Infant pain management: a developmental neurobiological approach

Neonatal amygdala volumes, procedural pain and the association with social-emotional development in children born very preterm

Very preterm birth (< 32 weeks' gestational age) is associated with later social and emotional impairments, which may result from enhanced vulnerability of the limbic system during this period of heightened vulnerability. Evidence suggests that early procedural pain may be a key moderator of early brain networks. In a prospective cohort study, neonates born very preterm (< 30 weeks' gestation) underwent MRI scanning at term-equivalent age (TEA) and clinical data were collected (mechanical ventilation, analgesics, sedatives). Procedural pain was operationalized as the number of skin breaking procedures. Amygdala volumes were automatically extracted. The Strengths and Difficulties questionnaire was used to assess social-emotional outcomes at 5 years of age (mean age 67.5 months). General linear models were employed to examine the association between neonatal amygdala volumes and social-emotional outcomes and the timing and amount of procedural pain exposure (early within the first weeks of life to TEA) as a moderator, adjusting for biological sex, gestational age, 5-year assessment age, days of mechanical ventilation and total cerebral volumes. A total of 42 preterm infants participated. Right amygdala volumes at TEA were associated with prosocial behaviour at age 5 (B = -0.010, p = 0.005). Procedural pain was found to moderate the relationship between right amygdala volumes in the neonatal period and conduct problems at 5 years, such that early skin breaking procedures experienced within the first few weeks of life strengthened the association between right amygdala volumes and conduct problems (B = 0.005, p = 0.047). Late skin breaking procedures, experienced near TEA, also strengthened the association between right amygdala volumes and conduct problems (B = 0.004, p = 0.048).

Effects of pain, sedation and analgesia on neonatal brain injury and brain development

Critically ill newborns experience numerous painful procedures as part of lifesaving care in the Neonatal Intensive Care Unit. However, painful exposures in the neonatal period have been associated with alterations in brain maturation and poorer neurodevelopmental outcomes in childhood. The most frequently used medications for pain and sedation in the NICU are opioids, benzodiazepines and sucrose; these have also been associated with abnormalities in brain maturation and neurodevelopment making it challenging to know what the best approach is to treat neonatal pain. This article provides clinicians with an overview of how neonatal exposure to pain as well as analgesic and sedative medications impact brain maturation and neurodevelopmental outcomes in critically ill infants. We also highlight areas in need of future research to develop standardized neonatal pain monitoring and management strategies.

Dexmedetomidine as a Short-Use Analgesia for the Immature Nervous System

Pain management in neonates continues to be a challenge. Diverse therapies are available that cause loss of pain sensitivity. However, because of side effects, the search for better options remains open. Dexmedetomidine is a promising drug; it has shown high efficacy with a good safety profile in sedation and analgesia in the immature nervous system. Though dexmedetomidine is already in use for pain control in neonates (including premature neonates) and infants as an adjunct to other anesthetics, the question remains whether it affects the neuronal activity patterning that is critical for development of the immature nervous system. In this study, using the neonatal rat as a model, the pharmacodynamic effects of dexmedetomidine on the nervous and cardiorespiratory systems were studied. Our results showed that dexmedetomidine has pronounced analgesic effects in the neonatal rat pups, and also weakly modified both the immature network patterns of cortical and hippocampal activity and the physiology of sleep cycles. Though the respiration and heart rates were slightly reduced after dexmedetomidine administration, it might be considered as the preferential independent short-term therapy for pain management in the immature and developing brain.

Brain health in preterm infants: importance of early-life pain and analgesia exposure

"Everyday" exposures in the neonatal period, such as pain, may impact brain health in preterm infants. Specifically, greater exposure to painful procedures in the initial weeks after birth have been related to abnormalities in brain maturation and growth and poorer neurodevelopmental outcomes in preterm infants. Despite an increasing focus on the importance of treating pain in preterm infants, there is a lack of consensus of optimal approaches to managing pain in this population. This may be due to recent findings suggesting that commonly used analgesic and sedative medications in preterm infants may also have adverse effects of brain maturation and neurodevelopmental outcomes. This review provides an overview of potential impacts of pain and analgesia exposure on preterm brain health while highlighting research areas in need of additional investigations for the development of optimal pain management strategies in this population.

Pain Exposure and Brain Connectivity in Preterm Infants

Importance

Early-life exposure to painful procedures has been associated with altered brain maturation and neurodevelopmental outcomes in preterm infants, although sex-specific differences are largely unknown.

Objective

To examine sex-specific associations among early-life pain exposure, alterations in neonatal structural connectivity, and 18-month neurodevelopment in preterm infants.

Design, Setting, and Participants

This prospective cohort study recruited 193 very preterm infants from April 1, 2015, to April 1, 2019, across 2 tertiary neonatal intensive care units in Toronto, Canada. Structural connectivity data were available for 150 infants; neurodevelopmental outcomes were available for 123 infants. Data were analyzed from January 1, 2022, to December 31, 2023.

Exposure

Pain was quantified in the initial weeks after birth as the total number of invasive procedures.

Main Outcome and Measure

Infants underwent early-life and/or term-equivalent-age magnetic resonance imaging with diffusion tensor imaging to quantify structural connectivity using graph theory measures and regional connection strength. Eighteen-month neurodevelopmental outcomes were assessed with the Bayley Scales of Infant and Toddler Development, Third Edition. Stratifying by sex, generalized estimating equations were used to assess whether pain exposure modified the maturation of structural connectivity using an interaction term (early-life pain exposure × postmenstrual age [PMA] at scan). Generalized estimating equations were used to assess associations between structural connectivity and neurodevelopmental outcomes, adjusting for extreme prematurity and maternal education.

Results

A total of 150 infants (80 [53%] male; median [IQR] gestational age at birth, 27.1 [25.4-29.0] weeks) with structural connectivity data were analyzed. Sex-specific associations were found between early-life pain and neonatal brain connectivity in female infants only, with greater early-life pain exposure associated with slower maturation in global efficiency (pain × PMA at scan interaction P = .002) and local efficiency (pain × PMA at scan interaction P = .005). In the full cohort, greater pain exposure was associated with lower global efficiency (coefficient, -0.46; 95% CI, -0.78, to -0.15; P = .004) and local efficiency (coefficient, -0.57; 95% CI, -1.04 to -0.10; P = .02) and regional connection strength. Local efficiency (coefficient, 0.003; 95% CI, 0.001-0.004; P = .005) and regional connection strength in the striatum were associated with cognitive outcomes.

Conclusions and Relevance

In this cohort study of very preterm infants, greater exposure to early-life pain was associated with altered maturation of neonatal structural connectivity, particularly in female infants. Alterations in structural connectivity were associated with neurodevelopmental outcomes, with potential regional specificities.

Intravenous dexamethasone does not prolong the duration of pudendal nerve block in infants and children undergoing hypospadias surgery: A randomized clinical trial

BACKGROUND

The administration of intravenous dexamethasone increases the duration of neuraxial block and improves the quality of analgesia. However, little is known about these effects of dexamethasone on peripheral nerve blocks in children.

AIMS

In this study, we aimed to investigate the benefit of intravenous dexamethasone for enhancing the effect of pudendal block on postoperative analgesia in children who underwent hypospadias surgery.

METHODS

In total, 46 children aged 6-36 months who underwent hypospadias surgery were randomly allocated to either a control group (normal saline, group C) or dexamethasone group (0.5 mg/kg, group D). Pudendal block was performed before the surgery using 0.3 mL/kg of 0.225% ropivacaine on both sides. Parents were instructed to press the patient-controlled analgesia bolus button when their children's pain score was >4 points. The primary outcome measure was the time at which the first patient-controlled analgesia by proxy bolus dose was administered. The secondary outcome measures were pain score, number of patient-controlled analgesia administration by proxy bolus attempts, number of rescue analgesics required, total amount of fentanyl administered, and overall parental satisfaction.

RESULTS

The time of first patient-controlled analgesia bolus administration by proxy was not different between the control and dexamethasone groups (5.6 [5.2, 8.8] h versus 6.5 [5.4, 8.1] h, hazard ratio 0.8, 95% confidence intervals 0.43 to 1.47, p = .46). There were no statistically significant differences among the secondary outcomes.

CONCLUSIONS

Administration of intravenous dexamethasone did not enhance the duration of pudendal nerve block in infants and children aged 6-36 months who underwent hypospadias surgery.

Developmental impact of peripheral injury on neuroimmune signaling

A peripheral injury drives neuroimmune interactions at the level of the injury and throughout the neuraxis. Understanding these systems will be beneficial in the pursuit to target persistent pain that involves both neural and immune components. In this review, we discuss the impact of injury on the development of neuroimmune signaling, along with data that suggest a possible cellular immune memory. We also discuss the parallel effects of injury in the nervous system and immune related areas including bone marrow, lymph node and central nervous system-related cells. Finally, we relate these findings to patient populations and current research that evaluates human tissue.

Early-Life Iron Deficiency Persistently Alters Nociception in Developing Mice

Clinical association studies have identified early-life iron deficiency (ID) as a risk factor for the development of chronic pain. While preclinical studies have shown that early-life ID persistently alters neuronal function in the central nervous system, a causal relationship between early-life ID and chronic pain has yet to be established. We sought to address this gap in knowledge by characterizing pain sensitivity in developing male and female C57Bl/6 mice that were exposed to dietary ID during early life. Dietary iron was reduced by ∼90% in dams between gestational day 14 and postnatal day (P)10, with dams fed an ingredient-matched, iron-sufficient diet serving as controls. While cutaneous mechanical and thermal withdrawal thresholds were not altered during the acute ID state at P10 and P21, ID mice were more sensitive to mechanical pressure at P21 independent of sex. During adulthood, when signs of ID had resolved, mechanical and thermal thresholds were similar between early-life ID and control groups, although male and female ID mice displayed increased thermal tolerance at an aversive (45 °C) temperature. Interestingly, while adult ID mice showed decreased formalin-induced nocifensive behaviors, they showed exacerbated mechanical hypersensitivity and increased paw guarding in response to hindpaw incision in both sexes. Collectively, these results suggest that early-life ID elicits persistent changes in nociceptive processing and appears capable of priming developing pain pathways. PERSPECTIVE: This study provides novel evidence that early-life ID evokes sex-independent effects on nociception in developing mice, including an exacerbation of postsurgical pain during adulthood. These findings represent a critical first step towards the long-term goal of improving health outcomes for pain patients with a prior history of ID.

A developmental shift in habituation to pain in human neonates

Habituation to recurrent non-threatening or unavoidable noxious stimuli is an important aspect of adaptation to pain. Neonates, especially if preterm, are exposed to repeated noxious procedures during their clinical care. They can mount strong behavioral, autonomic, spinal, and cortical responses to a single noxious stimulus; however, it is not known whether the developing nervous system can adapt to the recurrence of these inputs. Here, we used electroencephalography to investigate changes in cortical microstates (representing the complex sequential processing of noxious inputs) following two consecutive clinically required heel lances in term and preterm infants. We show that stimulus repetition dampens the engagement of initial microstates and associated behavioral and autonomic responses in term infants, while preterm infants do not show signs of habituation. Nevertheless, both groups engage different longer-latency cortical microstates to each lance, which is likely to reflect changes in higher-level stimulus processing with repeated stimulation. These data suggest that while both age groups are capable of encoding contextual differences in pain, the preterm brain does not regulate the initial cortical, behavioral, and autonomic responses to repeated noxious stimuli. Habituation mechanisms to pain are already in place at term age but mature over the equivalent of the last trimester of gestation and are not fully functional in preterm neonates.

Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks-American Pain Society-American Academy of Pain Medicine Pain Taxonomy Diagnostic Criteria for Acute Needle Pain

Needle procedures are among the most common causes of pain and distress for individuals seeking health care. While needle pain is especially problematic for children needle pain and associated fear also has significant impact on adults and can lead to avoidance of appropriate medical care. Currently there is not a standard definition of needle pain. A taxonomy, or classification system, for acute needle pain would aid research efforts and enhance clinical care. To meet this need, the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks public-private partnership with the U.S. Food and Drug Administration, the American Pain Society, and the American Academy of Pain Medicine formed the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks-American Pain Society-American Academy of Pain Medicine Pain Taxonomy initiative. One of the goals of this initiative was to develop taxonomies for acute pain disorders, including needle pain. To accomplish this, a working group of experts in needle pain was convened. Based on available literature and expert opinion, the working group used a 5-dimenional structure (diagnostic criteria, common features, modulating factors, impact and/or functional consequences, and putative mechanisms) to develop an acute pain taxonomy that is specific needle pain. As part of this, a set of 4 diagnostic criteria, with 2 modifiers to account for the influence of needle associated fear, are proposed to define the types of acute needle pain. PERSPECTIVE: This article presents a taxonomy for acute needle pain. This taxonomy could help to standardize definitions of acute pain in clinical studies of patients undergoing needle procedures.

A Randomized Comparative Effectiveness Study of Reflexology, Sucrose, and Other Treatments for Needle Procedures in Newborns

BACKGROUND

Approximately 10 to 14 painful procedures per day are performed in infants during the hospital stay. We aimed to determine the effect of reflexology applied to the sole during painful procedures on pain perception in newborns compared with other nonpharmacologic methods.

METHODS

Our study was planned as a randomized controlled trial in term infants being followed up in the neonatal intensive care unit and maternity ward. To reduce pain during collection of venous blood or heel lance reflexology on the soles of the foot, 24% sucrose solution, kangaroo care, and classical music listening were applied to the infants. The Neonatal Infant Pain Scale (NIPS) was used to assess newborns during acute pain.

RESULTS

A total of 300 patients were enrolled in the study. Higher pain scores and crying times were observed during heel blood collection. All analgesic methods significantly reduced NIPS scores during heel blood collection. Sucrose was the most effective method, followed by reflexology. The best method that significantly shortened the crying time was again sucrose solution followed by reflexology, kangaroo care, and classical music, during heel blood collection. However, none of the nonpharmacologic methods was effective during venous blood collection.

CONCLUSIONS

Although sucrose was the most effective method, reflexology has significant positive effects, especially on average heartbeat, reducing pain, and shortening crying times during heel blood sampling. Reflexology might be considered among the nonpharmacologic methods to be applied before routine interventions, but still, there is a need for further studies to investigate the efficiency.

Early-life exposure to analgesia and 18-month neurodevelopmental outcomes in very preterm infants

BACKGROUND

We assessed variability of analgesic use across three tertiary neonatal intensive care units (NICUs) accounting for early-life pain, quantified as number of invasive procedures. We also determined whether analgesia exposure modifies associations between early-life pain and neurodevelopment.

METHODS

Multicenter prospective study of 276 very preterm infants (born <24-32 weeks' gestational age [GA]). Detailed data of number of invasive procedures and duration of analgesia exposure were collected in initial weeks after birth. Eighteen-month neurodevelopmental assessments were completed in 215 children with Bayley Scales for Infant Development-Third edition.

RESULTS

Multivariable linear regressions revealed significant differences in morphine use across sites, for a given exposure to early-life pain (interaction p < 0.001). Associations between early-life pain and motor scores differed by duration of morphine exposure (interaction p = 0.01); greater early-life pain was associated with poorer motor scores in infants with no or long (>7 days) exposure, but not short exposure (≤7 days).

CONCLUSIONS

Striking cross-site differences in morphine exposure in very preterm infants are observed even when accounting for early-life pain. Negative associations between greater early-life pain and adverse motor outcomes were attenuated in infants with short morphine exposure. These findings emphasize the need for further studies of optimal analgesic approaches in preterm infants.

IMPACT

In very preterm neonates, both early-life exposure to pain and analgesia are associated with adverse neurodevelopment and altered brain maturation, with no clear guidelines for neonatal pain management in this population. We found significant cross-site variability in morphine use across three tertiary neonatal intensive care units in Canada. Morphine use modified associations between early-life pain and motor outcomes. In infants with no or long durations of morphine exposure, greater early-life pain was associated with lower motor scores, this relationship was attenuated in those with short morphine exposure. Further trials of optimal treatment approaches with morphine in preterm infants are warranted.

Skin-to-skin contact-An effective intervention on pain and stress reduction in preterm infants

Introduction

The outcomes of pain and stress in preterm infants in the neonatal intensive care units (NICUs) compel the continued search for pain- and stress-reducing interventions.

The objective of the study

To investigate how skin-to-skin contact (SSC) influences chronic pain and stress in preterm infants in the NICU.

Materials and methods

The study included 140 preterm infants in the NICU with gestational age less than 34 weeks. The overall design was a baseline-response design. Urine and saliva were collected before (baseline) and after SSC to measure pain and stress markers by enzyme immunoassay method. The behavioral indicators of chronic pain were assessed using the EDIN (Échelle Douleur Inconfort Nouveau-Né-neonatal pain and discomfort).

Results

There was a significant decrease in the dopamine level in preterm infants after SSC in comparison with baseline values (85.99 [69.35; 112.20] pg/ml vs. 132.20 [104.80; 183.70] pg/ml), p < 0.001. The β-endorphin and serotonin levels increased after SSC (40.09 [26.81; 70.63] pg/ml vs. 29.87 [20.61; 46.94] pg/ml, p = 0.009 and 25.49 [20.45; 40.08] ng/ml vs. 22.30 [15.13; 31.65] ng/ml, p = 0.011, respectively). A significant decrease in cortisol levels in saliva and urine after SSC in comparison with baseline values (0.125 [0.079; 0.225] μg/dl vs. 0.371 [0.188; 1.002] μg/dl, p = 0.000 and 27.06 [14.59; 35.35] ng/ml vs. 35.25 [19.78; 61.94] ng/ml, p = 0.001, with a simultaneous increase of oxytocin level (57.00 [36.55; 88.49] pg/ml vs. 38.20 [28.78; 56.04] pg/ml, p = 0.009 were revealed. The total pain EDIN score in infants after SSC was below 6 points, significantly decreasing compared to the baseline (p < 0.05).

Conclusion

Preterm infants in the NICU experience stress and pain, which were confirmed by the EDIN pain scale and laboratory markers. The level of dopamine and cortisol as pain and stress hormones were reliably high, and normalized after regular SSC. Simultaneously, pain-relieving and anti-stress markers of oxytocin, β-endorphin and serotonin reliably increased in preterm infants in response to the SSC.

Early life events in functional abdominal pain disorders in children

Objectives

Functional abdominal pain disorders (FAPDs) are common gastrointestinal problems in children, and the pathophysiology is thought to be multifactorial. Adverse early life events (ELE) induce alterations in the central nervous system, perhaps predisposing individuals to develop FAPDs. We aimed to study the potential adverse ELE that are associated with FAPDs.

Methods

We steered a school-based survey involving 1000 children from 4 randomly selected schools. FAPDs were assessed using the translated Rome III questionnaire, and ELE were identified using a pre-tested, parental questionnaire. FAPDs were diagnosed using the Rome III criteria.

Results

Hundred and eighty-two (182) children had FAPDs (62.1% girls, mean age 8.5, SD 2.1). ELE of them were compared with 571 children without FAPDs (51.1% girls, mean age 8.8, SD 1.9). According to the binary logistic regression analysis, family members with abdominal pain, family member with chronic pain other than abdominal pain, prenatal maternal complications and interventional deliveries, were recognized as potential risk factors for the development of FAPDs. Breast feeding over two years has shown to reduce the prevalence of FAPDs.a.

Conclusions

Prenatal maternal medical problems are associated a with higher prevalence of FAPDs later in life. Prolonged breastfeeding and normal vaginal delivery could be considered as factors that reduce the vulnerability of developing FAPDs in children. Therefore, minimizing pregnancy-related complications, encouraging vaginal deliveries, and encouraging breastfeeding are potentially valuable measures to prevent FAPDs during childhood.

Evolving approaches in neonatal postoperative pain management

Neonates experience significant moderate and severe postoperative pain. Effective postoperative pain management in neonates is required to minimize acute and long-term effects of neonatal pain. Protecting the developing nervous system from persistent sensitization of pain pathways and developing primary hyperalgesia is essential. Opioids and acetaminophen are commonly analgesics used for pain control. Regional anesthesia provides adequate intraoperative and postoperative analgesia in neonates. It decreases exposure to opioids, reduces adverse drug effects, and facilitates early extubation. It suppresses the stress response and can prevent long-term behavioral responses to pain. The most common blocks performed in neonates are neuraxial blocks. Using ultrasound increased the number of peripheral nerve blocks performed in neonates. Recently, various peripheral nerve blocks (paravertebral, transverse abdominis plane, rectus sheath, quadratus lumborum, erector spinae plane blocks) were safely used. Many studies support analgesic efficacy but highlight neonates' unpredictability and variability of fascial blocks.

Evaluation of the Premature Infant Pain Profile-Revised (PIPP-R) e-Learning Module: Immediate and Sustained Competency

BACKGROUND

Electronic health (e-health) learning is a potential avenue to educate health professionals about accurately using infant pain assessment tools, although little is known about the impact of e-health interventions on clinical competence.

PURPOSE

To evaluate whether an e-health learning module for teaching the accurate use of the Premature Infant Pain Profile-Revised (PIPP-R) pain assessment tool results in immediate and sustained competency to assess infant pain.

METHODS

Neonatal intensive care unit (NICU) nurses who participated in a larger study across 2 tertiary NICUs in Canada examining the implementation and clinical utility of the PIPP-R e-learning module completed 2 follow-up evaluations at 1 week and 3 months. Participants were asked to view a video recording of an infant undergoing a painful procedure and to assess the infant's pain intensity response using the PIPP-R measure. Immediate and sustained competency was assessed via interrater consensus of participant-reported PIPP-R scores compared with those of an experienced trained coder.

RESULTS

Of the 25 eligible nurses, 22 completed 1-week and 3-month follow-up evaluations. At the 1-week follow-up, 84% of nurses scored the video accurately compared with 50% at 3 months. Behavioral pain indicators were more likely to be scored incorrectly than physiological indicators.

IMPLICATIONS FOR PRACTICE

Follow-up training after completion of the initial e-learning module training may improve competency related to the clinical use of the PIPP-R tool to assess infant pain over time.

IMPLICATIONS FOR RESEARCH

Additional study regarding the need and timing of e-health training to optimize sustained competency in infant pain assessment is warranted.

Genetic and epigenetic mechanisms influencing acute to chronic postsurgical pain transitions in pediatrics: Preclinical to clinical evidence

Background

Chronic postsurgical pain (CPSP) in children remains an important problem with no effective preventive or therapeutic strategies. Recently, genomic underpinnings explaining additional interindividual risk beyond psychological factors have been proposed.

Aims

We present a comprehensive review of current preclinical and clinical evidence for genetic and epigenetic mechanisms relevant to pediatric CPSP.

Methods

Narrative review.

Results

Animal models are relevant to translational research for unraveling genomic mechanisms. For example, Cacng2, p2rx7, and bdnf mutant mice show altered mechanical hypersensitivity to injury, and variants of the same genes have been associated with CPSP susceptibility in humans; similarly, differential DNA methylation (H1SP) and miRNAs (miR-96/7a) have shown translational implications. Animal studies also suggest that crosstalk between neurons and immune cells may be involved in nociceptive priming observed in neonates. In children, differential DNA methylation in regulatory genomic regions enriching GABAergic, dopaminergic, and immune pathways, as well as polygenic risk scores for enhanced prediction of CPSP, have been described. Genome-wide studies in pediatric CPSP are scarce, but pathways identified by adult gene association studies point to potential common mechanisms.

Conclusions

Bench-to-bedside genomics research in pediatric CPSP is currently limited. Reverse translational approaches, use of other -omics, and inclusion of pediatric/CPSP endophenotypes in large-scale biobanks may be potential solutions. Time of developmental vulnerability and longitudinal genomic changes after surgery warrant further investigation. Emergence of promising precision pain management strategies based on gene editing and epigenetic programing emphasize need for further research in pediatric CPSP-related genomics.

Utilizing umbilical cord blood - Minimizing blood sampling and pain in healthy infants at risk for polycythemia

BACKGROUND

Exposure to pain in early life was associated with long term consequences, therefore strategies for minimizing painful procedures in newborns should be employed. The utility and reliability of cord blood CBC was demonstrated before, however data regarding use of cord blood in healthy infants at risk for polycythemia are lacking.

METHODS

A single-center, paired-sampling prospective laboratory study including all healthy asymptomatic infants born after 36 weeks gestation who were SGA (<2500 g), LGA (>4000 g), or born to mothers with diabetes in pregnancy. Blood count indices were compared between umbilical and neonatal capillary or venous blood samples. In order to predict cut-off values for neonatal polycythemia using umbilical hematocrit, receiver operator curves (ROC) were plotted.

RESULTS

Paired samples were collected from 433 infants. Mean gestational age and birth-weight were 39.0 ± 1.3 weeks and 3489 ± 682 g. Hemoglobin, hematocrit and WBC values were lower in cord blood compared to neonatal, but PLT count was higher. Pearson r showed only modest correlation between peripheral capillary and umbilical or venous Hct - 0.35 (p < 0.001), and 0.44 (p < 0.001), respectively. In order to try and capture clinically significant polycythemia ROC was plotted for hematocrit >70% and <40%. In our cohort, using the calculated cutoff values (>51% and <35%) could have resulted in a decrease of 72% of neonatal blood draws.

CONCLUSION

This analysis should be interpreted with caution, as currently it cannot support the routine use of umbilical samples' hematocrits for making treatment decision in newborns at risk for polycythemia. Further larger studies are needed.

Mother-Infant Dyadic Synchrony in the NICU Context

BACKGROUND

Dyadic synchrony is a co-constructed social process relating to the back and forth interactions between mothers and infants that are strongly associated with neurodevelopment, self-regulation, and attachment. In the neonatal intensive care unit (NICU), this process may become interrupted because of the physiological state of the infant, the emotional state of the mother, and the physical environment of the NICU.

PURPOSE

In applying Feldman's Biobehavioral Model of Synchrony, this empirical review deconstructs the process of dyadic synchrony in the NICU context and provides a conceptual approach to guide both research and clinical practice.

METHODS

First, we examine the theoretical and empirical literature to explicate the primary structural and biophysiological components of synchrony and relate these constructs to the extant research on premature infants. Next, we synthesize the maternal, infant, and contextual factors that facilitate or inhibit the ontogenesis of dyadic synchrony in the NICU. The final section highlights the state of the science in dyadic synchrony in the NICU including gaps and recommendations for future research.

FINDINGS

An empirical review synthesis presents a visual conceptual framework to illustrate multiple processes that depict maternal, infant, and contextual influences of mother-infant synchrony in the NICU.

IMPLICATIONS FOR PRACTICE/RESEARCH

Despite the challenges posed to mother-infant relationships in the NICU, high-quality mother-infant interactions are possible, dyadic synchrony can emerge, and premature infants can develop secure attachments. Clinicians and researchers can apply this conceptual framework of mother-infant dyadic synchrony in the NICU to promote evidence-based research and clinical practice.

Assessment and Management of Pain in Preterm Infants: A Practice Update

Infants born preterm are at a high risk for repeated pain exposure in early life. Despite valid tools to assess pain in non-verbal infants and effective interventions to reduce pain associated with medical procedures required as part of their care, many infants receive little to no pain-relieving interventions. Moreover, parents remain significantly underutilized in provision of pain-relieving interventions, despite the known benefit of their involvement. This narrative review provides an overview of the consequences of early exposure to untreated pain in preterm infants, recommendations for a standardized approach to pain assessment in preterm infants, effectiveness of non-pharmacologic and pharmacologic pain-relieving interventions, and suggestions for greater active engagement of parents in the pain care for their preterm infant.

The neurobiology of childhood trauma, from early physical pain onwards: as relevant as ever in today's fractured world

Background: The situation in the world today, encompassing multiple armed conflicts, notably in Ukraine, the Coronavirus pandemic and the effects of climate change, increases the likelihood of childhood exposure to physical injury and pain. Other effects of these worldwide hardships include poverty, malnutrition and starvation, also bringing with them other forms of trauma, including emotional harm, neglect and deliberate maltreatment. Objective: To review the neurobiology of the systems in the developing brain that are most affected by physical and emotional trauma and neglect. Method: The review begins with those that mature first, such as the somatosensory system, progressing to structures that have a more protracted development, including those involved in cognition and emotional regulation. Explored next are developing stress response systems, especially the hypothalamic-pituitary-adrenal axis and its central regulator, corticotropin-releasing hormone. Also examined are reward and anti-reward systems and genetic versus environmental influences. The behavioural consequences of interpersonal childhood trauma, focusing on self-harm and suicide, are also surveyed briefly. Finally, pointers to effective treatment are proffered. Results: The low-threshold nature of circuitry in the developing brain and lack of inhibitory connections therein result in heightened excitability, making the consequences of both physical and emotional trauma more intense. Sensitive and critical periods in the development of structures such as the amygdala render the nervous system more vulnerable to insults occurring at those points, increasing the likelihood of psychiatric disorders, culminating in self-harm and even suicide. Conclusion: In view of the greater excitability of the developing nervous system, and its vulnerability to physical and psychological injuries, the review ends with an exhortation to consider the long-term consequences of childhood trauma, often underestimated or missed altogether when faced with adults suffering mental health problems.

Developmental Mechanisms of CPSP: Clinical Observations and Translational Laboratory Evaluations

Understanding mechanisms that underly the transition from acute to chronic pain and identifying potential targets for preventing or minimizing this progression have specific relevance for chronic postsurgical pain (CPSP). Though it is clear that multiple psychosocial, family, and environmental factors may influence CPSP, this review will focus on parallels between clinical observations and translational laboratory studies investigating the acute and long-term effects of surgical injury on nociceptive pathways. This includes data related to alterations in sensitivity at different points along nociceptive pathways from the periphery to the brain; age- and sex-dependent mechanisms underlying the transition from acute to persistent pain; potential targets for preventive interventions; and the impact of prior surgical injury. Ongoing preclinical studies evaluating age- and sex-dependent mechanisms will also inform comparative efficacy and preclinical safety assessments of potential preventive pharmacological interventions aimed at reducing the risk of CPSP. In future clinical studies, more detailed and longitudinal peri-operative phenotyping with patient- and parent-reported chronic pain core outcomes, alongside more specialized evaluations of somatosensory function, modulation, and circuitry, may enhance understanding of individual variability in postsurgical pain trajectories and improve recognition and management of CPSP.

Psychosocial and Neurobiological Vulnerabilities of the Hospitalized Preterm Infant and Relevant Non-pharmacological Pain Mitigation Strategies

Background: Preterm pain is common in the Neonatal Intensive Care Unit (NICU), with multiple invasive procedures occurring daily. Objective: To review the psychosocial and neurobiological vulnerabilities of preterm infants and to provide an updated overview of non-pharmacological strategies for acute procedural pain in hospitalized preterm infants. Methods: We utilized a narrative review methodology, which also included a synthesis of key pieces of published systematic reviews that are relevant to the current work. Results and Conclusions: Preterm infants are uniquely susceptible to the impact of painful procedures and prolonged separation from caregivers that are often inherent in a NICU stay. Non-pharmacological interventions can be efficacious for mitigating procedural pain for preterm infants. Interventions should continue to be evaluated with high quality randomized controlled trials, and should endeavor to take into account the neurobiological and psychosocial aspects of preterm vulnerability for pain prevention and management strategies.

Oxidative Stress in Preterm Newborns

Preterm babies are highly susceptible to oxidative stress (OS) due to an imbalance between the oxidant and antioxidant systems. The generation of free radicals (FR) induces oxidative damage to multiple body organs and systems. OS is the main factor responsible for the development of typical premature infant diseases, such as bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, intraventricular hemorrhage, periventricular leukomalacia, kidney damage, eryptosis, and also respiratory distress syndrome and patent ductus arteriosus. Many biomarkers have been detected to early identify newborns at risk of developing a free radical-mediated disease and to investigate new antioxidant strategies. This review reports the current knowledge on OS in the preterm newborns and the newest findings concerning the use of OS biomarkers as diagnostic tools, as well as in implementing antioxidant therapeutic strategies for the prevention and treatment of these diseases and their sequelae.

Does Repeated Painful Stimuli Change Cerebral Near-Infrared Spectroscopy Response in Healthy, Term, Large for Gestational Age Newborns?

OBJECTIVE

The objective of this study was to evaluate the effect of repeated painful stimuli on short-term pain response in healthy, term, large for gestational age newborns by measuring the regional cerebral oxygen saturation (rScO2), and behavioral and physiological responses.

METHODS

We compared term large for gestational age infants who received repeated painful stimuli (study group) with term, appropriate for gestational age infants (control group). A pulse oximeter and a near-infrared spectroscopy probe were connected to babies during the study period, and the responses of the babies were recorded by video, from which the crying time and the Neonatal Infant Pain Scale were obtained. The heart rate, peripheral oxygen saturation (SpO2), and rScO2 data were sampled every 1 second and exported to a personal computer via digital output during the study period. The maximum heart rate, the minimum SpO2, and peak, baseline, and mean rScO2 measurements following skin puncture were recorded. Data were compared within 1 group and between the 2 groups.

RESULTS

After the heel prick, crying time (P<0.001) and Neonatal Infant Pain Scale scores (P=0.024) increased, and SpO2 levels decreased significantly (P=0.012) in the study group versus the control group. Although mean rScO2 increased significantly within 1 group (P<0.001), it was not significant between the 2 groups. The percent change in rScO2 was greater in the study group (5.2 [2.5 to 9.3]) compared with the control group (2.8 [1.1 to 8.2], P=0.037).

CONCLUSION

We showed that rScO2 values changed significantly within the first few days of life in babies who received more painful stimuli compared with the control group, similar to behavioral and physiological responses.

Validity and reliability of the Neonatal Infant Acute Pain Assessment Scale (NIAPAS) in Turkish: prospective study

BACKGROUND

Using pain scales helps nurses in making early diagnoses and in assessing and managing pain symptoms and findings when developing a nursing care plan.

OBJECTIVE

To determine the validity and reliability of the Turkish form of the Neonatal Infant Acute Pain Assessment Scale (NIAPAS).

DESIGN AND SETTING

Prospective study conducted in Istanbul Bakırköy Dr. Sadi Konuk Training and Research Hospital, Istanbul, Turkey.

METHODS

145 newborns in the 26th to 42nd gestational weeks that were receiving treatment and care in the neonatal intensive care unit were included in this study. A total of 1740 pain assessments were made by two independent observers on these 145 newborns. The research data was collected using a newborn description form, NIAPAS and the Neonatal Infant Pain Scale (NIPS).

RESULTS

The scope validity index of NIAPAS was found to be between 0.90 and 1.00 and its Cronbach's alpha coefficient was 0.914. Correlations between characteristics and total scores (r = 0.20-0.82) were found to be sufficiently high. In an assessment on concurrency validity, there was a strong positive relationship between NIAPAS and NIPS scores (r = 0.73-0.82; P < 0.000). From kappa analysis (0.73-0.99) and intraclass correlation (r = 0.75-0.96), it was determined that there was concordance between the observers.

CONCLUSION

NIAPAS was found to be a valid and reliable scale for evaluating acute pain in newborns.

Recommendations for a Pediatric Pain Education Curriculum for Physical and Occupational Therapists: Scoping Review and Survey

Specialization training for physiotherapists, occupational therapists, and sports therapists involved in pediatric pain is scarce and curricula are rarely published. The objectives of this study are twofold: firstly, to perform a scoping review to derive important contents for a pediatric pain education curriculum for specialized pain therapists. Secondly, to conduct a survey on specific contents in curricula currently used by pain experts and to obtain their evaluation regarding the importance of such contents for a specialized curriculum. The review substantiated the importance of a specific curriculum in pediatric pain education, but provided little information on adequate contents. In the survey, 45 experts in pediatric pain education confirmed that specific curricula and specialized contents for pediatric pain education are missing. Their answers give a well-defined picture of the specifics needed in the interaction with a pediatric population. The most important items they classified were e.g., the biopsychosocial framework and the impact of pediatric pain on daily life. Those expert ratings were in line with the recommendations of pediatric pain management guidelines. Further curriculum work in an interdisciplinary, international network is highly recommended.

Microglial activation in the trigeminal spinal subnucleus interpolaris/caudalis modulates orofacial incisional mechanical pain hypersensitivity associated with orofacial injury in infancy

PURPOSE

Infantile tissue injury induces sensory deficits in adulthood. Infantile facial incision (IFI) was reported to cause an enhancement of incision-induced mechanical hypersensitivity in adulthood due to acceleration of the trigeminal ganglion neuronal excitability. However, the effects of IFI on activation of microglia in the spinal trigeminal nucleus and its involvement in facial pain sensitivity is not well known.

METHODS

A facial skin incision was made in the left whisker pad in infant (IFI) and/or adult rats (AFI). Mechanical head withdrawal threshold and microglial activation in the trigeminal spinal nucleus were analyzed.

RESULTS

Mechanical pain hypersensitivity induced by AFI was significantly exacerbated and prolonged by IFI. The number of Iba1-immunoreactive cells in the trigeminal spinal nucleus following AFI was increased by IFI, suggesting that IFI facilitates microglial hyperactivation following AFI. Intraperitoneal administration of minocycline, a microglial activation inhibitor, suppressed the facial incision-induced microglial hyperactivation in the trigeminal spinal nucleus and the exacerbation of the facial mechanical pain hypersensitivity induced by IFI.

CONCLUSION

These results suggest that facial trauma in infants causes hyperactivation of microglia in the trigeminal spinal nucleus following AFI, leading to the prolongation of the facial mechanical pain hypersensitivity.

Tapentadol for the Treatment of Moderate-to-Severe Acute Pain in Children Under the Age of Two Years

Background

Pharmacokinetics (PK), efficacy, and safety of the opioid analgesic tapentadol in the treatment of moderate-to-severe acute pain have so far not been investigated in pediatric patients <2 years of age.

Patients and Methods

Two multicenter, open-label trials assessed the pharmacokinetic profile, safety, tolerability, and efficacy of single doses of tapentadol oral solution (OS; NCT02221674; n=19) or intravenous infusion (IV, EudraCT 2014-002259-24; n=38) in children from birth to <2 years of age. Of these, 8 preterm neonates were included in the IV trial. A third randomized, double-blind, placebo-controlled trial (NCT02081391) investigated the efficacy and safety of multiple tapentadol OS doses in patients from birth to <2 years (placebo n=4, tapentadol n=11) using an immediate rescue trial design. Patients in all three trials underwent surgery that, in the investigator’s opinion, reliably produced moderate-to-severe pain requiring opioid treatment.

Results

Administration of single tapentadol doses resulted in tapentadol serum concentrations within the targeted range known to be safe and efficacious in adults and compared well to the range observed for children aged 2 to <18 years. Pain intensity already improved 15 min after administration. In the multiple dose trial, amounts of supplemental opioid analgesic medication within the first 24 h after start of trial medication were low (placebo 0.02 mg/kg, tapentadol 0.05 mg/kg). All patients stopped treatment with the trial medication because opioid analgesics were no longer required. Treatment-emergent adverse events occurred in 42.1% (tapentadol OS single dose), 28.9% (tapentadol IV), and 75% of placebo and 54.5% of tapentadol patients (tapentadol OS multiple doses), none of them serious.

Conclusion

Tapentadol showed a favorable PK and safety profile in children <2 years of age. Multiple tapentadol OS dosing is efficacious and generally well tolerated in children ≥2 years and might also be a useful treatment option for children <2 years in need of strong analgesics.

Premature Birth and Developmental Programming: Mechanisms of Resilience and Vulnerability

The third trimester of pregnancy represents a sensitive phase for infant brain plasticity when a series of fast-developing cellular events (synaptogenesis, neuronal migration, and myelination) regulates the development of neural circuits. Throughout this dynamic period of growth and development, the human brain is susceptible to stress. Preterm infants are born with an immature brain and are, while admitted to the neonatal intensive care unit, precociously exposed to stressful procedures. Postnatal stress may contribute to altered programming of the brain, including key systems such as the hypothalamic-pituitary-adrenal axis and the autonomic nervous system. These neurobiological systems are promising markers for the etiology of several affective and social psychopathologies. As preterm birth interferes with early development of stress-regulatory systems, early interventions might strengthen resilience factors and might help reduce the detrimental effects of chronic stress exposure. Here we will review the impact of stress following premature birth on the programming of neurobiological systems and discuss possible stress-related neural circuits and pathways involved in resilience and vulnerability. Finally, we discuss opportunities for early intervention and future studies.

Using sensor-fusion and machine-learning algorithms to assess acute pain in non-verbal infants: a study protocol

INTRODUCTION

Objective pain assessment in non-verbal populations is clinically challenging due to their inability to express their pain via self-report. Repetitive exposures to acute or prolonged pain lead to clinical instability, with long-term behavioural and cognitive sequelae in newborn infants. Strong analgesics are also associated with medical complications, potential neurotoxicity and altered brain development. Pain scores performed by bedside nurses provide subjective, observer-dependent assessments rather than objective data for infant pain management; the required observations are labour intensive, difficult to perform by a nurse who is concurrently performing the procedure and increase the nursing workload. Multimodal pain assessment, using sensor-fusion and machine-learning algorithms, can provide a patient-centred, context-dependent, observer-independent and objective pain measure.

METHODS AND ANALYSIS

In newborns undergoing painful procedures, we use facial electromyography to record facial muscle activity-related infant pain, ECG to examine heart rate (HR) changes and HR variability, electrodermal activity (skin conductance) to measure catecholamine-induced palmar sweating, changes in oxygen saturations and skin perfusion, and electroencephalography using active electrodes to assess brain activity in real time. This multimodal approach has the potential to improve the accuracy of pain assessment in non-verbal infants and may even allow continuous pain monitoring at the bedside. The feasibility of this approach will be evaluated in an observational prospective study of clinically required painful procedures in 60 preterm and term newborns, and infants aged 6 months or less.

ETHICS AND DISSEMINATION

The Institutional Review Board of the Stanford University approved the protocol. Study findings will be published in peer-reviewed journals, presented at scientific meetings, taught via webinars, podcasts and video tutorials, and listed on academic/scientific websites. Future studies will validate and refine this approach using the minimum number of sensors required to assess neonatal/infant pain.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT03330496).

Cumulative procedural pain and brain development in very preterm infants: A systematic review of clinical and preclinical studies

Very preterm infants may manifest neurodevelopmental impairments, even in the absence of brain lesions. Pathogenesis is complex and multifactorial. Evidence suggests a role of early adversities on neurodevelopmental outcomes, via epigenetic regulation and changes in brain architecture. In this context, we focused on cumulative pain exposure which preterm neonates experience in neonatal intensive care unit (NICU). We systematically searched for: i) evidence linking pain with brain development and exploring the potential pathogenetic role of epigenetics; ii) preclinical research supporting clinical observational studies. Nine clinical neuroimaging studies, during neonatal or school age, mostly from the same research group, revealed volume reduction of white and gray matter structures in association with postnatal pain exposure. Three controlled animal studies mimicking NICU settings found increased cell death or apoptosis; nevertheless, eligible groups were limited in size. Epigenetic modulation (SLC6A4 promoter methylation) was identified in only two clinical trials. We call for additional research and, although knowledge gaps, we also point out the urgent need of minimizing painful procedures in NICUs.

Neonatal complete Freund's adjuvant-induced inflammation does not induce or alter hyperalgesic priming or alter adult distributions of C-fibre dorsal horn innervation

Introduction:

Inflammation during the neonatal period can exacerbate pain severity following reinjury in adulthood. This is driven by alterations in the postnatal development of spinal and supraspinal nociceptive circuitry. However, the contribution of alterations in peripheral nociceptor function remains underexplored.

Objectives:

We examined whether neonatal complete Freund's adjuvant (CFA)-induced inflammation induced or altered adult development of hyperalgesic priming (inflammation-induced plasticity in nonpeptidergic C fibres) or altered postnatal reorganization of calcitonin gene-related peptide (CGRP)-expressing and isolectin B4 (IB4)-binding C fibres in the spinal dorsal horn (DH).

Methods:

After intraplantar injection of CFA at postnatal day (P) 1, we assessed mechanical thresholds in adult (P60) rats before and after intraplantar carrageenan. One week later, intraplantar PGE₂-induced hypersensitivity persisting for 4 hours was deemed indicative of hyperalgesic priming. CGRP expression and IB4 binding were examined in adult rat DH after CFA.

Results:

P1 CFA did not alter baseline adult mechanical thresholds, nor did it change the extent or duration of carrageenan-induced hypersensitivity. However, this was slower to resolve in female than in male rats. Rats that previously received carrageenan but not saline were primed, but P1 hind paw CFA did not induce or alter hyperalgesic priming responses to PGE₂. In addition, CFA on P1 or P10 did not alter intensity or patterns of CGRP or IB4 staining in the adult DH.

Conclusion:

Complete Freund's adjuvant-induced inflammation during a critical period of vulnerability to injury during early postnatal development does not induce or exacerbate hyperalgesic priming or alter the broad distribution of CGRP-expressing or IB4-binding afferent terminals in the adult dorsal horn.

Qualitative review on N-methyl-D-aspartate receptor expression in rat spinal cord during the postnatal development: Implications for central sensitization and pain

The N‐methyl‐D‐aspartate receptor (NMDAR) is an important mediator of central sensitization and nociception in the rat spinal dorsal horn. The NMDAR subunits and splice variants determine the properties of the receptor. Understanding the expression of NMDAR subunits in spinal cord during the neonatal development is important as it may have consequences for the process of central sensitization and nociception in later life. In this review, a systematic literature search was conducted using three databases: Medline, Embase, and PubMed. A quality assessment was performed on predetermined entities of bias. Thirteen articles were identified to be relevant. The results show that NMDAR subunits and splice variants are dynamically expressed during postnatal development in the spinal dorsal horn. During the first 2 weeks, the expression of less excitable GluN2A subunit and more sensitive GluN2B subunit increases while the expression of high excitable GluN2C subunit decreases. During the 2nd week of postnatal development GluN1 subunits with exon 21 spliced in but exon 22 spliced out are predominantly expressed, increasing phosphorylation, and transport to the membrane. The data suggest that in rats, the nociceptive system is most susceptible to central sensitization processes during the first two postnatal weeks. This may have important consequences for nociception and pain responses in later life. From this, we conclude that targeted therapy directed toward specific NMDAR subunits is a promising candidate for mechanism‐based treatment of pain in neonates.

Feasibility and Clinical Utility of the Finnish Version of the FLACC Pain Scale in PICU

PURPOSE

To describe the feasibility and clinical utility of the Finnish FLACC scale when assessing children's pain in a Pediatric Intensive Care Unit (PICU).

DESIGN AND METHODS

A non-experimental, descriptive cross-sectional study design was used to describe the feasibility and clinical utility in a Finnish PICU between May and August 2018. The nurses were asked to complete a data collection questionnaire about the feasibility and clinical utility of the Finnish FLACC every time they used the scale to assess pain in children. In total, the data consisted of 157 pain assessments cases. Quantitative data were analyzed statistically and responses to open-ended questions were analyzed using content analysis.

RESULTS

In most cases, the nurses agreed that the Finnish FLACC scale was clearly structured (97%), easy to use (98%), helpful in assessing pain intensity (77%), and useful when reassessing pain after interventions (67%). Nurses found the scale more useable for children over one year old than for younger children. When assessing cry and consolability, pain was easier to score if the child was not intubated.

CONCLUSIONS

The Finnish FLACC scale exhibits adequate feasibility and clinical utility when assessing pain in children in a PICU. However, more information is needed about its use during painful short-term procedures and with children under one year old.

PRACTICE IMPLICATIONS

The Finnish FLACC scale is a helpful tool for nurses when assessing children's pain in a PICU. However, the Finnish version of the modified FLACC is needed for use with intubated children in the future.

Pain response to vaccination in newborn infants of diabetic mothers

BACKGROUND

Response to pain is altered in infants who were exposed to pain- and stressful events in the neonatal period. Infants of diabetic mothers receive several heel sticks after birth for measuring blood glucose and thus may show changes in their behavioral and physiologic response to pain. Moreover, maternal hyperglycemia may alter activity of the hypothalamic pituitary adrenal (HPA) axis reactivity.

STUDY DESIGN

In total, 43 infants of diabetic mothers and 30 control infants were included into the study. Response to pain was assessed at 3 months of age following two intramuscular injections for vaccination. We assessed behavioral (Bernese pain scale), physiologic (heart rate) and hormonal (salivary cortisol) pain response to vaccination as well as spinal sensitization (flexion withdrawal reflex).

RESULTS

Infants of diabetic mothers received a median number of 5 [4-19] painful events compared to 1 [1-3] in the control group. Heart rate reactivity differed significantly between groups. Infants of diabetic mothers had higher peaks (p = 0.002) and needed more time to recover to baseline (p < 0.001). Moreover, infants of diabetic mothers showed higher peak cortisol (p = 0.001) and a higher relative cortisol increase (p = 0.015). Flexor withdrawal reflex thresholds were significantly lower in infants of diabetic mothers (p = 0.003).

CONCLUSION

The increase of physiologic and hormonal responses to pain in infants of diabetic mothers is probably caused by repeated painful events and an altered metabolic profile.

Discovery and validation of biomarkers to aid the development of safe and effective pain therapeutics: challenges and opportunities

Pain medication plays an important role in the treatment of acute and chronic pain conditions, but some drugs, opioids in particular, have been overprescribed or prescribed without adequate safeguards, leading to an alarming rise in medication-related overdose deaths. The NIH Helping to End Addiction Long-term (HEAL) Initiative is a trans-agency effort to provide scientific solutions to stem the opioid crisis. One component of the initiative is to support biomarker discovery and rigorous validation in collaboration with industry leaders to accelerate high-quality clinical research into neurotherapeutics and pain. The use of objective biomarkers and clinical trial end points throughout the drug discovery and development process is crucial to help define pathophysiological subsets of pain, evaluate target engagement of new drugs and predict the analgesic efficacy of new drugs. In 2018, the NIH-led Discovery and Validation of Biomarkers to Develop Non-Addictive Therapeutics for Pain workshop convened scientific leaders from academia, industry, government and patient advocacy groups to discuss progress, challenges, gaps and ideas to facilitate the development of biomarkers and end points for pain. The outcomes of this workshop are outlined in this Consensus Statement.

Pain profile of premature infants during routine procedures in neonatal intensive care: An observational study

Background:

Premature neonates receive a large number of painful procedures during their stay in the neonatal intensive care unit (NICU). However, there are many other processes that happen in the NICU, which may not be considered painful but can cause discomfort and/or stress to the neonate.

Method:

Pain profile during routine procedures in NICU was assessed using the premature infant pain profile (PIPP) score. Neonates of gestational age >26 weeks, less than 7 days old and admitted for less than 7 days in the NICU were included.

Results:

A total of 662 procedures were observed in 132 (78 M, 54 F) neonates. The mean (SD) age of the neonates was 2.4 (1.8) days and the mean (SD) birth weight was 2.3 (0.6) kg. 63 (54.5%) were of low birth weight (LBW), 85 (64.39%) were full term. High PIPP score was noted in blood sampling, heel prick, suction, and weight measurement. Significant differences were observed in the PIPP score during blood sampling and suction across gender. Some ordinary and non-stressful procedures also scored very high on the PIPP scale.

Conclusions:

The validity of PIPP needs to be reexamined. Our understanding of pain during routine procedures may need to be revisited.

Role of OPRM1, clinical and anthropometric variants in neonatal pain reduction

An increased awareness on neonatal pain-associated complications has led to the development of pain scales adequate to assess the level of pain experienced by newborns such as the ABC score. A commonly used analgesic procedure is to administer a 33% oral dextrose solution to newborns prior to the painful intervention. Although this procedure is very successful, not in all subjects it reaches complete efficacy. A possible explanation for the different response to the treatment could be genetic variability. We have investigated the genetic variability of the OPRM1 gene in 1077 newborns in relation to non-pharmacologic pain relief treatment. We observed that the procedure was successful in 966 individuals and there was no association between the genotypes and the analgesic efficacy when comparing individuals that had an ABC score = 0 and ABC score >0. However, considering only the individuals with ABC score>0, we found that the homozygous carriers of the G allele of the missense variant SNP rs1799971 (A118G) showed an interesting association with higher ABC score. We also observed that individuals fed with formula milk were more likely to not respond to the analgesic treatment compared to those that had been breastfed.

Mechanisms of Timing, Timbre, Repertoire, and Entrainment in Neuroplasticity: Mutual Interplay in Neonatal Development

Neonatal brain development relies on a combination of critical factors inclusive of genetic predisposition, attachment, and the conditions of the pre and postneonatal environment. The status of the infant’s developing brain in its most vulnerable state and the impact that physiological elements of music, silences and sounds may make in the earliest stages of brain development can enhance vitality. However, little attention has been focused on the integral aspects of the music itself. This article will support research that has hypothesized conditions of music therapeutic applications in an effort to further validate models of neurobehavioral care that have optimized conditions for growth, inclusive of recommendations leading toward the enhancement of self-regulatory behaviors.

Evaluation of the Reliability and Validity of the Behavioral Indicators of Infant Pain Scale in Chinese Neonates

BACKGROUND

Behavioral Indicators of Infant Pain scale (BIIP) has been shown to be a good tool to assess pain in infants.

AIMS

This paper aimed to translate BIIP into Chinese and evaluate its reliability and validity for neonates in China.

DESIGN

A prospective observational study. SETTING AND PARTICIPANTS: A convenience sample of 396 neonates (preterm and term infants) were recruited from neonatal intensive care units in China from July to October 2016.

METHODS

The BIIP was translated and adjusted for semantic adaption.396 neonates were assessed during 3 phases of blood collection from an artery/vein. A video camera was positioned for a close-up view of the face and body. The neonates' pain was rated independently by 2 nurses who were trained and familiar with the Chinese version of BIIP (C-BIIP)and FLACC (Facial expression, Legs, Activity, Crying and Consolability).

RESULTS

The internal consistency were 0.904 (preterm) and 0.895 (term). The test-retest reliability were 0.947 (preterm) and 0.938 (term) and the interclass correlation coefficients were 0.921 to 0.959 (preterm) and 0.921 to 0.959 (term). The correlations between the C-BIIP and FLACC were high (preterm: r = 0.948, term: r = 0.896). Using the C-BIIP, the 3 phases of blood collection were found to be statistically different (preterm: F = 635.76, term: F = 675.54; P < 0.001), which showed that the construct validity of C-BIIP was good.

CONCLUSION

The BIIP is a reliable and valid tool to assess pain in term and preterm neonates in China.

Breastfeeding Support Team: When to Add a Chiropractor

Objective

Chiropractors are primary care clinicians with a musculoskeletal focus. As community-based practitioners, they are educated and available to treat the common problems of infancy, including sub-optimal breastfeeding. The objective of this investigation was to highlight some of the key skills and techniques used by chiropractors to assist the breastfeeding dyad.

Methods

The method of this paper was a brief review of the evidence for chiropractic care to improve breastfeeding problems and to highlight the biological plausibility for that evidence. The primary evidence was evaluated by expert opinion.

Results

Mechanical forces during intrauterine life and during birth may negatively affect the oral-motor function of the newborn. Although it is difficult to establish exact reasons for these problems, assisted births such as forceps, vacuum extraction and cesarean section have been implicated. It is the job of the chiropractor to examine the infant to detect and diagnose musculoskeletal problems that may impair the infant's feeding efficiency. After making a diagnosis, a treatment plan of precise, gentle manipulation can help maximize the functional effectiveness of the muscles and joints involved in breastfeeding and comfort for the child.

Conclusion

The chiropractor is one of many professionals poised to support and assist effective breastfeeding. A collaborative team can be helpful to gain early establishment and continuation of breastfeeding.

Early Neonatal Pain-A Review of Clinical and Experimental Implications on Painful Conditions Later in Life

Modern health care has brought our society innumerable benefits but has also introduced the experience of pain very early in life. For example, it is now routine care for newborns to receive various injections or have blood drawn within 24 h of life. For infants who are sick or premature, the pain experiences inherent in the required medical care are frequent and often severe, with neonates requiring intensive care admission encountering approximately fourteen painful procedures daily in the hospital. Given that much of the world has seen a steady increase in preterm births for the last several decades, an ever-growing number of babies experience multiple painful events before even leaving the hospital. These noxious events occur during a critical period of neurodevelopment when the nervous system is very vulnerable due to immaturity and neuroplasticity. Here, we provide a narrative review of the literature pertaining to the idea that early life pain has significant long-term effects on neurosensory, cognition, behavior, pain processing, and health outcomes that persist into childhood and even adulthood. We refer to clinical and pre-clinical studies investigating how early life pain impacts acute pain later in life, focusing on animal model correlates that have been used to better understand this relationship. Current knowledge around the proposed underlying mechanisms responsible for the long-lasting consequences of neonatal pain, its neurobiological and behavioral effects, and its influence on later pain states are discussed. We conclude by highlighting that another important consequence of early life pain may be the impact it has on later chronic pain states-an area of research that has received little attention.

Paracetamol (acetaminophen) for prevention or treatment of pain in newborns

BACKGROUND

Newborn infants have the ability to experience pain. Hospitalised infants are exposed to numerous painful procedures. Healthy newborns are exposed to pain if the birth process consists of assisted vaginal birth by vacuum extraction or by forceps and during blood sampling for newborn screening tests.

OBJECTIVES

To determine the efficacy and safety of paracetamol for the prevention or treatment of procedural/postoperative pain or pain associated with clinical conditions in neonates. To review the effects of various doses and routes of administration (enteral, intravenous or rectal) of paracetamol for the prevention or treatment of pain in neonates.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 4), MEDLINE via PubMed (1966 to 9 May 2016), Embase (1980 to 9 May 2016), and CINAHL (1982 to 9 May 2016). We searched clinical trials' databases, Google Scholar, conference proceedings, and the reference lists of retrieved articles.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials of paracetamol for the prevention/treatment of pain in neonates (≤ 28 days of age).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from the articles using pre-designed forms. We used this form to decide trial inclusion/exclusion, to extract data from eligible trials and to request additional published information from authors of the original reports. We entered and cross-checked data using RevMan 5 software. When noted, we resolved differences by mutual discussion and consensus. We used the GRADE approach to assess the quality of evidence.

MAIN RESULTS

We included nine trials with low risk of bias, which assessed paracetamol for the treatment of pain in 728 infants. Painful procedures studied included heel lance, assisted vaginal birth, eye examination for retinopathy of prematurity assessment and postoperative care. Results of individual studies could not be combined in meta-analyses as the painful conditions, the use of paracetamol and comparison interventions and the outcome measures differed. Paracetamol compared with water, cherry elixir or EMLA cream (eutectic mixture of lidocaine and prilocaine) did not significantly reduce pain following heel lance. The Premature Infant Pain Profile score (PIPP) within three minutes following lancing was higher in the paracetamol group than in the oral glucose group (mean difference (MD) 2.21, 95% confidence interval (CI) 0.72 to 3.70; one study, 38 infants). Paracetamol did not reduce "modified facies scores" after assisted vaginal birth (one study, 119 infants). In another study (n = 123), the Échelle de Douleur et d'Inconfort du Nouveau-Né score at two hours of age was significantly higher in the group that received paracetamol suppositories than in the placebo suppositories group (MD 1.00, 95% CI 0.60 to 1.40). In that study, when infants were subjected to a heel lance at two to three days of age, Bernese Pain Scale for Neonates scores were higher in the paracetamol group than in the placebo group, and infants spent a longer time crying (MD 19 seconds, 95% CI 14 to 24). For eye examinations, no significant reduction in PIPP scores in the first or last 45 seconds of eye examination was reported, nor at five minutes after the eye examination. In one study (n = 81), the PIPP score was significantly higher in the paracetamol group than in the 24% sucrose group (MD 3.90, 95% CI 2.92 to 4.88). In one study (n = 114) the PIPP score during eye examination was significantly lower in the paracetamol group than in the water group (MD -2.70, 95% CI -3.55 to 1.85). For postoperative care following major surgery, the total amount of morphine (µg/kg) administered over 48 hours was significantly less among infants assigned to the paracetamol group than to the morphine group (MD -157 µg/kg, 95% CI -27 to -288). No adverse events were noted in any study. The quality of evidence according to GRADE was low.

AUTHORS' CONCLUSIONS

The paucity and low quality of existing data do not provide sufficient evidence to establish the role of paracetamol in reducing the effects of painful procedures in neonates. Paracetamol given after assisted vaginal birth may increase the response to later painful exposures. Paracetamol may reduce the total need for morphine following major surgery, and for this aspect of paracetamol use, further research is needed.

Repetitive noxious stimuli during early development affect acute and long-term mechanical sensitivity in rats

BACKGROUND

Prematurely born infants are frequently exposed to painful procedures in the neonatal intensive care unit, causing changes to the development of the nervous system lasting into adulthood. The current study aims to study acute and long-term consequences of neonatal repetitive noxious stimulation.

METHODS

Rat pups received either 4 or 10 unilateral needle pricks per day, while control littermates received 4 or 10 tactile stimuli in the first postnatal week. Behavioural sensitivity was assessed in the neonatal phase, in adulthood, and after re-injury of the same dermatome in adulthood.

RESULTS

An increase in the number of repetitive painful stimuli, from 4 to 10 needle pricks per day, resulted in increased mechanical hypersensitivity during the neonatal period. In adulthood, repetitive painful stimuli resulted in hyposensitivity to mechanical stimuli, while thermal sensitivity was unaffected. After re-injury of the same dermatome in adulthood, the number of repetitive noxious stimuli did not affect mechanical hypersensitivity. Both needle prick groups showed an increased duration of postoperative hypersensitivity compared to control.

CONCLUSION

This study shows that repetitive noxious stimulation during the early postnatal period affects acute and long-term mechanical sensitivity. Therefore, the amount of nociceptive stimuli should be minimized or adequately treated in a clinical setting.

Does epigenetic 'memory' of early-life stress predispose to chronic pain in later life? A potential role for the stress regulator FKBP5

Animal behaviours are affected not only by inherited genes but also by environmental experiences. For example, in both rats and humans, stressful early-life events such as being reared by an inattentive mother can leave a lasting trace and affect later stress response in adult life. This is owing to a chemical trace left on the chromatin attributed to so-called epigenetic mechanisms. Such an epigenetic trace often has consequences, sometimes long-lasting, on the functioning of our genes, thereby allowing individuals to rapidly adapt to a new environment. One gene under such epigenetic control is FKBP5, the gene that encodes the protein FKPB51, a crucial regulator of the stress axis and a significant driver of chronic pain states. In this article, we will discuss the possibility that exposure to stress could drive the susceptibly to chronic pain via epigenetic modifications of genes within the stress axis such as FKBP5. The possibility that such modifications, and therefore, the susceptibility to chronic pain, could be transmitted across generations in mammals and whether such mechanisms may be evolutionarily conserved across phyla will also be debated. This article is part of the Theo Murphy meeting issue 'Evolution of mechanisms and behaviour important for pain'.