I had my first lumbar sympathetic block and my foot is completely pain free. how long will it stay like this? should i get the second?

Pain free: This is great. Typically the second is done only when and if the symptoms return. When the pain returns that is how long the block lasted.

Unpredictable: lumbar sympathetic blockade can sometimes last forever. In many cases temporary pain relief is obtained and repeated injections can sometimes cause the progressive lessening of symptoms. The number of blocks varies between 2-10. Ask your Interventional neurologist for more information. Good luck.