I had shoulder surgery yesterday. Prior to the procedure an anesthetist performed a nerve block. It’s been 16 hours and I still cannot feel or move my arm. I am just now starting to be able to wiggle my fingers.
I don’t understand how the anesthesia can last so long. I saw the needle with the medication and there really wasn’t much of it. How is the medication not quickly carried away from the injection site?
Thank you in advance!
In: 26
They used a kind of medication called a Sodium Channel Blocker. These work by stopping the nerves from being able to send signals back to the nervous system. You only need a really small amount in the right spot to block these signals.
You can think of it like freezing a water pipe. You don’t need to freeze all of the pipe to stop the flow, just a small section. As time goes on, the ice melts and the flow returns.
Much like freezing water, how long it will last can vary from person to person. Some people are more sensitive to these medications and take a longer time to clear them out of their system. The amount of circulation to the area, amount of medication used and specific nerve can also be factors in the duration of action.
For surgeries like this, it is better to overshoot duration than have it wear off early, so a long-acting medication like bupivacaine or ropivacaine will be used. When you inject these directly into and around the nerve, they “hang out” there for quite a while. The areas around nerves can create little pockets of medication that slowly works it’s way into the nerve.
We pick our spots carefully as well. Knowing just where to inject a local anaesthetic is really important. The best places are easy to access and away from any major blood vessels.
Latest Answers