Hi Shelley,
Over the last many years I have had many Brachial Plexus blocks.
My doctor inserts a catheter into The Bracial plexus ( a group of nerves)
in the armpit then leaves it in for at least a week. It is connected to a pump which delivers the anaesthetic at a measured dose consistantly onto the nerves. It doesn't go into the artery or the vein. I have has the block running for 3 weeks sometimes and it is 3 weeks of bliss!
The dose can be kept at an amount to numb the arm but not paralyse it, it is trial and error.
Whilst the pain does come back to some extent as soon as the block is removed there is residual pain relief for sometime after.
More than happy to answer any other questions you may have.
cheers Tayla