I've had the DHE infusion, about 4-5 years ago as an outpatient, do not admitted. I had to go every day for I think 7 days. It made me incredibly sick and I didn't complete the last infusion day because I was so sick. However, it gave me a HUGE amount of relief, For the first time in years I was migraine free. Unfortunately the migraines eventually came back. I couldn't tell you how long I had relief for, can't actually remember. It isn't available anymore where I live otherwise I would give it another try.
I had a lot of success with cafergot when it was on the market, so that was a good indicator for my neurologist that the DHE may work. Cafergot can still be compounded, even though the pill isn't available in most tablets. So perhaps ask your neurologist about trying compounded cafergot or another ergotamine-based medication before committing to the DHE.