Epidural Ketamine in Healthy Children—What’s the Point?

Efficacy and adverse effects of ketamine as an additive for paediatric caudal anaesthesia: a quantitative systematic review of randomized controlled trials

BACKGROUND

The aim of this quantitative systematic review was to assess the efficacy and adverse effects of ketamine added to caudal local anaesthetics in comparison with local anaesthetics alone in children undergoing urological, lower abdominal, or lower limb surgery.

METHODS

The systematic search, data extraction, critical appraisal, and pooled data analysis were performed according to the PRISMA statement. All randomized controlled trials (RCTs) were included in this meta-analysis and relative risk (RR), mean difference (MD), and the corresponding 95% confidence intervals (CIs) were calculated using the Revman(®) statistical software for dichotomous and continuous outcomes.

RESULTS

Thirteen RCTs (published between 1991 and 2008) including 584 patients met the inclusion criteria. There was a significant longer time to first analgesic requirements in patients receiving ketamine in addition to a local anaesthetic compared with a local anaesthetic alone (MD: 5.60 h; 95% CI: 5.45-5.76; P<0.00001). There was a lower RR for the need of rescue analgesia in children receiving a caudal regional anaesthesia with ketamine in addition to local anaesthetics (RR: 0.71; 95% CI: 0.44-1.15; P=0.16).

CONCLUSIONS

Caudally administered ketamine, in addition to a local anaesthetic, provides prolonged postoperative analgesia with few adverse effects compared with local anaesthetics alone. There is a clear benefit of caudal ketamine, but the uncertainties about neurotoxicity relating to the dose of ketamine, single vs repeated doses and the child's age, still need to be clarified for use in clinical practice.

Neuropathological findings after continuous intrathecal administration of S(+)-ketamine for the management of neuropathic cancer pain

Questions have been raised about the potential neurotoxicity of the neuraxial use of ketamine although ketamine and its active enantiomer S(+)-ketamine have been used intrathecally and epidurally (caudally) for the management of perioperative pain and in a variety of chronic pain syndromes. Clinical experience following neuraxial administration of S(+)-ketamine has been documented without reference to local central nervous system toxicity following this approach. In addition, there are no preclinical safety data regarding stability, compatibility, and neurotoxicity on intrathecal use of single S(+)-ketamine or combinations of S(+)-ketamine, morphine, bupivacaine, and clonidine. In the present case, the continuous intrathecal administration of S(+)-ketamine, in combination with morphine, bupivacaine, and clonidine resulted in adequate pain relief in a patient suffering from intractable neuropathic cancer pain. However, postmortem observation of the spinal cord and nerve roots revealed severe histological abnormalities including central chromatolysis, nerve cell shrinkage, neuronophagia, microglial upregulation, and gliosis. Based on our results, neuraxial administration of S (+)-ketamine cannot be recommended for clinical practise before a systematic study of toxicology of neuraxial S(+)-ketamine in animals or humans has been performed.