Post by Brian G on Oct 16, 2014 9:09:03 GMT
How to differentiate between a myastenic crisis and a cholinergic crisis. There's two ways mentioned in the book-the first using edrophonium was in larger print, so probably important. The second using tubocurarine was in smaller print, so it may not be so important, but I did see it in a quizlet question, so it is possible to see it on a test.
First, some definitions...
Myastenia gravis-you (or the patient you are treating) don't have enough ACH going around to properly activate your muscles. You are weak. Fix this by administering a cholinesterase inhibiter because ACH is broken down by cholinesterase inhibitors, and if you break down less ACH, more is available to move your muscles. If you are in a myastenic crisis, you haven't given yourself enough of the inhibitor and are losing the battle.
Cholinergic crisis-you have too much stimulation of your muscles and they are basically frozen. Same result as myasthenia gravis, you can't move. This could be caused by a deficiency of the natural cholinesterase inhibitors in your body, by giving too much of a muscle paralyzer, or you have myasthenia gravis and you administered too much cholinesterase inhibitor by accident.
It is this last point that can help you to determine if you have a cholinergic crisis or a myastenic crisis and It is important to know which condition you have because the treatment is different.
You give a little dose of edrophonium, which is a short-acting cholinesterase inhibitor, and you get better. This means you suffer from myasthenia gravis and just need more inhibitor. If you didn't get better, it has to be the other-a cholinergic crisis. The treatment for this is atropine, which is a muscarinic antagonist (blocks ACH) and oxygen.
The second test uses a little bit of tubocurarine. Tubocurarine is a non-depolarizing neuromuscular blocker, a muscle paralyzer. You are just giving a little bit here, not enough to cause any noticeable symptoms in a healthy person. A person with myasthenia gravis though will notice it cause they don't have enough ACH to start with, so if the symptoms get worse after administering tubocurarine, you have myastenic crisis. Treat this like above with more cholinesterase inhibitor. Use caution here and have oxygen or a ventilator around. If the patient does have myasthenia gravis, you might push them into respiratory distress by administering the tubocurarine.
Regards
Brian
First, some definitions...
Myastenia gravis-you (or the patient you are treating) don't have enough ACH going around to properly activate your muscles. You are weak. Fix this by administering a cholinesterase inhibiter because ACH is broken down by cholinesterase inhibitors, and if you break down less ACH, more is available to move your muscles. If you are in a myastenic crisis, you haven't given yourself enough of the inhibitor and are losing the battle.
Cholinergic crisis-you have too much stimulation of your muscles and they are basically frozen. Same result as myasthenia gravis, you can't move. This could be caused by a deficiency of the natural cholinesterase inhibitors in your body, by giving too much of a muscle paralyzer, or you have myasthenia gravis and you administered too much cholinesterase inhibitor by accident.
It is this last point that can help you to determine if you have a cholinergic crisis or a myastenic crisis and It is important to know which condition you have because the treatment is different.
You give a little dose of edrophonium, which is a short-acting cholinesterase inhibitor, and you get better. This means you suffer from myasthenia gravis and just need more inhibitor. If you didn't get better, it has to be the other-a cholinergic crisis. The treatment for this is atropine, which is a muscarinic antagonist (blocks ACH) and oxygen.
The second test uses a little bit of tubocurarine. Tubocurarine is a non-depolarizing neuromuscular blocker, a muscle paralyzer. You are just giving a little bit here, not enough to cause any noticeable symptoms in a healthy person. A person with myasthenia gravis though will notice it cause they don't have enough ACH to start with, so if the symptoms get worse after administering tubocurarine, you have myastenic crisis. Treat this like above with more cholinesterase inhibitor. Use caution here and have oxygen or a ventilator around. If the patient does have myasthenia gravis, you might push them into respiratory distress by administering the tubocurarine.
Regards
Brian