Prematurity and neonatal noxious events exert lasting effects on infant pain behaviour

Impact of neonatal pain and opiate administration in animal models: A meta-analysis concerning pain threshold

BACKGROUND AND AIM

Neonatal intensive care treatment, including frequently performed painful procedures and administration of analgesic drugs, can have different effects on the neurodevelopment. This systematic review and meta-analysis aimed to investigate the influence of pain, opiate administration, and pre-emptive opiate administration on pain threshold in animal studies in rodents, which had a brain development corresponding to preterm and term infants.

METHODS

A systematic literature search of electronic data bases including CENTRAL (OVID), CINAHL (EBSCO), Embase.com, Medline (OVID), Web of Science, and PsycInfo (OVID) was conducted. A total of 42 studies examining the effect of pain (n = 38), opiate administration (n = 9), and opiate administration prior to a painful event (n = 5) in rodents were included in this analysis.

RESULTS

The results revealed that pain (g = 0.42, 95%CI 0.16-0.67, p = 0.001) increased pain threshold leading to hypoalgesia. Pre-emptive opiate administration had the opposite effect, lowering pain threshold, when compared to pain without prior treatment (g = -1.79, 95%CI -2.71-0.86, p = 0.0001). Differences were found in the meta regression for type of stimulus (thermal: g = 0.66, 95%CI 0.26-1.07, p = 0.001; vs. mechanical: g = 0.13, 95%CI -0.98-1.25, p = 0.81) and gestational age (b = -1.85, SE = 0.82, p = 0.027). In addition, meta regression indicated an association between higher pain thresholds and the amount of cumulative pain events (b = 0.06, SE = 0.03, p = 0.05) as well as severity of pain events (b = 0.94, SE = 0.28, p = 0.001).

CONCLUSION

Neonatal exposure to pain results in higher pain thresholds. However, caution is warranted in extrapolating these findings directly to premature infants. Further research is warranted to validate similar effects in clinical contexts and inform evidence-based practices in neonatal care.

The genetic variant SLC2A1 -rs1105297 is associated with the differential analgesic response to a glucose-based treatment in newborns

ABSTRACT

Neonatal pain is a critical issue in clinical practice. The oral administration of glucose-based solutions is currently one of the most common and effective nonpharmacologic strategies for neonatal pain relief in daily minor procedures. However, a varying degree of analgesic efficacy has been reported for this treatment. Environmental, maternal, and genetic factors may explain this variability and potentially allow for a personalized analgesic approach, maximizing therapeutic efficacy and preventing side effects. We investigated the exposome (ie, the set of clinical and anthropometric variables potentially affecting the response to the therapy) and the genetic variability of the noradrenaline transporter gene (solute carrier family 6 member 2 [ SLC6A2 ]) and 2 glucose transporter genes (solute carrier family 2 member 1 [ SLC2A1 ] and 2 [ SLC2A2 ]) in relation to the neonatal analgesic efficacy of a 33% glucose solution. The study population consisted in a homogeneous sample of more than 1400 healthy term newborns. No association for the exposome was observed, whereas a statistically significant association between the G allele of SLC2A1 -rs1105297 and a fourfold decreased probability of responding to the therapy was identified after multiple-testing correction (odds ratio of 3.98, 95% confidence interval 1.95-9.17; P = 4.05 × 10 -4 ). This allele decreases the expression of SLC2A1-AS1 , causing the upregulation of SLC2A1 in the dorsal striatum, which has been suggested to be involved in reward-related processes through the binding of opioids to the striatal mu-opioid receptors. Altogether, these results suggest the involvement of SLC2A1 in the analgesic process and highlight the importance of host genetics for defining personalized analgesic treatments.

Effect of White Noise on Pain Response, Heart Rate, and Oxygen Saturation During Heel Puncture in Premature Infants: A Randomized Controlled Trial

OBJECTIVE

This study aimed to investigate the effect of white noise on pain response, heart rate, and oxygen saturation during heel puncture in premature infants.

METHODS

A randomized, controlled, pretest-posttest design was used. The participants were premature infants admitted to the neonatal intensive care unit of a university hospital in Gyeonggi Province. Sixty premature infants were assigned to either an experimental (n = 30) or control (n = 30) group. The experimental group was exposed to white noise during heel puncture, and the measured variables were pain response, heart rate, and oxygen saturation. The data were analyzed using the independent t test, chi-squared test, and analysis of covariance.

RESULTS

Premature infants in the experimental group had a lower pain response and heart rate than the control group (F = 81.26, P < .01; F = 7.05, P = .01), and higher oxygen saturation than the control group (F = 4.76, P = .03).

CONCLUSION

These results demonstrated that the white noise intervention is an effective nursing intervention to reduce the pain response and stabilize heart rate and oxygen saturation in premature infants during heel puncture.

Improving pain management in a neonatal intensive care unit with single-family room-A quality improvement project

Preterm birth is a risk factor for early experience of pain. Despite advances in neonatal care, evidence‐based knowledge of the importance of adequate pain management and strong international guidelines for assessment and treatment of neonatal pain, only 10% of sick term and preterm infants were assessed for pain and stress on a daily basis. The aim of this quality improvement (QI) project is evaluation of implemented guidelines for pain assessment and management, and increased parental involvement in a Norwegian single‐family room NICU. Method: The different steps of the project entailed translation of the English version of COMFORTneo, development and implementation of guidelines with flowcharts for pain management, and pain assessment certification of the interprofessional staff. Part two of the project is supervision of the interprofessional staff in parental involvement in stress‐ and painful procedures. Our study showed that one year after implementation, 88.8% of the COMFORTneo assessments were performed according to the pain management guidelines. The staff used the flowcharts to assess, treat and reassess pain and stress. There was a high interrater reliability with linearly weighted Cohen's kappa values ranging from 0.81 to 0.95, with a median of 0.90. In addition, our study showed increased parental involvement in procedures, from 50.3% before to 82.3% after the quality improvement project. The success of this quality improvement project is explained by systematic use of flowcharts and implemented guidelines for pain management, interprofessional collaboration, and cultural change agents. Theoretical lectures and practical bedside supervision to interprofessional staff increased parental involvement in stress‐ and painful procedures.

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.

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.

Available Instruments to Assess Pain in Infants

Pain assessment in newborns and infants is challenging for clinicians. Although behavioral and behavioral-physiological scales are validated pain assessment instruments, their use in this age group has significant limitations. In this review, we summarize the methods currently available for assessing pain in neonates and infants. It is possible that these pain detection methods are also useful for assessing the quality of anesthesia and analgosedation in these populations. Further research should be aimed at confirming the usefulness of these tools in infants and identifying additional pain assessment options for clinical practice.

Procedural Pain in Hospitalized Neonates in Kenya

PURPOSE

The study was conducted to understand the nature and frequency of painful procedures and use of analgesia in neonatal units in Kenya.

DESIGN AND METHODS

Descriptive prospective study was conducted in a regional Level I and a university-affiliated Level II neonatal unit in Western Kenya. Two hundred term and preterm neonates who were hospitalized during the first day of life were recruited. A validated checklist was used to audit medical charts of hospitalized neonates. Painful procedures and pain treatment interventions accompanying all procedures performed during the first seven days of hospitalization were documented. Descriptive statistics, t-tests and χ² were usedto determine frequency and factors influencing the frequency of procedures.

RESULTS

A total of 1693 painful procedures (mean = 1.6 ± 1.1) were performed with most of them being tissue-damaging (n = 1291) including intravenous cannulation and intramuscular injection. Neonates were less likely to undergo procedures if there were born at term (RR 0.85; 95% CI, 0.76-0.95, p = .003) but more likely to experience procedures if admitted in a higher level of care (RR 1.57, 95% CI, 1.43-1.74, p < .001). Only one procedure was accompanied by analgesia.

CONCLUSIONS

Neonates underwent few but highly invasive procedures without analgesia. Prematurity and a high level of care predisposed neonates to a higher burden of pain.

IMPLICATIONS

Our findings underscore the urgent need for development of context-specific clinical practice guidelines on procedural pain treatment in sub-Saharan Africa.

The use and reporting of neonatal pain scales: a systematic review of randomized trials

ABSTRACT

The burden of pain in newborn infants has been investigated in numerous studies, but little is known about the appropriateness of the use of pain scales according to the specific type of pain or infant condition. This systematic review aimed to evaluate the reporting of neonatal pain scales in randomized trials. A systematic search up to March 2019 was performed in Embase, PubMed, PsycINFO, CINAHL, Cochrane Library, Scopus, and Luxid. Randomized and quasirandomized trials reporting neonatal pain scales were included. Screening of the studies for inclusion, data extraction, and quality assessment was performed independently by 2 researchers. Of 3718 trials found, 352 with 29,137 infants and 22 published pain scales were included. Most studies (92%) concerned procedural pain, where the most frequently used pain scales were the Premature Infant Pain Profile or Premature Infant Pain Profile-Revised (48%), followed by the Neonatal Infant Pain Scale (23%). Although the Neonatal Infant Pain Scale is validated only for acute pain, it was also the second most used scale for ongoing and postoperative pain (21%). Only in a third of the trials, blinding for those performing the pain assessment was described. In 55 studies (16%), pain scales that were used lacked validation for the specific neonatal population or type of pain. Six validated pain scales were used in 90% of all trials, although not always in the correct population or type of pain. Depending on the type of pain and population of infants included in a study, appropriate scales should be selected. The inappropriate use raises serious concerns about research ethics and use of resources.

Procedural Pain Assessment in Infants Without Analgosedation: Comparison of Newborn Infant Parasympathetic Evaluation and Skin Conductance Activity - A Pilot Study

Objective: New technologies to measure pain responses, such as heart rate variability and skin conductance hold promise in the development of tools that can be reliable and quantifiable of detecting pain. The main objective of this study was to assess the capability of two monitors i.e., Newborn Infant Parasympathetic Evaluation (NIPE) and Skin Conductance Algesimeter for detecting procedural pain in non-anesthetized infants. Materials and Methods: Thirty-three non-anesthetized infants were enrolled to the study. To detect pain caused by heel stick, NIPE, and Skin Conductance monitors and behavioral pain scales were used. Three minutes before and just after heel stick, pain was evaluated by behavioral scales, and simultaneously over the whole period by NIPE and SCA. Results: A statistically significant decrease of NIPE Index and an increase of SCA values were found after the HS procedure. There were no statistically significant differences between the decrease in NIPEi values and the increase in PPS values between subgroups based on pain assessment by behavioral-scale scores. Conclusion: Both NIPE and SCA can be useful for detection of procedural pain and may constitue an additional valuable tool for better handling of pain among patients treated in NICUs. More studies on larger groups of patients are needed.

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.

Higher tactile sensitivity in preterm infants at term-equivalent age: A pilot study

Despite a growing body of research on perinatal sensory abilities, data on the extent of tactile sensitivity and more particularly passive touch (i.e. sensitivity to a stimulation imposed on the skin) are relatively limited, and the development and processing of tactile function are still thus little known. This question is particularly of high importance for infants with atypical early development such as those born prematurely who are exposed to many sensory (including tactile) stimulations (being in a hospital setting) during a critical period of brain development and those born at early term whose birth occurs at the precise time of cortical reorganization, in particular in the sensory areas. Some parents and health-care providers have for instance reported that children born prematurely exhibit atypical (e.g. higher) sensitivity to “benign” tactile stimuli. In the present study, we hypothesized that preterm and early-term infants may show altered tactile sensitivity. We compared the behavioral responses around term-equivalent age of infants born either pre-term, early-term or at term to the application of a light (0.008 grams) mechanical stimulus. We found that almost all preterm infants perceive this tactile stimulus, contrarily to the two other groups of infants. This extreme tactile sensitivity may be due to experiential, maturational or more likely both processes. We also compared the tactile sensitivity of these infants to that of adults. We found that adults were irresponsive to the light mechanical stimulus. This finding opens not only new insights in understanding development of tactile processing, but also new lines of thought about the particular sensory world of premature and early-term infants and hence about the potential impact of early care practices.

Mothers' Perceptions about Pain in Hospitalized Newborn Infants in Kenya

PURPOSE

Explore views of mothers about pain and pain treatment practices in hospitalized newborn infants.

DESIGN AND METHODS

A Qualitative descriptive study using photo-elicitation technique was conducted in a level I and a level II neonatal units in Kenya. Fifteen semi-structured interviews were conducted with mothers of hospitalized infants. The interviews were audio-recorded, transcribed verbatim and analysed using inductive content analysis approach.

RESULTS

Mothers described the experience of witnessing their infants undergo painful procedures as emotionally and psychologically traumatic. Participants felt helpless for not being able to protect their infants from pain a situation which was made worse by health care providers who appeared less concerned about pain relief during procedures. Mothers' views demonstrated a good understanding of pain-relief strategies; they identified strategies that health care providers should routinely use to relief pain in hospitalized infants. Furthermore, participants desired to be involved in comforting their infants during clinical procedures.

CONCLUSION

Repeated and untreated painful procedures continue to define the hospitalisation experience of newborn infants despite the presence of mothers who desire to be involved in comforting their infants during procedures.

PRACTICE IMPLICATION

Minimizing the burden of pain and using pain-relieving interventions could reduce parental stress and optimize parental role attainment following hospitalisation.

The flexion withdrawal reflex increases in premature infants at 22-26 weeks of gestation due to changes in spinal cord excitability

Aim

Our aim was to study the development of the cutaneous flexion withdrawal reflex among premature infants admitted to the neonatal intensive care unit of the Children's Hospital, University of Cologne, in 2013.

Methodology

This longitudinal cohort study explored the development of spinal cord excitability of 19 premature infants born at 22–26 weeks of gestation. We performed five investigations per subject and studied changes in the reflex threshold with increasing postnatal age at different behavioural states. The premature infants were stimulated with von Frey filaments on the plantar surface of the foot near the first metatarsophalangeal joint during the first 3 days of life and at postnatal ages of 10–14 days, 21–28 days, 49–59 days and a corrected gestational age of 37–40 weeks.

Results

The mean gestational age of the premature infants included in the study was 24 weeks. Premature infants with a gestational age of less than 26 weeks presented a flexion withdrawal reflex with a low threshold (0.5–2.85 milli‐Newton) in the first 72 hours of life.

Conclusion

The flexion withdrawal reflex among premature infants born at less than 26 weeks showed a continuous threshold increase with increasing postnatal age, reflecting changes in spinal cord excitability.

Neurobiological Consequences of Early Painful Experience: Basic Science Findings and Implications for Evidence-Based Practice

As healthcare teams have worked to improve infant survival rates, the management of painful events experienced by these hospitalized neonates has increased and yet pain management remains highly variable between healthcare institutions. At the same time, emerging evidence suggests that these early painful experiences may alter the trajectory of development for pain-processing pathways both peripherally and centrally. This concise review highlights findings from both the basic and clinical science literature supporting the hypothesis that early painful experiences can have long-lasting negative effects on biological, psychological, and socioemotional functions. Implications for pain management in neonates and considerations for evidence-based practice change are discussed.

Infant Medical Trauma in the Neonatal Intensive Care Unit (IMTN): A Proposed Concept for Science and Practice

BACKGROUND

Trauma is an innately subjective experience ensuing from a deeply distressing event. Research has demonstrated that while the environment of the neonatal intensive care unit (NICU) is capable of providing extraordinary lifesaving measures following birth, the experience may be disruptive to several key aspects of early development, placing infants at risk for adverse behavioral, cognitive, and emotional outcomes.

PURPOSE

This article provides rationale for the concept of Infant Medical Trauma in the NICU (IMTN) as a means of describing this unique stress experience. A triad of cumulative early life NICU experiences (stress, parental separation, and pain) is proposed to influence an infant's swinging neurodevelopmental pendulum amid the potential outcomes of risk and resilience.

IMPLICATIONS FOR PRACTICE AND RESEARCH

Creating language that describes the infant experience brings meaning and calls caregivers and parents to action to consider strategies that may improve long-term health. Actively seeking opportunities to decrease the allostatic load of at-risk infants may support an infant's pendulum to swing toward a path of resilience, thereby moderating his or her early life adverse experience.

Effects of Kangaroo Care on Neonatal Pain in South Korea

Blood sampling for a newborn screening test is necessary for all neonates in South Korea. During the heel stick, an appropriate intervention should be implemented to reduce neonatal pain. This study was conducted to identify the effectiveness of kangaroo care (KC), skin contact with the mother, on pain relief during the neonatal heel stick. Twenty-six neonates undergoing KC and 30 control neonates at a university hospital participated in this study. Physiological responses of neonates, including heart rate, oxygen saturation, duration of crying and Premature Infant Pain Profile (PIPP) scores were measured and compared before, during and 1 min and 2 min after heel sticks. The heart rate of KC neonates was lower at both 1 and 2 min after sampling than those of the control group. Also, PIPP scores of KC neonates were significantly lower both during and after sampling. The duration of crying for KC neonates was around 10% of the duration of the control group. In conclusion, KC might be an effective intervention in a full-term nursery for neonatal pain management.

Neonatal pain and reduced maternal care: Early-life stressors interacting to impact brain and behavioral development

Advances in neonatal intensive care units (NICUs) have drastically increased the survival chances of preterm infants. However, preterm infants are still exposed to a wide range of stressors during their stay in the NICU, which include painful procedures and reduced maternal contact. The activation of the hypothalamic-pituitary-adrenal (HPA) axis, in response to these stressors during this critical period of brain development, has been associated with many acute and long-term adverse biobehavioral outcomes. Recent research has shown that Kangaroo care, a non-pharmacological analgesic based on increased skin-to-skin contact between the neonate and the mother, negates the adverse outcomes associated with neonatal pain and reduced maternal care, however the biological mechanism remains widely unknown. This review summarizes findings from both human and rodent literature investigating neonatal pain and reduced maternal care independently, primarily focusing on the role of the HPA axis and biobehavioral outcomes. The physiological and positive outcomes of Kangaroo care will also be discussed in terms of how dampening of the HPA axis response to neonatal pain and increased maternal care may account for positive outcomes associated with Kangaroo care.

Neonatal pain and developmental outcomes in children born preterm: a systematic review

BACKGROUND

Neonates cared for in neonatal intensive care units are exposed to many painful and stressful procedures that, cumulatively, could impact later neurodevelopmental outcomes. However, a systematic analysis of these effects is yet to be reported.

OBJECTIVES

The aim of this research was to review empirical studies examining the association between early neonatal pain experiences of preterm infants and the subsequent developmental outcomes of these children across different ages.

METHODS

The literature search was performed using the PubMed, PsycINFO, Lilacs, and SciELO databases and included the following key words: "pain," "preterm," and "development." In addition, a complementary search was performed in online journals that published pain and developmental studies to ensure all of the target studies had been found. The data were extracted according to predefined inclusion and exclusion criteria.

RESULTS

Thirteen studies were analyzed. In infants born extremely preterm (gestational age ≤29 wk) greater numbers of painful procedures were associated with delayed postnatal growth, with poor early neurodevelopment, high cortical activation, and with altered brain development. In toddlers born very preterm (gestational age ≤32 wk) biobehavioral pain reactivity-recovery scores were associated with negative affectivity temperament. Furthermore, greater numbers of neonatal painful experiences were associated with a poor quality of cognitive and motor development at 1 year of age and changes in cortical rhythmicity and cortical thickness in children at 7 years of age.

CONCLUSIONS

For infants born preterm, neonatal pain-related stress was associated with alterations in both early and in later developmental outcomes. Few longitudinal studies examined the impact of neonatal pain in the long-term development of children born preterm.

Sensory processing disorder in children ages birth-3 years born prematurely: a systematic review

This systematic review of multidisciplinary literature synthesizes evidence of the prevalence and patterns of sensory processing disorder (SPD) in children ages birth-3 yr born preterm. Forty-five articles including physiological, behavioral, temperament, and SPD research met the inclusion criteria and provided 295 findings related to SPD-130 (44%) positive (evidence of SPD) and 165 (56%) negative (no evidence of SPD). The majority of findings related to sensory modulation disorder (SMD; 43% positive). The most prevalent subcategory of SMD was sensory overresponsivity (82% of findings positive). Evidence of sensory underresponsivity and sensory-seeking SMD, sensory discrimination disorder, and sensory-based motor disorder was limited. This study supports the education of neonatologists, pediatricians, and caregivers about the symptoms and potential consequences of SPD and helps justify the need for follow-up screening for SPD in children ages birth-3 yr born preterm. Research using measures based on sensory processing theory is needed.

Cerebral Oxygenation and Pain of Heel Blood Sampling Using Manual and Automatic Lancets in Premature Infants

Heel blood sampling is a common but painful procedure for neonates. Automatic lancets have been shown to be more effective, with reduced pain and tissue damage, than manual lancets, but the effects of lancet type on cortical activation have not yet been compared. The study aimed to compare the effects of manual and automatic lancets on cerebral oxygenation and pain of heel blood sampling in 24 premature infants with respiratory distress syndrome. Effectiveness was measured by assessing numbers of pricks and squeezes and duration of heel blood sampling. Pain responses were measured using the premature infant pain profile score, heart rate, and oxygen saturation (SpO2). Regional cerebral oxygen saturation (rScO2) was measured using near-infrared spectroscopy, and cerebral fractional tissue oxygen extraction was calculated from SpO2 and rScO. Measures of effectiveness were significantly better with automatic than with manual lancing, including fewer heel punctures (P = .009) and squeezes (P < .001) and shorter duration of heel blood sampling (P = .002). rScO2 was significantly higher (P = .013) and cerebral fractional tissue oxygen extraction after puncture significantly lower (P = .040) with automatic lancing. Premature infant pain profile scores during (P = .004) and after (P = .048) puncture were significantly lower in the automatic than in the manual lancet group. Automatic lancets for heel blood sampling in neonates with respiratory distress syndrome significantly reduced pain and enhanced cerebral oxygenation, suggesting that heel blood should be sampled routinely using an automatic lancet.

Multidimensional response to vaccination pain in very preterm, moderate- to-late preterm and full-term infants at age three months

BACKGROUND

Very early life pain exposure and stress induces alterations in the developing brain and leads to altered pain sensitivity. In premature infants with a history of numerous early postnatal adverse events, behavioral responsiveness and hypothalamic-pituitary-adrenal (HPA) axis reactivity may show alterations as well.

AIMS

We compared a multidimensional response to a painful situation (vaccination) in three month old infants. The study involved very preterm, moderate to late preterm infants and full-term infants with varying exposure to pain and stress within the first weeks of life.

STUDY DESIGN

At the age of three months, we evaluated the infants' reactivity to intramuscular injections for immunization.

SUBJECTS

The study included 61 very preterm infants, 30 moderate to late preterm infants and 30 full-term infants.

OUTCOME MEASURES

We assessed heart rate recovery, Bernese pain Score and increase of salivary cortisol following vaccination. We also evaluated the flexor withdrawal reflex threshold as well as Prechtl's General Movements. Secondly, we assessed factors potentially influencing pain reactivity such as exposure to pain/stress, gender, use of steroids or opioids and mechanical ventilation.

RESULTS

Very preterm, moderate to late preterm and full-term infants showed different reactivity to pain in all analyzed aspects. Very preterm infants showed a lower level of behavioral and physiologic reactivity and exposure to pain/stress predicted lower cortisol increase.

CONCLUSION

At three months of age, very preterm infants show an altered level of HPA axis reactivity. Efforts aiming at minimizing pain and stress in premature infants should be taken.

Knowledge, attitudes and practices of neonatal staff concerning neonatal pain management

BACKGROUND

Neonatal pain management has received increasing attention over the past four decades. Research into the effects of neonatal pain emphasises the professional, ethical and moral obligations of staff to manage pain for positive patient outcomes. However, evaluation studies continuously report evidence of inadequate neonate pain management and a gap between theory and practice.

OBJECTIVE

This study reviewed current practice in neonatal pain management to describe the knowledge, attitudes and practices of nurses and doctors regarding pain management for neonates in two academic hospitals.

METHOD

A non-experimental, prospective quantitative survey, the modified Infant Pain Questionnaire, was used to collect data from 150 nurses and doctors working in the neonatal wards of two academic hospitals in central Gauteng.

RESULTS

The response rate was 35.33% (n=53), most respondents being professional nurses (88.68%; n=47) working in neonatal intensive care units (80.77%; n=42); 24 (45.28%) had less than 5 years' and 29 respondents 6 or more years' working experience in neonatal care. A review of pain management in the study setting indicated a preference for pharmacological interventions to relieve moderate to severe pain. An association (p<0.05) was found between pain ratings on 5 procedures and frequency of administration of pharmacological pain management. Two-thirds of respondents (64%) reported that there were no pain management guidelines in the neonatal wards in which they worked.

CONCLUSION

The interventions to manage moderate neonatal pain are in line with international guidelines. However, neonatal pain management may not occur systematically based on prior assessment of neonatal pain, choice of most appropriate intervention and evaluation. This study recommends implementation of a guideline to standardise practice and ensure consistent and adequate pain management in neonates.

Early repetitive pain in preterm infants in relation to the developing brain

Infants born preterm (<37 weeks of gestation) are particularly vulnerable to procedural stress and pain exposure during neonatal intensive care, at a time of rapid and complex brain development. Concerns regarding effects of neonatal pain on brain development have long been expressed. However, empirical evidence of adverse associations is relatively recent. Thus, many questions remain to be answered. This review discusses the short- and long-term effects of pain-related stress and associated treatments on brain maturation and neurodevelopmental outcomes in children born preterm. The current state of the evidence is presented and future research directions are proposed.

Neonatal pain: What's age got to do with it?

Background:

The neurobiology of neonatal pain processing, especially in preterm infants, differs significantly from older infants, children, adolescence, and adults. Research suggests that strong painful procedures or repeated mild procedures may permanently modify individual pain processing. Acute injuries at critical developmental periods are risk factors for persistent altered neurodevelopment. The purpose of this narrative review is to present the seminal and current literature describing the unique physiological aspects of neonatal pain processing.

Methods:

Articles describing the structures and physiological processes that influence neonatal pain were identified from electronic databases Medline, PubMed, and CINAHL.

Results:

The representation of neonatal pain physiology is described in three processes: Local peripheral nervous system processes, referred to as transduction; spinal cord processing, referred to as transmission and modulation; and supraspinal processing and integration or perception of pain. The consequences of undermanaged pain in preterm infants and neonates are discussed.

Conclusion:

Although the process and pain responses in neonates bear some similarity to processes and pain responses in older infants, children, adolescence, and adults; there are some pain processes and responses that are unique to neonates rendering them at risk for inadequate pain treatment. Moreover, exposure to repeated painful stimuli contributes to adverse long-term physiologic and behavioral sequelae. With the emergence of studies showing that painful experiences are capable of rewiring the adult brain, it is imperative that we treat neonatal pain effectively.

Abnormal sensory reactivity in preterm infants during the first year correlates with adverse neurodevelopmental outcomes at 2 years of age

BACKGROUND

Sensory experience is the basis for learning in infancy. In older children, abnormal sensory reactivity is associated with behavioural and developmental disorders. We hypothesised that in preterm infants, abnormal sensory reactivity during infancy would be associated with perinatal characteristics and correlate with 2-year neurodevelopmental outcomes.

METHODS

We conducted a prospective observational study of infants with birth weight ≤1500 g using the Test of Sensory Function in Infants (TSFI) in the first year. Infants with gestational age ≤30 weeks were tested with the Bayley Scales of Infant and Toddler Development III (BSID III) at 24 months.

RESULTS

Of the 72 participants evaluated at 4-12 months corrected age (median 8 months), 59 (82%) had a least one TSFI score concerning for abnormal sensory reactivity. Lower gestational age was associated with abnormal reactivity to deep pressure and vestibular stimulation (p<0.001). Poor ocular-motor control predicted worse cognitive and motor scores in early childhood (OR 16.7; p=0.004), but was tightly correlated to the presence of severe white matter injury. Poor adaptive motor function in response to tactile stimuli predicted worse BSID III motor (p=0.01) and language scores (p=0.04) at 2 years, even after adjusting for confounders.

CONCLUSIONS

Abnormal sensory reactivity is common in preterm infants; is associated with immaturity at birth, severe white matter injury and lower primary caregiver education; and predicts neurodevelopmental delays. Early identification of abnormal sensory reactivity of very preterm infants may promote parental support and education and may facilitate improved neurodevelopment.

Association of Fentanyl With Neurodevelopmental Outcomes in Very-Low-Birth-Weight Infants

Background: Opioids are commonly used in the neonatal intensive care unit (NICU). Negative neurodevelopmental effects in the short-term setting have been associated with opioids ; however, long-term studies have been limited. Objective: The primary objective was to determine if there is a dose relationship between fentanyl and neurodevelopmental outcomes, as measured by Bayley Scales of Infant and Toddler Development (Bayley-III) composite scores for language, cognition, and motor skills. Secondary objectives included comparison of Bayley-III scores and neurodevelopmental impairment classification based on fentanyl exposure. Methods: A retrospective evaluation of 147 very-low-birth-weight infants with Bayley-III scores obtained at a chronological age of 6 months to 2 years at clinic follow-up was conducted. Univariate and multivariable linear regression analyses were used to determine if there was a dose-related association between fentanyl and neurodevelopmental outcomes. To evaluate secondary outcomes, patients were divided based on cumulative fentanyl dose (“high-dose” versus “low/no-dose”). Results: The univariate analysis found a statistically significant decrease in cognition ( P = .034) and motor skills scores ( P = .006). No association was found in the multi-variable regression between fentanyl cumulative dose and Bayley-III scores. There was a significant decrease in the motor skills score between the high-dose versus low/no-dose group, 94 ± 20 versus 102 ± 15, respectively ( P = .026); however, no statistical differences were noted for language or cognition scores or neurological impairment classification. Conclusions: When controlling for other variables, the cumulative fentanyl dose did not correlate with neurodevelopmental outcomes. Further evaluation of benefits and risks of opioids in premature infants are needed.

Translation and adaptation of the Premature Infant Pain Profile into Brazilian Portuguese

The study aimed to translate and to adapt a version of the Premature Infant Pain Profile into the Brazilian Portuguese language. This is a cross-sectional and methodological study for the validation of a translated version of a tool. The process was conducted in four stages: initial translation, synthesis, back-translation, and analysis by experts. Four independent versions of the instrument translated into Brazilian Portuguese were produced. Based on these initial translations, a synthesis version was developed. Two back-translated versions were independently produced, and none showed major differences compared to the original instrument. An expert committee reviewed the summary version and the back-translations with respect to semantic and idiomatic equivalence. The committee considered the translation into Brazilian Portuguese as appropriate. Therefore, the Perfil de Dor no Recém-Nascido Pré-termo was considered adapted to Brazilian Portuguese, for research purposes and for clinical practice. It will contribute to the internationalization of research results in Brazil.

Pain evaluation after a non-nociceptive stimulus in preterm infants during the first 28days of life

BACKGROUND

Protective mechanisms that modulate and lead to habituation to pain are immature in preterm newborn infants.

AIMS

To evaluate if a routine non-painful handling will be perceived as painful throughout the neonatal period in newborn infants with 28-32 weeks of gestational age.

STUDY DESIGN

Prospective cohort study.

SUBJECTS

36 preterm infants without malformations evaluated for pain during a diaper change.

OUTCOME MEASURES

Patients were studied at three times (5 min prior, during, and 3 min after the diaper change) during five moments (72 h, 7, 14, 21 and 28 days of life) by evaluation of heart rate, oxygen saturation and 3 validated pain assessment tools: the Neonatal Infant Pain Scale (NIPS), the Behavioral Indicators of Infant Pain (BIIP) and Premature Infant Pain Profile (PIPP). Results were analyzed by repeated measures ANOVA adjusted for gender, gestational age at birth, number of painful procedures and use of opioids.

RESULTS

Patients had, at birth, mean gestational age of 30.2±1.4 weeks, birthweight of 1257±238g, with 50% males. Analysis of pain assessment tools did not show increase of pain presence or pain scores at the five sequential evaluation moments. The variation of oxygen saturation during the three study times was similar at the different post-natal ages, but heart rate variation increased significantly from 72 h until the 28th day of life.

CONCLUSIONS

In preterm infants, the non-nociceptive handling does not trigger pain responses even after 28 days of neonatal care, which includes the experience of repetitive procedural pain.

Remifentanil-induced tolerance, withdrawal or hyperalgesia in infants: a randomized controlled trial. RAPIP trial: remifentanil-based analgesia and sedation of paediatric intensive care patients

BACKGROUND

Short-acting opioids like remifentanil are suspected of an increased risk for tolerance, withdrawal and opioid-induced hyperalgesia (OIH). These potential adverse effects have never been investigated in neonates.

OBJECTIVES

To compare remifentanil and fentanyl concerning the incidence of tolerance, withdrawal and OIH.

METHODS

23 mechanically ventilated infants received up to 96 h either a remifentanil- or fentanyl-based analgesia and sedation regimen with low-dose midazolam. We compared the required opioid doses and the number of opioid dose adjustments. Following extubation, withdrawal symptoms were assessed by a modification of the Finnegan score. OIH was evaluated by the CHIPPS scale and by testing the threshold of the flexion withdrawal reflex with calibrated von Frey filaments.

RESULTS

Remifentanil had to be increased by 24% and fentanyl by 47% to keep the infants adequately sedated during mechanical ventilation. Following extubation, infants revealed no pronounced opioid withdrawal and low average Finnegan scores in both groups. Only 1 infant of the fentanyl group and 1 infant of the remifentanil group required methadone for treatment of withdrawal symptoms. Infants also revealed no signs of OIH and low CHIPPS scores in both groups. The median threshold of the flexion withdrawal reflex was 4.5 g (IQR = 2.3) in the fentanyl group and 2.7 g (IQR = 3.3) in the remifentanil group (p = 0.312), which is within the physiologic range of healthy infants.

CONCLUSIONS

Remifentanil does not seem to be associated with an increased risk for tolerance, withdrawal or OIH.

Neonatal repetitive needle pricking: plasticity of the spinal nociceptive circuit and extended postoperative pain in later life

Repetitive exposure of neonates to noxious events is inherent to their health status monitoring in neonatal intensive care units (NICU). Altered basal nociception in the absence of an injury in later life has been demonstrated in ex-NICU children, but the impact on pain hypersensitivity following an injury in later life is unknown. Also, underlying mechanisms for such long-term changes are relatively unknown. The objective of this study is to investigate acute and long-term effects of neonatal repetitive painful skin-breaking procedures on nociception and to investigate plasticity of the nociceptive circuit. The repetitive needle prick animal model was used in which neonatal rats received four needle pricks into the left hind paw per day during the first postnatal week and control animals received nonpainful tactile stimuli. Repetitive needle pricking during the first week of life induced acute hypersensitivity to mechanical stimuli. At the age of 8 weeks, increased duration of postoperative hypersensitivity to mechanical stimuli after ipsilateral hind paw incision was shown in needle prick animals. Basal nociception from 3 to 8 weeks of age was unaffected by neonatal repetitive needle pricking. Increased calcitonin gene-related peptide expression was observed in the ipsilateral and contralateral lumbar spinal cord but not in the hind paw of needle prick animals at the age of 8 weeks. Innervation of tactile Aβ-fibers in the spinal cord was not affected. Our results indicate both acute and long-term effects of repetitive neonatal skin breaking procedures on nociception and long-term plasticity of spinal but not peripheral innervation of nociceptive afferents.

Effects of skin-to-skin contact on autonomic pain responses in preterm infants

The purpose of this randomized crossover trial was to determine the effects on autonomic responses in preterm infants of longer Kangaroo Care (30 minutes, KC30) and shorter KC (15 minutes, KC15) before and throughout heel stick compared with incubator care (IC). Beat-to-beat heart rate (HR) and spectral power analysis of heart rate variability, low frequency power (LF), high frequency power (HF), and LF/HF ratio were measured in 26 infants. HR changes from Baseline to Heel Stick were significantly less in KC30 and KC15 than in IC, and more infants had HR decrease in IC than in 2 KC conditions. In IC, LF and HF significantly increased from Baseline to Heel Stick and dropped from Heel Stick to Recovery; in 2 KC conditions, no changes across study phases were found. During Heel Stick, LF and HF were significantly higher in IC than in KC30. In all 3 conditions, LF/HF ratio decreased from Baseline to Heel Stick and increased to Recovery; no differences were found between IC and two KC conditions. Both longer and shorter KC before and throughout heel stick can stabilize HR response in preterm infants, and longer KC significantly affected infants' sympathetic and parasympathetic responses during heel stick compared with incubator care.

PERSPECTIVE

This study showed that KC has a significant effect on reducing autonomic pain responses in preterm infants. The findings support that KC is a safe and effective pain intervention in the neonatal intensive care unit.

Breast milk and glucose for pain relief in preterm infants: a noninferiority randomized controlled trial

OBJECTIVE

The study goal was to compare the efficacy of expressed breast milk (EBM) versus 25% glucose on pain responses of late preterm infants during heel lancing.

METHODS

In a noninferiority randomized controlled trial, a total of 113 newborns were randomized to receive EBM (experimental group [EG]) or 25% glucose (control group [CG]) before undergoing heel lancing. The primary outcome was pain intensity (Premature Infant Pain Profile [PIPP]) and a 10% noninferiority margin was established. Secondary outcomes were incidence of cry and percentage of time spent crying and adverse events. Intention-to-treat (ITT) analysis was used.

RESULTS

Groups were similar regarding demographics and clinical characteristics, except for birth weight and weight at data collection day. There were lower pain scores in the CG over 3 minutes after lancing (P < .001). A higher number of infants in the CG had PIPP scores indicative of minimal pain or absence of pain (P = .002 and P = .003 on ITT analysis) at 30 seconds after lancing, and the mean difference in PIPP scores was 3 (95% confidence interval: 1.507-4.483). Lower incidence of cry (P = .001) and shorter duration of crying (P = .014) were observed for CG. Adverse events were benign and self-limited, and there was no significant difference between groups (P = .736 and P = .637 on ITT analysis).

CONCLUSIONS

Results based on PIPP scores and crying time indicate poorer effects of EBM compared with 25% glucose during heel lancing. Additional studies exploring the vol and administration of EBM and its combination with other strategies such as skin-to-skin contact and sucking are necessary.

Early life adversity as a risk factor for fibromyalgia in later life

The impact of early life events is increasingly becoming apparent, as studies investigate how early childhood can shape long-term physiology and behaviour. Fibromyalgia (FM), which is characterised by increased pain sensitivity and a number of affective co-morbidities, has an unclear etiology. This paper discusses risk factors from early life that may increase the occurrence or severity of FM in later life: pain experience during neonatal life causes long-lasting changes in nociceptive circuitry and increases pain sensitivity in the older organism; premature birth and related stressor exposure cause lasting changes in stress responsivity; maternal deprivation affects anxiety-like behaviours that may be partially mediated by epigenetic modulation of the genome—all these adult phenotypes are strikingly similar to symptoms displayed by FM sufferers. In addition, childhood trauma and exposure to substances of abuse may cause lasting changes in developing neurotransmitter and endocrine circuits that are linked to anxiety and stress responses.

Kangaroo care and behavioral and physiologic pain responses in very-low-birth-weight twins: a case study

The purpose of this case study was to describe pain responses in three study conditions: longer (30 minutes) kangaroo care (KC) before and throughout heel stick (KC30), shorter (15 minutes) KC before and throughout heel stick (KC15), and incubator care throughout heel stick (IC) in 28-week gestational age twins. Pain responses were measured by crying time, Preterm Infant Pain Profile (PIPP), and heart rate variability indexes, including low-frequency power (LF, representing sympathetic activity), high-frequency power (HF, parasympathetic activity), and LF/HF ratio (sympathetic-parasympathetic balance). Both twins cried more and had higher PIPP pain scores and tachycardia during heel stick in the IC condition. Infant B had an incident of apnea and tachycardia by the end of the heel stick and a bradycardia episode during recovery in the IC condition. The twins had lower LF/HF ratios (better autonomic nervous system balance) during recovery in both longer and shorter KC conditions compared with the IC condition. Infant B had difficulty returning to LF/HF ratio baseline level after the painful procedure in the IC condition. These data suggest that both longer and shorter KC before and throughout painful procedures can be helpful in reducing behavioral and physiologic pain responses in preterm infants.

Cortisol, behavior, and heart rate reactivity to immunization pain at 4 months corrected age in infants born very preterm

OBJECTIVE

Pain response may be altered in infants born very preterm owing to repeated exposure to procedures in the neonatal intensive care unit. Findings have been inconsistent in studies of behavioral and cardiac responses to brief pain in preterm versus full-term infants following neonatal intensive care unit discharge. To our knowledge, cortisol reactivity to pain has not been compared in preterm and full-term infants. We examined pain reactivity to immunization in preterm and full-term infants.

METHOD

Cortisol, facial behavior, and heart rate reactivity before, during, and after immunization were examined in infants born preterm at extremely low gestational age (ELGA 24 to 28 wk), very low gestational age (VLGA 29 to 32 wk), and full-term, at corrected age 4 months.

RESULTS

In all groups, cortisol, behavior, and heart rate increased during immunizations. Cortisol concentrations were lower in preterm ELGA and VLGA boys, compared with full-term boys. In contrast, facial and heart rate responses to immunization did not differ between preterm and full-term infants.

DISCUSSION

Although earlier reports found differences in pain processing in preterm infants earlier and later in development, the present findings indicate that pain responses, indexed by behavior and heart-rate, do not seem to differ in preterm compared with full-term infants at 4 months corrected age. Importantly, however, stress regulation seems altered in preterm male infants. As cortisol impacts development and functioning of the brain, altered stress regulation has important implications beyond pain systems.

Randomized crossover trial of kangaroo care to reduce biobehavioral pain responses in preterm infants: a pilot study

Kangaroo care (KC), skin-to-skin contact between mother and infant, is a promising method for blunting pain responses. This crossover pilot tested KC effects on biobehavioral responses to heel stick in preterm infants (30-32 weeks' gestational age, 2-9 days old) measured by Premature Infant Pain Profile (PIPP) and salivary and serum cortisol. Mother-infant dyads were randomly assigned to KC heel stick (KCH) first or incubator heel stick (IH) first. Study 1 (80-min study, N = 18) tested the effect of 80 min of KC before and throughout the heel stick procedure versus incubator care. Study 2 (30-min study, N = 10) tested 30 min of KC before and throughout the heel stick versus incubator care. KCH and IH began during a premeasurement phase and continued through four data collection phases: baseline, heel warming, heel stick, and recovery. PIPP responses were measured every 30 s during data collection; salivary cortisol was measured at the end of baseline and recovery; and serum cortisol was measured during heel stick. Study 1 showed no differences between KCH and IH. Study 2 showed lower PIPP scores at four time points during recovery (p < .05 to p < .001), lower salivary cortisol at the end of recovery (p < .05), and lower serum cortisol during heel stick for the KCH condition (p < .05) as well as clinically lower PIPP scores in the KCH condition during heel stick. Thirty minutes of KC before and throughout the heel stick reduced biobehavioral responses to pain in preterm infants.

Developmental neurotoxicity of sedatives and anesthetics: a concern for neonatal and pediatric critical care medicine?

OBJECTIVE

To evaluate the currently available evidence for the deleterious effects of sedatives and anesthetics on developing brain structure and neurocognitive function.

DESIGN

A computerized, bibliographic search of the literature regarding neurodegenerative effects of sedatives and anesthetics in the developing brain.

MEASUREMENTS AND MAIN RESULTS

A growing number of animal studies demonstrate widespread structural damage of the developing brain and long-lasting neurocognitive abnormalities after exposure to sedatives commonly used in neonatal and pediatric critical care medicine. These studies reveal a dose and exposure time dependence of neuronal cell death, characterize its molecular pathways, and suggest a potential early window of susceptibility in humans. Several clinical studies document neurologic abnormalities in neonatal intensive care unit graduates, usually attributed to comorbidities. Emerging human epidemiologic data, however, do not exclude prolonged or repetitive exposure to sedatives and anesthetics in early childhood as contributing factors to some of these abnormalities.

CONCLUSIONS

Neuronal cell death after neonatal exposure to sedatives and anesthetics has been clearly demonstrated in developing animal models. Although the relevance for human medicine remains speculative, the phenomenon's serious implications for public health necessitate further preclinical and clinical studies. Intensivists using sedatives and anesthetics in neonates and infants need to stay informed about this rapidly emerging field of research.

Challenges of functional imaging research of pain in children

Functional imaging has revolutionized the neurosciences. In the pain field it has dramatically altered our understanding of how the brain undergoes significant functional, anatomical and chemical changes in patients with chronic pain. However, most studies have been performed in adults. Because functional imaging is non-invasive and can be performed in awake individuals, applications in children have become more prevalent, but only recently in the pain field. Measures of changes in the brains of children have important implications in understanding neural plasticity in response to acute and chronic pain in the developing brain. Such findings may have implications for treatments in children affected by chronic pain and provide novel insights into chronic pain syndromes in adults. In this review we summarize this potential and discuss specific concerns related to the imaging of pain in children.