Rationale For Use of Lower Extremity Conduction Nerve Blocks

Because the attachment of perineural sheaths to the underlying structures is loose, the LA can occasionally reach distant nerves or anatomical spaces (e.g. an epidural, even a subarachnoid block may result from a posterior approach to the lumbar plexus) and cause complications unexpected by those unaware of this possible effect. Such a possibility must be considered when selecting a block procedure. Special precautions must be taken with agitated children to avoid postoperative trauma in anesthetized areas. Careful monitoring of the anesthetized extremity must be performed hourly to prevent the development of a compartment syndrome. This hourly evaluation includes monitoring of the hemodynamic status, the local temperature and re-coloration time of the limb, the mobility of the toes or fingers and increasing numbness and/or paresthesia.

After surgery resulting in a more significant tissue trauma, analgesia of adequate duration cannot be achieved with a single shot block, even when a long-acting local anesthetic is used. Concomitant administration of adjuvants, such as clonidine (1-2 µg/kg) may extend the duration of analgesia [18,19] without precluding hospital discharge. However, when long lasting pain relief is mandatory, placement of an indwelling catheter in the vicinity of the nerve or within a fascial compartment traversed by the nerve to be blocked are the most suitable and effective alternatives. These techni-ques are however relatively new in pediatric practice and the scientific data documenting our clinical impression is not available yet in the literature.[20,21] While continuous nerve block techniques are currently widely used in inpatients, there is a trend toward extending their use also in outpatient population. The indications for these techniques must take into consideration the agitated or diffi-cult child and the patients at risk of developing a compartment syndrome, particularly in patients receiving a cast.[22-24]