Nolan Machado: Troubleshooting Epidural Catheters.
Either volume problem (window too small, block not high enough, give more volume) or density problem (adequate size, but still having pain, need stronger medication).
Nolan recommends 0.2% ropivacaine, 10-15 mL. Administer in 5 mL boluses to check size effect and not overdose. Check where level is before administering (or just after since it will take a few minutes to work).
If the level is high enough (T8 is Nolan’s preference), then it is a density problem.