Caudal block in children Soroka University Medical Center, Soroka University Medical Center, Israel, Beer-Sheva 2004

What is caudal anaesthesia? Caudal anaesthesia (block) is an extradural anaesthesia, produced by injection of local anaesthetic into the caudal canal. This produces block of the sacral and lumbar nerve roots et it is useful as a supplement to general anaesthesia and for provision of postoperative analgesia.

Anatomy The sacrum is a triangular bone that articulates with the fifth lumbar vertebra, the coccyx and the ilia. The dorsal roof consists of the fused laminae of the five sacral vertebrae and is convex dorsally. In the midline is a median crest which represents the sacral spinous processes. Lateral to this is the intermediate sacral crest with a row of four tubercles which represent the articular processes.

Anatomy of sacral hiatus The sacral hiatus situated on the caudal part of the sacrum's posterior wall is an orifice U or V shaped that the bords are the sacral cornua (embrionary reliquats of the S5 inferior articulary processes) and the top is the S4 spinal process. The sacral hiatus is partly on entirely covered by the sacrococcygeal ligament (fibres relying the coccyx to the sacral cornua)

Sacral canal - areolar connective tissue - fat - sacral nerves, - lymphatics, - the filum terminale - rich venous plexus.

INDICATIONS 1. Emergency or one day-case surgery 2. Subumbilical surgery (abdominal, pelvic, orthopaedic). 3. Intra and postoperative analgesia is provide 4. In association with a light general anaesthesia (inguinal and scrotal hernia, the hydrocel cure, testicular ectopy, the anorectal surgery, the genito-urinary surgery, the retroperitoneal tumors surgery as well as the surgery of the basin, hips or lower limbs)

Contraindications absolute 1. Coagulopathy or anti coagulation 2. The administration of aspirin in the 7 days preceding the caudal anaesthesia, diminished the platelets aggregability. 3. The local or systemic infections problems. 4. The major sacrum malformations, pilonidal kyst. 5. Meningitis. 6. Myelomeningoceale 7. Hypovolaemia 8. Hydrocephalus shunted or not 9. Real allergy to local anaesthetics. 10. Parental refuse

Relative contraindication The relative contraindication for caudal anaesthesia results after evaluating the risk-benefice statement for the patient : 1. the existence of an evolutive neuropathy 2. in the spina bifida presence 3. neural blockade dismatched to the surgical 4. procedure needs 5. serious psychiatric disease 6. three unachieved attempts should lead to abandon this technique

Technique The patient is usually in the left lateral position with the knees drawn up to the chest. Adopt an aseptic technique. A needle (or 22/20 g cannula) is introduced in a slightly cranial direction through the hiatus. A click is felt as the needle pierces the sacrococcygeal membrane. The needle/cannula is then directed cranially.

Technique The dura ends at S2, but may extend further. Aspirate to confirm the absence of blood/cerebrospinal fluid and inject local anaesthetic while feeling for inadvertent subcutaneous injection with the other hand. There should be very little resistance to injection. In children, the block should be performed after general anaesthesia has been induced and before surgery has commenced.

Choice of local anaesthetic 0.5 ml/kg, 0.25% bupivacaine (sacro-lumbar block) 1.0 ml/kg, 0.25% bupivacaine (upper abdominal block) 1.2 ml/kg,0.25% bupivacaine (mid-thoracic block) Doses described by Armitage Therefore the maximum acceptable volume seems to be situated between 20 and 25 ml.

Choice of local anaesthetic Continuous caudal catheters have been used intraoperatively for more prolonged surgery. The maximum safe dose range for epidural bupivacaine is mg/kg/h in neonates and mg/kg/h in infants. The addition of clonidine (1-2 mcg/kg) to bupivacaine extends its duration of action significantly. Preservative-free Ketamine (0.5 mg/kg) also prolongs the duration of analgesia. Opiods may be added to local anaesthetic to prolonge it's duration: morphine (30 mcg/kg) fentanyl (1-1.5 mcg/kg) sufentanil ( mcg/kg)

Complications 1. Subcutaneous puncture (rapid diagnosis if the palpating index keeps it's positioning during the injection (1 ml injected in the subcutaneous tissue is very easy recognised) 2. Vascular puncture (the puncture of a epidural vein, recognised on aspiration test, has no gravity. The needle is withdrawn than reintroduced) 3. Subperiosteal puncture (it will be recognised during the puncture or while injecting the test dose (important injecting resistance or tachycardia during the test dose) 4. Intravascular injection (convulsions, arrhythmias even ventricular fibrillation, respiratory arrest could be observed. The immediate resuscitation is to be performed).

Complications 5. Dural tap (If the needle is too long or too deep inserted in the sacral canal or if there is an anatomical anomaly such as a sacral hiatus at S1 or S2 level, all these could lead to a dural tap. In the presence of cerebral spinal fluid at aspiration test the needle has to be withdrawn) 6. Rectal puncture (Almost rare, appears often if obstinacy in difficulties and wrong anatomical guide marks) 7. Nerves injury 8. Cauda equina syndrom is exceptionally reported since the technique and the equipment are codified. 9. Allergic reactions on local anaesthetic agents

Experience DiagnosisWeight (kg) Age (months) N Fimosis4.221 Inguinal Hernia Undescending Testis6.454 Inguinal Hernia645 Rectovaginal Fistula11186 Rectovaginal Fistula Circumcision6.248

Experience 1.The procedure has been effectuated in association with a light general anaesthesia. 2. In all the cases it was introduced Bupivacain 0.25% 1.0 ml/kg. 3. Analgesia was accompanied by very little changes in blood pressure. 4. There were no complications.

Conlusion Caudal block is an easy and safe technique which can be used provide anaesthesia and postoperatve analgesia for a wide range of surgical procedures. When performed carefully complications are rare.