Tool
Reference
Age range
Clinical indications for use
Guidelines for use
Advantages and disadvantages
PIPP
28–40 weeks gestational age
Procedural pain, postoperative pain
Score ranges from 0 to 3 in each indicator, scores can range from 0 to 21 in infants less than 36 weeks gestation, maximum score 21 in infants over 36 weeks gestation
Includes cutoff scores for mild, moderate, and severe pain
Multidimensional; 7 indicators, including two physiological, three behavioral, and two contextual
N-PASS
Hummel et al. [26]
0–100 days old; 23 weeks gestation and above
Ventilated and/or postoperative infants
Scoring determines whether infant is sedated or in pain
Multidimensional; 5 indicators, including four behavioral and one physiological. Measures sedation and pain on a continuum. Includes scoring criteria for corrected age. Has been validated in ventilated infants
CRIES
Krechel and Bildner [27]
32–60 weeks gestational age
Postoperative infants
Scoring ranges from 0 to 2 in each of the 5 indicators for a total score of 0–10
Multidimensional; 5 indicators, including two physiological and three behavioral
6.3.1 The Premature Infant Pain Profile (PIPP)
This tool consists of a seven-item, 4-point scale that measures behavioral, physiological, and contextual indicators [24] (Fig. 6.1). These measures include gestational age, behavioral state, oxygen saturation, brow bulge, eye squeeze, and nasolabial furrows. Initial reliability and validity testing involved procedural pain such as heel lance, circumcision, and venipuncture. Research on the PIPP has demonstrated construct validity of the tool as a measure of prolonged postoperative pain in premature infants who underwent surgical procedures [25].
Fig. 6.1
Scoring method for the premature infant pain profile (PIPP) (Adapted from Stevens et al. [24]. With permission from Wolters Kluwer Health)
6.3.2 Neonatal Pain Agitation and Sedation Scale (N-PASS)
The N-PASS [26] consists of five indicators that have demonstrated reliability and validity as pain measures in various neonatal pain assessment scales (Fig. 6.2). These indicators are cry/irritability, behavior state, facial expression, extremities/tone, and vital signs. The tool was tested on infants in the neonatal intensive care unit who had received surgical procedures [26]. The infants ranged in postnatal age from 0 to 100 days, and gestational age ranged from 23 to 40 weeks. Convergent validity, assessed by correlation with the PIPP, was 0.83 at high pain scores and 0.61 at low pain scores. Inter-rater reliability was high (0.85–0.95). The N-PASS is validated up to 3 years of age.
Fig. 6.2
N-PASS assessment table. Used with permission
6.3.3 CRIES
CRIES [27] is a tool that measures five physiological and behavioral variables: C-crying, R-requires increased oxygen administration, I-increased vital signs, E-expression, and S-sleepiness (Fig. 6.3). The tool was tested on infants between 32 and 60 weeks gestational age who underwent surgical procedures, including insertion of ventriculoperitoneal shunts and thoracotomies. Construct validity was established by comparing scores pre- and post-analgesia administration. Inter-rater reliability was found to be acceptable (r = 0.72).
Fig. 6.3
CRIES neonatal pain assessment tool. Used with permission
6.3.4 Assessing Postoperative Pain in Infants and Young Children
Although most children over the age of 18 months are verbal, their ability to communicate pain may still be limited to crying or to providing information only about the presence or absence of pain. Assessing pain in infants and preschool age children is best accomplished by measures that include behavioral manifestations of pain. Tools that have shown reliability and validity in assessing postoperative pain in infants and young children include the Faces, Limb, Activity, Cry, and Consolability (FLACC) scale for hospital use and the Parents’ Postoperative Pain Measure (PPPM) for use at home [28].
6.3.4.1 FLACC (Faces, Limb, Activity, Cry, and Consolability)
The FLACC [29] has been shown to be a reliable tool for measuring postoperative pain in young children (Fig. 6.4). The acronym FLACC incorporates the different domains of the assessment – Facial expression, Leg movement, Activity level, Cry, and Consolability. Each domain receives a score between 0 and 2 for a total score of between 0 and 10. Initial testing of the tool involved assessment of children between 2 months and 7 years of age who had undergone surgical procedures in the postanesthesia care unit. Inter-rater reliability was found to be high using simultaneous independent evaluations (r = 0.94). Validity testing has demonstrated that FLACC scores decrease with analgesia administration in children under the age of 3 years [30].
6.3.4.2 Parents’ Postoperative Pain Measure (PPPM)
The Parents’ Postoperative Pain Measure [31] has been validated as a measure for home use in children who are discharged to home following day surgery procedures. This 15-item tool includes cutoff scores which show excellent sensitivity and specificity (>80 %) in determining clinically meaningful pain scores. The initial validation of this tool was completed on children ages 7–12 years undergoing procedures which were ranked by experts into three classes – highly painful (e.g., tonsillectomies), moderately painful (e.g., sinus surgeries), or little or no pain (e.g., myringotomies). Further validation of the PPPM [32] demonstrated that the tool is a reliable valid measure for home use on children between the ages of 2 and 6 years.
6.4 Assessing Pain in Children and Adolescents
Children over the age of 3 years can often provide reliable information about the intensity or severity of their pain using validated self-report scales. Much of the research related to pain assessment tools for this population has focused on the use of the scales in clinical trials rather than in clinical practice. The Pediatric Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (Ped-IMMPACT) by Stinson et al. [33] reviewed 34 self-report tools and found that while no single tool was optimal for all types of pain, six were shown to be reliable and valid for acute pain (Table 6.3). The Faces Pain Scale [34] and Faces Pain Scale-Revised [35] have both been shown to be reliable, valid, simple, easy to use, and require minimal instruction. Other recommended pain scales include the Oucher, the Pieces of Hurt, the Wong-Baker FACES Pain Scale, and the Visual analogue scale. Numeric rating scales are frequently used in clinic practice. Each of these scales is discussed below.
6.4.1 Faces Pain Scale-Revised
The Faces Pain Scale-Revised [35] has been translated into more than 40 languages and can be obtained free of charge for use in clinical practice. Obviously, it is important when using pain assessment tools with young verbal children to communicate in a language that they understand whenever possible. These pictorial scales with accompanying instructions have a series of six faces that the child points to, indicating how much they hurt or how sore they feel. This scale has strong psychometric properties and is widely used in research and clinical practice internationally.
6.4.2 Numeric Rating Scales (NRS)
Older children are often asked to rate their pain using these scales (Fig. 6.5). The NRS is generally composed of an 11-point numeric rating scale, with anchors of 0 (No Pain) and 10 (Worst Pain Imaginable). A recent publication by von Baeyer et al. [36] reviewed the use of the numeric rating scale to define age limits for which it would be appropriate and concluded that the scale is supported for use in children over the age of 8 years.
Fig. 6.5
Numeric rating scale (NRS)
6.4.3 Oucher
The Oucher [37] consists of a numeric rating scale combined with six photographs of children’s faces. Caucasian, African-American, Hispanic, First Nations (boy/girl), and Asian (boy/girl) versions are available. Using this scale, the child chooses the face that best reflects the pain level. The picture selection is then converted to a number between 0 and 10. The scale must be printed in color in order for the child to accurately see the faces, making it a more expensive tool to use.
6.4.4 Pieces of Hurt/Poker Chip Scale
The Pieces of Hurt, or Poker Chip Scale [38], consists of four chips or pieces of hurt. The child chooses how many pieces of hurt they are experiencing. The tool is difficult to use in postoperative care in hospitals because of infection control concerns and availability of poker chips on the unit.
6.4.5 Wong-Baker FACES Pain Scale
The Wong-Baker FACES Pain Scale [39] is a reliable and valid tool for assessing pain in children over 3 years of age. It is similar to the Faces Pain Scale-Revised in that it consists of a series of six cartoon faces depicting “no hurt” to “hurts worst.” The child then chooses the face that best describes his/her pain. Recent research [40, 41] has found that children’s pain ratings are influenced by the pictorial anchors, as the “no pain” face has a smile and the “most pain” face has tears. These findings suggest that the faces in this scale may measure pain affect rather than pain intensity.
6.4.6 Visual Analogue Scale (VAS)
The visual analogue scale (VAS) [42], which has several forms, is composed of a line with the words “no pain” and “worst” or “most pain” as anchors (Fig. 6.6). The line can be vertical or horizontal. The child is asked to mark a point on the line to indicate pain intensity. The VAS has been used extensively in research studies. It is not as clinically useful as a tool as it may be difficult to interpret and difficult to include in a chart document and requires careful explanation to the child. Debate continues as to optimal line length and the choice of anchor words.
Fig. 6.6
Visual analogue scale (VAS). A 10-cm scale is recommended; the child marks a point along the scale that corresponds with his/her pain. A ruler is then used to determine the score by measuring the distance between the “no pain” anchor and the mark
6.4.7 Children’s Hospital of Eastern Ontario Pain Scale (CHEOPS)
The Children’s Hospital of Eastern Ontario Pain Scale [43] is a time-sampling behavioral pain scale. It looks for behaviors related to six items: cry, facial, child verbal, torso, touch, and legs. Each behavior listed under each item is given a numerical score and definition. The numerical scores are assigned based on the following criteria: 0 is behavior that is the antithesis of pain; 1 is behavior not indicative of pain, and not the antithesis of pain; 2 is behavior indication of mild or moderate pain; and 3 is behavior indicative of severe pain. Therefore, the total score can be from 4 to 13 for each time period sampled. It showed good inter-rater reliability, with average percentage of agreement by patients ranging from 90 to 99.5 %.
6.5 Assessing Postoperative Pain in Critically Ill Children
Assessing postoperative pain in critically ill children in an intensive care unit requires multidimensional tools. If a critically ill child is not sedated, a self-report should be obtained where possible. However, for many of these children, sedation is a required part of their care, making valid assessment by self-reporting more difficult. The COMFORT scale [44, 45] (Fig. 6.7) was developed to assess distress in critically ill children. In many critically ill children, pain may be a contributor to the distress. The COMFORT scale consists of behavioral and physiological indicators. The tool requires extensive training of clinical staff but is one of the few tools validated for use in this population. The modified FLACC [46] is valid in measuring postoperative pain in intubated children. The Cry section is modified to reflect the facial expression associated with crying.
Fig. 6.7
COMFORT scale for pain assessment in critically ill children (Reprinted from van Dijk et al. [45]. With permission from Wolters Kluwer Health)
6.6 Assessing Postoperative Pain in Children with Cognitive Impairments
Assessing postoperative pain in children with cognitive impairments requires the use of multidimensional tools and parental input. It can be difficult to determine which behaviors are pain related in this population. The Non-Communicating Children’s Pain Checklist-Postoperative Version (NCCPC-PV) by Breau et al. [47] (Fig. 6.8) demonstrated good inter-rater reliability and included cutoff scores to determine mild or moderate to severe pain. The tool requires a 10-min observation of behaviors in six domains – vocal, social, facial, activity, body and limbs, and physiological. The FLACC has also shown reliability and validity in assessing postoperative pain in children with cognitive impairments. Malviya et al. [48] utilized the FLACC as well as individualized behaviors identified by the parent for each child in assessing pain postoperatively in children aged 4–19 years with cognitive impairments.
Fig. 6.8
The Non-Communicating Children’s Pain Checklist-Postoperative Version (NCCPC-PV). Used with permission
6.7 Summary
In summary, there are many tools available for assessing postoperative pain in children. Clinicians need to use tools that are reliable, valid, and easy to use. Many of the tools are designed to capture pain intensity, which is only one part of a comprehensive pain assessment. Figure 6.9 and the following tables summarize current tools for assessing pain in children of different age groups. Table 6.1 addresses tools for use in neonates, Table 6.2 addresses behavioral tools, and Table 6.3 addresses self-report tools. Whichever tool is chosen for use, it must be used regularly to effectively manage postoperative pain in children.
Fig. 6.9
Appropriate pain assessment scales for children of different age groups (See text for details)
Table 6.2
Behavioral pain assessment tools
Tool | Reference | Age range | Clinical indications for use | Guidelines for use | Advantages and disadvantages |
|---|---|---|---|---|---|
FLACC | Merkel et al. [29] | 2 months–7 years; ages 4–19 years for children with cognitive impairments | Postoperative pain | Scoring ranges from 0 to 2 in each of the 5 indicators for a total score of 0–10 | Child needs to be observed for a minimum of 2 min while awake, 5 min while asleep. Five behavioral indicators |
COMFORT | Ambuel et al. [44] | 0–18 years | Postoperative pain | 8 categories with scores for each of 1–5. Scoring between 8 and 40. Score determines optimal sedation in child | Multidimensional; 8 indicators, including six behavioral and two physiological. Requires extensive training. Only tool validated for use in intubated sedated children |
NCCPC-PV | Breau et al. [47] | Children ages 3–18 years who are able to provide a verbal report including children with cognitive impairments | Postoperative pain | 6 categories with indicators for a total of 27 indicators. Scores 0–3 or not applicable for each indicator scores are tabulated. A score of 11 or more is indicative of moderate to severe pain; a score of 6–10 is indicative of mild pain | Requires a 10-min observation time. More comprehensive than FLACC in that it includes five behavioral indicators and one physiological. Includes cutoff scores |
Table 6.3
Self-reporting pain assessment tools
Tool | Reference | Age range | Clinical indications for use | Guidelines for use | Advantages and disadvantages |
|---|---|---|---|---|---|
Faces Pain Scale-Revised | Hicks et al. [35] | 4–18 years | Postoperative pain, acute procedural pain | Series of 6 faces depicting “no pain” to “most pain possible.” Scoring 0–10 | Simple, easy to use and explain. Translated into 32 languages and available on the Internet, although not all translations have been validated |
Wong-Baker FACES Pain Scale | Wong and Baker [39] | 3 years and older | Postoperative pain, procedural pain | Series of six faces ranging from smiling to crying. Scoring 0–5 | Simple, easy to use, and readily available. Children have demonstrated a tendency to choose the anchors; may measure pain affect rather than pain intensity |
Numeric rating scale | von Baeyer et al. [36] | 8–18 years | Postoperative pain, procedural pain | 11-point scale with 0 = no pain and 10 = most pain | Easy and quick to use. Does not require tools. Can be explained verbally |
Visual analogue scale | Huskisson [42] | 8 years and older | Procedural pain | Premeasured horizontal or vertical line, usually 100 mm in length. Child indicates pain intensity by marking a point along the line | Easy and quick to use. Limited clinical utility: difficult to interpret and document; requires careful explanation. Variability in length of line, use of marking, and choice of anchor words |
Oucher | Beyer and Aradine [37] | 3–18 years | Postoperative pain, procedural pain | Two scales; a series of 6 photographic faces and a 0–100-mm vertical numeric scale | Expensive (must be printed in color). Children should be screened to determine their ability to use the numeric rating scale |
Pieces of Hurt | Hester [38] | 3–18 years | Procedural pain | Four red plastic poker chips representing “little hurt” to “most hurt you could have.” Child chooses the chip that represents his/her pain intensity. Scoring 0–4 | Need to have poker chips. Infection control (cannot be used between patients); need to store chips at the bedside |
6.8 Developmental, Familial, and Psychological Factors
6.8.1 Age
Historically, some have been tempted to erroneously conceptualize children as “mini-adults” when it came to formulating practice guidelines. It is now clear that many aspects of children’s behavior are unique and dissimilar to corresponding behavior in adults. Age-related developmental changes interact with many factors that influence pain assessment. The effects of age in the context of pain assessment have been increasingly studied over the past 20 years. Some of these effects are clear and some are more subtle.
One of the most obvious and pertinent factors relevant to assessing a child’s pain is the level of the child’s ability to communicate the experience of pain. While self-report is the gold standard for pain assessment [49], this is often difficult or impossible for young children or for children with developmental delays. Further, as pain is by nature a subjective experience, reporting something as complex as one’s pain experience is inherently challenging [50]. In addition to possible limitations in communicating information about pain being experienced, what a developing child understands when questioned about pain or the child’s understanding of how to respond using pain assessment tools can be limited or qualitatively different from what the assessing adult understands. These differences can be a result of a number of factors including the child’s level of communication sophistication, past pain experiences, and culture. Furthermore, a child who is ill and/or in pain may have more difficulty engaging effectively in tasks, particularly if those tasks are complex.
Neonates and Infants
There is considerable evidence from biological measures that newborns and infants experience pain at the same level of intensity as adults [51]. There is strong evidence from the use of physiological and behavioral measures that infants show enhanced acute pain responses [52]. It has long been known that as the number of painful procedures that a neonate or infant experiences increases, there can be a corresponding increase in anticipatory fear reactions related to cues for an upcoming medical procedure [53]. Obviously, given the very limited ability of an infant to communicate, physiological, biological, and observational measures must be relied upon to assess pain in very young children. In many cases, parents can provide valuable information based on behavioral observations of an infant that can be valid and reliable estimates of pain and distress.
Preschoolers
Preschool age children present with some remarkable abilities but also experience considerable challenges in many cases when trying to rate their pain. As children develop and as new skills are acquired in cognitive, motor, and social domains, new abilities emerge. Along with these abilities come unique response tendencies that correspond with a child’s developmental stage. For example, it has been found that younger children tend to assign higher intensity scores to pain descriptors than older children [54]. It has also been noted that as cognitive skills such as seriation, classification, matching, and estimation develop, children are able to more reliably produce valid pain scores. The younger a child is, the greater the tendency that a child will be more egocentric and concrete and focus excessively on perceptually salient aspects of a scale [55]. Younger children such as those in the 3–4-year age range have been found to be more likely to choose endpoints of visual analogue or categorical scales [56]. It is also important to note that a child’s ability to attend to and complete tasks such as pain ratings is affected by stressors [57]. This is particularly pertinent given the stressful nature of pain. As well, there also appears to be a strong developmental trend with regard to a child’s ability to use words that label one’s emotional state [58]. As a child’s language skills become more sophisticated, his/her ability to provide valid and reliable pain reports also increases.
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