Analgesic Guidelines for Infants and Children

Synonyms

Drug Guidelines; Pediatric Dosing Guidelines

Definition

The goal of administering analgesia is to relieve pain without intentionally producing a sedated state.

Characteristics

Oral Analgesics

Analgesics include acetaminophen, non-steroidal anti-inflammatory drugs and opioids. While acetaminophen and opioids remain the cornerstone for providing analgesia for our youngest patients, the scope and diversity of drugs expand as those patients grow older. Adjuvant analgesics include a variety of drugs with analgesic properties that were initially developed to treat other health problems. These adjuvant analgesics (such as anticonvulsants and antidepressants) have become a cornerstone of pain control for children with chronic pain, especially when pain has a neuropathic component.

Pain control should include regular pain assessments, appropriate analgesics and adjuvant analgesics administered at regular dosing intervals, adjunctive drug therapy for symptom and side-effects control and non-drug therapies to modify the situational factors that can exacerbate pain and suffering. The guiding principles of analgesic administration are ‘by the ladder’, ‘by the clock’, ‘by the child’ and ‘by the mouth’. By the ladder’ refers to a three-step approach for selecting drugs according to their analgesic potency based on the child’s pain level – acetaminophen to control mild pain, codeine to control moderate pain and morphine for strong pain (World Health Organization 1990). The ladder approach was based on our scientific understanding of how analgesics affect pain of nociceptive origins (nociceptive pain). If pain persists despite starting with the appropriate drug, recommended doses and dosing schedule, move up the ladder and administer the next more potent analgesic. Even when children require opioid analgesics, they should continue to receive acetaminophen (and non-steroidal anti-inflammatory drugs, if appropriate) as supplemental analgesics. The analgesic ladder approach is based on the premise that acetaminophen, codeine and morphine should be available in all countries and that doctors and health-care providers can relieve pain in the majority of children with a few drugs.

However, increasing attention is focusing on ‘thinking beyond the ladder’ in accordance with our improved understanding of pain of neuropathic origins (Krane et al. 2003). Children should receive adjuvant analgesics to more specifically target neuropathic mechanisms. Regrettably, two of the main classes of adjuvant analgesics, antidepressants and anticonvulsants, have unfortunate names. Proper education of health care providers, parents and children should lead to a wider acceptance and use of these medications for pain management. For example, amitriptyline may require 4–6 weeks to affect depression, but often requires only 1–2 weeks to affect pain. The newer classes of antidepressants, the selective serotonin reuptake inhibitors (SSRI’s), may be beneficial to treat depression in a child with pain, but have not been shown to be beneficial for pain management. The other main class of adjuvant analgesics is the anticonvulsants. The two principal medications used for this purpose in pediatrics are carbamazepine and gabapentin. With gabapentin, the main dose limiting side effect is sedation, so that a slow titration to maximal dose is required. Because of its greater number of significant side effects, the use of carbamazepine has decreased recently and the use of gabapentin has increased. We still await published studies to support the wide use of gabapentin.

Non-steroidal anti-inflammatory drugs (NSAIDs) are similar in potency to aspirin. NSAIDs are used primarily to treat inflammatory disorders and to lessen mild to moderate acute pain. They should be used with caution in children with hepatic or renal impairment, compromised cardiac function, hypertension (since they may cause fluid retention and edema) and a history of GI bleeding or ulcers. NSAIDs may also inhibit platelet aggregation and thus must be monitored closely in patients with prolonged bleeding times. NSAIDs have been used for many years in pediatrics and with their minimal side effects and many advantages (no effect on ventilation, no physical dependence, morphine sparing effect, etc) their use should be encouraged.

The specific drugs and doses are determined by the needs of each child. The drugs listed in this chapter are based on guidelines from our institution (The Hospital for Sick Children 2004–2005). Recommended starting doses for analgesic medications to control children’s disease-related pain are listed in Table 1 and Table 2; starting doses for adjuvant analgesic medications to control pain, drug related side effects and other symptoms are listed in Table 3. (For further review of analgesics and adjuvant analgesics in children, see (McGrath and Brown 2004; Schechter et al. 2003).

Table 1 Non-opioid drugs to control pain in children

Table 2 Opioid analgesics: Usual starting doses for children

Table 3 Adjuvant analgesics: doses for children

Oral Analgesic Dosing Schedules

Children should receive analgesics at regular times, ‘by the clock’, to provide consistent pain relief and prevent breakthrough pain. The specific drug schedule (e.g. every 4 or 6 h) is based on the drug’s duration of action and the child’s pain severity. Although breakthrough pain episodes have been recognized as a problem in adult pain control, they may represent an even more serious problem for children. Unlike adults, who generally realize that they can demand more potent analgesic medications or demand more frequent dosing intervals, children have little control, little awareness of alternatives and fear that their pain cannot be controlled. They may become progressively frightened, upset and preoccupied with their symptoms. Thus, it is essential to establish and maintain a therapeutic window of pain relief for children.

Analgesic doses should be adjusted ‘by the child’. There is no one dose that will be appropriate for all children with pain. The goal is to select a dose that prevents children from experiencing pain before they receive the next dose. It is essential to monitor the child’s pain regularly and adjust analgesic doses as necessary to control the pain. The effective opioid dose to relieve pain varies widely among different children or in the same child at different times. Some children require large opioid doses at frequent intervals to control their pain. If such doses are necessary for effective pain control and the side effects can be managed by adjunctive medication (adjunctive drugs) so that children are comfortable, then the doses are appropriate. Children receiving opioids may develop altered sleep patterns so that they are awake at night fearful and complaining about pain and sleep intermittently throughout the day. They should receive adequate analgesics at night with antidepressants or hypnotics as necessary to enable them to sleep throughout the night. To relieve ongoing pain, opioid doses should be increased steadily until comfort is achieved, unless the child experiences unacceptable side effects, such as somnolence or respiratory depression (Table 4).

Table 4 Opioid side effects

‘By the mouth’ refers to the oral route of drug administration. Medication should be administered to children by the simplest and most effective route, usually by mouth. Since children are afraid of painful injections they may deny that they have pain or they may not request medication. When possible, children should receive medications through routes that do not cause additional pain. Although optimal analgesic administration for children requires flexibility in selecting routes according to children’s needs, parenteral administration is often the most efficient route for providing direct and rapid pain relief. Since intravenous, intramuscular and subcutaneous routes cause additional pain for children, serious efforts have been expended on developing more pain-free modes of administration that still provide relatively direct and rapid analgesia. Attention has focused on improving the effectiveness of oral routes.

Intravenous Analgesia

Many hospitals have restricted the use of intramuscular injections because they are painful and drug absorption is not reliable; they advocate the use of intravenous lines into which drugs can be administered directly without causing further pain. Topical anesthetic creams should also be applied prior to the insertion of intravenous lines in children. The use of portacatheters has become the gold standard in pediatrics, particularly for children with cancer under the care of the physician, who require administration of multiple drugs at weekly intervals.

Continuous infusion has several advantages over intermittent subcutaneous, intramuscular or intravenous routes. This method circumvents repetitive injections, prevents delays in analgesic drug administration and provides continuous levels of pain control without children experiencing increased side effects at peak level and pain breakthroughs at trough level. Continuous infusion should be considered when children have pain for which oral and intermittent parenteral opioids do not provide satisfactory pain control, when intractable vomiting prevents the use of oral medications and when intravenous lines are not desirable. Children receiving a continuous infusion should continue to receive ‘rescue doses’ to control breakthrough pain, as necessary. As outlined in Table 2, the rescue doses should be 50–200% of the continuous infusion hourly dose. If children experience repeated breakthrough pain, the basal rate can be increased by 50% or by the total amount of morphine administered through the rescue doses over a 24 h period (divided by 24 h).

Patient-controlled Analgesia

Patient-controlled analgesia (PCA) enables children to administer analgesic doses according to their pain level. PCA provides children with a continuum of analgesia that is prompt, economical, not nurse dependent and results in a lower overall narcotic use (Rodgers et al. 1988; Schechter et al. 2003). It has a high degree of safety, allows for wide variability between patients and removes delay in analgesic administration (for review, see (Berde and Solodiuk 2003).) It can now be regarded as a standard for the delivery of analgesia in children aged >5 years (McDonald and Cooper 2001). However, there are opposing views about the use of background infusions with PCA. Although they may improve efficacy, they may increase the occurrence of adverse effects such as nausea and respiratory depression. In a comparison of PCA with and without a background infusion for children having lower extremity surgery, the total morphine requirements were reduced in the PCA only group and the background infusion offered no advantage (McNeely and Trentadue 1997). In another study comparing background infusion and PCA, children between 9 and 15 achieved better pain relief with PCA while children between 5 and 8 showed no difference (Bray et al. 1996). Our current standard is to add a background infusion to the PCA if the pain is not controlled adequately with PCA alone. The selection of opioid used in PCA is perhaps less critical than the appropriate selection of parameters such as bolus dose, lockout and background infusion rate. The opioid choice may be based on adverse effect profile rather than efficacy. Clearly, patient controlled analgesia offers special advantages to children who have little control and who are extremely frightened about uncontrolled pain. PCA is, as it states, patient controlled analgesia. When special circumstances require that alternate people administer the medication, we do allow both nurse and parent controlled analgesia. Under these circumstances, parents require our nurse educators to fully educate them on the use of PCA. In a recent alert by the Joint Commission on Accreditation of Health Care Organizations (JCAHO), they advise that serious adverse events can result when family members, caregivers or clinicians who are not authorized become involved in administering the analgesia for the patient “by proxy” (Sentinel Event Alert 2004).

Transdermal Fentanyl

Fentanyl is a potent synthetic opioid, which like morphine binds to mu receptors. However, fentanyl is 75–100 × more potent than morphine. The intravenous preparation of fentanyl has been used extensively in children. A transdermal preparation of fentanyl was introduced in 1991 for use with chronic pain. This route provides a noninvasive but continuously controlled delivery system. Although limited data is available on transdermal fentanyl (TF) in children, its use is increasing for children with pain. In a 2001 study, TF was well tolerated with effective pain relief in 11 of 13 children and provided an ideal approach for children where compliance with oral analgesics was problematic (Noyes and Irving 2001). In another study, when children were converted from oral morphine doses to TF, the investigators noted diminished side effects and improved convenience with TF (Hunt et al. 2001). The majority of parents and investigators considered TF to be better than previous treatment. No serious adverse events were attributed to fentanyl, suggesting that TF was both effective and acceptable for children and their families. Similarly, no adverse effects were noted in a study of TF for children with pain due to sickle cell crisis (Christensen et al. 1996). This study showed a significant relationship between TF dose and fentanyl concentration; pain control with the use of TF was improved in 7 of 10 patients in comparison to PCA alone. In a multicenter crossover study in adults, TF caused significantly less constipation and less daytime drowsiness in comparison to morphine, but greater sleep disturbance and shorter sleep duration (Ahmedzai and Brooks 1997). Of those patients able to express a preference, significantly more preferred fentanyl patches. As with all opioids, fatal adult complications have been noted with the use of multiple transdermal patches.

Summary

I have guided you through the basics of the administration of analgesics for the pediatric patient from the oral route, through to intravenous and the PCA route and finally discussed a fairly recently employed analgesic administered by the transdermal route. By the use of these drugs as examples and with the simple principles discussed to apply them, we can hopefully attain the goal of decreasing the intensity of pain in children – no matter what the setting.