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

Pain in Neonates: Perceptions and Current Practices

All newborns experience pain during routine care, which can have long-lasting negative effects. Despite the availability of effective methods to prevent and reduce pain, most infants will receive ineffective or no treatment. Optimal pain management includes the reduction of the number of procedures performed, routine pain assessment and the use of effective pain-reducing interventions, most notably breastfeeding, skin-to-skin contact and sweet-tasting solutions. Parents are an essential component of the comprehensive assessment and management of infant pain; however, a gap exists regarding the uptake of parent-led interventions and the engagement of families. Practice recommendations for infant pain care are discussed.

Parent-led neonatal pain management-a narrative review and update of research and practices

Introduction

Research related to parent-led neonatal pain management is increasing, as is the clinical implementation. Skin-to-skin contact, breastfeeding and parents' vocalizations are examples of pain reducing methods that give parents an opportunity to protect their infant from harm while alleviating their anxiety and developing their parenting skills.

Methods

In this paper we will provide a narrative review and describe the current research about parent-led neonatal pain management. Based on this we will discuss clinical challenges, implementation strategies and implications for future research.

Results

Parents express great readiness to embrace opportunities to increase their self-efficacy in their ability to address infant pain. Parent-led pain-reducing methods are effective, feasible, cost-effective, culturally sensitive, and can be individualized and tailored to both the parent's and infant's needs. Both barriers and facilitators of parent-led pain care have been studied in research highlighting structural, organizational, educational, and intra- and interpersonal aspects. For example, health care professionals' attitudes and beliefs on parent-led methods, and their concern that parental presence during a procedure increases staff anxiety. On the other hand, the presence of a local pain champion whose duty is to facilitate the adoption of pain control measures and actively promote parent-professional collaboration, is crucial for culture change in neonatal pain management and nurses have a key role in this change. The knowledge-to-practice gap in parent-led management of infants' procedure-related pain highlight the need for broader educational applications and collaborative professional, parental and research initiatives to facilitate practice change.

Conclusion

Parent-led neonatal pain management is more than simply a humane and compassionate thing to do. The inclusion of parent-led pain care has been scientifically proven to be one of the most effective ways to reduce pain associated with repeated painful procedures in early life and parents report a desire to participate. Focus on enablers across interprofessional, organizational and structural levels and implementation of recommended pediatric pain guidelines can support the provision of optimal evidence-based family-centered neonatal pain management.

Effect of parental touch on relieving acute procedural pain in neonates and parental anxiety (Petal): a multicentre, randomised controlled trial in the UK

BACKGROUND

Touch interventions such as massage and skin-to-skin contact relieve neonatal pain. The Parental touch trial (Petal) aimed to assess whether parental stroking of their baby before a clinically required heel lance, at a speed of approximately 3 cm/s to optimally activate C-tactile nerve fibres, provides effective pain relief.

METHODS

Petal is a multicentre, randomised, parallel-group interventional superiority trial conducted in the John Radcliffe Hospital (Oxford University Hospitals NHS Foundation Trust, Oxford, UK) and the Royal Devon and Exeter Hospital (Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK). Neonates without neurological abnormalities who were born at 35 weeks gestational age or more and required a blood test via a heel lance in the first week of life were randomly assigned (1:1) to receive parental touch for 10 s either before (intervention group) or after (control group) the clinically required heel lance. Randomisation was managed at the Oxford site using a web-based minimisation algorithm with allocation concealment. The primary outcome measure was the magnitude of noxious-evoked brain activity in response to the heel lance measured with electroencephalography (EEG). Secondary outcome measures were Premature Infant Pain Profile-Revised (PIPP-R) score, development of tachycardia, and parental anxiety score. For all outcomes, the per-protocol effect was estimated via complier average causal effect analysis on the full analysis set. The trial is registered on ISRCTN (ISRCTN14135962) and ClinicalTrials.gov (NCT04901611).

FINDINGS

Between Sept 1, 2021, and Feb 7, 2023, 159 parents were approached to participate in the study, and 112 neonates were included. 56 neonates were randomly assigned to the intervention group of parental stroking before the heel lance and 56 to the control group of parental stroking after the heel lance. The mean of the magnitude of the heel lance-evoked brain activity was 0·85 arbitrary units (a.u.; SD 0·70; n=39; a scaled magnitude of 1 a.u. represents the expected mean response to a heel lance in term-aged neonates) in the intervention group and 0·91 a.u. (SD 0·76; n=43) in the control group. Therefore, the primary outcome did not differ significantly between groups, with a mean difference of -0·11 a.u. (lower in intervention group; SD 0·77; 95% CI -0·42 to 0·20; p=0·38; n=82). No significant difference was observed across secondary outcomes. The PIPP-R difference in means was 1·10 (higher in intervention group, 95% CI -0·42 to 2·61; p=0·15; n=100); the odds ratio of becoming tachycardic was 2·08 (95% CI 0·46 to 9·46; p=0·34, n=105) in the intervention group with reference to the control group; and the difference in parental State-Trait Anxiety Inventory-State score was -0·44 (higher in control group; SD 6·85; 95% CI -2·91 to 2·02; p=0·72; n=106). One serious adverse event (desaturation) occurred in a neonate randomly assigned to the control group, which was not considered to be related to the study.

INTERPRETATION

Parental stroking delivered at an optimal speed to activate C-tactile fibres for a duration of 10 s before the painful procedure did not significantly change neonates' magnitude of pain-related brain activity, PIPP-R score, or development of tachycardia. The trial highlighted the challenge of translating an experimental researcher-led tactile intervention into a parent-led approach, and the value of involving parents in their baby's pain management.

FUNDING

Wellcome Trust and Bliss.

Clinical thresholds in pain-related facial activity linked to differences in cortical network activation in neonates

ABSTRACT

In neonates, a noxious stimulus elicits pain-related facial expression changes and distinct brain activity as measured by electroencephalography, but past research has revealed an inconsistent relationship between these responses. Facial activity is the most commonly used index of neonatal pain in clinical settings, with clinical thresholds determining if analgesia should be provided; however, we do not know if these thresholds are associated with differences in how the neonatal brain processes a noxious stimulus. The objective of this study was to examine whether subclinical vs clinically significant levels of pain-related facial activity are related to differences in the pattern of nociceptive brain activity in preterm and term neonates. We recorded whole-head electroencephalography and video in 78 neonates (0-14 days postnatal age) after a clinically required heel lance. Using an optimal constellation of Neonatal Facial Coding System actions (brow bulge, eye squeeze, and nasolabial furrow), we compared the serial network engagement (microstates) between neonates with and without clinically significant pain behaviour. Results revealed a sequence of nociceptive cortical network activation that was independent of pain-related behavior; however, a separate but interleaved sequence of early activity was related to the magnitude of the immediate behavioural response. Importantly, the degree of pain-related behavior is related to how the brain processes a stimulus and not simply the degree of cortical activation. This suggests that neonates who exhibit clinically significant pain behaviours process the stimulus differently and that neonatal pain-related behaviours reflect just a portion of the overall cortical pain response.

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.

The influence of skin-to-skin contact on Cortical Activity during Painful procedures in preterm infants in the neonatal intensive care unit (iCAP mini): study protocol for a randomized control trial

Background

Strong evidence suggests that maternal-infant skin-to-skin contact (SSC) is effective in reducing behavioural responses to pain. Given the multi-sensory benefits of SSC, it is highly likely that SSC provided during pain in early life may reduce pain-induced brain activity. The aim of this study is to examine the effect of SSC compared to 24% sucrose on pain-induced activity in the preterm infant brain during a medically required heel lance. Secondary objectives include determining (a) differences between behavioural pain response and noxious-related brain activity during heel lance and (b) rate of adverse events across groups.

Methods

We will randomly assign 126 babies (32 to 36 completed weeks gestational age) admitted to the neonatal intensive care unit, and their mothers within the first seven days of age to receive (i) SSC plus sterile water and (ii) 24% oral sucrose. Each baby will receive a medically indicated heel lance, following a no treatment baseline period. The primary outcome is noxious-related brain activity measured using an electroencephalogram (EEG) pain-specific event-related potential. Secondary outcomes include pain intensity measured using a bio-behavioural infant pain assessment tool (Premature Infant Pain Profile-Revised) and rate of adverse events.

Discussion

This will be the first clinical trial to compare the effect of SSC and 24% sucrose on pain-induced brain activity in the preterm infant brain during a clinical noxious stimulus, measured using EEG. Given the negative neurodevelopmental outcomes associated with unmanaged pain, it is imperative that preterm babies receive the most effective pain-reducing treatments to improve their health outcomes. Our findings will have important implications in informing optimal pain assessment and management in preterm infants.

Trial registration

ClinicalTrials.gov NCT03745963. Registered on November 19, 2018.

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.

Tactile sensitivity and motor coordination in infancy: Effect of age, prior surgery, anaesthesia & critical illness

BACKGROUND

Tactile sensitivity in the infant period is poorly characterized, particularly among children with prior surgery, anaesthesia or critical illness. The study aims were to investigate tactile sensitivity of the foot and the associated coordination of lower limb motor movement in typically developing infants with and without prior hospital experience, and to develop feasible bedside sensory testing protocols.

MATERIALS AND METHODS

A prospective, longitudinal study in 69 infants at 2 and 4 months-old, with and without prior hospital admission. Mechanical stimuli were applied to the foot at graded innocuous and noxious intensities. Primary outcome measures were tactile and nociceptive threshold (lowest force required to evoke any leg movement, or brisk leg withdrawal, respectively), and specific motor flexion threshold (ankle-, knee-, hip-flexion). Secondary analysis investigated (i) single vs multiple trials reliability, and (ii) the effect of age and prior surgery, anaesthesia, or critical illness on mechanical threshold.

RESULTS

Magnitude of evoked motor activity increased with stimulus intensity. Single trials had excellent reliability for knee and hip flexion at age 1-3m and 4-7m (ICC range: 0.8 to 0.98, p >0.05). Nociceptive threshold varied as a function of age. Tactile sensitivity was independent of age, number of surgeries, general anaesthesia and ICU stay.

CONCLUSIONS

This brief sensory testing protocol may reliably measure tactile and nociceptive reactivity in human infants. Age predicts nociceptive threshold which likely reflects ongoing maturation of spinal and supraspinal circuits. Prior hospital experience has a negligible global effect on sensory processing demonstrating the resilience of the CNS in adverse environments.

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.

Maternal speech decreases pain scores and increases oxytocin levels in preterm infants during painful procedures

Preterm infants undergo early separation from parents and are exposed to frequent painful clinical procedures, with resultant short- and long-term effects on their neurodevelopment. We aimed to establish whether the mother's voice could provide an effective and safe analgesia for preterm infants and whether endogenous oxytocin (OXT) could be linked to pain modulation. Twenty preterm infants were exposed to three conditions-mother's live voice (speaking or singing) and standard care-in random order during a painful procedure. OXT levels (pg/mL) in saliva and plasma cortisol levels were quantified, and the Premature Infant Pain Profile (PIPP) was blindly coded by trained psychologists. During the mother's live voice, PIPP scores significantly decreased, with a concomitant increase in OXT levels over baseline. The effect on pain perception was marginally significant for singing. No effects on cortisol levels were found. The mother's live voice modulated preterm infants' pain indicators. Endogenous OXT released during vocal contact is a promising protective mechanism during early painful interventions in at-risk populations.

State of the Art in Parent-Delivered Pain-Relieving Interventions in Neonatal Care: A Scoping Review

Introduction: Parents' active involvement during painful procedures is considered a critical first step in improving neonatal pain practices. Of the non-pharmacological approaches in use, the biopsychosocial perspective supports parent-delivered interventions, in which parents themselves mediate pain relief, consistent with modern family-integrated care. This scoping review synthesizes the available research to provide an overview of the state of the art in parent-delivered pain-relieving interventions. Methods: A scoping review was performed to achieve a broad understanding of the current level of evidence and uptake of parent-driven pain- and stress-relieving interventions in neonatal care. Results: There is a strong evidence for the efficacy of skin-to-skin contact and breastfeeding, preferably in combination. These parent-delivered interventions are safe, valid, and ready for prompt introduction in infants' pain care globally. Research into parents' motivations for, and experiences of, alleviating infant pain is scarce. More research on combined parent-delivered pain alleviation, including relationship-based interventions such as the parent's musical presence, is needed to advance infant pain care. Guidelines need to be updated to include infant pain management, parent-delivered interventions, and the synergistic effects of combining these interventions and to address parent involvement in low-income and low-tech settings. Conclusions: A knowledge-to-practice gap currently remains in parent-delivered pain management for infants' procedure-related pain. This scoping review highlights the many advantages of involving parents in pain management for the benefit not only of the infant and parent but also of health care.

The burden of early life stress on the nociceptive system development and pain responses

For a long time, the capacity of the newborn infant to feel pain was denied. Today it is clear that the nociceptive system, even if still immature, is functional enough in the newborn infant to elicit pain responses. Unfortunately, pain is often present in the neonatal period, in particular in the case of premature infants which are subjected to a high number of painful procedures during care. These are accompanied by a variety of environmental stressors, which could impact the maturation of the nociceptive system. Therefore, the question of the long-term consequences of early life stress is a critical question. Early stressful experience, both painful and non-painful, can imprint the nociceptive system and induce long-term alteration in brain function and nociceptive behavior, often leading to an increase sensitivity and higher susceptibility to chronic pain. Different animal models have been developed to understand the mechanisms underlying the long-term effects of different early life stressful procedures, including pain and maternal separation. This review will focus on the clinical and preclinical data about early life stress and its consequence on the nociceptive system.

Can Event-Related Potentials Evoked by Heel Lance Assess Pain Processing in Neonates? A Systematic Review

To clarify the possibility of event-related potential (ERP) evoked by heel lance in neonates as an index of pain assessment, knowledge acquired by and problems of the methods used in studies on ERP evoked by heel lance in neonates were systematically reviewed, including knowledge about Aδ and C fibers responding to noxious stimuli and Aβ fibers responding to non-noxious stimuli. Of the 863 reports searched, 19 were selected for the final analysis. The following points were identified as problems for ERP evoked by heel lance in neonates to serve as a pain assessment index: (1) It is possible that the ERP evoked by heel lance reflected the activation of Aβ fibers responding to non-noxious stimuli and not the activation of Aδ or C fibers responding to noxious stimulation; (2) Sample size calculation was presented in few studies, and the number of stimulation trials to obtain an averaged ERP was small. Accordingly, to establish ERP evoked by heel lance as a pain assessment in neonates, it is necessary to perform a study to clarify ERP evoked by Aδ- and C-fiber stimulations accompanied by heel lance in neonates.

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.