Paediatric caudal anaesthesia
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Originally from Update in Anaesthesia | www.wfsahq.org/resources/update-in-anaesthesia
O Raux*, C Dadure, J Carr, A Rochette and X Capdevila *Correspondence email: o-raux@chu-montpellier.fr
Reprinted with minor changes from O Raux, C Dadure, J Carr, A Rochette, X Capdevila. Paediatric caudal anaesthesia. Update in Anaesthesia (2010); 26: 32-6
| Caudal anaesthesia (CA) is epidural anaesthesia of the cauda equina roots in the sacral canal, accessed through the sacral hiatus. CA is a common paediatric regional technique that is quick to learn and easy to perform, with high success and low complication rates. CA provides high quality intraoperative and early postoperative analgesia for sub-umbilical surgery. In children, CA is most effectively used as adjunct to general anaesthesia and has an opioid-sparing effect, permitting faster and smoother emergence from anaesthesia. |
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INDICATIONS FOR CAUDAL ANAESTHESIA
The indications for single shot CA are abdominal, urologic or orthopaedic surgical procedures located in the sub-umbilical abdominal, pelvic and genital areas, or the lower limbs, where postoperative pain does not require prolonged strong analgesia. Examples of appropriate surgery include inguinal or umbilical herniorrhaphy, orchidopexy, hypospadias and club foot surgery. CA is useful for day case surgery, but opioid additives to the local anesthetic agent should be avoided in this setting. When CA is used, requirement for mild or intermediate systemic analgesia must be anticipated to prevent pain resurgence at the end of caudal block. Catheter insertion can extend the indications to include surgical procedures located in the high abdominal or thoracic areas, and to those requiring prolonged effective analgesia.
CONTRAINDICATIONS
The usual contraindications to regional anaesthesia such as coagulation disorders, local or general infection, progressive neurological disorders and patient or parental refusal apply to CA. Furthermore, cutaneous anomalies (angioma, hair tuft, naevus or a dimple) near the puncture point require radiological examination (ultrasound, CT or MRI), in order to rule out underlying spinal cord malformation such as a tethered cord.23 A Mongolian spot is not a contraindication to CA.
ANATOMY
Anatomical landmarks (Figure 1)
The sacrum is roughly the shape of an equilateral triangle, with its base identified by feeling the two posterosuperior iliac processes and a caudal summit corresponding to the sacral hiatus. The sacrum is concave anteriorly. The dorsal aspect of the sacrum consists of a median crest, corresponding to the fusion of sacral spinous processes. Moving laterally, intermediate and lateral crests correspond respectively to the fusion of articular and transverse processes. The sacral hiatus is located at the caudal end of the median crest and is created by failure of the S5 laminae to fuse (Figure 1). The hiatus is surrounded by the sacral cornua, which represent remnants of the inferior S5 articular processes and which face the coccygeal cornua. Palpation of the sacral cornua is fundamental to locating the sacral hiatus and to successful caudal block. O Raux C Dadure J Carr A Rochette X Capdevila Département d’Anesthésie Réanimation Centre HospitaloUniversitaire Lapeyronie Montpellier France CHU Montpellier Figure 1. The posterior aspect of the sacrum and sacral hiatus The sacral hiatus is the shape of an inverted U, and is covered by the sacro-coccygeal ligament, which is in continuity with the ligamentum flavum. It is large and easy to locate until 7-8 years of age. Later, progressive ossification of the sacrum (until 30 years old) and closing of the sacro-coccygeal angle make its identification more difficult. Note that anatomical anomalies of the sacral canal roof are observed in 5% of patients and this can lead to unplanned cranial or lateral puncture.
The sacral canal
The sacral canal is in continuity with the lumbar epidural space. It contains the nerve roots of the cauda equina, which leave it through anterior sacral foraminae. During CA, leakage of local anaesthetic agent (LA) through these foraminae explains the high quality of analgesia, attributable to diffusion of LA along the nerve roots. Spread of analgesia cannot be enhanced above T8-T9 by increasing injected LA volume.