Failed caudal block due to physiologic changes associated with a cerebrospinal fluid leak: a case report

Conclusions The possible mechanism of this failed caudal block was high systemic absorption of anesthetic given the epidural venous plexus engorgement thus leaving less anesthetic acting within the CSF and on the exiting spinal nerves. Decreased CSF flow in the thecal sac might also have contributed, as might dilution of the remaining local anesthetic caused by large amounts of leaking CSF within the epidural space.
Source: Canadian Journal of Anesthesia - Category: Anesthesiology Source Type: research