start increasing by 1 mcg/kg/m. If the pressure doesn't respond then you could go up by 2.
some people are so affected by dopamine, i've seen patients who had a map>65 with 6.3mcg/kg/m and when you dropped them to 6.0 their maps fell into the 40-50 range.
very narrow therapeutic range for some patients.
Do you guys have Lexicomp access? They have good information in their drug guides. Typically the hospital will have a policy on "Adult Titration of Vasoactive Infusions" or something similar that will review all the vasoactive meds and how to titrate them according to hospital policy.