let me try and explain it.

breathing is one of the most important functions of living organisms. therefore we have a very effective "alarm sytem" letting us know that there is some problem with it, long before it becomes a true threat to our life.

when ever we have difficulty breathing, we feel scared (and trust me I have seen amazing machos, they are just as scared, because it is almost an insticnt), and this is the way nature protects us from anything that can jeopardize our breathing.

also this feeling of fear, makes our heart rate go faster, our breathing rate go faster etc.

another word for breathing fast is hyperventilation, and fear from any cause (including anxiety) will cause us to breath faster. so when we have weakness of the respiratory muscles that leads to fear, the first thing we do is breath faster. many times this can lead to an "overshoot", and the CO2 levels will go down just as if we were hyperventilating due to anxiety.

but, as you breath faster (and your CO2 initially goes down), you also make your respiratory muscles weaker (as exertion always worsens MG weakness), and then you can no longer breath faster, so you go from having shallow and fast breathing to shallow and slow breathing, and then your CO2 levels start to rise, as you can no longer move enough air to get rid of it.

this can be a very rapid down hill course, and one way to stop it, is by learning to actively avoid this rapid breathing phase. this is not always possible, because as I said it is an instict, and the worse the weakness of the respiratory muscles is the more you feel this suffocation and the need to breath faster, and then the faster you go down hill.

another, and in my oppinion much better way to stop this, is by providing non-invasive respiratory support as soon as there are early signs of respiratory muscle weakness. and there are studies that show that this can many times lead to the avoidance of the need for intubation.

this is also why I don't like using the word "crisis" as when does the crisis start? when someone is having early respiratory signs, or only when he/she is on the verge of intubation, and why wait for that to happen, if you can recognize it much earlier in a large percent of the patients?

it is also a frightening word that gives you the feeling of some disaster that can happen without any warning signs, and can't be predicted or avoided, and then you may find yourself in the ICU with an endotracheal tube for a very long times, when this is most likely not the case.

MG is a disease of fatiguability of the muscles, and there is no reason why the respiratory muslces should be different in that sense. over exert them, without giving them proper rest on time, can lead to severe and extreme weakness. recognize early signs and rest on time, and more times then not they will gradually recover, just like the muscles of your eyes, arms, legs etc.

at least this is the way I see it. and this has been my own experience, although I do have a fairly unusual form of this illness, so it may be true only for me.

alice