Principles of Pain Management
Pain has been defined by the International Association for the Study of Pain (IASP) as an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage (IASP, 1979). Acute (nociceptive) pain is a common adverse stimulus that occurs as the result of injury, surgery, or illness. The severity of the physical damage and physiologic response may play a role in the child’s overall perception of pain. The acute pain experience generally resolves as the body heals.
Acute pain may develop into chronic pain if the pain experience extends beyond the normal trajectory of healing for the amount of tissue damage sustained. Chronic nociceptive stimulation may alter excitability in the peripheral and central nervous systems, resulting in sustained or recurrent pain with neuropathic qualities. Defining clinical characteristics of neuropathic pain are dysesthesia (impaired sensitivity to touch, such as paresthesia and cutaneous hypesthesia), hyperalgesia (excessive sensation from pain), and allodynia (nonpainful stimuli, such as light touch, is perceived as painful), motor abnormalities, and autonomic disturbances. Differing from acute pain, neuropathic pain involves the erroneous generation and transmission of information in the nervous system; it often persists and even intensifies over time.
Children experience just as much pain as adults. Although pain management has improved over the past few decades, particularly for predictable pain problems such as postoperative pain, underestimation and undertreatment of pain in children remain problems (Stevens, Abbott, Yamada et al., 2011; Tsze, Asnis, Merchant et al., 2012; Twycross, 2010; Vincent & Gaddy, 2009). Untreated pain may have significant and lifelong physiologic and psychological consequences, such as altered pain sensitivity (Fitzgerald & Walker, 2009; Grunau, 2013).
The problem of untreated pain in children has been recognized by professional organizations whose members care for children. The American Academy of Pediatrics (AAP) and the Canadian Paediatric Society (CPS) published a joint statement underscoring the need for effective pain management in the neonate and providing recommendations for management (AAP & CPS, 2006, reaffirmed 2010). The American Pain Society (APS) and the AAP have issued a joint statement that reinforces the need to treat pain and suffering in all infants, children, and adolescents (AAP & APS, 2001). The APS has issued a position statement on chronic pain in children that addresses special needs in pediatric pain assessment, treatment, research, and education (APS, 2012). Effective pain management is an essential component of healthcare that encompasses initial pain assessment, therapeutic interventions, and reassessment.
INITIAL PAIN ASSESSMENT
Many factors, including emotions of anxiety, anger, depression, fear, loneliness, and fear of body intrusion, can alter perception and expression of pain. The following must be considered when assessing pain:
Biologic factors: Age (children of all ages experience pain; preterm infants likely experience even more pain than an adult when subjected to the same stimulus [Fitzgerald & Beggs, 2001]); genetic characteristics (may have differing levels of neurotransmitters or response to medications) (Young, Lariviere, & Belfer, 2012); ethnicity (neurophysiologic factors, socialization, coping factors may influence response as well as management [Campbell & Edwards, 2012]); gender (biologic differences may exist [Fillingim, King, Ribeiro-Dasilva, et al., 2009; Greenspan, Craft, LeResche, et al., 2007; Guinsburg, de Araújo Peres, Branco de Almeida, et al., 2000; Kim, Neubert, San Miguel, et al., 2004; Linnman, Beucke, Jensen, et al., 2012; Pagé, Stinson, Campbell, et al., 2012] coupled with societal expectations of pain response [e.g., girls may cry, boys are discouraged from crying]); and previous pain experiences (may have caused alterations in pain signal processing).
Type of pain: Acute, chronic, recurrent, extensive, minor, traumatic, surgical, or treatment.
Psychological factors: Child’s coping style (e.g., information seeking vs. information avoiding; if we try to teach an information avoider all about a painful event, it may increase the child’s anxiety), child’s perception of the pain and previous coping techniques (whether
successful or not), child’s perception of control (lack of control may intensify the perception of pain), and temperament (ability to adapt to situations, negative vs. positive in mood and reactions).
Cognitive factors: Child’s cognitive level influences his or her ability to describe pain and understanding of the pain experience.
Cultural and societal factors: Culture and society transmit accepted standards of behavior (e.g., okay to express pain, or accept it stoically because succumbing to pain is shameful).
Family influence: Parental/family reaction to situation (a positive reaction may help the child cope, a negative reaction may exacerbate the child’s pain); separation from family often intensifies the child’s pain experience.
An initial pain assessment includes the child’s past and current pain history (see Chapter 121 for questions included in an initial history of the current pain). Ranked in hierarchical order by their importance and reliability for assessing pain are self-report, presence of pathology or a condition associated with pain, behavior, proxy ratings, and, finally, physiologic indicators of pain. Factors that influence the pain experience must also be considered. The most accurate assessment of pain uses a combination of the above. One must maintain a high index of suspicion regarding the presence of pain, particularly in nonverbal children.
SUBJECTIVE REPORTING
The subjective rating remains the gold standard for pain assessment: believe that the child has pain if he or she says so. Pain in infants or other nonverbal children with cognitive impairment must be assessed using other methods. Children in early childhood can provide simple sensory information about their current pain and location of pain, but likely cannot comprehend quality or intensity (Twycross, Dowden, & Bruce, 2009). By about 19 months of age, children have words for pain such as “hurt” and “owie” and are able to point to the general location of their pain (Stanford, Chambers, & Craig, 2006); by age 3 or 4 years, children have the cognition to report degree of pain (e.g., “a lot,” “a little”) (Oakes, 2011). Children in middle childhood and adolescents can communicate pain in more abstract terms such as quantifying pain intensity and descriptions of pain characteristics such as location, onset, progression, quality, and effect on daily activities (Twycross et al., 2009).
BEHAVIORAL OBSERVATIONS
Use measures of pain-related behaviors when self-report cannot be obtained or to supplement self-report. These ratings should be interpreted cautiously as the evidence regarding accuracy is mixed. Meta-analysis demonstrated that child self-report did not correlate strongly with either parent or nurse (Zhou, Roberts, & Horgan, 2008) or between adolescent-reported pain intensity and parentreported pain behaviors (Lynch-Jordan, Kashikar-Zuck, & Goldschneider, 2010). Conversely, a small study (n = 33) demonstrated strong correlation between children’s, parent’s, and nurses’ pain ratings for postoperative pain (Brahmbhatt, Adeloye, Ercole, et al., 2012).
In an infant, state (e.g., level of wakefulness or sleep) influences intensity of response to pain. Preterm infants show a less robust response to painful stimuli than do term infants. Thus, when an infant does not demonstrate pain behaviors, do not assume that the infant has no pain—it may be that the infant is in a sound sleep state or is too weak to respond. Behaviors that are indicators of pain in infants are the following:
Crying that is high-pitched, tense, and irregular and that arouses the listener.
Facial expression with eyes tightly closed, brows lowered and drawn together, a deepened nasolabial furrow (line between outer aspect of nares and outer corner of mouth), and a square-shaped mouth with a cupped tongue.
Simple motor responses of withdrawal from the stimulus; newborns show a generalized poorly localized response, but older infants localize more and attempt to push away or escape.
Behaviors of acute immediate pain, often associated with procedural pain experiences, change rapidly within a few minutes of the stimulus; thus, reliance on these signs as indicators of acute established pain may be misleading. Behavioral responses, in addition to clinical data regarding likelihood of pain and the infant’s ability to be consoled in response to comfort measures, must be considered in pain assessment.
Children in early childhood may lie still and rigid or be curled in a fetal position. They may clench their fists, guard or touch the painful area, and have a facial grimace of pain; they may also be irritable, sad, or depressed.
Children in middle childhood and adolescents may try to rest quietly when in pain and may demonstrate pain behaviors similar to younger children. They typically demonstrate fewer overt pain behaviors than younger children because of increasing cognitive abilities. They understand the need for aversive procedures and can use behavioral and cognitive coping strategies to deal with pain.
Children of any age may demonstrate complex behavioral responses, which vary from child to child. Some become withdrawn and quiet, whereas others demonstrate active agitated behaviors. They may show a lack of interest in their surroundings and decreased ability to concentrate. A child may also demonstrate an alteration in sleep patterns, using activity as a coping mechanism or being unable to sleep because of the pain. Alternately, the child may sleep as a coping mechanism or from exhaustion due to pain.
Cognitive Impairment
For the child who is cognitively impaired or nonverbal, identify pain and discomfort behaviors specific to that child in conjunction with family members. Parents can reasonably estimate their child’s pain using a structured pain assessment tool, although they may overestimate the child’s pain in the early postoperative period (Voepel-Lewis, Malviya, & Tait, 2005). Pain responses in children with cognitive impairment are often under or overexaggerated in comparison with developmentally appropriate children and vary from child to child. A hallmark study by Terstegen, Koot, de Boer, et al. (2003) categorized responses according to facial expression, motor behavior, social behavior and mood, attitudes toward sore part of body, vocalization, and physiologic signs. Children with cognitive impairment were found to have tense facial features, facial restlessness, grimace, downward extension of the corners of the mouth, eyes almost closed or squeezed tight, sad and/or fearful look, deeper nasolabial furrow, and trembling chin. Motor responses are characterized by tensed behaviors. Social behavior and mood pain responses included panic and resistance. Children attempted to protect the sore body part. Vocal responses ranged from penetrating sounds of restlessness, moaning, and soft and loud-hard cries. Physiologic responses to pain in the cognitively impaired child include episodes of breath holding, shocking respiration, looks red, and has tears. Fanurik, Koh, Harrison, et al. (1998) described a useful screening method to determine whether a cognitively impaired child can accurately use a self-report pain scale.
Chronic Pain
When children experience pain of longer duration, they may forget what it feels like to be pain free and thus no longer complain of pain. The body adapts to chronic pain so that changes in vital signs are not apparent. Children with chronic pain may show disrupted sleep resulting in fatigue, irritability, and decreased ability to concentrate; developmental regression; a change in eating patterns; behavior or school problems; withdrawal from peer group activities; depression; or aggression.
PHYSIOLOGIC MONITORING
Pain is a stressor that activates the compensatory mechanisms of the autonomic nervous system (ANS). The ANS has two branches: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). SNS stimulation produces the “fight or flight” response, which results in tachycardia, peripheral vasoconstriction, diaphoresis, pupil dilation, and increased secretion of catecholamines as well as adrenocortical, thyroid, and pancreatic hormones.
Other signs of autonomic arousal are found in response to painful stimuli. Respiratory rate, systolic blood pressure, transcutaneous oxygen (TcPo2) levels, heart rate, and intracranial pressure have been found to increase with painful stimuli. Conversely, decreases in respiratory rate, oxygen saturation, and TcPo2 levels have also been noted in response to pain. When assessing vital sign changes, it is important to consider the influence of other factors, such as the child’s position, fear, anxiety, crying, handling for procedures, medications, and clinical situation. Electrical skin conductance may predict the presence of pain but further research is needed (Hullett, Chambers, Pruess, et al., 2009; Maxwell, Malavolta, & Fraga, 2013).
Research yields conflicting results, possibly because of differences in measurement, populations, and pain situations. Studies in adults and children, for example, showed a decrease in heart rate with painful stimuli (Foster, Yucha, Zuk, et al. 2003; Logan, Sheffield, Lutgendorf, et al. 2002), others showed no change in sedated adults (Grap, Munro, Wetzel, et al., 2014). Physiologic variations in response to pain warn that vital sign changes may be a general reaction to physiologic stress rather than as a specific barometer of pain. Vital sign changes may stabilize fairly quickly; thus, reliance on these signs as indicators of acute established pain may be misleading. Use vital sign changes as an indicator of response considering the child’s situation, behavior, and subjective reports.
PAIN ASSESSMENT TOOLS
When selecting a method of pain assessment, consideration must be given to the developmental age of the child and the type of pain situation (e.g., procedural, postoperative, disease). Typically, assessment tools for younger children can be used with older children, but other tools require a degree of cognitive development. It is important to remember that children may regress when in pain, and a simpler tool may need to be used to ensure that the child understands proper use of the tool. Use tools that have been tested and demonstrate adequate reliability and validity. Staff familiarity with a tool increases accuracy of the assessment; thus education regarding appropriate use of the tool is essential. For subjective ratings of pain, identify two or three tools and educate staff regarding correct usage, including developmentally appropriate selection based on the child’s age and cognitive level. Use these tools to perform pain assessments. This promotes ease of comparison and tracking of adequacy of pain interventions over time. See Table 7-1 for examples of tools used to assess different types of pain, such as procedural, postoperative, and chronic or recurrent pain.
In the absence of subjective ratings, multidimensional measurement and rating tools, including behavioral observations and physiologic parameters, most accurately assess pain. Multidimensional tools may also be used to augment the subjective rating of pain.
TABLE 7-1 Pain Assessment Methods and Toolsa | |||||||||||||||||||||||||||||||||||||||||||||||||||||
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Children older than 3 years of age can reliably report their pain. A younger child may express pain; evaluate this in the context of a multidimensional assessment. Assess ability to use pain-rating tools, such as a 0 to 10 scale, by a simple test of serialization: have the child place different-sized objects (e.g., lines, pieces of paper) in order from smallest to largest. If a child does not understand how to use one of the two or three tools identified for that age group, select another.
THERAPEUTIC INTERVENTIONS
Assessment of comfort level for pain is the first step in the process of pain management. Once the presence of pain is identified, interventions must be implemented to treat the pain. Pain management interventions consist of teaching the child and family about pharmacologic agents for pain relief techniques and how to use biobehavioral techniques. When selecting treatment options, one must evaluate the type and intensity of pain, the situation, and the child’s characteristics (e.g., age, coping strategies, cognitive level, effectiveness of pain treatment used in the past). It is also important to discuss expectation of pain management with the child and family. Do they expect complete pain relief and absence of pain? Is this realistic in the child’s situation? Build on previously successful coping and pain management techniques that the child has used. If the family believes in folk practices, incorporate these into the treatment whenever possible. Develop realistic goals for the plan of pain management in conjunction with the child and family.
PHARMACOLOGIC MANAGEMENT
Pain is best managed using a proactive approach. It is much more effective to anticipate pain and treat it adequately than to treat it once it is present. Mild pain may be effectively managed using biobehavioral methods alone or in conjunction with nonopioid analgesics. Medications must be administered to manage moderate-to-severe pain; use biobehavioral techniques to enhance the effectiveness of medications. If pain is present for most of the time, medications must be administered on an around-the-clock basis. If pain is present on an episodic basis (e.g., headaches), asneeded administration may be adequate.
Assess for pain before administering medications to obtain a baseline for determining need for medication, selecting the most effective type of medication, and evaluating effectiveness of the medication after administration. Healthcare providers often assume that adolescents, because they are typically verbal and based on their increasing capacity for abstract reasoning, will tell the healthcare provider when pain medications are needed; however, this assumption may not be valid. Adolescents often assume that the healthcare provider knows when pain medication is needed and will give it; therefore assessment must be completed.
If the child can take oral medications and pain is controlled, this is optimum. Intravenous (IV) administration of medication provides a rapid onset of action and is the method of choice when treating severe pain. Intramuscular injections are not recommended for the administration of analgesics to children (AAP & APS, 2001). Not only is absorption variable but painful administration also makes this route inconsistent with the goal of analgesic therapy. Children are fearful of needles and will deny the presence of pain rather than receive an injection.
Pharmacologic medications include nonopioid analgesics, opioids, local anesthetics, and coanalgesics. Coanalgesics have a primary indication other than pain relief but also provide analgesia in certain painful conditions. These three categories of medications are typically used in combination to attack pain in a variety of ways at various points on the nociceptive pathway. By combining these analgesics, less of each individual medication is required to relieve pain, thereby reducing the potential for analgesic side effects as compared with single-agent therapy.
Nonopioid Analgesics
Nonopioids include acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) and salicylates. They are most effective for mild-to-moderate pain or can be used as a component of a multimodal approach (e.g., in conjunction with an opioid) for severe pain. Nonopioids have a ceiling effect; that is, there is a maximum dose beyond which added analgesia does not occur. The use of salicylates has decreased dramatically because of their probable association with Reye syndrome; they are now most commonly used in treating children with rheumatoid arthritis. See Munir, Enany, and Zhang (2009) for a more detailed discussion of nonopioid analgesics.
