It is this difference that gives rise to the predictability of caudal local anaesthetic spread in children and its unpredictability in adults. Drugs used for epidural injections should come from single use ampoules and be preservative free. If the child is of average weight for its height both figures will be the same. If the child is overweight use the figure based on age to avoid the possibility of overdose. Scott's lower doses are more likely to produce analgesia to the expected height, whereas Armitage will get anaesthesia.
Care is needed to avoid the use of toxic doses of drugs for high blocks.
These dosages are the maximum for a correctly injected dose. If the drug is mistakenly injected intravenously very small dosages may cause serious toxicity.