Pain relief in children

Childhood pain is often complex (particularly cancer pain) and ideally a multidisciplinary approach should be used.

While providing analgesia, the underlying cause of the pain should be determined and treated if possible, remembering that the pain of both diagnostic and therapeutic procedures (eg, bone marrow biopsy) may often be worse than that of the disease. Such pain due to procedures should be treated appropriately.

Assessment of children

The initial pain assessment of a child reporting or presenting behavioural signs of pain includes:

• A detailed pain history including location, duration and characteristics of the pain.

• Details regarding the impact of the pain on the child's sleep, emotional state, relationships, development and physical function.

• A physical examination.

• The diagnosis of the causes.

• The measurement of pain severity using an age-appropriate pain measurement tool.

• Information regarding treatments already tried.

Non-drug

• Sucrose, glucose or other sweet solutions have been all shown to reduce pain responses during commonly performed painful procedures in diverse populations of infants up to 12 months of age.¹

• Sucrose has been shown to be safe and effective for reducing procedural pain from single events.²

• Although sucrose has been widely recommended for routine use during painful procedures in newborn and young infants, the use of sucrose is still not very common³ but can be improved with concerted efforts.⁴

• If available, breastfeeding or breast milk should be used, rather than placebo, positioning or no intervention, to alleviate procedural pain in neonates undergoing a single painful procedure. Administration of glucose or sucrose has been shown to have similar effectiveness to breastfeeding for reducing pain.⁵

• There is also evidence that play therapy can be useful in reducing pain via distraction and making the child more comfortable in a potentially threatening environment.⁶

Drugs

The correct use of analgesic medicines will relieve pain in most children with persisting pain due to medical illness, and relies on the following key concepts:

• Using a two-step strategy.

• Dosing at regular intervals.

• Using the appropriate route of administration.

• Adapting treatment to the individual child.

Mild pain

For children aged under 3 months, paracetamol should be offered.

Children aged over 3 months (and 5kg) can be offered both paracetamol and ibuprofen.

Moderate-to-severe pain

When the pain is more severe, an opioid drug may be necessary to control the pain. Morphine is the medicine of choice.

It is recommended that medication should be given regularly for persisting pain, rather than on an 'as required basis', unless pain episodes are truly intermittent and unpredictable. Children should, therefore, receive analgesics at regular intervals, with the addition of 'rescue doses' for intermittent and breakthrough pain.

Non-opioids

Paracetamol

• Sugar-free preparation is appropriate for many children with mild-to-moderate pain.

• It does not cause respiratory depression but overdose is dangerous, as it may cause hepatic damage and not be apparent for 4-6 days.

• The dosing for liquid paracetamol products for children was revised in 2011 to one that is based on narrower age bands with a single dosing option per band.⁷

• The current recommended oral paracetamol doses are:⁸

Non-steroidal anti-inflammatory drugs (NSAIDs)

• These are particularly useful where pain is associated with fever (especially in children over the age of 5 years), dental pain, ear pain and for control of pain in long-term inflammatory conditions.

• They do, however, cause more gastric irritation than paracetamol and for mild-to-moderate pain, paracetamol is often preferred.

• Warn asthmatic patients/parents taking NSAIDs for the first time to watch for worsening of bronchospasm although this is uncommon in children.⁹

• Avoid aspirin in children aged under 16 years, due to risk of Reye's syndrome.

• The current recommended immediate-release oral ibuprofen doses are:⁸

Opioids

• Morphine is recommended as the first-line strong opioid for the treatment of persisting moderate-to-severe pain in children with diagnosed medical illnesses. These should be initiated by paediatricians.

• As when prescribing for adults, immediate-release tablets are recommended for titrating morphine dosage and also for defining the adequate dose for pain control. They should also be given for episodic or breakthrough pain.

• The oral route is usually preferable in children. Palatability, availability of oral solutions, size of tablets and frequency of dosing are important factors to consider.

• In some children alternative opioids may be given. However, switching opioids should only be considered when the administered medicine has been adequately titrated but the analgesic response is inadequate and side-effects experienced by the child are intolerable.

• There is insufficient evidence to recommend any alternative opioid in preference to morphine as the opioid of first choice.

• Fentanyl, hydromorphone, methadone and oxycodone formulations have been considered alternatives to morphine for switching in children with persisting pain.

• Intranasal fentanyl is being used in some countries, as it has been shown to be safe and also equally effective as intravenous morphine in paediatric patients with moderate-to-severe acute pain.¹⁰¹¹

• However, in the UK fentanyl is currently licensed for usage for paediatric pain via the intravenous route but not via the intranasal route.⁸

• The main side-effects of opioids as a class are nausea, vomiting, constipation, and drowsiness. Respiratory depression and hypotension occur in larger doses. Neonates, particularly if preterm, may be more susceptible.

• As long-term opioid use is usually associated with constipation, patients should also receive a combination of a stimulant laxative and a stool softener prophylactically.

• Doses may need to be adjusted individually according to the degree of analgesia and side-effects.

• Opioid doses should be calculated and checked with care.

Other medications

• Pain associated with acute problems of the oral mucosa (eg, acute herpetic gingivostomatitis, erythema multiforme) are sometimes given benzydamine or topical anaesthetics until resolution, in addition to paracetamol or ibuprofen.

• However, there is actually little evidence for topical lidocaine's efficacy as an analgesic and in aiding oral intake in children with painful infectious mouth conditions.¹²

• A recent study has shown that topical lidocaine is actually no more effective than a flavoured gel placebo in improving oral intake in children with painful infectious mouth ulcers.¹³

• Inhaled nitrous oxide provides useful short-term analgesia for patients undergoing painful procedures and for those who have needle phobia.¹⁴

• EMLA® cream may be used to reduce the pain of venepuncture and has also been successfully used to reduce pain post-circumcision.¹⁵

• Ketamine can be used for management of pain in acute settings, such as burn management, joint reduction or wound exploration, amongst others. ¹⁶

Controlling pain in palliative care¹⁷

Whilst the same principles apply to the palliative control of pain in children as for any other condition, additional considerations apply. Care should be comprehensive and address psychological, cultural and spiritual needs. If so desired, this care should be provided at home. Remember factors such as the physical environment, attitudes and behaviours can profoundly increase or decrease children's pain. Pain management therefore relies not only on the use of pain-relieving drugs but also on practical cognitive, behavioural, physical and supportive therapies (many of these therapies can be provided by family members).

• Paracetamol or an NSAID given regularly will often make the use of opioids unnecessary.

• NSAIDs are also useful in controlling bone secondaries.

• Treatment of bone cancer pain usually requires a multidisciplinary approach, such as an orthopaedic intervention, palliative radiotherapy alongside disease-modifying treatment (chemotherapy) and supportive care (analgesic and integrative therapies).

• When reducing or stopping opioids, doses should be tapered gradually to avoid causing severe pain flare or withdrawal symptoms.

• Morphine is given by mouth as an oral solution or as standard (immediate-release') tablets regularly every four hours, the initial dose depending largely on the patient's previous treatment. Increase the next dose by 50% if the previous dose was no more effective than the preceding analgesic. Choose the lowest dose which prevents pain and consider adjuvant analgesics (eg, NSAIDs). Titrate stepwise depending on response. Omit an overnight dose if double the usual dose is given at bedtime.

• Consider rescue doses for breakthrough pain and prophylactic doses 30 minutes before a potentially painful procedure (eg, dressing changes). Use oral morphine solution or standard tablets, about one sixth of the total daily dose every four hours.

• Side-effects of opioids (eg, constipation) should be anticipated, aggressively treated and regularly reassessed.

• Once the daily requirement is established, give the total dose od or bd. If required, increase the strength of the dose, not the frequency of administration.

• Situations when the enteral route is not suitable and an alternative route (eg, subcutaneous, rectal or transdermal) should be sought include:
  

  • Pain crisis requiring rapid titration of intravenous opioids.

  • Poor absorption: vomiting, disordered gastrointestinal motility.

  • Inability to comply: unconscious; severe nausea, poor swallow; risk of aspiration, medication refusal.

• Gastrointestinal pain - bowel colic pain may be reduced by loperamide or hyoscine hydrobromide sublingually. Subcutaneous hyoscine can be given via a syringe driver.

• Muscle spasm - antispasmodic agents, such as baclofen and dantrolene, can be useful although they can cause sedation and hypersalivation. Targeted treatments such as botulinum toxin, surgical intervention and intrathecal drug delivery are becoming more common.

• Neuropathic pain - a combination of integrative, rehabilitative and supportive treatments with medications such as NSAIDs, opioids, low-dose tricyclics and gabapentinoids are often given.¹⁸ However, there are very few trials regarding the management of neuropathic pain in children with cancer.

• Nerve compression may be reduced by a corticosteroid such as dexamethasone, which reduces oedema around the tumour, thus reducing compression.

Although children's understanding of death may vary at different times in their development, they often know when they are dying; their major concerns are frequently fear of abandonment and fear of suffering. It is important to emphasise to such children that they will be kept comfortable and that the people they love will always be with them.