Contextual factors associated with pain response of preterm infants to heel-stick procedures.

BACKGROUND: Evidence indicates that medical and demographic contextual factors (cFs) impact pain responses in preterm neonates, but the existing evidence is very heterogeneous. AIM: To explore the effect of cFs on pain responses to heel-stick procedures of preterm infants. METHODS: This study was a secondary analysis of data collected during a randomized controlled trial examining pain response to non-pharmacological interventions across repeated heel sticks. Five heel sticks across the first 14 days of life were videotaped. Pain response was rated with the Bernese Pain Scale for Neonates (BPSN) by four raters blinded to the heel-stick phases (baseline, heel stick, recovery). Demographic and medical cFs were extracted from medical charts. Mixed single and multiple regression analyses were performed controlling for the intervention group, site and heel-stick phase. RESULTS: Apgar scores at 1 min were negatively associated with behavioural (p = 0.002) BPSN scores, while Apgar scores at 5 min after birth were positively associated with behavioural (p = 0.006) scores. Accumulated number of painful procedures (p = 0.002) and gender (p = 0.02) were positively associated with physiological scores while continuous positive airway pressure CPAP (p = 0.009) and mechanical ventilation (p = 0.005) were negatively associated. CONCLUSION: Higher exposure to painful procedures, male infants and having CPAP or mechanical ventilation were cFs associated with physiological response. The only variables significantly associated with behavioural BPSN scores were Apgar scores but these relationships were inconsistent.

The communication of pain in paediatric dentistry.

AIM: In this paper the communication model of pain is reviewed and the information then applied to understanding the acute pain experience of children in dentistry, with attention directed to improving the process of pain assessment. BACKGROUND: Expression of pain in children is of great importance as it enables them to engage others who may provide care. The experience of pain, however, is inherently private and not directly accessible to others. Therefore, it requires judgment and skill on the part of observers if pain is to be assessed accurately. In addition, there are striking individual differences in how people react to pain, which makes the assessment of pain in others an even greater challenge. Craig and colleagues [2008] have proposed the use of the social communication model of pain that gives priority to understanding the numerous social factors that affect whether children are successful in communicating painful distress. CONCLUSION: When children's pain is underestimated or a child's self-report is not seen as credible, there is a considerable risk of failure to deliver needed dental care.

Sex differences in parent and child pain ratings during an experimental child pain task.

Research in the field of pediatric pain has largely ignored the role of fathers in their children's pain experiences. The first objective of the present study was to examine the effect of the presence of mothers versus fathers on children's subjective ratings, facial expressions and physiological responses to acute pain. The second objective was to examine whether child and parent sex influence parents' proxy ratings of their children's pain. The final objective was to compare levels of agreement between mothers' and fathers' assessments of their children's pain. Participants included 73 children (37 boys, 36 girls), four to 12 years of age, along with 32 fathers and 41 mothers. Children undertook the cold pressor pain task while observed by one of their parents. During the task, the children's heart rates and facial expressions were recorded. Children provided self-reports and parents provided proxy reports of child pain intensity using the seven-point Faces Pain Scale. Neither child nor parent sex had a significant impact on children's subjective reports, facial expressions or heart rates in response to acute pain. Fathers gave their sons higher pain ratings than their daughters, whereas mothers' ratings of their sons' and daughters' pain did not differ. Kappa statistics and t tests revealed that fathers tended to be more accurate judges of their children's pain than mothers. Overall, this research highlights the importance of examining both parent and child sex differences in pediatric pain research.

Expressive dimensions of pain catastrophizing: a comparative analysis of school children and children with clinical pain.

We investigated the role of the child's pain catastrophizing in explaining (1) children's self-reported tendency to verbally share their pain experience with others and (2) different dimensions of pain expression, as described by the mother and the father, including non-verbal and verbal communicative pain behaviour and protective pain behaviour. Participants were school children, children with chronic or recurrent pain, and their parents. The results showed that: (1) Pain catastrophizing was associated with children's greater self-acknowledged tendency to verbally share their pain experience with others. (2) Mothers and fathers perceived highly catastrophizing children to be more communicative about their pain. (3) The role of pain catastrophizing in the child's verbal sharing of pain experiences and in explaining expressive behaviour as rated by parents did not differ between the school children and children with recurrent and chronic pain. (4) Nevertheless, findings indicated marked differences between school children and the clinical sample. Children of the clinical sample experienced more severe pain, more pain catastrophizing, more protective pain behaviour, but less verbal communications about their pain. These results further corroborate the position that catastrophic thoughts about pain have interpersonal consequences. Findings are discussed in terms of the possible functions and effects upon others of pain catastrophizing and associated categories of pain behaviour.

A theoretical framework for understanding self-report and observational measures of pain: a communications model.

Self-report and observational measures of pain are examined from the perspective of a model of human communication. This model examines the experience of pain as affected by intrapersonal and contextual factors, the process whereby it is encoded into expressive behaviour, and the process of decoding by observers prior to their engaging in action. Self-report measures primarily capture expressive pain behaviour that is under the control of higher mental processes, whereas observational measures capture behaviour that is less subject to voluntary control and more automatic. Automatic expressive behaviours are subject to less purposeful distortion than are behaviours dependent upon higher mental processes. Consequently, observational measures can be used and have clinical utility as indices of pain when self-report is not available, for example, in infants, young children, people with intellectual disabilities or brain damage, and seniors with dementia. These measures are also useful when the credibility of self-report is questioned and even when credible self-report is available. However, automatic behaviours may be more difficult for observers to decode. The model outlined herein takes into account the role of various human developmental stages in pain experience and expression and in understanding the utility of self-report and observational measures. We conclude that both observational and self-report measures are essential in the assessment of pain because of the unique information that each type contributes.

Facial expression of children receiving immunizations: a principal components analysis of the child facial coding system.

OBJECTIVE: To identify the structure of facial reaction to procedural pain and to determine the subset of facial actions that best describe the response. DESIGN: Observational. SETTING: Five rural and five urban physicians' offices. PATIENTS: One hundred twenty-three children aged 4 to 5 years undergoing routine diphtheria, pertussis, tetanus, and polio immunization. OUTCOME MEASURES: The Child Facial Coding System, comprising 13 discrete facial actions, was used to code each second of five 10-second phases from videotape: baseline, preneedle, needle, postneedle, and posthandling. Parents and a technician provided visual analog scale ratings of children's pain. Children provided a self-report using a Faces Pain Scale, and parents and nurses rated the children's pain and anxiety using visual analog scales. RESULTS: A "pain face" similar to that reported in adults emerged with the onset of pain. Principal component analyses revealed the frequency and intensity of facial action during the needle phase could be represented by components reflecting pain sensation, a "brave face," and the children's expectations for pain. Children's Faces Pain Scale and adult visual analog scale ratings were best predicted by components reflecting pain sensation and expectations of high pain. CONCLUSIONS: These results provide a preliminary indication that the Child Facial Coding System can be reduced to components that reflect several aspects of children's acute pain experience and predict self-reports and observer reports of children's pain.

Nonneurologic hand pain versus carpal tunnel syndrome: do psychological measures differentiate?

OBJECTIVE: To determine whether psychological measures would differentiate a group of patients with physician-diagnosed nonneurologic hand pain from patients with carpal tunnel syndrome (CTS). Many patients, who also displayed symptoms of psychological distress, were referred to an electrodiagnostic clinic with a diagnosis of possible CTS; they subsequently had normal nerve conduction studies. DESIGN: Sixty patients with hand pain were referred to either of two university clinics for electrophysiologic testing, were assigned to either the CTS or nonneurologic group, and were compared on a series of psychometric tests. RESULTS: The Beck Depression Inventory and McGill Pain Questionnaire showed that the physician-assigned nonneurologic patients have a greater degree of depression, use more affective adjectives, and choose more words on the McGill Pain Questionnaire than the physician-assigned CTS group. The nonneurologic group also scored higher on indices of self-reported disability on the Pain Disability Inventory in five of seven categories. Although the CTS group perceived more control over their pain, no differences were observed in the types of coping strategies used on the Coping Strategy Questionnaire. Finally, the nonneurologic group had more Workers' Compensation Board claims. CONCLUSION: Evidence of important psychological issues in some patients with hand pain suggests a need for greater awareness among treating physicians.

Everyday pain responses in children with and without developmental delays.

OBJECTIVE: To examine whether children with developmental delays respond to painful events differently than nondelayed children. METHODS: Sixty families participated. Children between the ages of 2 and 6 years were observed at daycare centers while engaged in usual daily activities, such as free play. Spontaneous painful incidents and the child's responses were recorded using an observational measure (Dalhousie Everyday Pain Scale) designed to capture pain behavior. RESULTS: Children with developmental delays (n = 24) displayed a less intense distress response to an equivocal pain event than nondelayed children (n = 36). Children with developmental delays were more likely to display no reaction following a pain event, whereas children without delays cried more often. Further, children with developmental delays engaged in fewer help-seeking behaviors and were less likely to display a social response following a pain event than nondelayed children. CONCLUSIONS: Children with developmental delays appear to react in a different manner to pain events than nondelayed children do; we discuss a possible socio-communicative deficit.

Measuring movement-exacerbated pain in cognitively impaired frail elders.

OBJECTIVE: Prior research examining the utility of nonverbal measures of pain in persons with cognitive impairments has focused on acute procedurally-induced phasic pain (i.e., venipuncture and needle injections). The goal of the current project was to examine the utility of both self-report and nonverbal measures of pain in frail elders experiencing exacerbations of chronic musculoskeletal pain. These were assumed to be more representative of the day-to-day pain experience of elderly patients. DESIGN: Participants were 58 frail elders, 29 of whom had been found to have significant cognitive impairments. All were filmed as they undertook a series of structured activities (e.g., walking and reclining), and pain was assessed using self-report. Trained coders identified the incidence of pain-related behaviors using the videotapes. The various pain measures (i.e., self-report and nonverbal indices) were compared across both patient groups and the several activities. RESULTS: Consistent with our hypotheses, more pain was identified (using both self-report and nonverbal measures) when patients engaged in more physically demanding activities. Facial reactions varied as a function of patient cognitive status, with those participants who were cognitively impaired more responsive. Of the various nonverbal indices that we examined, guarded behavior appeared to be especially sensitive. The various pain indices were only modestly correlated with one another. CONCLUSIONS: This study supports the validity of self-report and behavioral measures of pain in frail elders with and without cognitive impairments. Each of the measures used contributed different information to pain assessment, suggesting that investigations of pain in elders with cognitive impairments should employ varying types of pain assessment tools.

A comparison of faces scales for the measurement of pediatric pain: children's and parents' ratings.

Faces scales have become the most popular approach to eliciting children's self-reports of pain, although different formats are available. The present study examined: (a) the potential for bias in children's self-reported ratings of clinical pain when using scales with smiling rather than neutral 'no pain' faces; (b) levels of agreement between child and parent reports of pain using different faces scales; and (c) preferences for scales by children and parents. Participants were 75 children between the ages of 5 and 12 years undergoing venepuncture, and their parents. Following venepuncture, children and parents independently rated the child's pain using five different randomly presented faces scales and indicated which of the scales they preferred and why. Children's ratings across scales were very highly correlated; however, they rated significantly more pain when using scales with a smiling rather than a neutral 'no pain' face. Girls reported significantly greater levels of pain than boys, regardless of scale type. There were no age differences in children's pain reports. Parents' ratings across scales were also highly correlated; however, parents also had higher pain ratings using scales with smiling 'no pain' faces. The level of agreement between child and parent reports of pain was low and did not vary as a function of the scale type used; parents overestimated their children's pain using all five scales. Children and parents preferred scales that they perceived to be happy and cartoon-like. The results of this study indicate that subtle variations in the format of faces scales do influence children's and parents' ratings of pain in clinical settings.

Morphine pharmacokinetics and pain assessment in premature newborns.

OBJECTIVES: To determine morphine pharmacokinetics in premature neonates varying in postconceptional age (PCA) and evaluate behavioral pain response in relationship to serum morphine concentrations. METHODS: Premature neonates (n = 48), stratified by weeks of PCA (group 1 = 24-27 weeks, group 2 = 28-31 weeks, group 3 = 32-35 weeks, and group 4 = 36-39 weeks) received morphine infusions. Blood samples were drawn at 48, 60, and 72 hours and at discontinuation of morphine, followed by 3 samples obtained during the next 24 hours. Newborns were videotaped during heel lances and restful states, with morphine at steady-state concentrations and without morphine. Pain was assessed by using the Neonatal Facial Coding System (NFCS). Statistical analysis included regression between NFCS score changes from baseline to painful procedure with and without morphine. RESULTS: Morphine clearance for groups 1, 2, 3, and 4 was calculated as 2.27 +/- 1.07, 3.21 +/- 1.57, 4.51 +/- 1.97, and 7.80 +/- 2.67 mL/kg/min, respectively, and correlated with PCA (r = 0.63, P <.001). Pain measured by facial expression was diminished; however, it did not correlate with morphine concentrations. CONCLUSION: Morphine clearance in premature neonates is less than reported, increasing with PCA. Facial activity discloses morphine analgesia; however, it is unrelated to morphine concentrations.

Postoperative pain expression in preschool children: validation of the child facial coding system.

OBJECTIVE: The purposes of the study were threefold: (a) to determine whether a measurement system based on facial expression would be useful in the assessment of post-operative pain in young children; (b) to examine construct validity in terms of structure, consistency, and dynamics of the facial display; and (c) to evaluate concurrent validity in terms of associations with global judgments of the children's pain. PATIENTS: One hundred children between the ages of 13 and 74 months were video-taped for a maximum of 1 hour after arrival in the postanesthesia care unit (PACU) at British Columbia's Children's Hospital. OUTCOME MEASURES: Videotapes were edited into 20-second blocks, randomly selected from each 2-minute time period taped during the hour following surgery, and coded for the presence or absence of 13 facial actions in the Child Facial Coding System (CFCS). RESULTS: Facial expressions were characterized primarily by the following constellation of actions: open lips, lowered brows, a deepened nasolabial furrow, mouth stretched wide in both horizontal and vertical directions, eyes squeezed shut or squinted, and raised cheeks. A principal components analysis indicated that these actions comprised a single factor, accounting for 55% of the variance in CFCS actions. Facial action summary scores were correlated with a visual analog rating of global pain, confirming that the CFCS has convergent validity. Facial action summary scores, i.e., pain displays, were at their lowest immediately after admittance to the PACU and just before the child's release from the PACU. CONCLUSIONS: The present study demonstrated that the CFCS serves as a valid measurement tool for persistent pain in children.

Biobehavioral responses to acute pain in adolescents with a significant neurologic impairment.

OBJECTIVE: To further understand acute pain response in children with a significant neurologic impairment (SNI), we undertook a descriptive hypothesis-generating study of the response to a routine vaccine among adolescents with SNI. DESIGN: Within-subject crossover design. SETTING: Tertiary care facility for children and adolescents with SNI. PATIENTS: Eight adolescents (mean age = 15 years). INTERVENTIONS: Mock and real vaccine injections. OUTCOME MEASURES: Quantitative measures of heart rate, videotaped facial action, Child Facial Coding System (CFCS), and Facial Action Coding System (FACS); observer ratings visual analog scale (VAS) were obtained before, during, and after a mock injection and routine annual influenza vaccine injection presented in a counterbalanced order. RESULTS: VAS scores were significantly higher during the injection phase than during the other time periods; however, there were no significant differences across study time periods when using the other outcome measures. CONCLUSIONS: Although the dampened behavioral and physiologic reactions to an acute noxious stimulus were similar to those of previous work with developmentally delayed children and frail elderly, it remains unclear what underlies the apparent reduced pain response in this setting. These findings have potentially important implications for the daily care of individuals with significant neurologic impairment and illustrate the compelling need tor further study of the unique character of the pain experience in this setting.

Pain measurement in persons with intellectual disabilities.

OBJECTIVE: The goal was to study the utility of nonverbal facial expressions as a research tool for assessing pain in persons with intellectual disabilities. Biases and stereotypes related to age, gender, physical attractiveness, and intellectual disability that may influence the ability of observers to evaluate pain reactions were also examined. DESIGN: Facial reactions to an intramuscular injection of 40 adults (mean age = 49.6 years) with an intellectual disability were videotaped and objectively examined using the Facial Action Coding System. Self-reported pain ratings were obtained using a Colored Visual Analogue Scale for pain. Pain reactions were also rated by untrained observers. RESULTS: A significant proportion of participants (35%) was unable to provide valid self-report. The intensity of objectively coded facial activity as well as observer-rated pain intensity showed significant increases from baseline to injection segments. Observers' pain ratings were primarily determined by the intensity of facial activity and were not significantly affected by stereotypes based on perceived level of intellectual disability, gender, age, or physical attractiveness. CONCLUSIONS: The findings support the validity of both objectively coded and observer-rated facial expressions of pain as research tools in treatment outcome studies involving persons with intellectual disabilities. Self-report has substantial limitations for the assessment of pain in this population.

Cognitive and behavioral responses to illness information: the role of health anxiety.

The cognitive-behavioral theory of health anxiety predicts atypical responses in health anxious individuals when exposed to health related information. Systematic research is still needed to support the theory. This investigation examined 192 participants varying a subclinical levels of health anxiety, who were randomly given feedback on an ostensible diagnostic measure, indicating positive, negative or ambiguous risk for health complications. Responses to a cold pressor task were then measured. The results indicated that regardless of the type of feedback patients were given, health anxious individuals displayed the predicted cognitive (e.g. negatively interpreted information) and behavioral responses (e.g. increased reassurance seeking). Important and perhaps central cognitions to health anxiety were identified. Health anxious individuals regarded themselves to be at greater risk for disease overall, and attached greater accuracy to health related information. Extending the cognitive-behavioural theory, health anxiety was found to be associated with decreased usage of positive somatic monitoring of symptoms, suggesting health anxiety may be associated with a failure to engage in protective strategies. Health anxiety did not result in cognitive or behavioural avoidance of illness information. Clinical implications and future directions for research are described.

Agreement between child and parent reports of pain.

OBJECTIVE: Parents are often the primary source of information regarding their children's pain in both research and clinical practice. However, parent-child agreement on pain ratings has not been well established. The objective of the present study was to examine agreement between child- and parent-rated pain following minor surgery. SETTING: Tertiary care children's hospital. PARTICIPANTS: A total of 110 children (56.4% male) aged 7-12 years undergoing surgery and their parents. OUTCOME MEASURES: Parents and children independently rated pain intensity by using a 7-point Faces Pain Scale on the day of the child's surgery and the following 2 days. RESULTS: Correlations (both Pearson's and intraclass correlation coefficients) indicated a highly significant relationship between child and parent ratings. However, kappa statistics indicated only poor to fair agreement beyond chance. Parents tended to underestimate their children's pain on the day of surgery and the following day, but not on the second day following surgery. When children's and parents' pain ratings for each of the 3 days were collapsed into a no-pain/low-pain group or a clinically significant pain group, kappa statistics indicated fair to good agreement. Parents demonstrated low levels of sensitivity in identifying when their children were experiencing clinically significant pain. CONCLUSIONS: Correlations between parent and child pain reports do not accurately represent the relationship between these ratings and in fact overestimate the strength of the relationship. Parents' underestimation of their child's pain may contribute to inadequate pain control.

The expression of pain in infants and toddlers: developmental changes in facial action.

Age-related changes in the facial expression of pain during the first 18 months of life have important implications for our understanding of pain and pain assessment. We examined facial reactions video recorded during routine immunization injections in 75 infants stratified into 2-, 4-, 6-, 12-, and 18-month age groups. Two facial coding systems differing in the amount of detail extracted were applied to the records. In addition, parents completed a brief questionnaire that assessed child temperament and provided background information. Parents' efforts to soothe the children also were described. While there were consistencies in facial displays over the age groups, there also were differences on both measures of facial activity, indicating systematic variation in the nature and severity of distress. The least pain was expressed by the 4-month age group. Temperament was not related to the degree of pain expressed. Systematic variations in parental soothing behaviour indicated accommodation to the age of the child. Reasons for the differing patterns of facial activity are examined, with attention paid to the development of inhibitory mechanisms and the role of negative emotions such as anger and anxiety.

Social barriers to optimal pain management in infants and children.

OBJECTIVE: To examine the social barriers that lead to less than optimal management of pain in children. DESIGN: Recognizing the vulnerabilities of infants and children and their dependence on caring adults, a model of pain communication is proposed. The model examines (a) the pain experiences of children, including social determinants; (b) developmental variations in the capacity to encode the severity and qualities of pain as expressive behavior; (c) adult skills and deficiencies in decoding pain; and (d) the actions of adults predicated on the meaning and significance attached to children's actions. Limitations in care were examined. DATA SOURCES: The current research and professional literature were accessed through searches of the Psyclit and Medline databases for relevant investigations on the basis of our working knowledge of the literature. CONCLUSION: Numerous deterrents to optimal care are identified in the domains of commonplace beliefs about the nature of pain in infants and children: failure to recognize the impact of socialization in familial and cultural modes of experience and expression; needs for age-specific assessment instruments; the limited capacity to use available evidence concerning pain; the need to employ clinicians, parents, and other adults more effectively in delivering care; and structural problems in the health care system.

Subjective judgments of deception in pain expression: accuracy and errors.

Accuracy and errors in judges' attempts to differentiate facial expressions that displayed genuine pain, no pain or were dissimulated (i.e., masked and exaggerated) were examined. Judges were informed that misrepresentations in the facial expressions were present and were asked to rate their confidence in classifying these expressions. Detailed, objective coding of the patients' facial reactions (e.g., brow lowering, mouth opening) were related to judges' decisions. Judges' classification decisions were better than chance, but there were many errors. Extreme expressions (i.e., no pain, and exaggerated expressions) were identified more accurately than genuine and masked expressions. Judges level of confidence was consistent with their level of accuracy. Judges consistently used rules of thumb based on specific facial cues when making judgments. Certain cues were effectively discriminative. Systematic training in the use of specific cues or the use of articulated decision rules may be helpful in improving judges' accuracy.