الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Caudal pediatric anaesthesia is the most frequently performed epidural block in children. It combines the advantages of a simple technique with a high success rate. It can be used as an adjunct to general anaesthesia or administered at the completion of the operation to provide postoperative analgesia.
Bupivacaine is the currently available local anaesthetic with the longest duration of action. A dose of 2.0 - 2.5 mg/kg of it lasts for 2-4 hours.
Additives are drugs administrated with caudal epidural local anaesthetics to maximize the effect and extend the duration of analgesia. They include epinephrine, opioids as morphine, fentanyl and diamorphine, nonopioids as ketamine, clonidine, neostigmine, midazolam, and tramadol.
The effect of caudal epidural epinephrine with bupivacaine depends on the concentration of the bupivacaine. It is more marked with 0.125% or 0.25% than with 0.5 % or 0.75% concentration. Epinephrine has a role in early detection of inadvertent intravascular injection. In such circunstance, the ECG changes are more readly identified if the child is premedicated with atropine.
Caudal epidural morphine has a synergistic effect with the caudal epidural local anaesthetic. Its effect is dose dependent and associated with nausea, vomiting, pruritis and urinary retention in addition to the risk of delayed respiratory depression.
Fentanyl like morphine has synergistic effect with the caudal epidural local anaesthetic While diamorphine reduces the early pain scores.
Caudal epidural ketamine with the local anaesthetic prolong the duration of the postoperative analgesia with the advantage of rapid regression of the motor block.Being optimal a 0.5mg/kg ketamine dose is not associated with any of the respiratory depression, cardiovascular changes, major psychotic or neurological problems. Behavioral side effects such as ”odd” behavior and vacant stares appear only with the use of 1mg/kg dose. The use of preservative free ketamine abolishes the risk of neurotoxicity.
Caudal epidural clonidine with bupivacaine is superior to epinephrine with bupivacaine in prolonging of the postoperative analgesia together with reduction of the analgesic requirement within the first 24 hours after surgery. Yet hypotension, bradycardia and dose dependent sedation were all reported as side effects of it.This added to the risk of long aponoeic episodes with bradycardia and decrease in oxygen saturation below 80% within the first 24 hours after surgery in children <1 year and patients weighing <10kg.
Neostigmine modulate the pain processing in the spinal cord by inhibiting the central neurotransmitter acetyl choline. Caudal epidural neostigminealone, in an optimal dose of 2µg/kg, provides analgesia comparable with that of caudal epidural bupivacaine. Co-administration of the two extend the postoperative analgesia and reduce the need for supplementry analgesics.This with the advantages of not requiring a specific free preparation and not causing respiratory depression , sedation or pruritis as reported with opioids. Another advantage is that it is not associated with haemodynamic disturbance as it counteracts the inhibitory effect of bupivacaine on the sympathetic nervous system therepy blunting the hypotension induced by neuroaxial local anaesthetics or clonidine. Vomiting was reported but with doses larger than this optimal dose.
Caudal epidural midazolam in 50µg/kg dose with bubivacaine in 0.75 ml/kg dose significantly increase the duration of postoperative analgesia. This compared well with the duration achived with its combination with morphine.There is only a high score of sedation but without respiratory depression or motor block.
Tramadol is a synthetic analogue of codeine that is only licened for use in children over 12 years old. The analgesic efficacy of epidural tramadol remains controversial. The interval between caudal injection and recovery from anaesthesia was <2 hours with 30% incidence of immediate pain requiring rescue analgesia. This necessitating its use with bupivacaine to ensure good analgesia during recovery. Since caudal tramadol is absorbed systemically and it is equally efficacious whether given caudally or parently there is no advantage in its caudal use and this cannot be recommended.
In the last caudal epidural anaesthesia is not free from complications such as failed or incomplete block, unilateral block, local anaesthetic toxicity from inadvertent intravascular injection or absorption / overdose, subcutaneous or intraosseous injection, dural puncture, penetration of the sacrum, perforation of the rectum, bleeding and infection. Nevertheless, better knowledge of the child sacral anatomy for adoption of the technique according to it togrther with the physiology of and pharmacokinetics in the child for estimation of the optimal dose of the well selected drug, practical experience that follow the precautions against infection in addition to the appropriate and careful monitoring should all prevent these complications and enable the technique to be a well tolerated and effective tool to overcome pain associated with minimal morbidity.