Pediatric Patients

Like that seen in adults, undertreatment of acute pain occurs in a substantial percentage of children.^[422] In addition to anatomic, physiologic, pharmacodynamic, and pharmacokinetic differences between children and adults (see Chapter 60 ), there are barriers unique to pediatric patients that may interfere with effective postoperative pain control.^[423] Control of postoperative pain is important in the pediatric patient because poor pain control may result in increased morbidity or mortality.^{[424] [425]}

One of the most important barriers to pain control in pediatric patients are the myths that children and infants do not feel pain, that pain is not remembered, and that there is no untoward consequence of experiencing pain.^[422] These myths and other incorrect assumptions about pain in pediatric patients may hinder management of pain.^[426] Because of developmental, cognitive, and emotional differences, the assessment of pain in pediatric patients can be difficult. Pediatric patients may have difficulty in conceptualizing and quantifying a subjective experience such as pain. The lack of routine assessment and

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A plan for postoperative pain management should be discussed with the family and patient before surgery because pediatric patients may have many anxieties about pain and analgesic use after surgery. In general, the oral route is preferred for analgesic administration for mild to moderate pain. Intravenous or regional analgesia is appropriate for moderate to severe postoperative pain.^[422] Use of intramuscular injections is strongly discouraged because of the pain associated with injection and variable absorption of analgesic medication. The fear of needles may inhibit control of postoperative pain because pediatric patients may choose to suffer in silence rather than receive a painful and anxiety-provoking intramuscular injection. Addressing medication-related side effects is important to alleviate patient-related distress and improve compliance with the postoperative analgesic regimen.

Use of an intravenous PCA device allows individualization of analgesic requirements and offers pediatric patients autonomy. Children as young as 4 years have the cognitive and physical capabilities to appropriately use an intravenous PCA device.^[427] Although morphine is the standard by which other opioids are compared, morphine does not appear to have an analgesic advantage compared with other opioids (e.g., hydromorphone) when given in equianalgesic doses.^[428] Because of toxicity from its metabolite, meperidine is not an opioid of choice in acute pain management of pediatric patients. ^[422] Unlike adult patients, initial use of a background or continuous infusion in addition to the intravenous PCA demand dose appears to be more acceptable in pediatric patients.^[427] Some data suggest that addition of an intravenous PCA background infusion is associated with improved sleep,^{[74] [429]} but other studies demonstrate a higher incidence of nausea, sedation, and hypoxemia with the addition of a background infusion.^{[74] [430] [431]} None of these trials demonstrated superior analgesia with the addition of a background infusion. Nurse- or parent-controlled analgesia is also effective and may be used in certain circumstances, but close monitoring of the patient may be needed because significant respiratory depression occurs in approximately 1.7% of patients.^[432]

For pediatric patients unable to use intravenous PCA, continuous infusions or intermittent intravenous administration of opioids is effective in providing postoperative analgesia.^{[433] [434]} Although respiratory depression may occur with opioids regardless of the route administered, clinically significant respiratory depression in pediatric patients is rare.^[427] Unlike adults, pediatric patients do not appear to exhibit multiple episodes of clinically significant oxygen desaturation postoperatively when treated with neuraxial, intravenous, or intramuscular opioids.^[435] Use of nonopioid analgesic agents, such as NSAIDs or acetaminophen, may improve overall analgesia, reduce the amount of opioid used postoperatively, and decrease some opioid-related side effects.^{[436] [437] [438]} Some data suggest that for rectal administration of acetaminophen postoperatively, a higher dose (40 mg/kg followed by three doses of 20 mg/kg at 6-hour intervals) than previously recommended may result in appropriate serum analgesic levels.^{[436] [439]}

Peripheral and neuraxial regional analgesic techniques are commonly used and effective for acute pain management in pediatric patients. One of the most commonly used techniques is epidural analgesia, which can be delivered as a single dose or by using a continuous-infusion catheter technique. The catheter may be inserted (typically under general anesthesia^[440] ) anywhere along the epidural space (e.g., thoracic, lumbar, caudal), but the caudal approach seems to be the most common technique because the catheter can be easily advanced cephalad to the appropriate dermatome.^[427] Local anesthetics or opioids, or both, can be administered through the epidural catheter or needle to provide effective postoperative analgesia.^{[441] [442]} Although epidural (caudal) analgesia may be safely administered to neonates, the clinician should recognize that the maximal continuous infusion dose is probably lower than that in older children because of the lower levels of α₁ -acid glycoprotein (which binds local anesthetics) and diminished ability of the relatively immature liver to metabolize amide local anesthetics.^[443] Addition of adjuvant drugs such as clonidine in the epidural infusion may enhance postoperative analgesia.^[444]

Continuous epidural (caudal) analgesia may be used safely in the postoperative setting,^[445] and the infection rate of continuous epidural analgesia is extremely low despite the relatively high colonization rate.^{[308] [309] [310]} Continuous peripheral catheter techniques can be used effectively in pediatric patients.^{[427] [446]} Regional analgesic techniques may be useful in providing analgesia for wound incision (e.g., herniorrhaphy or orchiopexy), thoracotomy, and orthopedic procedures.^[427] Local anesthetics may also be administered topically to provide analgesia. Although there is a lack of data comparing outcomes for regional analgesia versus systemic opioids in the pediatric population, some data suggest that use of epidural analgesia is associated with improvement in some outcomes such as earlier tracheal extubation, return of gastrointestinal function, and length of hospital stay.^{[447] [448]}