Indications include surgery below the umbilicus including: Hernia repair , lower limb surgery, skin grafting, GU procedures, procedures on the anus and rectum, orthopedic surgery on the pelvic girdle and obstetric analgesia.
Done infrequently in adults because lumbar and thoracic epidural space is easier to access in the adult than is the caudal space.
The sacral hiatus is more difficult to identify in adults and and the caudal space is more difficult to enter as the sacral bones begin to fuse with age.
Not done often with delivery as there is Increased risk of injecting local anesthetic into the fetus due to the level of fetus and the level of needle insertion site.
The sacrum is a triangular bone that consists of the five fused sacral vertebrae (S1- S5). It articulates with the fifth lumbar vertebra and the coccyx.
The caudal epidural space is the lowest portion of the epidural system and is entered through the sacral hiatus.
The sacral canal contains the terminal part of the dural sac, ending between S1 and S3, the five sacral nerves and coccygeal nerves making up the cauda equina, the sacral epidural veins generally end at S4, but may extend throughout the canal.
The filum terminale exits via the sacral hiatus and is the final part of the spinal cord which does not contain nerves.
Epidural fat has a fibrous close-meshed texture in adults and is the reason that anesthetic spread is unpredictable in adults compared to children.
The sacrum is cartilaginous in infants and children nad during caudal block inadvertent intra-osseous injection can occur.
The distance from the tip of the coccyx to the sacral hiatus is approximately the same as the distance from the tip of the index finger to the proximal inter- phalangeal joint.
The most commonly used drugs include preservative free Lidocaine 1% and Bupivacaine 0.25%.
Bupivacaine is used more frequently because it has a longer duration of action.
Inadvertent intravascular or intrathecal Injection may lead to grand mal seizures and/or cardiac arrest.
Dural puncture must be avoided as total spinal block.