Management of pain in children is often inadequate and there is no evidence to support the idea that pain is less intense in neonates and young children due to their developing nervous system. Children tend to receive less analgesia than adults and the drugs are often discontinued sooner. Furthermore, it is simply not true that potent analgesics are dangerous when used in children because of the risks of side effects and addiction. As with all pain, successful management depends upon the identification and treatment of all the factors which contribute, in particular fear and anxiety. In this context, careful explanations to child and parents can be helpful. A major problem in treating pain in children is associated with the difficulty in assessment

Assessment presents a major challenge, especially in those patients who cannot explain how they feel and who cannot understand the relationship between the treatment and the pain. The worst response is to ignore the presence of pain and the best is to assess the pain and the patients response to treatment as thoroughly as possible. In very young children observational measures may be helpful, but absence of these signs does not rule out the existence of pain. Assessing simple factors such as whether or not the child is asleep, crying, relaxed, tense or are responding to their parents may be used to create a cumulative pain score (see Table 6).

Management of pain in children needs to be handled more actively than in adults. Greater effort should be made to anticipate pain as children cannot be relied upon to ask for analgesia as might an adult. It may be better to establish a schedule of regular analgesia. The route of administration will depend on the drug to be used, the severity of the pain and the likely side effects. Drugs are best given by mouth if possible but the rectal route may be tolerated better if vomiting is a problem. The parenteral route (by injection) should only be used if the drug selected can only be given by that method or where other methods have failed. Intramuscular injections should be avoided as they may be very painful themselves and subcutaneous or intravenous routes are to be preferred.

Local anaesthetic creams are available that can be applied under an occlusive dressing to produce anaesthesia of the underlying skin for up to an hour. These may enable painless placement of venous catheters or allow infiltration of the area with local anaesthetic. These creams should not be used rectally, directly on the wound or on mucous membranes.

Many procedures associated with the relief of pain can themselves be painful. The performance of regional blockade, wound infiltration and the placement of intravenous or subcutaneous lines and catheters may be carried out without discomfort or resistance whilst the patient is anaesthetised.

Infiltration of local anaesthetic agent into the wound before wakening can reduce postoperative pain for long periods. Equally, regional anaesthesia undertaken while the child is under general anaesthesia can give prolonged control of pain and avoid the use of opioids. It is particularly suitable where early discharge from hospital is required. Extradural anaesthesia by the caudal route will provide excellent analgesia for any surgery below the waist such as herniorrhaphy, orchidopexy or circumcision. Children and their parents should be warned of the possibility of urinary retention and of transient weakness or numbness. Hypotension does not seem to be a problem in children under the age of six, but can be anticipated in older children and adults.

Dose schedule for caudal block with bupivacaine in children. 0.25% solution is satisfactory for blocks requiring a volume of 20ml or less. A more dilute solution (0.2% bupivacaine) should be used where volumes of 20ml or more are required.

For short cases 1% lignocaine will be effective and the required volume can be calculated in a similar fashion.

Type of block	Volume (ml/kg)
Lumbosacral	0.5
Thoracolumbar	1.0
Mid-thoracic	1.25

Maximum doses of bupivacaine in any four hour period are 2-3mg/kg and for lignocaine 3mg/kg (without adrenaline), 6mg/kg (with 1:200,000 adrenaline)

Non-opioid analgesics

Paracetamol is effective for mild to moderate pain. It can be given as an oral suspension in a dose of 15mg/kg to a maximum of 60mg/kg in 24 hours. Slightly higher doses (20mg/kg) are needed if this drug is used rectally as absorption is less reliable.

NSAIDs

Aspirin should not be given to children under 12 years old because of the association with Reye's syndrome. There is little experience with the use of NSAIDs in children except in the case of ibuprofen. This is available as a suspension or a syrup and should be given up to a dose of 20mg /kg/day. Diclofenac is available as a suppository (12.5mg or 25mg) for paediatric use and can be used as a premedicant or administered at induction of anaesthesia. Dosage can be up to 3mg/kg/day.

Opioids

Opioids can be used in the same way for children as for adults. The chief concern is that of respiratory depression when larger doses are being used. Suggested dose guidelines given here will minimise the possibility of this and yet still give effective pain relief.

Codeine is effective by mouth for mild to moderate pain and is usually taken in combination with paracetamol. Caution is needed when using this drug with neonates who may be more liable to respiratory depression. Codeine can be given by subcutaneous or intramuscular injection to provide pain relief for babies or children who are outpatients. Doses are similar whichever route is chosen. Codeine is effective when given by suppository. However, children between the ages of 2 and 12 may not always appreciate the virtues of giving the drug by this method.

Codeine is not suitable for intravenous use as it can produce severe falls in blood pressure and apnoea.

Doses of codeine syrup range from 0.5-1mg/kg 4 hourly given orally or by intramuscular injection. Codeine given as a suppository: 1mg/kg 4 hourly.

Morphine is the drug of choice for children who are inpatients. The preferred route of injection is intravenous but other routes can be used. Intramuscular injection is painful and unpopular with patients and nurses, however, this route may be used during the operation to provide analgesia at the time the child awakens from anaesthesia. The subcutaneous route can be useful when venous access is difficult. Intravenous morphine is painless once access has been established and if an infusion is to be used the same precautions must be taken to prevent accumulation as were outlined earlier. Normally a loading dose is infused over 30 minutes followed by a background infusion, titrated against the child's pain and the presence of side effects. If staff are experienced in looking after children postoperatively, there is no need for high dependency or intensive care facilities whilst these techniques are employed.

Doses of morphine orally are 200-400mcg/kg 4 hourly.

Subcutaneous or intramuscular routes 100-150mcg/kg 4 hourly. Intravenous doses 50-100mcg/kg over 30 minutes as a loading dose and then 5-40mcg/kg hourly.

Children as young as five years can use PCA satisfactorily. This is one of the rare circumstances where a background infusion may be of some benefit, as children rarely remember preoperative instructions immediately upon waking. Great care must be taken to ensure that parents do not use the device on behalf of the child. PCA may be of value when dealing with other acute pains such as may accompany sickle cell crisis or the mucositis associated with chemotherapy.

PCA Doses: background infusion 4mcg/kg/h. Additional doses 10-20mcg/kg and a 5-15 minute lock -out. A four hour dose limit is advisable and should be calculated after the patient's response is assessed (usually around 400mcg/kg).

Intrathecal and epidural opioids have been used in children. There is a very high incidence of nausea and vomiting, itching, urinary retention and late (up to 24 hours) respiratory depression. Although analgesia is good, the potential for unpleasant and serious side effects limits the use of these approaches in children.

(Continued...)

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