An examination of the reciprocal and concurrent relations between behavioral and cardiac indicators of acute pain in toddlerhood

Caregivers' physiological responses during toddler vaccinations: associations with psychological and behavioral responses

OBJECTIVE

This study investigated biological, psychological, and behavioral aspects of caregivers' responses to toddlers' pain-related distress by measuring caregivers' high-frequency heart rate variability (HRV) responses during toddler vaccination pain and examining associations with caregivers' behavioral responses and psychological stress.

METHODS

Participants included caregiver-toddler dyads (N = 194) from a longitudinal cohort-sequential study who were observed during toddlers' 12-, 18-, or 24-month routine vaccinations. Changes in caregiver HRV were analyzed using growth curve modeling. Conditional growth curve models examined associations between caregiver HRV and caregivers' concurrent behavior and psychological stress.

RESULTS

The unconditional growth curve model indicated a slight linear decrease in caregiver HRV (i.e., vagal withdrawal) across the 3 min post-needle (unstandardized B = -0.06, p = .049). In conditional growth curve models, higher levels of parenting stress were associated with less vagal withdrawal during the post-needle period (standardized B = 0.47, unstandardized B = 0.02, p = .003). Caregivers' behavioral responses (i.e., use of soothing and distress-promoting behaviors), state anxiety, and general anxiety symptomology were not significantly associated with HRV responses.

CONCLUSIONS

Caregiver parasympathetic nervous system activity levels changed minimally from baseline to post-needle and decreased slightly across the post-needle period. Caregivers' self-reported parenting stress was associated with their parasympathetic responses to the procedure. Findings support an improved understanding of the mechanisms underlying caregivers' responses to children's pain-related distress in a naturalistic setting.

Unraveling the role of oligodendrocytes and myelin in pain

Oligodendrocytes, the myelin-producing cells in the central nervous system (CNS), are crucial for rapid action potential conduction and neuronal communication. While extensively studied for their roles in neuronal support and axonal insulation, their involvement in pain modulation is an emerging research area. This review explores the interplay between oligodendrocytes, myelination, and pain, focusing on neuropathic pain following peripheral nerve injury, spinal cord injury (SCI), chemotherapy, and HIV infection. Studies indicate that a decrease in oligodendrocytes and increased cytokine production by oligodendroglia in response to injury can induce or exacerbate pain. An increase in endogenous oligodendrocyte precursor cells (OPCs) may be a compensatory response to repair damaged oligodendrocytes. Exogenous OPC transplantation shows promise in alleviating SCI-induced neuropathic pain and enhancing remyelination. Additionally, oligodendrocyte apoptosis in brain regions such as the medial prefrontal cortex is linked to opioid-induced hyperalgesia, highlighting their role in central pain mechanisms. Chemotherapeutic agents disrupt oligodendrocyte differentiation, leading to persistent pain, while HIV-associated neuropathy involves up-regulation of oligodendrocyte lineage cell markers. These findings underscore the multifaceted roles of oligodendrocytes in pain pathways, suggesting that targeting myelination processes could offer new therapeutic strategies for chronic pain management. Further research should elucidate the underlying molecular mechanisms to develop effective pain treatments.

It takes two: The relative contributions of parent versus child-led regulatory behaviours on toddler vaccination pain

BACKGROUND

Past research has established the important role of parent soothing in early childhood pain management. However, limited research has assessed children's own emerging emotion regulation strategies to reduce their pain during vaccination. The purpose of the current study was to understand the relative contributions of child-led emotion-regulation behaviours over and above parent regulatory behaviours and pre-needle distress.

METHODS

Toddler-caregiver dyads were videotaped at their 12- and/or 18-month vaccinations. Videos were coded for pain-related behavioural distress, child-led regulatory behaviours (disengagement of attention, parent-focused behaviours, and physical self-soothing), and parent regulatory/soothing behaviours (distraction, physical comfort, rocking, verbal reassurance). Pre-needle distress, followed by parent regulatory behaviours, followed by child regulatory behaviours were used as hierarchical predictors of pain regulation. Two sets of models were estimated at each age, by incorporating parent and child regulatory behaviours at 1 min and 2 min post-needle, separately.

RESULTS

At both ages, child-led parent-focused behaviours predicted less regulation. At 18 months, parent soothing behaviours (e.g. distraction, verbal reassurance, rocking) played a stronger role in regulation, however; the only behaviour that increased regulation was rocking.

CONCLUSIONS

Measuring both parent and child regulatory behaviours was important for fully understanding pain-related distress regulation. Toddlers' use of parent-focused regulatory behaviours (e.g. proximity seeking) suggests that they signal to their parent directly when they are struggling to regulate post-needle. The only parent behaviour that supported this regulation was rocking at 18 months, suggesting a greater need to understand the sensitivity of parent behaviours post-needle.

SIGNIFICANCE

To our knowledge, this is the first study to examine both parent and child regulatory behaviours following vaccination at different stages in toddlerhood. This investigation allows a deeper understanding of the dyadic nature of early childhood vaccination, as well as the evolving role of the parent through toddlerhood. Importantly, findings suggest that toddlers do not simply wait for their parents to respond to their pain post-needle and provide clear signals to show their need of support in regulation.

A Measure of Caregivers' Distress-Promoting Behaviors During Toddler Vaccination: Validation of the OUCHIE-RV

OBJECTIVE

The current study discusses the development and preliminary validation of an observational measure of caregivers' distress-promoting behavior (OUCHIE-RV) in the context of toddler routine vaccination.

METHODS

Measure validation was based on a sample of caregiver-toddler dyads (N = 223) from a longitudinal cohort-sequential study who were observed during toddlers' 12-, 18-, or 24-month routine vaccinations. Validity was assessed using correlations and cross-lagged path analysis and associations were tested between OUCHIE-RV composite scores and toddlers' pain-related distress as well as caregivers' state anxiety, soothing behaviors, heart rate, and heart rate variability. Interrater reliability was examined using intraclass correlations (ICC) and kappa coefficients.

RESULTS

Results of a cross-lagged path analysis indicated positive concurrent (β = .27 to β = .37) and cross-lagged predictive associations (β = .01 to β = .34) between OUCHIE-RV composite scores (reflecting the frequency and intensity of caregivers' distress-promoting behavior) and toddlers' pain-related distress. OUCHIE-RV composite scores were negatively associated with caregivers' concurrent use of physical comfort (r = -.34 to -.24) and rocking (r = -.36 to -.19) and showed minimal associations with caregivers' use of verbal reassurance (r = .06 to .12), state anxiety (r = -.02 to r = .09), heart rate (r = -.15 to r = .05), and heart rate variability (r = -.04 to r = .13). Interrater reliability was strong (Cohen's k = .86 to .97, ICC = .77 to .85).

CONCLUSIONS

Findings provide support for the validity and reliability of the OUCHIE-RV as a research tool for measuring caregiver behaviors that promote toddlers' pain-related distress during routine vaccinations and contribute to a better understanding of the dynamics of caregiver-toddler interaction in acute pain contexts.

Non-pharmacological management of infant and young child procedural pain

BACKGROUND

Despite evidence of the long-term implications of unrelieved pain during infancy, it is evident that infant pain is still under-managed and unmanaged. Inadequately managed pain in infancy, a period of exponential development, can have implications across the lifespan. Therefore, a comprehensive and systematic review of pain management strategies is integral to appropriate infant pain management. This is an update of a previously published review update in the Cochrane Database of Systematic Reviews (2015, Issue 12) of the same title.

OBJECTIVES

To assess the efficacy and adverse events of non-pharmacological interventions for infant and child (aged up to three years) acute pain, excluding kangaroo care, sucrose, breastfeeding/breast milk, and music.

SEARCH METHODS

For this update, we searched CENTRAL, MEDLINE-Ovid platform, EMBASE-OVID platform, PsycINFO-OVID platform, CINAHL-EBSCO platform and trial registration websites (ClinicalTrials.gov; International Clinical Trials Registry Platform) (March 2015 to October 2020). An update search was completed in July 2022, but studies identified at this point were added to 'Awaiting classification' for a future update.  We also searched reference lists and contacted researchers via electronic list-serves.  We incorporated 76 new studies into the review.  SELECTION CRITERIA: Participants included infants from birth to three years in randomised controlled trials (RCTs) or cross-over RCTs that had a no-treatment control comparison. Studies were eligible for inclusion in the analysis if they compared a non-pharmacological pain management strategy to a no-treatment control group (15 different strategies). In addition, we also analysed studies when the unique effect of adding a non-pharmacological pain management strategy onto another pain management strategy could be assessed (i.e. additive effects on a sweet solution, non-nutritive sucking, or swaddling) (three strategies). The eligible control groups for these additive studies were sweet solution only, non-nutritive sucking only, or swaddling only, respectively. Finally, we qualitatively described six interventions that met the eligibility criteria for inclusion in the review, but not in the analysis.  DATA COLLECTION AND ANALYSIS: The outcomes assessed in the review were pain response (reactivity and regulation) and adverse events. The level of certainty in the evidence and risk of bias were based on the Cochrane risk of bias tool and the GRADE approach. We analysed the standardised mean difference (SMD) using the generic inverse variance method to determine effect sizes.  MAIN RESULTS: We included total of 138 studies (11,058 participants), which includes an additional 76 new studies for this update. Of these 138 studies, we analysed 115 (9048 participants) and described 23 (2010 participants) qualitatively. We described qualitatively studies that could not be meta-analysed due to being the only studies in their category or statistical reporting issues. We report the results of the 138 included studies here. An SMD effect size of 0.2 represents a small effect, 0.5 a moderate effect, and 0.8 a large effect. The thresholds for the I2 interpretation were established as follows: not important (0% to 40%); moderate heterogeneity (30% to 60%); substantial heterogeneity (50% to 90%); considerable heterogeneity (75% to 100%). The most commonly studied acute procedures were heel sticks (63 studies) and needlestick procedures for the purposes of vaccines/vitamins (35 studies). We judged most studies to have high risk of bias (103 out of 138), with the most common methodological concerns relating to blinding of personnel and outcome assessors. Pain responses were examined during two separate pain phases: pain reactivity (within the first 30 seconds after the acutely painful stimulus) and immediate pain regulation (after the first 30 seconds following the acutely painful stimulus). We report below the strategies with the strongest evidence base for each age group. In preterm born neonates, non-nutritive sucking may reduce pain reactivity (SMD -0.57, 95% confidence interval (CI) -1.03 to -0.11, moderate effect; I2 = 93%, considerable heterogeneity) and improve immediate pain regulation (SMD -0.61, 95% CI -0.95 to -0.27, moderate effect; I2 = 81%, considerable heterogeneity), based on very low-certainty evidence. Facilitated tucking may also reduce pain reactivity (SMD -1.01, 95% CI -1.44 to -0.58, large effect; I2 = 93%, considerable heterogeneity) and improve immediate pain regulation (SMD -0.59, 95% CI -0.92 to -0.26, moderate effect; I2 = 87%, considerable heterogeneity); however, this is also based on very low-certainty evidence. While swaddling likely does not reduce pain reactivity in preterm neonates (SMD -0.60, 95% CI -1.23 to 0.04, no effect; I2 = 91%, considerable heterogeneity), it has been shown to possibly improve immediate pain regulation (SMD -1.21, 95% CI -2.05 to -0.38, large effect; I2 = 89%, considerable heterogeneity), based on very low-certainty evidence. In full-term born neonates, non-nutritive sucking may reduce pain reactivity (SMD -1.13, 95% CI -1.57 to -0.68, large effect; I2 = 82%, considerable heterogeneity) and improve immediate pain regulation (SMD -1.49, 95% CI -2.20 to -0.78, large effect; I2 = 92%, considerable heterogeneity), based on very low-certainty evidence.  In full-term born older infants, structured parent involvement was the intervention most studied. Results showed that this intervention has little to no effect in reducing pain reactivity (SMD -0.18, 95% CI -0.40 to 0.03, no effect; I2 = 46%, moderate heterogeneity) or improving immediate pain regulation (SMD -0.09, 95% CI -0.40 to 0.21, no effect; I2 = 74%, substantial heterogeneity), based on low- to moderate-certainty evidence. Of these five interventions most studied, only two studies observed adverse events, specifically vomiting (one preterm neonate) and desaturation (one full-term neonate hospitalised in the NICU) following the non-nutritive sucking intervention. The presence of considerable heterogeneity limited our confidence in the findings for certain analyses, as did the preponderance of evidence of very low to low certainty based on GRADE judgements.

AUTHORS' CONCLUSIONS

Overall, non-nutritive sucking, facilitated tucking, and swaddling may reduce pain behaviours in preterm born neonates. Non-nutritive sucking may also reduce pain behaviours in full-term neonates. No interventions based on a substantial body of evidence showed promise in reducing pain behaviours in older infants. Most analyses were based on very low- or low-certainty grades of evidence and none were based on high-certainty evidence. Therefore, the lack of confidence in the evidence would require further research before we could draw a definitive conclusion.

Understanding the concurrent and predictive relations between child-led emotion regulation behaviors and pain during vaccination in toddlerhood

ABSTRACT

The purpose of this study was to further our understanding of early childhood pain-related distress regulation. Concurrent and predictive relations between child-led emotion regulation (ER) behaviors and pain-related distress during vaccination were examined at 2 different ages using autoregressive cross-lagged path analyses. Toddlers were video-recorded at the 12- and 18-month routine vaccination appointments (12-month-old [N = 163]; 18-month-old [N = 149]). At 1, 2, and 3 minutes postneedle, videos were coded for 3 clusters of child-led ER behaviors (disengagement of attention, parent-focused behaviors, and physical self-soothing) and pain-related distress. The concurrent and predictive relations between child-led ER behaviors and pain-related distress behaviors were assessed using 6 models (3 emotion regulation behaviors by 2 ages). At 18 months, disengagement of attention was significantly negatively related to pain-related distress at 1 minute postneedle, and pain-related distress at 1 minute postneedle was significantly related to less disengagement of attention at 2 minutes postneedle. Parent-focused behaviors had significant positive relations with pain-related distress at both ages, with stronger magnitudes at 18 months. Physical self-soothing was significantly related to less pain-related distress at both ages. Taken together, these findings suggest that disengagement of attention and physical self-soothing may serve more of a regulatory function during toddlerhood, whereas parent-focused behaviors may serve more of a function of gaining parent support for regulation. This study is the first to assess these relations during routine vaccination in toddlerhood and suggests that toddlers in the second year of life are beginning to play a bigger role in their own regulation from painful procedures than earlier in infancy.

Distinct trajectories of caregiver-toddler physiological attunement during routine vaccinations

Introduction

Toddlers rely on their caregivers for regulatory support when faced with pain-related distress. The caregiver's ability to support their toddler relies on their capacity to regulate their own distress and respond effectively to the child's need for support. The aim of the current study was to describe patterns of caregiver-toddler physiological co-regulatory patterns, also known as attunement, during routine vaccinations across the second year of life.

Methods

Caregiver-toddler dyads (N = 189) were part of a longitudinal cohort observed at either 12-, 18-, or 24-month well-baby vaccinations. Parallel-process growth-mixture modeling was used to examine patterns of dyadic physiological co-regulatory responses, indexed by high-frequency heart rate variability (HF-HRV).

Results

Three groups of dyads were discerned. The largest group (approximately 80%) demonstrated physiological attunement, with a stable and parallel regulatory pattern of HF-HRV from baseline to postneedle. The second group (7.9%) had parallel regulatory trajectories but with notably lower (ie, less regulated) HF-HRV values, which indicates independent regulatory responses (ie, a lack of attunement among dyad members). The third group (11.1%) showed diverging regulatory trajectories: Caregivers showed a stable regulatory trajectory, but toddlers demonstrated a steep decrease followed by an increase in HF-HRV values that surpassed their baseline levels by the third minute postneedle. Post hoc analyses with the HF-HRV groupings explored heart rate patterns and potential predictors.

Conclusions

These findings elucidate potential adaptive and maladaptive co-regulatory parasympathetic patterns in an acute pain context.

Child Distress Expression and Regulation Behaviors: A Systematic Review and Meta-Analysis

The goal of the current study was to review and meta-analyze the literature on relationships between child distress expression behaviors (e.g., cry) and three clusters of child distress regulation behaviors (disengagement of attention, parent-focused behaviors, and self-soothing) in the first three years of life. This review was registered with PROSPERO (CRD42020157505). Unique abstracts were identified through Medline, Embase, and PsycINFO (n = 13,239), and 295 studies were selected for full-text review. Studies were included if they provided data from infants or toddlers in a distress task, had distinct behavioral measures of distress expression and one of the three distress regulation clusters, and assessed the concurrent association between them. Thirty-one studies were included in the meta-analysis and rated on quality. Nine separate meta-analyses were conducted, stratified by child age (first, second, and third year) and regulation behavior clusters (disengagement of attention, parent-focused, and self-soothing). The weighted mean correlations for disengagement of attention behaviors were -0.28 (year 1), -0.44 (year 2), and -0.30 (year 3). For parent-focused behaviors, the weighted mean effects were 0.00 (year 1), 0.20 (year 2), and 0.11 (year 3). Finally, the weighted mean effects for self-soothing behaviors were -0.23 (year 1), 0.25 (year 2), and -0.10 (year 3). The second year of life showed the strongest relationships, although heterogeneity of effects was substantial across the analyses. Limitations include only analyzing concurrent relationships and lack of naturalistic distress paradigms in the literature.

Trajectories of Distress Regulation During Preschool Vaccinations: Child and Caregiver Predictors

ABSTRACT

Recent research has highlighted the need for a deeper understanding of the heterogeneity in trajectories of children's distress following acute pain exposure, moving beyond group means of behavioural pain scores at a single timepoint. During preschool vaccinations, three distinct trajectories of post-vaccination pain regulation have been elucidated, with approximately 75% of children displaying trajectories characterized by down-regulation to no distress by two minutes post-needle and 25% concerningly failing to down-regulate by two-minutes. The objective of the present study was to examine child and caregiver predictors of preschool children's post-vaccination regulatory patterns. Our results indicated that higher child baseline distress, more caregiver coping-promoting verbalizations in the first minute following the needle, less coping -promoting verbalizations in the second minute, and more caregiver distress-promoting verbalizations in the second minute following the needle were associated with membership in the trajectories characterized by high distress. Further, while all children's pain-related distress at various timepoints throughout the appointment was most strongly predicted by prior pain scores, different patterns of associations emerged depending on the trajectory exhibited. This research highlights both the need to minimize distress prior to the needle in order to avoid the highly distressed trajectory as well as the importance of considering the heterogeneity of trajectories of preschool pain responding when examining the factors that are associated with children's pain-related distress.

A Multi-Method Approach to Understand Parent Behaviors During Child Acute Pain

Abstract. Parent behaviors strongly predict child responses to acute pain; less studied are the factors shaping parent behaviors. Heart rate variability (HRV) is considered a physiological correlate of emotional responding. Resting or “trait” HRV is indicative of the capacity for emotion regulation, while momentary changes or “state” HRV is reflective of current emotion regulatory efforts. This study aimed to examine: (1) parent state HRV as a contributor to parent verbal behaviors before and during child pain and (2) parent trait HRV as a moderator between parent emotional states (anxiety, catastrophizing) and parent behaviors. Children 7–12 years of age completed the cold pressor task (CPT) in the presence of a primary caregiver. Parents rated their state anxiety and catastrophizing about child pain. Parent HRV was examined at 30-second epochs at rest (“trait HRV”), before (“state HRV-warm”), and during their child’s CPT (“state HRV-cold”). Parent behaviors were video recorded and coded as coping-promoting or distress-promoting. Thirty-one parents had complete cardiac, observational, and self-report data. A small to moderate negative correlation emerged between state HRV-cold and CP behaviors during CPT. Trait HRV moderated the association between parent state catastrophizing and distress-promoting behaviors. Parents experiencing state catastrophizing were more likely to engage in distress-promoting behavior if they had low trait HRV. This novel work suggests parents who generally have a low (vs. high) HRV, reflective of low capacity for emotion regulation, may be at risk of engaging in behaviors that increase child distress when catastrophizing about their child’s pain.

Investigating convergence of cardiac and behavioral indicators of distress during routine vaccinations over the second year of life

There is considerable variability regarding the convergence between behavioral and biological aspects of distress responses in toddlerhood, and little research has investigated the convergence of these measures in high distress. The aim of the current study was to describe patterns of distress responses to vaccinations as indexed by both pain-related behavioral distress and heart rate (HR) at 12 and 18 months. Caregiver-toddler dyads were part of an ongoing longitudinal cohort observed during 12- (N = 158) and 18-month (N = 122) well-baby vaccinations. Parallel-process growth mixture models discerned two distinct groups at 12 months and three distinct groups at 18 months. All groups had comparable pain-related behavioral distress and HR responses post-vaccination, with most participants displaying high arousal and regulation to baseline levels following the vaccination. However, at 18 months, an important minority had a blunted response or did not regulate to a low level of distress by 3 min post-needle. Post hoc analyses revealed that higher baseline pain-related behavioral distress predicted membership in the majority groups at 12 and 18 months. These results highlight the developmental differences and variability in behavioral and cardiac indicators of distress regulation across the second year of life.

The impact of parental contact upon cortical noxious-related activity in human neonates

BACKGROUND

Neonates display strong behavioural, physiological and cortical responses to tissue-damaging procedures. Parental contact can successfully regulate general behavioural and physiological reactivity of the infant, but it is not known whether it can influence noxious-related activity in the brain. Brain activity is highly dependent upon maternal presence in animal models, and therefore this could be an important contextual factor in human infant pain-related brain activity.

METHODS

Global topographic analysis was used to identify the presence and inter-group differences in noxious-related activity in three separate parental contexts. EEG was recorded during a clinically required heel lance in three age and sex-matched groups of neonates (a) while held by a parent in skin-to-skin (n = 9), (b) while held by a parent with clothing (n = 9) or (c) not held at all, but in individualized care (n = 9).

RESULTS

The lance elicited a sequence of 4-5 event-related potentials (ERPs), including the noxious ERP (nERP), which was smallest for infants held skin-to-skin and largest for infants held with clothing (p=0.016). The nERP was then followed by additional and divergent long-latency ERPs (> 750 ms post-lance), not previously described, in each of the groups, suggesting the engagement of different higher level cortical processes depending on parental contact.

CONCLUSIONS

These results show the importance of considering contextual factors in determining infant brain activity and reveal the powerful influence of parental contact upon noxious-related activity across the developing human brain.

SIGNIFICANCE

This observational study found that the way in which the neonatal brain processes a noxious stimulus is altered by the type of contact the infant has with their mother. Specifically, being held in skin-to-skin reduces the magnitude of noxious-related cortical activity. This work has also shown that different neural mechanisms are engaged depending on the mother/infant context, suggesting maternal contact can change how a baby's brain processes a noxious stimulus.

Getting to the heart of childhood empathy: Relations with shyness and respiratory sinus arrhythmia

Although prior studies have found that shyness and empathy are inversely related and that well-regulated children tend to express empathic behaviors more often, little work has assessed combinations of these factors in predicting affective and cognitive empathy in early childhood. The authors examined relations among shyness, resting respiratory sinus arrhythmia (RSA), and observed affective and cognitive empathy in a sample of 130 typically developing children (M_age  = 63.5 months, SD = 12.2; 62 males). Shyness was assessed by observing children's behaviors during a self-presentation task, and this observed measure was then combined with a maternal report of children's temperamental shyness. Children's shyness predicted lower levels of both affective and cognitive responses to an experimenter feigning an injury. Resting RSA moderated the relation between children's shyness and observed empathy such that relatively higher shyness combined with lower RSA levels conferred the lowest levels of cognitive empathy. Children who were relatively low in shyness exhibited similar levels of cognitive empathy across different levels of RSA. However, this moderation was not found when predicting children's affective empathy. Our results suggest that not all shy children are alike in terms of their empathic behaviors: shy children who are physiologically dysregulated appear to have difficulties exploring and/or processing others' pain.