Recognition and treatment of acute pain in children have vastly improved the care of pediatric patients. Data emphasizing the efficacy of adequate pain control and decreases in adverse neurohormonal changes have led to better treatment of infants and children. Recent advances in pharmacologic therapy and regional anesthetic techniques have helped expand the scope of pediatric acute pain management. In addition, the establishment of pediatric acute pain services has played an important role in ensuring timely and consistent care of children.
Developmental Neurobiology of Pain
The study of pain in neonates has been a major focus in the field of neuroscience. Nociceptive pathways are well developed even at birth. A study of brain perfusion in response to pain has demonstrated significant changes in perfusion with noxious stimuli versus non-noxious stimuli. Newborn rats appear to have significant proliferation of A and C fibers at the site exposed to pain; a pattern of hyperalgesia appears to develop in these animals. Human neonates exposed to repeated heel sticks may have cutaneous hyperalgesia, which can be reversed with topical local analgesia. Studies in the area of pain in infants and children continue to be published, thus signifying interest in both pediatric pain management and its neurobiology.
Assessment of Pediatric Acute Pain
Essential to acute pain management in children is assessment of pain. Unlike adults, pediatric patients may be too young, developmentally immature, or unwilling to provide adequate interpretation of their pain. Measures of acute pain in such patients often rely on observer reports, whereas assessment in older children involves self-report measures (see Table 20.1 ). Observational pain assessment tools use information about pain-related behavior, such as body movements, facial expression, and vocalizations; physiologic changes such as heart rate and oxygen saturation; and the child’s behavioral state. These measures have been designed to assess procedural pain (e.g., Premature Infant Pain Profile [PIPP], Neonatal Facial Coding System [NFCS] ) or postoperative pain (e.g., Children’s Hospital of Eastern Ontario Pain Scale [CHEOPS], Toddler-Preschooler Postoperative Pain Scale [TPPPS] ). The FLACC scale (faces, legs, activity, cry, consolability) is another pain assessment tool that can be used for all ages, including mentally challenged children (see Table 20.2 ). These scales have been shown to have construct validity and internal and inter-rater reliability despite intrinsic limits in their specificity for pain, such as physiologic parameters, which can vary because of other conditions not associated with pain.
| Age Group | Measure | Type of Measurement | Type of Pain |
|---|---|---|---|
| Neonates and infants | Premature Infant Pain Profile (PIPP) (preterm and full-term neonates) Neonatal Facial Coding System (NFCS) (preterm and full-term neonates, infants ≤18 mo) | Behavioral, physiologic; gestational age | Procedural |
| COMFORT scale (0-3 yr) | Behavioral, physiologic | Procedural, postoperative | |
| Toddlers and preschoolers | Faces scales | Self-report | Procedural, postoperative |
| Oucher (≥3 yr) | Self-report | Procedural | |
| Poker chip tool (4-8 yr) | Self-report | Procedural | |
| Toddler-Preschooler Postoperative Pain Scale (TPPPS) (1-5 yr) | Behavioral | Postoperative | |
| Children’s Hospital of Eastern Ontario Pain Scale (CHEOPS) (1-7 yr) | Behavioral | Postoperative | |
| Children’s and Infants’ Postoperative Pain Scale (CHIPPS) (0-4 yr) | Behavioral, physiologic, alertness, calmness | Postoperative | |
| School-age children and adolescents | Colored analog scale (CAS) (≥5 yr) | Self-report | Procedural, recurrent, chronic |
| Visual analog scale (VAS) (≥5 yr) | Self-report | Procedural, recurrent, chronic | |
| Faces Pain Scale | Self-report | Procedural, recurrent, chronic | |
| Non-communicating children, children with cognitive impairment | Non-communicating Children’s Pain Checklist—Postoperative Version (NCCPC-PV), Non-Communicating Children’s Pain Checklist—R (NCCPC-R) | Behavioral | Procedural, postoperative injury, pain related to chronic medical condition |
| VAS | Self-report | Procedural |
| Categories | Scoring 0 | Scoring 1 | Scoring 2 |
|---|---|---|---|
| Face | No particular expression or smile | Occasional grimace or frown, withdrawn, disinterested | Frequent to constant frown, clenched jaw, quivering chin |
| Legs | Normal position or relaxed | Uneasy, restless, tense | Kicking or legs drawn up |
| Activity | Lying quietly, normal position, moves easily | Squirming, shifting back and forth, tense | Arched, rigid, or jerking |
| Cry | No cry (awake or asleep) | Moans or whimpers, occasional complaint | Crying steadily, screams or sobs, frequent complaints |
| Consolability | Content, relaxed | Reassured by occasional touching, hugging, being talked to; distractible | Difficult to console or comfort |
Developmentally appropriate children 5 years and older can typically provide self-reports on one of several validated visual analog (e.g., coloured analogue scale [CAS] ) or faces scales (e.g., Faces Pain Scale—Revised [FPS-R], Oucher ) ( Fig. 20.1 ). McGrath and Hillier developed a separate Facial Affective Scale (FAS) designed to measure pain affect, as distinct from pain intensity. Interestingly, the faces scales anchored with a smiling face produce higher pain ratings than do those anchored with a neutral face. The well-described discordance between an observer’s ratings of a child’s pain and the child’s self-report allows the clinician to consider the child’s self-report as the “gold standard” whenever it can reliably be obtained.
The majority of pediatric pain assessment measures that have been developed focus on acute, procedure-related pain. Alterations in the behavioral and sensory aspects of pain that can habituate when pain becomes chronic may not be captured by these measurement scales. However, a systematic evaluation of chronic pain in children is beyond the scope of this chapter (see Chapter 33).
Assessment of Pediatric Acute Pain
Essential to acute pain management in children is assessment of pain. Unlike adults, pediatric patients may be too young, developmentally immature, or unwilling to provide adequate interpretation of their pain. Measures of acute pain in such patients often rely on observer reports, whereas assessment in older children involves self-report measures (see Table 20.1 ). Observational pain assessment tools use information about pain-related behavior, such as body movements, facial expression, and vocalizations; physiologic changes such as heart rate and oxygen saturation; and the child’s behavioral state. These measures have been designed to assess procedural pain (e.g., Premature Infant Pain Profile [PIPP], Neonatal Facial Coding System [NFCS] ) or postoperative pain (e.g., Children’s Hospital of Eastern Ontario Pain Scale [CHEOPS], Toddler-Preschooler Postoperative Pain Scale [TPPPS] ). The FLACC scale (faces, legs, activity, cry, consolability) is another pain assessment tool that can be used for all ages, including mentally challenged children (see Table 20.2 ). These scales have been shown to have construct validity and internal and inter-rater reliability despite intrinsic limits in their specificity for pain, such as physiologic parameters, which can vary because of other conditions not associated with pain.
| Age Group | Measure | Type of Measurement | Type of Pain |
|---|---|---|---|
| Neonates and infants | Premature Infant Pain Profile (PIPP) (preterm and full-term neonates) Neonatal Facial Coding System (NFCS) (preterm and full-term neonates, infants ≤18 mo) | Behavioral, physiologic; gestational age | Procedural |
| COMFORT scale (0-3 yr) | Behavioral, physiologic | Procedural, postoperative | |
| Toddlers and preschoolers | Faces scales | Self-report | Procedural, postoperative |
| Oucher (≥3 yr) | Self-report | Procedural | |
| Poker chip tool (4-8 yr) | Self-report | Procedural | |
| Toddler-Preschooler Postoperative Pain Scale (TPPPS) (1-5 yr) | Behavioral | Postoperative | |
| Children’s Hospital of Eastern Ontario Pain Scale (CHEOPS) (1-7 yr) | Behavioral | Postoperative | |
| Children’s and Infants’ Postoperative Pain Scale (CHIPPS) (0-4 yr) | Behavioral, physiologic, alertness, calmness | Postoperative | |
| School-age children and adolescents | Colored analog scale (CAS) (≥5 yr) | Self-report | Procedural, recurrent, chronic |
| Visual analog scale (VAS) (≥5 yr) | Self-report | Procedural, recurrent, chronic | |
| Faces Pain Scale | Self-report | Procedural, recurrent, chronic | |
| Non-communicating children, children with cognitive impairment | Non-communicating Children’s Pain Checklist—Postoperative Version (NCCPC-PV), Non-Communicating Children’s Pain Checklist—R (NCCPC-R) | Behavioral | Procedural, postoperative injury, pain related to chronic medical condition |
| VAS | Self-report | Procedural |
| Categories | Scoring 0 | Scoring 1 | Scoring 2 |
|---|---|---|---|
| Face | No particular expression or smile | Occasional grimace or frown, withdrawn, disinterested | Frequent to constant frown, clenched jaw, quivering chin |
| Legs | Normal position or relaxed | Uneasy, restless, tense | Kicking or legs drawn up |
| Activity | Lying quietly, normal position, moves easily | Squirming, shifting back and forth, tense | Arched, rigid, or jerking |
| Cry | No cry (awake or asleep) | Moans or whimpers, occasional complaint | Crying steadily, screams or sobs, frequent complaints |
| Consolability | Content, relaxed | Reassured by occasional touching, hugging, being talked to; distractible | Difficult to console or comfort |
Developmentally appropriate children 5 years and older can typically provide self-reports on one of several validated visual analog (e.g., coloured analogue scale [CAS] ) or faces scales (e.g., Faces Pain Scale—Revised [FPS-R], Oucher ) ( Fig. 20.1 ). McGrath and Hillier developed a separate Facial Affective Scale (FAS) designed to measure pain affect, as distinct from pain intensity. Interestingly, the faces scales anchored with a smiling face produce higher pain ratings than do those anchored with a neutral face. The well-described discordance between an observer’s ratings of a child’s pain and the child’s self-report allows the clinician to consider the child’s self-report as the “gold standard” whenever it can reliably be obtained.
The majority of pediatric pain assessment measures that have been developed focus on acute, procedure-related pain. Alterations in the behavioral and sensory aspects of pain that can habituate when pain becomes chronic may not be captured by these measurement scales. However, a systematic evaluation of chronic pain in children is beyond the scope of this chapter (see Chapter 33).
Nonmedical Management of Pediatric Acute Pain
Management of pain through nonmedical techniques (e.g., environmental and behavioral strategies) has proved effective in modulating pain, both independently and in conjunction with pharmacologic interventions in children. Cognitive-behavioral therapy (e.g., relaxation, problem solving, cognitive coping skills) and distraction techniques such as deep breathing, cartoon videos, party blowers, and hypnosis have strong empirical support for their efficacy in easing procedure-related pain in children. Distraction methods are hypothesized to work by engaging children and redirecting their attention away from the pain, thereby reducing perceived pain intensity and inhibiting the neural activity that underlies pain perception. Complementary and alternative medicine techniques such as acupuncture have also been described as potential treatments of acute pain in children.
Pain Treatment Modalities
Acute pain in infants and children can be treated with various analgesics. The use of multimodal analgesia is beneficial for the management of pediatric pain. A pain treatment plan is best developed before the patient’s surgery, and an important goal is to provide a consistent approach to treating pain with minimal adverse effects.
Mild Analgesics
Sucrose
Administration of glucose and sucrose orally can provide mild analgesia since opioid peptides in the ventral striatum and cingulate gyrus may play a role in regulating positive responses to energy-rich food sources. A Cochran database review suggested that sucrose may be effective in reducing procedural pain in neonates. Doses in the range of 0.01 to 0.1 g can be used to reduce procedural pain in infants younger than 6 months.
Acetaminophen
Acetaminophen is commonly used in children to reduce or eliminate pain. It can be administered via the oral, rectal, and intravenous routes. The rectal and intravenous routes are preferable during the perioperative period. Rectal suppositories require higher dosing and may have variable absorption but can be an effective analgesic for postoperative pain in children. Specifically, an initial rectal dose of 30-40 mg/kg is recommended, followed by subsequent doses of 15-20 mg/kg at 4- to 6-hour intervals. This produces therapeutic plasma levels that may be adequate for managing pain. Intravenous acetaminophen has recently been made available in the United States; it has more predictable bioavailability and achieves maximum concentration more rapidly than rectal dosing does.
Dosing in premature and term neonates can be affected by renal and hepatic immaturity. Hepatotoxicity is a potential risk with acetaminophen use and is dose dependent. Though a rare complication, the incidence of hepatic toxicity with higher doses of acetaminophen should be presented cautiously to parents so that injudicious use of the medication is avoided.
Nonsteroidal Anti-Inflammatory Drugs
Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used in children in the perioperative and postoperative periods and can be administered via the oral, intravenous, or intramuscular routes. NSAIDs have been used effectively in children undergoing surgery to reduce postoperative pain and decrease requirements for supplemental pain medications. Neonatal clearance of NSAIDs improves with age. Ibuprofen is metabolized by the 2C9 and 2C8 subgroups of cytochrome P-450 (CYP). Ketorolac is commonly used in children and can be administered via the intravenous or intramuscular routes. The clinical significance of the effects of NSAIDs on bleeding remains controversial, which has led to its avoidance by some for procedures such as tonsillectomy. Known side effects, including bleeding, renal toxicity, and gastritis, are more likely to occur with prolonged administration and in the presence of coexisting disease. Despite conflicting views about the use of intravenous ketorolac following orthopedic surgery in animal experiments, a short duration of therapy does not seem to affect bone healing. NSAIDs are excellent adjuvants to opioids for pain relief. In certain surgeries that could lead to postoperative bleeding, it may be wise to avoid using ketorolac (see Table 20.3 ). A randomized controlled trial of acetaminophen, ibuprofen, and codeine for relief of acute pain in children with musculoskeletal trauma demonstrated that ibuprofen provided the best analgesia among the three study medications.
| Medication | Dose (mg/kg) | Dosing Interval (hr) | Maximum Daily Dose (mg/kg) | Maximum Daily Dose (mg) |
|---|---|---|---|---|
| Acetaminophen (oral) | 10-15 | 4 | 75 | 4000 |
| Acetaminophen (IV) | 15 | 6 | 75 | 4000 |
| Acetaminophen (rectal) | 30-40 as loading dose, 15-20 thereafter | 6 | 75 | 4000 |
| Ibuprofen | 10 | 6 | 40 | 2400 |
| Ketorolac (IV) | 0.5 | 6 | 2 | 120 |
Tramadol
Tramadol is increasingly being used for the control of pain in children. The absence of respiratory depression, along with a decrease in postoperative nausea and vomiting, makes it an attractive alternative to conventional opioids. It is metabolized to O -desmethyltramadol by CYP2D6. The recommended dose of tramadol is 1 mg/kg orally every 6 hours. Children with significant obstructive sleep apnea may particularly benefit from the use of tramadol as an alternative to intravenous opioids with respect to respiratory compromise.
Opioid Analgesics
Opioids can be used effectively in infants and children, particularly in the postoperative setting and for managing chronic painful conditions, including sickle cell disease, cystic fibrosis, and painful cancer states. Dosing may be achieved via the oral, parenteral, intranasal, and epidural routes. Opioids have lower clearance in neonates and infants but reach normal mature values in the first 6 months of life. Opioid-induced respiratory depression may be more pronounced in neonates and infants, whose respiratory reflex responses to airway obstruction and hypoxemia are immature at birth but mature during the first year of life. Opioids are commonly used in combination with acetaminophen or NSAIDs (or both) to achieve multimodal analgesia. Commonly used oral opioids are listed in Table 20.4 and parenteral opioids in Table 20.5 .
| Medication | Potency Relative to Morphine | Typical Starting Dose (mg/kg) | Typical Dose (mg if >60 kg) | Dosing Interval (hr) |
|---|---|---|---|---|
| Morphine | 1 | 0.3 | 15-20 | 3-4 |
| Codeine | 0.1 | 0.5-1 | 30-60 | 4-6 |
| Hydrocodone | 1-1.5 | 0.1-0.2 | 5-10 | 4-6 |
| Oxycodone | 1-1.5 | 0.1-0.2 | 5-10 | 4-6 |
| Hydromorphone | 5-7 | 0.04-0.08 | 2-4 | 3-4 |
| Methadone | 1 | 0.1-0.2 | 10 | 6-12 |
| Medication | Loading Dose | Demand Dose | Lockout Time (min) | Continuous Infusion |
|---|---|---|---|---|
| Morphine | 0.05-0.20 (mg/kg) | 0.01-0.02 (mg/kg) | 5-15 | 0.01-0.02 (mg/kg) |
| Fentanyl | 0.5-2.0 (µg/kg) | 0.2-0.4 (µg/kg) | 5-15 | 0.2-0.4 (µg/kg) |
| Hydromorphone | 1-4 (µg/kg) | 2-3 (µg/kg) | 5-15 | 2-3 (µg/kg) |
Intravenous opioids are chosen when patients are unable to take oral medications or require markedly increased pain control. Adverse effects of opioids, including respiratory depression, nausea and vomiting, pruritus, and itching, can be managed effectively, thereby resulting in a favorable postoperative outcome ( Table 20.6 ).
| Adverse Effect | Initial Management | Secondary Management |
|---|---|---|
| Pruritus | Benadryl, hydroxyzine | IV low-dose naloxone |
| Nausea, vomiting | Phenergan | Ondansetron, IV naloxone |
| Urinary retention | Decrease opioid dose | Urinary catheterization |
| Respiratory depression | Decrease opioid dose | IV naloxone |
Patient-Controlled Analgesia
Patient-controlled analgesia (PCA) can be used to provide analgesia to children and adolescents in a controlled autonomous fashion. Several controlled trials support the safety and efficacy of PCA in children older than 6 years. In the pediatric realm, PCA use is commonly extended to include the educated provider of the child, most often the patient’s nurse or parent. The use of nurse-controlled or parent-controlled analgesia has been controversial because of safety issues. However, cautious use of PCA, whether it is nurse or parent controlled, can provide excellent pain relief in the postoperative period, even in developmentally delayed children or infants. Morphine, fentanyl, and hydromorphone are commonly used opioids for PCA. A basal infusion may be added to PCA settings to increase analgesia in patients undergoing major surgery. Children likely to experience significant postoperative pain may require additional continuous infusions of adjuvant medications for further pain control. Appendix A is a sample order set for managing PCA in children undergoing spinal fusion, for which we administer continuous epidural analgesia in addition to PCA.
Regional Anesthesia
Enthusiasm for the use of regional anesthesia to manage acute pain in children has been increasing. Despite some controversy regarding the performance of regional anesthesia in children under general anesthesia, there is consensus among pediatric anesthesiologists about the importance and use of safely providing a regional anesthetic technique under general anesthesia.
Caudal Analgesia
One of the most commonly used pediatric regional anesthetic techniques for postoperative analgesia is a caudal block, which is used in children undergoing surgery from the lumbosacral to midthoracic dermatome levels with anticipated moderate postoperative pain. Its popularity originates in part from the readily palpable landmarks and relative ease of placement in infants and children versus adults. A needle with a blunt stylet is passed through the sacrococcygeal ligament into the caudal space. A distinct “pop” is usually felt when the caudal space is entered. Nerve stimulation and ultrasonography have also been described as tools to assist in caudal placement. Local anesthetics include bupivacaine (0.125% to 0.25%) and ropivacaine (0.1% to 0.375%) with 1:200,000 epinephrine at a dose of 1 mL/kg (maximum dosage, 30 mL).
Spinal Anesthesia
Spinal anesthetic techniques have been used, especially in former preterm infants who are undergoing hernia repair as a method to avoid apnea and bradycardia. The procedure can be performed in an awake infant, thereby avoiding exposure to general anesthesia. This technique, though effective, has limitations because of the lack of adequate training to perform this block on a routine basis.
Continuous Neuraxial Catheters
Continuous epidural analgesia is a commonly used technique in infants and children. Epidural catheters may be placed in the thoracic, lumbar, or caudal regions. It is also possible to insert a caudal catheter and thread it cephalad to the desired dermatomal level. Bupivacaine and ropivacaine are frequently used local anesthetic solutions. Common additives to these solutions include opioids and α 2 -agonists, including fentanyl, morphine, hydromorphone, and clonidine. It is imperative that standardized dosing parameters for a single injection, as well as for continuous infusion, be used in neonates, infants, and children to avoid local anesthetic–related systemic toxicity. Suggested pediatric dosing regimens are listed in Table 20.7 . Patient-controlled epidural analgesia can be used successfully with continuous infusions of local anesthetic and patient-determined boluses, which are delivered to augment analgesia.
