- *Clinical Instructor of Pediatrics, Pediatric Pain Program, Department of Pediatrics.
- †Professor of Pediatrics and Anesthesiology; Chief, Division of Critical Care; Director, Pediatric Intensive Care Unit, Department of Pediatrics.
- ‡Professor of Pediatrics and Anesthesiology; Director, Pediatric Pain Program, Department of Pediatrics, University of California, Los Angeles, CA.
Upon completion of this article, the reader should be able to:
Understand when it is appropriate to administer analgesia and treat the pain of head and abdominal trauma.
Explain why pharmacological or psychological interventions must be administered with caution.
Explain what aspects of child development should be taken into account when assessing a child’s pain and selecting a pain treatment plan.
Determine the most reliable assessment tool of a child’s pain perception.
Describe the appropriate administration regimens for analgesics, sedatives, and nonpharmacologic therapies.
One of the primary duties in medicine is to treat pain. Historically this duty has been fulfilled poorly, especially for pediatric patients. Until recently, the prevailing dogma was that children did not perceive or remember painful occurrences as intensely or as unpleasantly as did adults. There also was fear, often unfounded, that treating traumatic pain would mask the symptoms of progressive injury. Such assumptions are false, and it is no longer appropriate simply to restrain children or to withhold analgesia. As recently as 1990, Selbst and Clark reported in a retrospective study that 60% of adults but only 28% of children presenting to an emergency department (ED) with long bone fractures received adequate analgesia. In 1997, Petrack, Christopher, and Kriwinsky documented a rate of analgesic use for long bone fractures in EDs of 53% in children and 73% in adults. This represents a significant improvement, but remains inadequate.
Although emergency medicine has made major strides in the treatment of pediatric trauma pain, multiple erroneous reasons have been offered not to treat pain in children. The most prevalent assumption is that children, especially infants, do not feel pain. Because the very young child is unable to verbalize and, thus, report pain, physicians simply may deny its existence. In fact, nociceptive neural pathways are in place by 23 to 24 weeks’ gestation. Term and preterm newborns have fully developed pain transmission pathways, but lack fully developed pain inhibitory systems. Thus, they may feel even more pain than older children in similar situations.
Many practitioners withhold opioids or administer inadequate doses to children because of a fear of serious side effects such as respiratory depression or hypotension. The potential for these adverse effects is real, but knowledge of the pharmacokinetics and proper dosing of any drug greatly reduces the risk, and several of the medications used are associated with readily reversible effects. One false assumption is that children are at increased risk for addiction to narcotics. In reality, the risk of addiction from short-term use of opioids in children is extremely low. Finally, many physicians fear that administering opioids will mask symptoms of progressing injury or complications. Studies in adults have shown an equal if not improved ability to diagnose intra-abdominal pathology after the administration of narcotics at appropriate doses.
There no longer is any reason to withhold careful and individualized use of pain medications from children in any clinical setting. There are many pharmacologic and non-pharmacologic treatments. To choose the best treatment, the clinician needs to know the factors that affect pain perception, the intensity of pain, and the available therapeutic options.
To choose the best pain management regimen, physicians need to understand what they are treating. As defined by the International Association for the Study of Pain, pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. In other words, pain is not simple. There is neurologic, endocrinologic, psychologic, and immunologic modulation of both the perceived noxious stimulus and the subsequent behavioral response.
Children’s perceptions of pain are influenced by many factors (Table 1⇓ ), including expectations, parental response, context, and cognitive level. Children’s expectations of pain come from their own memory of previous painful experiences and those learned from family or culture. They develop a memory of painful experiences very early. For example, a 6-month-old child will withdraw when a needle is brought into his or her field of vision. Often, expectation and waiting are the worst part of a painful experience. Children are very perceptive of their parents’ emotional responses, and the perception of parental anxiety can increase a child’s pain; a calm parent can be a strong analgesic. The perceived cause, control, and expected duration of the pain can modulate pain perception profoundly.
As children develop, their ability to understand, cope with, and describe pain changes dramatically. The preverbal infant can communicate pain only through behavior and physiologic changes. Pain behavior is characterized by the thrashing of extremities; attempts to touch the affected area; facial grimacing; a tense, cupped tongue; and a high-pitched, harsh, irregular cry. These behaviors are very consistent across genders and cultures. Infants also rely heavily on external cues for coping. Soothing practices, such as swaddling, sucking, and stroking, have been shown to reduce an infant’s physiologic and behavioral responses to pain.
Words for pain such as “owie” and “boo boo” are some of the first words a preschool-age child learns. By the age of 3 years, children can begin to assess pain intensity reliably by using a self-reporting scale such as the faces scale. Even though the preschool-age child has developed language to communicate pain, his or her lack of understanding and inability to localize the pain often create confusion for caretakers.
Preschool children have very little concept of what is inside their bodies. Any pain that is not on the surface or has not caused a visible injury may be poorly localized (eg, the toddler who has a tummy ache). Because toddlers also do not understand cause and effect, pain often is perceived as a punishment and, therefore, the child’s fault. This type of thinking is reinforced by comments such as, “If you move, this will only hurt more.” Control also is a major developmental issue for this age group; the more control that is lost during a painful episode, the more negative the experience will be. Consequently, preschoolers can tolerate pain better if they are allowed to have input into the how, when, and who of the situation.
School-age children have a much broader understanding of pain. It no longer is simply a physical entity, and they understand that pain can make them feel bad. Children at this age begin to use psychological coping mechanisms such as distraction. School-age children still have a firm belief in rules and often view pain as punishment for transgression of the rules. They have developed a greater understanding of their body, which enables them to locate internal pain better. Along with this increased body awareness comes the awareness of mortality and fatalism. In times of trauma, this fatalism can exacerbate fear and pain perception greatly.
For the adolescent, the psychological effects of pain and injury are paramount. The primary focus for these young people includes concern over alteration of body image, loss of relationships with peers, and maintenance of personal control. These issues may cause anxiety and may heighten pain perception after an injury. Along with a greater understanding of the psychological aspects of pain comes the ability to describe pain more precisely in terms of quality and timing. Adolescents also are better able to use cognitive coping strategies to diminish the perception of physical pain.
Coping with pain is the way a person uses cognitive skills to modulate the perception and expression of pain. As described previously, these skills broaden as children develop. Painful experiences (especially medical procedures) have two parts: preparation and the actual procedure. Children may employ different coping strategies during each part. Coping during preparation and anticipation is described on a spectrum ranging from seeking information to avoiding information. Information seekers are those children who ask many questions, want to see the medical tools, and derive comfort from the information. Avoiders have increased anxiety when presented with preparatory information. The clinician should assess the child’s reaction to explanations of medical treatment. The information seeker tends to become calmer during the actual procedure; the information avoider becomes more anxious.
During an actual painful experience, coping strategies range from focusing attention on the experience to distracting attention from it. Most children respond well to distraction techniques with reduced anxiety and pain sensation. Other children resist all attempts at distraction and become agitated unless they are allowed to watch the procedure. It is essential to monitor the effectiveness of any pain management strategy continually.
One crucial concept of pain assessment is the understanding that pain is an individual, subjective experience; no one can define another person’s pain experience. A good rule of thumb when caring for children is to acknowledge that children who say they are in pain are experiencing pain. If they appear to be in pain, they are in pain, and they are in as much pain as they say. After recognizing the existence of pain, the clinician must determine the intensity, cause, and nature of the pain before initiating therapy.
The clinician has many tools for assessing a child’s pain. Often the most reliable is the child’s self-report during questioning, but the child’s cognitive level may affect this reporting. Pain rating scales, evaluation of behavior, physiologic parameters, parental observations, and knowledge of the cause of the pain all can yield important information.
While questioning a child, it is important to use words that he or she understands, such as “boo boo” or “owie”. Because even preschoolers can localize pain, all children should be asked to point, with one finger, to the painful location on the body. Older children can provide detailed information regarding pain intensity, quality (eg, throbbing versus stabbing), duration (constant versus intermittent), and the factors that affect the intensity of the pain.
Pain rating scales provide a subjective and quantitative measure of pain intensity. Children as young as 3 years of age can use a cartoon facial affective expression scale. The faces range from happy, which represents no pain, to tearful, which represents as much pain as the child can imagine (Figure⇓ ). Once children gain a concept of numbers and their relative values (at approximately age 5 y), a numeric scale can be used. Arranging the numbers vertically with the highest value on top will aid in reliability. Children older than 7 to 8 years can use a 0 to 10 numerical scale where 0 represents no pain and 10 represents the worst pain they can imagine. To ensure reliability, it is essential to explain the rating scale fully to the child before seeking a score.
In the preverbal child, behavioral and physiologic assessments are necessary to determine pain. The most consistent indicator of pain in infants is the facial grimace. A furrowed brow, tightly shut eyes, raised cheeks, open mouth, and tense and cupped tongue characterize a painful grimace. The pain-elicited cry is high-pitched, harsh, and irregular. In general, the less consolable child is experiencing greater pain. Physiologic signs of pain include decreased oxygen saturation, increased heart rate, increased blood pressure, and sweating.
No one sign or behavior is an absolute indicator of pain; they all must be taken in clinical context. All pain assessment tools also can be used as measures of the effectiveness of analgesic therapy; the direction and degree of change provides important therapeutic information. No matter how a child’s pain is measured, it is paramount to assess the effectiveness of the analgesic intervention.
The rationale underlying most nonpharmacologic pain therapies is to change the child’s focus and conceptualization of the immediate situation. The therapist strives to alter the context from anxiety and chaos to mastery and control. This paradigm shift assists the child in modulating pain perception. Many techniques can be employed.
Positive reinforcement increases a child’s sense of self-esteem by reinforcing positive pain coping. The caregiver simply makes supportive comments regarding the child’s positive coping behavior, such as, “You are being so brave” or “You are doing a fantastic job of holding still.” It is important to reward any positive behavior that the child exhibits and not punish, threaten, or shame the child for uncooperative behavior. Comments such as, “If you don’t stop squirming, the doctor will give you a shot” only increase feelings of helplessness, anxiety, and pain.
Providing information and choices increase the child’s sense of control, and both procedural and sensory information should be given. Procedural information should include what is going to happen in broad terms (eg, cleaning the wound, applying topical anesthetic, then placing sutures). Sensory information addresses the sensations the child will experience (eg, washing the skin will feel cold and wet and a lidocaine injection may sting or burn a bit, but then you may notice a numb feeling). It is important to be honest when describing anticipated pain. Allowing the child to have input (when possible) into the therapy is another way of increasing his or her sense of control as long as what is chosen can be carried out. If a child needs an intramuscular injection, making the choice of which thigh gets the shot can be calming and recruits the child into his or her own care. Some children will become overly anxious when informed or presented with a choice, so it is important to evaluate the impact of this approach.
Distraction is useful to shift the child’s attention away from pain. Simple techniques such as singing, counting, watching a favorite video, listening to a story, squeezing a parent’s hand, or telling a story can refocus attention. The more the child is involved with the distraction, the less pain he or she will experience. Having a child use his or her imagination to describe being in a place he or she likes is more effective than simple distraction.
Hypnotherapy involves active and interactive imagination, and it has been used in burn treatment, laceration repair, fracture reduction, multiple trauma, and more. The clinician can help the child use his or her imagination to “be” somewhere else (eg, the amusement park, beach, home) and to engage in some fun activity (eg, swimming or playing with friends). Hypnotherapy not only shifts the child’s focus of attention and provides an engaging, sustaining distraction, but it can alter the child’s sensory experience. For example, the clinician can say,“ Notice how the magic glove begins to make your hand tingle, just like it does when it goes to sleep … really asleep … numb … with less and less feeling.” Transforming the meaning of pain from loss of control to mastery over adversity is always the central theme.
Acupuncture is a technique that involves inserting solid stainless steel needles (usually 32-gauge) into the skin and specific anatomic sites along organ meridians. Its purpose is to simulate these specific sites to change local circulation and develop systemic neural, hormonal, and circulatory effects. There is very little literature about the use of acupuncture in children; most involves disease-related therapy.
Acupuncture has been shown to increase levels of circulating endogenous opioids, thereby modulating pain. It is an additive therapy in which the effect grows with repeated treatment. This lends itself well to the management of chronic pain. Migraine pain responds very well to acupuncture in both adults and children. The effects of acupuncture on musculoskeletal pain in children has not been well studied. In adults, good results have been reported for the treatment of nausea, but results in the pediatric literature are equivocal. Good evidence exists in the adult literature that acute traumatic pain can be modulated by acupuncture, but there has been nothing conclusive within the pediatric arena.
MASSAGE AND TOUCH
Massage and touch are excellent interventions for decreasing acute anxiety and increasing the sensation of well-being; both have been shown to improve the well-being and development of children. Often, the simple act of touching the child during a painful procedure can lessen both the child’s fear and perception of pain. Touch seems to play a more central role among younger children.
Relaxation can be helpful in managing fear and anxiety. Deep breathing is the simplest method. For younger children, blowing bubbles or a noisemaker can facilitate deep breathing. Other techniques, such as progressive muscle relaxation (systematic tensing and relaxing of muscles), require more cooperation from the child, but can be even more effective. Biofeedback involves visual or auditory reinforcement of progressive relaxation.
Restraint is a much-debated technique of pain control. For infants, swaddling is very soothing, but for older children it represents a further loss of control. Wrapping the patient in a sheet or strapping him or her to a papoose board can cause bruising and edema and increase anxiety and the perception of pain. The goal of pain management therapy is to ease the child’s suffering rather than to make things easy for the clinician. With the proper use of pharmacologic and nonpharmacologic intervention, any level of patient cooperation and comfort can be achieved, preferably without the use of restraints.
Practitioners often need to perform painful procedures to facilitate recovery from a trauma. For many of these diagnostic and therapeutic procedures, the child must remain perfectly still. If a child’s perception of pain cannot be managed by distraction or mild analgesia, it is not acceptable to restrain children physically for such procedures. Rather, conscious or deep sedation is the therapy of choice when behavioral interventions alone will not suffice.
Adverse reactions during sedation are common, and the actual risk of their occurrence is unknown. What is known is that all drugs that have been used for pediatric sedation have been reported to cause adverse reactions, even when administered at recommended doses. Combining multiple drugs increases the risk of respiratory depression. Children who have a history of serious illness (Table 2⇓ ) or are younger than 5 years of age are at greater risk for adverse reactions, but most of these reactions occur in healthy children. The most common adverse reactions are respiratory depression, airway obstruction, and apnea. Common causes for adverse events include inadequate practitioner skill, poor evaluation before administering sedation, insufficient monitoring during administration of sedation, premature patient discharge, and drug errors.
To reduce the frequency of adverse events during pediatric sedation, the American Academy of Pediatrics (AAP), the American Society of Anesthesiologists (ASA), and the American College of Emergency Physicians (ACEP) all have established guidelines for the monitoring and treatment of children being sedated. The guidelines are similar, but for this review, those of the AAP are used as a template.
Conscious sedation is a medically controlled state of depressed consciousness in which protective reflexes, independent maintenance of a patent airway, and the ability to follow simple commands are maintained. Deep sedation is a medically controlled state of depressed consciousness in which protective reflexes and independent maintenance of a patent airway may be maintained, but the patient is unable to respond appropriately to physical stimulation or verbal commands. General anesthesia is a medically controlled state of unconsciousness in which protective reflexes, independent maintenance of a patent airway, and the ability to respond to physical stimulation are lost. Because these levels of sedation exist on a continuum, a child can move easily and sometimes unpredictably between levels, which makes vigilant monitoring essential.
There are several problems with the sedation continuum concept. For example, it is usually impossible to use conscious sedation in children because protective reflexes are maintained. For children, pulling away and screaming may be a natural protective reflex against a noxious stimulus, but a level of sedation that might include these behaviors is inadequate for most pediatric procedures. Thus, deep sedation often is required.
Evaluation, preparation, and monitoring are the keys to successful sedation. A presedation evaluation is essential and should focus on uncovering any condition or anatomic situation that would increase the child’s risk during sedation. The AAP guidelines employ the ASA physical status designations (Table 3⇓ ). Only children who are categorized as ASA physical status I and II are at low enough risk for sedation complications to be sedated by physicians who do not have training in anesthesiology. Children who are rated at physical status III or IV require an anesthesiology evaluation prior to any sedation. An appropriate presedation fasting period also is essential to reduce the risk of aspiration. Children younger than 6 months of age should not ingest milk and solids for a minimum of 4 hours, but may receive up to 59.14 mL (2 oz) of clear liquids 2 hours prior to the procedure. Children older than 6 months should be NPO for milk and solids for 6 to 8 hours and may receive clear liquids until 3 hours prior to being sedated. This information as well as parental consent should be documented prior to initiating sedation.
Personnel, equipment, and facilities to manage an emergency situation must be available during the procedure. A positive pressure oxygen system that can deliver more than 90% oxygen for longer than 60 minutes; suction equipment with appropriate catheters; pulse oximetry; age-appropriate equipment for monitoring blood pressure, pulse, and respiratory rate; age-appropriate size airway equipment; and an emergency cart with drugs and equipment for continuous life support must be present during any sedation. Capnography (the measurement of exhaled carbon dioxide), although not yet used widely, has been found to be a useful addition to the monitoring equipment. Vital signs and oxygen saturation should be documented every 5 minutes. One Pediatric Advanced Life Support (PALS)-certified clinician whose sole responsibility is to maintain sedation and monitor the child must be present.
The child continues to be at risk after the procedure. Without the anxiety or the stimulation of the procedure, children can become deeply sedated very easily and should be monitored following the procedure for at least 20 minutes or longer if drugs that have long half-lives, such as chloral hydrate or thorazine, are used. Before discharge from a recovery area, the child’s vital signs, oxygen saturation, and level of consciousness should return to presedation levels, and the child must be able to maintain his or her own airway. Pain and nausea should be controlled, and the child should return to the baseline level of functioning. If it was possible prior to sedation, the child should be able to tolerate liquids, speak, and sit in an age-appropriate fashion upon recovery. With a return to the conscious state, further risk is minimal, and the child can be discharged. Sedation always should be titrated to ensure comfort and maximize safety.
All of the medications used most commonly for pediatric analgesia and sedation are potentially dangerous, but they can be administered safely when titrated carefully. The doses suggested in Table 4⇓ provide a guideline, and the medications should be titrated to the desired effect.
Opioids are the most flexible and widely used analgesics. They can be administered orally, rectally, intranasally, intramuscularly (IM), or intravenously (IV) (all doses that follow are for the IV route). Opioid side effects include respiratory depression, hypotension, nausea, vomiting, and pruritus. Fortunately, for the majority of children, analgesia is reached prior to the onset of respiratory depression, and most adverse reactions are reversible with naloxone (1 to 2 mg/kg IV, repeat q 5 min until desired effect or 10 mg/kg). The maximal dosage of any opioid is the dose that provides analgesia without severe adverse reactions.
Morphine, the gold standard of opioids, works via the opioid receptors in the central nervous system and peripheral organs, producing analgesia, drowsiness, euphoria, dose-related respiratory depression, reduction in peripheral vascular resistance, nausea, vomiting, and pruritus. The recommended dose is 0.05 to 0.15 mg/kg infused over 5 to 20 minutes and administered every 2 to 4 hours. The onset of action is less than 1 minute, with a peak effect at 5 to 20 minutes and a duration of action of 2 to 7 hours. The long duration of action makes morphine a poor choice for short procedures, but it works well for patient-controlled analgesia, burn debridement pain, acute or postoperative fracture, and gunshot wound pain. For small infants, children in whom volume is depleted, those who have an altered level of consciousness, or those who have poor airway control, the initial dose should be lowered and subsequent doses titrated to effect.
Fentanyl is a synthetic opioid that is 75 to 125 times more potent than morphine. The recommended dose is 1 to 3 μg/kg. Its onset of action is within 30 seconds, peak effect is 5 to 15 minutes, and duration of action is 30 to 60 minutes. This drug’s rapid onset and short duration of action have made it the opioid of choice for sedation for procedures. Fentanyl rarely causes cardiovascular instability and is, therefore, safer for children who have hypovolemia, congenital heart disease, or head trauma. Fentanyl use is associated with the same dose-dependent respiratory depression as morphine, but the effect can be prolonged and can outlast the analgesic properties. Apnea, bradycardia, and chest wall and glottic rigidity occur primarily with rapid infusion and high dosing (>5 μg/kg), but such effects can occur at any dose. Chest wall and glottic rigidity can be reversed with naloxone or neuromuscular blockade.
Fentanyl is available in a candy matrix that can be very useful for patients undergoing burn debridement or fracture reduction. The dose of this formulation is 10 to 15 μg/kg in 200-μg, 300-μg, and 400-μg suckers (which are meant to be placed along the bucal mucosa, not chewed and swallowed). Onset of action is slightly longer at 5 to 15 minutes, as is the duration of 1 to 2 hours.
Meperidine is another synthetic opioid. It is metabolized in the liver to normeperidine, a chemical that has little analgesic effect but great central nervous system stimulant activity. Seizures, agitation, and myoclonus have been attributed to normeperidine, and patient sensitivity is unpredictable. Meperidine is associated with the same respiratory depression and gastrointestinal side effects as other opioids and does not offer any benefit over the use of other opioids.
Nalbuphine is a synthetic opioid agonist-antagonist that is equal in analgesic potency to morphine. It exhibits a “ceiling effect,” meaning that a maximal amount of both beneficial and adverse affects can be achieved no matter how high the dose of the drug. This ceiling effect makes nalbuphine a safer drug, but it is only effective for minor to moderate pain. Its dosing is the same as morphine, and it has an onset of action of 2 to 3 minutes and a duration of activity of 3 to 6 hours.
Codeine and oxycodone are the most commonly used oral opioids. Codeine must be converted in the liver to morphine and can cause severe nausea and vomiting. The standard dose is 1 mg/kg of which only 10% is converted to morphine. Oxycodone is a much better choice, offering significantly less gastrointestinal upset and a more palatable suspension. The dose is 0.1 mg/kg, administered every 3 hours.
Benzodiazepines function as sedatives, anxiolytics, and amnestics by potentiating gama-aminobutyric acid. They also are used to relieve musculoskeletal spasticity and short-term insomnia. Benzodiazepines have no analgesic properties, and in some cases even may increase pain sensation. Amnesia, respiratory depression, hypotension, coma, paradoxic excitement, or agitation are adverse effects of all benzodiazepines. The circulatory, respiratory, and sedative properties of these drugs are potentiated by opioids, alcohol, and other central nervous system (CNS) depressants.
Benzodiazepine toxicity can be reversed with flumazenil 0.01 mg/kg IV. If there is no effect in 1 to 2 minutes, the dose is repeated every 2 minutes until the child responds or a total of 1 mg is given. Flumazenil’s activity may be shorter than that of the benzodiazepine, so the child needs to be monitored for return of symptoms. Flumazenil can precipitate seizures in patients who have epilepsy, have had an overdose of tricyclic antidepressants, or who use benzodiazepines chronically.
Diazepam (Valium) can be delivered orally, rectally, intravenously, or intramuscularly. Intravenous administration is painful and can cause venous thrombosis or phlebitis. The recommended dose is 0.1 to 0.2 mg/kg IV and 0.2 to 0.3 mg/kg orally or rectally. The time to onset of action is 1.5 to 3 minutes with IV administration and 7 to 15 minutes with rectal administration. The duration of action is 2 to 6 hours, but due to active metabolites and enterohepatic recirculation of drug, there may be rebound sedation 6 to 8 hours after administration. This long duration of action makes diazepam a poor choice for procedural sedation, but it is an excellent agent for relaxation of muscle spasticity (eg, with long-bone fractures) or prolonged sedation.
Lorazepam (Ativan) is used more commonly in pediatrics than diazepam because it is not painful when injected and does not cause thrombosis. The IV dose is 0.03 to 0.05 mg/kg (maximum of 2 mg), the onset of action is 1 to 5 minutes, and the duration of activity is 3 to 4 hours. This duration of action is too long for most procedures, but it is ideal for children who require prolonged anxiolysis.
Midazolam (Versed) is the benzodiazepine used most commonly for anxiolysis and short-term procedural sedation. It can be administered orally, nasally, rectally, intramuscularly, or intravenously. Midazolam has a very bitter taste and must be mixed with a flavored syrup to make it palatable. The dose is 0.025 to 0.05 mg/kg IV or 0.5 to 1.0 mg/kg orally. The dose should be titrated to achieve the desired level of sedation. Sedation is achieved 1 to 3 minutes after IV administration or 10 to 30 minutes after oral administration and has a duration of action of 1 to 2 hours. Midazolam does not have active metabolites and is 24 times as potent as diazepam.
Ketamine is a phencyclidine derivative that produces dissociative anesthesia and amnesia. It can induce a trance-like state in which the child may appear to be awake and may retain some purposeful movement in the presence of significant analgesia and amnesia. Ketamine acts primarily as an antagonist at the N-methyl-D-aspartate (NMDA) receptor, but it binds to many other receptors as well. It is effective when administered orally, rectally, intramuscularly, or intravenously. The recommended dose is 0.5 to 3 mg/kg IV, 2 to 5 mg/kg IM, and 4 to 8 mg/kg enterally. Because of the significant pain associated with injection, IM ketamine should be reserved for very uncooperative children or children in whom there is no IV access. Ketamine has a rapid onset and relatively short duration of action.
This agent may increase intracranial pressure; cause vivid auditory, visual, and tactile hallucinations upon emergence from sedation; increase salivation, heart rate, blood pressure, and systemic and pulmonary vascular pressures; depress myocardial function; cause apnea; increase muscle tone; and cause nausea and vomiting. Desired side effects include bronchodilation, maintenance of the ventilatory response to hypoxia, and relative maintenance of airway reflexes. To prevent delirium and hallucinations upon emergence from sedation, ketamine can be administered with a benzodiazepine such as midazolam. Atropine 0.01 mg/kg IV (or glycopyrolate 3 to 4 mg/kg) also is recommended to prevent complications from increased salivation. Ketamine should not be used in children who have a pre-existing psychosis, intracranial hypertension, or a full stomach. It is an excellent drug for burn debridement, laceration repair, and asthma.
Propofol is a general anesthetic agent that has an unknown mechanism of action and causes dose-dependent sedation. This medication has a very fast onset of action (0.5 to 1 min), a short duration of action (5 to 10 min), and minimal residual sedation. Propofol has no analgesic properties and must be used with an analgesic or anesthetic such as fentanyl, ketamine, or a local anesthetic. It can cause apnea and dose-dependent cardiorespiratory depression. The medication is available only as an intravenous soybean and egg emulsion that is very painful on injection in small veins and is a good bacterial culture medium. When infusing propofol through a peripheral vein, 1% lidocaine either should be preinjected into the vein or mixed (1:9) with the propofol prior to injection. The recommended dose is 1 to 3 mg/kg titrated to effect. There is no reversal agent for the effects of propofol, but its short duration of action makes it relatively safe in the hands of experienced practitioners.
Nitrous oxide (NO2) is a colorless, odorless gas that has profound analgesic and weak anesthetic effect. It causes euphoria, drowsiness, and the sensation of floating; it has been used for many years during painful procedures, such as laceration repair, fracture reduction, and burn debridement. It has a rapid onset of action (about 4 min), and recovery is rapid (about 5 min) because of poor solubility in blood. The primary adverse effect is hypoxia if NO2 is administered at high concentrations. NO2 should be administered only by highly trained personnel with the proper delivery devices and safeguards. Chronic exposure can lead to megaloblastic anemia, fetal wasting, and teratogenesis. When administered with any other sedative or an opioid, NO2 can induce general anesthesia.
Chloral hydrate is a poor agent for pediatric sedation. Enteral absorption of this drug is erratic, the potential for depressed respiration is high, reversal is not possible, and the duration of action is long. This unsafe medication is not recommended. Nonpainful procedures for which chloral hydrate traditionally is used often can be accomplished with good behavioral intervention and no sedation.
Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit the formation of proinflammatory and pain-promoting eicosanoids. They are mild analgesics and excellent antipyretics. NSAIDs are useful in the treatment of mild pain from strains, sprains, nondisplaced fractures, first-degree burns, and dislocation reduction. The primary adverse effects are gastrointestinal, including epigastric pain, gastritis, and bleeding. Rarely, NSAIDs interfere with platelet aggregation and can cause azotemia in patients in whom renal function is decreased.
Ketorolac is the parenteral NSAID used most commonly. The first dose is 1 mg/kg and is followed every 6 hours with a dose of 0.5 mg/kg to a maximum of 60 mg. This very potent agent can cause renal failure with prolonged use.
Ibuprofen is the NSAID prescribed most commonly. This potent anti-inflammatory agent causes relatively little gastrointestinal upset. The recommended dose is 10 mg/kg every 6 hours.
Acetaminophen, which is not a NSAID, has excellent antipyretic and mild analgesic properties. The recommended dose is 15 mg/kg every 4 to 6 hours. Acetaminophen does not cause gastric or hematologic side effects or have the anti-inflammatory properties of the NSAIDs. Its primary adverse reaction is liver injury, which can result in liver failure.
Local anesthetics block conduction of central or peripheral nerve signals. Their effect is dose-dependent and reversible. Because these drugs act locally, they must be administered at or near the desired site of action. They are all weak bases, and to increase shelf life, they are manufactured as hydrochloride salts. This formulation is very acidic and causes significant pain on injection. The addition of sodium bicarbonate to the local anesthetic solution (eg, 1.0 mEq to 1 mL of lidocaine) will reduce the injection pain and hasten the onset of action. Epinephrine (1:200,000) also can be added to local anesthetics to prolong the nerve blockade by decreasing vascular uptake. Systemic toxicity of local anesthetics can cause CNS depression that ranges from mild anxiety and tinnitus to muscle twitching, convulsions, coma, and death. Other adverse effects that may occur at high doses include respiratory arrest, ventricular dysrhythmias, myocardial depression, and cardiovascular collapse. There is no reversal agent for local anesthetics, and supportive care is the mainstay of therapy for toxicity.
Lidocaine is used primarily for minor laceration repair and placement of intravenous catheters. The maximum dose is 3 to 5 mg/kg (7 mg/kg when mixed with epinephrine). With local infiltration, lidocaine has a rapid onset of 0.5 to 1 minute and a duration of action of 90 to 200 minutes. To lessen the pain of injection, a sharp, small-gauge needle should be used. The skin should not be punctured more than three times (this will dull the needle). When infiltrating tissue other than skin, aspirate for blood initially to reduce the risk of intravenous injection. Bupivacaine is a longer-acting (up to 6 h) local anesthetic that often is used for abscess drainage, epidural infusions, and nerve blockade.
Epidural infusions of local anesthetic, peripheral nerve blocks, and hematoma blocks (local anesthetic is injected into a fracture site hematoma) have been used successfully in traumatic injury. These therapies can reduce the need for systemic opioid therapy and may be especially beneficial for children who have hemodynamic instability or respiratory compromise.
In an attempt to lessen the pain of wound repair or injection of local anesthesics, a number of topical local anesthetic preparations have been developed. TAC (0.5% tetracaine, 1:4000 adrenaline, 4% cocaine) is administered by a swab pressed firmly to a wound in a dose of 3 to 5 mL/3 cm of laceration. This provides good anesthesia within 10 to 20 minutes. The toxic dose of cocaine is 3.0 mg/kg, and this dose of the cocaine component of TAC can cause seizures, coma, and death. Adverse reactions occur primarily when mucous membranes are involved, but these reactions have been reported without such involvement. This potential toxicity led to the development of a myriad of alternatives. LET (lidocaine, epinephrine, tetracaine) is effective but contains epinephrine and, therefore, should not be applied to areas supplied by end arteries, such as fingers, toes, or the penis. The analgesic properties of TAC and LET are comparable to those of lidocaine when used on the face and scalp but are only half as effective when used on extremity lacerations.
EMLA cream is a mixture of prilocaine and lidocaine in emulsion. It anesthetizes intact skin and can be used to eliminate the pain of phlebotomy, arterial puncture, intramuscular injections, lumbar puncture, and intravenous catheter placement. EMLA is safe and effective for all age groups, even though the prilocaine component theoretically can cause methemoglobinemia. EMLA is applied over the site of desired anesthesia and covered with an occlusive dressing. Complete local anesthesia can be achieved in 60 to 90 minutes.
Many tools now are available to decrease pain perception in traumatic injury. All therapies, both psychologic and pharmacologic, have potential adverse effects. Interventions must be tailored for each child individually, then continuously reassessed for efficacy. The key to safe and effective pain management in any child, but especially in the unstable child, is to start “small,” evaluate results, and titrate to the desired effect.
Great strides have been made in the understanding of pain perception and management. The past myths and dogma regarding pediatric pain management have been dispelled, and there is no longer a valid reason to withhold analgesics after a traumatic injury. Children suffering trauma are confused, scared, and in significant physical distress. They may view their injury as a punishment or a major disfigurement. It is our duty as clinicians not only to assist wound healing in children but also to ease their suffering.
Attard AR, Corlett MJ, Kidner NJ, Leslie AP, Fraser IA. Safety of early pain relief for acute abdominal pain. BMJ. 1992;305:554-556
Petrack EM, Christopher NC, Kriwinsky J. Pain management in the emergency department: patterns of analgesic utilization. Pediatrics. 1997;99:711-714
Yaster M, Krane EJ, Kaplan RF, Cote CJ, Lappe DG. Pediatric Pain Management and Sedation Handbook. 1997 St Louis, Mo.: Mosby-Year Book, Inc
- Copyright © 1999 by the American Academy of Pediatrics