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:
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.