Pediatric Annals

Taming the Pain Monster: Pediatric Postoperative Pain Management

Kenneth A Holder, MD; Richard B Patt, MD

Abstract

Although the management of pain has improved dramatically over the past decade, advances have proceeded at an unequal pace for different types of pain. Improvements in the management of pain in children have been slow to accrue, and only recently has pediatrie pain management become a focus of interest. The most rapid developments have been in the management of postoperative pain where breakthroughs have contributed dramatically to the recognition of pediatrie pain and improvements in treatment for this previ' ously neglected population.1"3

Changes in postoperative care have been dramatic and pervasive. Services devoted exclusively to the management of postoperative pain, usually staffed by anesthesiologists, are common in contemporary hospital practice.4 Reliance on intramuscular injections of analgesics administered on an as-needed basis are giving way to individualized techniques that range from around-the-clock and patient-controlled administration, to treatment by a variety of novel routes (eg, intraspinal, topical, and transmucosal). The most fundamental determinant of the present-day status, postoperative pain management may be the recognition that pain is inadequately identified, assessed and treated in our society.5,6 Other critical factors include the development of new drugs and technologies,7 increased medical subspecialization,4 and the introduction of more sophisticated methodologies for assessing the outcomes of pain interventions.

Sadly, settings still exist where pain in children is either not identified or acetaminophen is all that is provided. Although the cause of this is multifactorial, it is well accepted that knowledge deficits, attitudes, and beliefe underlie most undertreatment. Studies have established that undertreatment in children is commonly related to fear of side effects, inadequate assessment, and inadequate knowledge of basic pharmacology, ie, optimal doses and expected duration of action.1,5,8 Other barriers include unsupported beliefs that children do not experience pain as acutely as adults8; that even when present, persistent pain is innocuous9'11; that children "bounce back" quickly from surgery and do not need aggressive pain management1; that medical exposure to opioids produces addiction1,8; and that the stoic endurance of pain builds moral character.1 Clinicians may be unclear about the effects of opioids in children,1'8 as well as concerned about the use of drugs that are not specifically sanctioned by the Food and Drug Administration for pediatrie applications. An important barrier relates to the persistent use of intramuscular injections that are themselves painful and discourage children from reporting pain.1,8

Table

Patient-controlled analgesia may be more effective than continuous infusion techniques in children who are capable of understanding its use.22'23 This era's children are technologically sophisticated and actually may be less intimidated by "high tech" than their adult counterparts. The child who has mastered the basics of video entertainment (eg, Nintendo) generally can understand and use PCA effectively. Although individual differences exist, children 5 years and older are usually candidates for PCA.24"28 Selected PCA regimens appear in Table 2.

Meperidine may cause central nervous system excitation and seizures due to accumulation of normeperidine, especially in the presence of changing renal function, and therefore is not preferred when repeated doses are required.29 Fentanyl, a potent mu agonist that is around 100 times more potent than morphine, may be associated with lower incidences of nausea and pruritus than morphine (K.A.H., unpublished data). Fentanyl recently has become available in topical and lozenge formulations for transdermal and transmucosal delivery, respectively. Neither formulation is desirable for managing postoperative pain. Transdermal fentanyl, which is not approved for pediatrie use, is not readily titratable and as a result is undesirable for conditions associated with fluctuating pain intensity (eg, postoperative pain). Transmucosal fentanyl (Fentanyl Oralet) is approved for pediatrie use, but for limited indications. While the Oralet has been shown to be effective as a sedative and analgesic…

Although the management of pain has improved dramatically over the past decade, advances have proceeded at an unequal pace for different types of pain. Improvements in the management of pain in children have been slow to accrue, and only recently has pediatrie pain management become a focus of interest. The most rapid developments have been in the management of postoperative pain where breakthroughs have contributed dramatically to the recognition of pediatrie pain and improvements in treatment for this previ' ously neglected population.1"3

Changes in postoperative care have been dramatic and pervasive. Services devoted exclusively to the management of postoperative pain, usually staffed by anesthesiologists, are common in contemporary hospital practice.4 Reliance on intramuscular injections of analgesics administered on an as-needed basis are giving way to individualized techniques that range from around-the-clock and patient-controlled administration, to treatment by a variety of novel routes (eg, intraspinal, topical, and transmucosal). The most fundamental determinant of the present-day status, postoperative pain management may be the recognition that pain is inadequately identified, assessed and treated in our society.5,6 Other critical factors include the development of new drugs and technologies,7 increased medical subspecialization,4 and the introduction of more sophisticated methodologies for assessing the outcomes of pain interventions.

Sadly, settings still exist where pain in children is either not identified or acetaminophen is all that is provided. Although the cause of this is multifactorial, it is well accepted that knowledge deficits, attitudes, and beliefe underlie most undertreatment. Studies have established that undertreatment in children is commonly related to fear of side effects, inadequate assessment, and inadequate knowledge of basic pharmacology, ie, optimal doses and expected duration of action.1,5,8 Other barriers include unsupported beliefs that children do not experience pain as acutely as adults8; that even when present, persistent pain is innocuous9'11; that children "bounce back" quickly from surgery and do not need aggressive pain management1; that medical exposure to opioids produces addiction1,8; and that the stoic endurance of pain builds moral character.1 Clinicians may be unclear about the effects of opioids in children,1'8 as well as concerned about the use of drugs that are not specifically sanctioned by the Food and Drug Administration for pediatrie applications. An important barrier relates to the persistent use of intramuscular injections that are themselves painful and discourage children from reporting pain.1,8

Table

TABLE 1OpIoId Analegesla for Children and Adolescents*

TABLE 1

OpIoId Analegesla for Children and Adolescents*

Table

TABLE 2Selected PCA Dose Regimens*

TABLE 2

Selected PCA Dose Regimens*

ASSESSMENT

Assessment of pain is challenging under any circumstances and may be particularly problematic in children.8,12,14 As described elsewhere in this issue, pain can be accurately assessed, although it requires indi vid uaiizat ion and may be time-consuming. Adequate assessment requires a willingness to believe the child's report of pain, as well as observation of pain-related behaviors.12'14 Assessment of pain in children who are preverbal, chronically ill, withdrawn, or regressed due to trauma is particularly challenging.

TREATMENT

Opioids

As in adults, opioid analgesics are the mainstay of treatment for severe pain. Depending on the circumstances, opioids may be administered orally, parenterally, or via novel routes. Parenteral opioids ideally are administered intravenously. Intramuscular injections should be avoided because the attendant pain and trauma are demoralizing and interfere with the development of a therapeutic alliance between patient, physician, nurse, and family members. Intramuscular injections are particularly undesirable in children with cancer who may need prolonged therapy, and are often cachectic, and in whom bone marrow depletion increases the risk of abscess formation and hematoma. When pain is relatively constant, treatment should be designed to maintain relatively consistent plasma levels of drug. Traditional as-needed administration typically produces wide swings in plasma levels (socalled "roller coaster" or "sine wave" kinetics) that predispose to alternating episodes of pain and side effects. Besides being ineffective,6,15 prolonged asneeded administration may establish patterns of anticipation and memory of pain that can be difficult to modify later. For pain that is sufficiently severe to require opioids and that is expected to persist, as is the case for postoperative pain, administration via an appropriate infusion pump is preferred.6,15,16 In such settings, opioids may be administered safely and effectively by a continuous intravenous infusion, patient activated boluses (patient controlled analgesia [PCA]), or a combination of these modalities. Morphine can be used safely in this fashion,17 and because of practitioner familiarity, it is considered by most authorities to be the drug of choice. Morphine metabolism and respiratory effects are similar for adults and children older than 4 months of age.18'20 As a result, intravenous infusions of morphine with or without PCA are routinely used in many hospitals. The interested reader is referred elsewhere for a more detailed discussion of opioid use in children.21

Table

TABLE 3Nonsteroldal Anti-Inflammatory Drugs

TABLE 3

Nonsteroldal Anti-Inflammatory Drugs

Patient-controlled analgesia may be more effective than continuous infusion techniques in children who are capable of understanding its use.22'23 This era's children are technologically sophisticated and actually may be less intimidated by "high tech" than their adult counterparts. The child who has mastered the basics of video entertainment (eg, Nintendo) generally can understand and use PCA effectively. Although individual differences exist, children 5 years and older are usually candidates for PCA.24"28 Selected PCA regimens appear in Table 2.

Meperidine may cause central nervous system excitation and seizures due to accumulation of normeperidine, especially in the presence of changing renal function, and therefore is not preferred when repeated doses are required.29 Fentanyl, a potent mu agonist that is around 100 times more potent than morphine, may be associated with lower incidences of nausea and pruritus than morphine (K.A.H., unpublished data). Fentanyl recently has become available in topical and lozenge formulations for transdermal and transmucosal delivery, respectively. Neither formulation is desirable for managing postoperative pain. Transdermal fentanyl, which is not approved for pediatrie use, is not readily titratable and as a result is undesirable for conditions associated with fluctuating pain intensity (eg, postoperative pain). Transmucosal fentanyl (Fentanyl Oralet) is approved for pediatrie use, but for limited indications. While the Oralet has been shown to be effective as a sedative and analgesic prior to surgery or distressing, painful procedures, its use is undesirable for postoperative pain because of its short duration of action and high incidences of associated nausea, vomiting, and pruritus.30'31

Intraspinal Opioid Analgesia

The epidural administration of opioids is one of the most important new trends in the management of chronic and postoperative pain.32 The instillation of local anesthetics into the epidural space has been popular for decades, but because pain relief is accompanied by numbness and motor weakness, the use of epidural anesthesia is usually restricted to relieving pain during surgery. In contrast, when opioids are administered into the epidural space, the resulting analgesia is selective. Epidural analgesia has become a common means for providing postoperative pain relief in adults and children.33'38 Profound pain relief results from the administration of minute doses because high drug concentrations are achieved locally at opioid receptors located in the dorsal horn's substantia gelatinosa.32

In children, the epidural space is most commonly accessed via a lumbar or caudal approach. Although caudal infusions are used successfully, for prolonged treatment (3 to 7 days) a lumbar catheter may be preferred to minimize the risk of infection.39 The technique for placement is similar in adults and children, although many practitioners prefer to use a shorter needle and smaller gauge catheter in younger children. In younger children and infants, the catheter is usually placed after the induction of general anesthesia with the aid of an assistant to stabilize the child and manage the airway. In experienced hands, placement is often simpler than in adults. The clearance of epidural morphine and fentanyl is similar in adults and children older than 4 months.40 In most settings, patients are nursed in a routine pediatrie impatient unit. Oxygen saturation usually is monitored continuously, although hourly nursing assessments of somnolence and respiratory rate are often more helpful in avoiding potential problems.

Regional Anesthesia

Local anesthetic neural blockade, either administered as a "single shot" during or just after surgery, or infused continuously through a catheter, represents another option for controlling postoperative pain. Although epidural infusions of bupivacaine and lidocaine have been used effectively to control postoperative pain in children from neonates to adolescents,41 many authorities prefer to combine dilute local anesthetics (eg, 0.125% bupivacaine) with an opioid to minimize side effects and hasten ambulation.42

Caudal ("kiddie caudal") nerve blocks are relatively simple to perform and are commonly performed after the induction of general anesthesia to reduce the need for postoperative analgesics. Qualified pediatrie anesthesiologists have reponed on the successful use of a variety of peripheral nerve blocks in children (eg, penile, intercostal, iUoingumal/iUohypogastric, sciatic, and femoral nerves, and lumbar plexus and brachial plexus).43'54 The interested reader is referred elsewhere for a more detailed discussion of specific techniques and indications.55 Preemptive analgesia,56 which is based on the theory that intraoperative neural blockade may reduce postoperative pain and the risk of developing chronic pain, recently has attracted considerable notoriety, although experts disagree on the validity of this concept. Nevertheless, the simple infiltration of the incision site prior to commencing even minor surgery is now practiced in many centers.

Adjuvant Drugs

Although severe pain requires treatment with opioids, other agents may be used concurrently for their opioid-sparing effects. The most common adjuvants used for postoperative pain management are acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDS) (Table 3).57 For patients who can tolerate oral medications, ibuprofen or another NSAID is a reasonable choice. Although acetaminophen enjoys wide use, it lacks anti' inflammatory activity,57,58 When the oral route cannot be used, options include intravenous ketorolac, and indotnethacin or aspirin suppositories (although the use of aspirin in children is controversial). In addition, there is ample experience outside the United States with diclofenac sodium suppositories in children.59 Antidepressants have an established role in the management of chronic pain and have been useful in our hands for children with cancer who may have neuropathic pain or who are demoralized and depressed from chronic illness and treatments.

Nonpharmacologic Approaches

Nonpharmacologic approaches to postoperative pain include behavioral techniques and transcutaneous electrical nerve stimulation (TENS). The efficacy of TENS for postoperative pain management is controversial, and most centers have not found its routine use practical.60 The most fundamental behaviorally oriented approach relies on preparing the child and the child's family through instruction and by creating a supportive environment. As described elsewhere in this issue, most verbal children are capable of mastering simple relaxation skills such as deep rhythmic breathing.

Distraction is a particularly useful strategy. For example, at the University of Texas M.D. Anderson Cancer Center, each pediatrie unit has a "safe" (no treatment) play area that is furnished with a variety of toys, pinball machines, and books. Each inpatient bed is equipped with a small color television with access to 24-hour children's programming, portable videocassette players, and a library of tapes. Portable video game units are in almost constant use by our patients and may be the most effective distraction tool. In addition, the institution uses child life specialists who organize a range of activities from painting and coloring contests to celebrity autograph signings and parades. Finally, parents are allowed and encouraged to reside in the child's room.

A growing body of research aimed at analyzing children's coping styles is expected to help clinicians design clinical strategies that identify and enhance different coping mechanisms. In addition to tailoring the analgesic technique to the individual child, a better understanding of the interaction between parental behaviors and children's coping styles should further facilitate individualization of treatment.

CONCLUSIONS

Successful treatment of postoperative pain in children is achievable in almost all cases. Important attributes of a successful treatment program include the availability of clinicians experienced in the care of children, vigilant nursing, and carefully individualized treatment planning. The foundation for success lies in a willingness to carefully apply treatments that most physicians do not hesitate to use in adults. In a society that professes to cherish its children, they surely deserve to be treated as well as their parents.

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TABLE 1

OpIoId Analegesla for Children and Adolescents*

TABLE 2

Selected PCA Dose Regimens*

TABLE 3

Nonsteroldal Anti-Inflammatory Drugs

10.3928/0090-4481-19950301-10

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