management of myasthenic crisis
 

myasthenic crisis is not a rare complication of MG. It is estimated to occur in 20% of patients and probably much more in MuSK.

I therefore think it is important that patients will know this:

There are more and more studies that show that 70% of patients with myasthenic crisis can be managed with non-invasive ventilation, without the need for intubation.

An important parameter for the success of NIV is the level of CO2 and bicarbonate in the blood.
a level of CO2 above 45 (which is marginally above normal levels for normal people) decreases the success rate significantly. (this goes with what Annie said, regarding CO2 levels in MG, and there is surprisingly sparse data regarding levels of CO2 in patients with MG at baseline).
More important is a bicarbonate of over 30. This means that the patient has been having relatively high levels of CO2 (compared to his normal) for a significant time. to the extent that his body started compensating for it.

the fact that 30% of patient do require intubation because of high levels of CO2 and bicarbonate means to me that those patients have arrived late. And possibly if they came earlier they would have done much better.

None of this comes as a surprise, because the same is true for any other illness. eg-asthma, myocardial infarction, sepsis etc. We know that once your body has to start compensating for the damage it is very late in the game, and intervention should have been done much earlier. This has a significant effect on morbidity and even mortality.

So, I think the bottom line is that patients with MG should learn to recognize early signs of respiratory failure, and also insist on having a trial of NIV. They also need to explain to their physicians that treatment should be started before there is a change in their CO2 level. The best parameters to follow are the negative inspiratory pressure and maximal expiratory pressure. which should be above 20-30 and 40 respectively. The vital capacity which is being used in many neurology wards around the world has been shown to be a very poor parameter.

Also, patients who have respiratory involvement should have a peak flow meter (like the one used by asthma patients), know their baseline and check it when they are experiencing respiratory symptoms.

I can tell you (from my own experience) that a timely treatment with NIV can lead to such a rapid and dramatic improvement that it looks "impossible" to some neurologists who have very little understanding in respiratory physiology.

alice

Thanks, Alice, for posting this.

When I had my crisis, I should've had a Bi-Pap. My O2 saturation was dropping to 66% while I was sleeping. But they were wholly incapable of dealing with an MG crisis. Like when they did my arterial blood gases; one while on oxygen and one right after I took it off. They saw the "hyperventilation" and chalked it up to anxiety. I'm always calm and never "anxious." Being on oxygen while having an ABG is like eating a hot fudge sundae before getting your glucose checked!

When I finally made it to urgent care, because my O2 saturation was not going up from 93%, I couldn't squeeze the doctor's fingers during the neuro exam. I "thought" I was squeezing them really hard. Sometimes the weakness can come on so slowly that you don't notice it. I highly recommend an oximeter so you can know your normal. And if you are doing worse, look in the mirror at your face, try to breath in and out into a peak flow meter, squeeze your hands, etc.

I sure didn't want to admit that I was on my way to a crisis and I think that's also a part of the problem. Who wants to be in a hospital? I'd rather do anything else. But you are right that getting help as soon as possible can help you avoid a full blown crisis. And the worse MG gets, the longer it takes to recover.

My average MIP in the hospital was -24. Yeah, that's "normal," right? :eek: Knowing what your normal is can help combat ignorance by hospital staff. My normal is in the -80's, so I was at 1/4 of my normal. It's not only how low but how far down you go! ;)

There sure is a lot to consider with this disease. It's nice that people here have so much to contribute to each other. Yes, Alice, that does give me hope.

Annie

My pulse ox is usually 98, but in the hospital it was 93. They still would say it was fine at 93, but it didn't seem so fine to me and I was having huge problems catching my breath.

A pulse ox of 93 is fine in the sense that you have enough oxygen in your tissues. It does not give any information about the degree of weakness of your respiratory muscles. Although, in someone with a baseline level of 98, a pulse ox of 93 would suggest significant respiratory muscle weakness. (unless there is some other cause that made it go down, such as pneumonia or a vascular event).

Tracy, I think you need to start a new post because you need help!!!

The afternoon before my crisis, my O2 saturation would not go above 93%, no matter how much I rested. That's a huge warning sign for two reasons. One, it wasn't my normal, as Alice alluded to. Two, it wouldn't move/fluctuate.

And your O2 was 93% while sitting. What was it if they had walked around with you, which they SHOULD have done. They also should've done an arterial blood gas, so ask for that next time.

From everything you're saying, you aren't well. No more activities!!! I understand that church is important but so is being alive. Sitting up is very hard work for the chest wall muscles that help you to breathe. ;)

If you have sudden shortness of breath, that's another huge warning sign. The inability to move limbs well is yet another reason to dial 911.

If you don't take care of this right now, you may end up on a vent.

:hug:
Annie