracranial pressure.

Link to this article:
http://www.marketwatch.com/news/story/Eye-Conditions-Linked-Obstruc...

so there seems to be a clear correlation between SA, increased intracranial pressure and eye disorders.

But also here I think we will see more studies in the future.

Henning
You beat me to it! Good for you, Henning. I was going to mention they are finding a correlation between OSA and glaucoma, etc. Thank you so much for sharing all of this information!! You are truly an asset to this forum and I wish lots of good luck at your next sleep study!! Do be sure to let us know your results. And I have to point out how important it can be to listen to our bodies, have faith in ourselves and advocate for our own health care and insist on being a partner w/our medical professionals in managing our healthcare.

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