Early pain experience, child and family factors, as precursors of somatization: a prospective study of extremely premature and fullterm children

Influence of peripheral inflammation on the postnatal maturation of primary sensory neuron phenotype in rats

The influence of early peripheral inflammation upon the postnatal development of rat primary sensory neuron subtypes was investigated. Lumbar dorsal root ganglia (DRG) were immunostained for calcitonin gene-related peptide (CGRP), neurofilament (NF200), and isolectin B4 (IB4) binding. Proportions of each subpopulation were measured at postnatal day (P) 0, P3, P7, and P21 in normal pups and in those that had received a unilateral hindpaw carrageenan injection at P1. The effects were compared with those following a similar injury in adults. Both the IB4 (positive [+ve]) and NF200+ve cell populations increased postnatally (IB4+ve: 23 +/- 1.6% to 32.6 +/- 1.3%; NF200+ve: 33.8 +/- 1.2% to 43.3 +/- 1.9%), whereas the population of CGRP+ve cells stayed the same. After neonatal inflammation, the rise in IB4+ve binding occurred earlier but was the same as that in controls by P21. The CGRP+ve population increased at 2 and 6 days after carrageenan in neonates, because of an increase in both small CGRP/IB4 and larger CGRP/NF200 double-labeled cells, but was normal by 3 weeks. Carrageenan in adults caused an increase in CGRP/IB4 cells only. The effects of peripheral inflammation differ in neonatal and adult DRG. Neonatal inflammation causes CGRP upregulation in both small and large cells and accelerates the postnatal increase in IB4 binding. These effects might influence subsequent central development.

Assessment and management of acute pain in high-risk neonates

Neonates in the neonatal intensive care unit experience hundreds of painful procedures at a time of rapid neurological development. Although the immediate responses to pain may be protective, the potential long-term effects of early and under-treated pain are concerning. As pain assessment is the first step in the provision of appropriate and timely pain management, attention should be directed to the quantification of pain in terms of its location, severity, intensity and duration. Over the past decade, numerous pain measures have been developed for preterm and term neonates, however, most of them have been developed for research purposes and have not been tested in the clinical setting. In order to effectively implement pain measures in the clinical setting, the psychometric properties of reliability, validity, feasibility and clinical utility must be established. This review paper will highlight the importance of neonatal pain assessment and examine the psychometric properties of various measures of neonatal pain. Pharmacological and non-pharmacological interventions to manage acute pain in high-risk neonates will be addressed and future research topics will be proposed.

[Clinical characteristics of children with chronic pain in a pediatric pain unit: oncologic pain versus non-oncologic pain]

BACKGROUND

Despite undoubted scientific advances in the field of chronic pain in children, there is no evidence of clinical application of this knowledge.

OBJECTIVE

To describe the experience of a pediatric pain unit (PPU) specifically dedicated to the treatment of chronic pain in children.

MATERIAL AND METHODS

We performed an analytic, observational, retrospective, cohort study of the clinical features of the first 42 patients treated for chronic pain in the PPU during a two-year period. The patients were assigned to two groups: an oncologic group and a non-oncologic group. ANOVA was used to analyze quantitative variables and the Chi-square test was used to analyze qualitative variables.

RESULTS

No significant differences were found between the two groups in the demographic variables studied (age and sex). Concerning the type of treatment used, no significant differences were found in effectiveness or compliance. However, treatment duration was significantly longer in the non-oncologic group than in the oncologic group (74.2 days vs 37.5 days, p(0.008). The duration of non-oncologic chronic pain before attending the PPU (mean: 557 days) influenced the effectiveness (r 5 0.781; p 5 0.0001) and duration of treatment (r 5 0.61; p 5 0.0051). However, the duration of previous chronic oncologic pain was significantly shorter (mean: 34 days) and showed no influence on treatment effectiveness or duration.

CONCLUSIONS

The pediatric population presents chronic pain syndromes that can be appropriately treated in a PPU with conventional, easy to manage analgesics. We recommend the establishment of pediatric pain units similar to those for adults, using a multidisciplinary approach to mitigate children's suffering.

Psychosocial effects of intensive care on infants and families after discharge

The neonatal intensive care environment exposes the developing immature newborn to many sources of stress and pain at a time when the infant is developmentally least able to cope with it. Animal and human evidence suggest that effects of stress, mediated through permanent changes in the brain and neuroendocrine responses, may result in changes in behaviour and information processing, which persist throughout childhood. These changes impact on the dynamics of the mother infant dyad and infant learning. Interactional styles arising in the newborn period tend to persist throughout childhood but may be amenable to intervention focusing on maternal recognition of infant cues, social stimulation of the infant, and family integration. Developmental care may promote better family, infant and child outcomes by both reducing neonatal stress and its neurobiological sequelae, and fostering an appropriate interactional relationship between mother and infant.

Early pain in preterm infants. A model of long-term effects

There are multiple lines of evidence suggesting that in vulnerable prematurely born infants, repeated and prolonged pain exposure may affect the subsequent development of pain systems, as well as potentially contribute to alterations in long-term development and behavior. Multiple factors cumulatively contribute to altered developmental trajectories in such infants. These include characteristics of the developing organism (low tactile threshold, sensitization, rapid brain development), characteristics intrinsic to the infant (gestation, illness severity), characteristics of the experience in the neonatal intensive care unit (pain exposure and cumulative stress), and characteristics of the caregivers within their family and social context. This article provides a model for examining long-term effects of pain in the newborn period embedded in a developmental context framework.

Challenges of judging pain in vulnerable infants

The inevitability of pain during infancy and its potential for destructive impact impose a burden on caregiving adults. An armamentarium of effective pharmacological, behavioral and environmental interventions is available if pain were recognized and accurately assessed. Infants have limited behavioral repertoires that make identification of specific needs difficult, mothers and other caregivers prone to high levels of protection and redundant care. But more specific care can best suit infant requirements. Certain behaviors are sensitive to states of distress, including pain, for example, cry and disruption of usual activities such as sleep. Others appear more specific, for example, facial activity. This paper proposes that effective care is best delivered to infants and children if we recognize the complexities of the sociocommunication process; subjective states are encoded in behavioral activity and caregivers must be able to recognize the meaning of these actions. The paper delineates some features of the process whereby caregivers arrive at judgments of infant's needs and make decisions concerning interventions.

Entwicklungspsychopathologie rekurrierender Bauchschmerzen und somatoformer Störungen

Zusammenfassung. Der Beitrag untersucht aus einer entwicklungspsychopathologischen Perspektive die störungs- und entwicklungsbezogenen Assoziationen zwischen rekurrierendem Bauchschmerz und somatoformer Störung sowie komorbiden Angststörungen bzw. Depression. Dazu werden eingangs Pfade des Übergangs von Störungsbildern der Eltern auf das Kind (Transmission) sowie die Stabilität bzw. Variabilität rekurrierender Bauchschmerzen und somatoformer Störungen vom Kindesalter zum Erwachsenenalter untersucht. Ein entwicklungspsychopathologisches Phasenmodell zeigt eine Sequenz von vier Etappen der Störungsentwicklung auf. Als Mediatoren eines ungünstigen Verlaufs werden Lernprozesse, Faktoren der kognitiv-behavioralen Schmerz- und Beschwerdeverarbeitung, beschwerdebezogene Copingstrategien sowie dysfunktionale Interaktionsmuster innerhalb der Familie sowie in der Arzt-Patient-Beziehung analysiert. Entwickelt sich eine Komorbidität mit einer Angststörung oder Depression, so zeigen diese Patienten störungsbedingt ein zusätzlich erhöhtes Risiko der verzerrten Verarbeitung abdomineller Beschwerden und Schmerzen.

Assessment and management of pain and distress in the neonate

Pain management is an integral focus of neonatal care. This article reviews the physiology and impact of neonatal pain and distress and pain assessment tools, as well as clinical interventions and current controversies in the management of pain and distress in neonates. Current guidelines to enhance the recognition and treatment of pain are highlighted.

Temperament in children with Down syndrome and in prematurely born children

Parents of three groups of children completed the Children's Behavior Questionnaire (CBQ). Participants were children with Down syndrome aged 4-11 years (n = 55), prematurely born children aged 5 years (n = 97), and a group of normally developing kindergarten children 5-7 years of age (n = 91). Mean levels and factor structures on the CBQ were compared between the three groups. The children with Down syndrome had less attentional focusing and expressed less inhibitory control and less sadness than the normally developing children. There were also group differences in temperament structures, especially a clearer emotional factor of "surgency" among the children with Down syndrome. The only significant difference in mean temperament scores between the premature children and the control group was that the former evinced less attentional focussing. The temperament structures in the Norwegian samples were very similar to those reported in earlier studies, conducted in China and the US.

Assessment and management of pain in neonates

Neonates are capable of experiencing pain from birth onwards. An impressive body of neuroanatomical, neurochemical and biobehavioural evidence, which has accumulated over the past 2 decades, supports this capability. This evidence mandates health professionals to attend to the prevention, elimination, or at the very least, control of pain for infants. This mandate is essential since pain is known to have both immediate and long term effects, especially if pain is untreated and is severe, prolonged or frequently experienced. Therefore, pain must be assessed frequently, not only to measure location, intensity and duration but also to determine the effectiveness of interventions implemented to control pain. An impressive array of measures for assessing acute pain in infants exists which incorporates valid pain indicators in this population. However, there is a need to develop new measures to assess chronic pain conditions and pain in infants in acute situations.

Learning about pain in preterm newborns

The first goal of the study was to explore whether preterm newborns can learn to predict painful stimulation. The second goal was to provide a description of physiological and behavioral responses to repeated heel-sticks over days. Preterm newborns, born between 28 and 32 weeks gestational age, were observed five times over a period of 2 weeks while undergoing heel-sticks. Infants' facial expressions, cardiac reactions, and movement durations were recorded before, during, and after the heel-stick procedure. On Tests 1, 3, and 5, the phlebotomist picked up the baby's leg and held it for 10 seconds before proceeding to the heel-stick. Infants showed significantly greater increase in heart rate during the leg pickup on Test 5 compared with Test 1. This increase in heart rate after 2 weeks of experience suggests that newborn infants learned to anticipate the painful stimulus. Infants also demonstrated reliable behavioral and cardiac reactions to the invasive part of the heel-stick, but no change was observed in reactivity over days. However, greater post-conceptional age (PCA) was associated with increased behavioral reactivity during heel-stick on Tests 4 and 5. The anticipatory heart rate increase during leg pickup highlights the preterm infant's early capacity to learn and react to experience in the neonatal intensive care unit. The lack of global change in reactivity to the invasive procedure over days illustrates the need to take into account specific factors such as PCA when investigating sensitivity to repeated pain experiences.

The neurobiology of pain: developmental aspects

Invasive procedures that would be painful in children and adults are frequently performed on infants admitted to the neonatal intensive care unit. This article discusses sensory responses to these procedures in the immature nervous system and highlights the fact that, in addition to causing distress and delayed recovery, pain in infancy is also a developmental issue. First, the immaturity of sensory processing within the newborn spinal cord leads to lower thresholds for excitation and sensitization, therefore potentially maximizing the central effects of these tissue-damaging inputs. Second, the plasticity of both peripheral and central sensory connections in the neonatal period means that early damage in infancy can lead to prolonged structural and functional alterations in pain pathways that can last into adult life.

Transcutaneous absorption of vitamin A in newborn rats

Very low birth weight neonates have low tissue concentrations of vitamin A, which may contribute to the development of lung disease. These infants, however, may not receive vitamin A supplementation for several days after birth. We determined if the relatively permeable skin of a newborn could be used to administer vitamin A. 25 control rat pups were killed and lungs and livers were collected. 20 microl (1,000 IU) of retinyl palmitate were applied to the skin surface of an additional 50 two-day-old pups. At 2.5 and 5 h after application, 25 pups were killed, and lungs and livers were collected. Concentrations of retinyl palmitate and retinol were significantly higher in the lungs of pups 5 h after administration of vitamin A compared with controls. There were no differences in concentrations of retinyl palmitate or retinol in livers. We conclude that transcutaneous administration may be an effective means of delivering vitamin A to the lungs of newborn rats.

Clinical importance of pain and stress in preterm neonates

Clinical and laboratory investigations of neonatal pain suggest that preterm neonates have an increased sensitivity to pain and that acute painful stimuli lead to the development of prolonged periods of hyperalgesia. Non-noxious stimuli during these periods of hyperalgesia may expose preterm neonates to established or chronic pain. Acute physiologic changes caused by painful or stressful stimuli can be implicated as important factors in the causation or subsequent extension of early intraventricular hemorrhage (IVH) or the ischemic changes leading to periventricular leukomalacia (PVL). Therapeutic interventions that provide comfort/analgesia in preterm neonates were correlated with a decreased incidence of severe IVH. Long-term follow-up studies of preterm neonates may substantiate the preliminary data associating repetitive painful experiences with some of the neurobehavioral and developmental sequelae resulting from neonatal intensive care.

The best interest principle as a standard for decision making in the care of neonates

In neonatal care, decisions are made on behalf of newborn infants by their parents or, in some instances, health professionals. This paper examines how the best interest standard is the most appropriate focus for decision-making concerning neonates. The components of surrogate decision-making are discussed from the perspective of the neonate's interests and the contribution of the various persons involved in caring for neonates. An argument is presented for the use of best interests when making decisions and the interpretation of best interests is explored. By examining the ethical approaches using best interests, an argument is put forward for caring as an expression of best interests. How some nurses use the best interest standard in their practice is described. The unique perspective nurses may have because of their philosophy, circumstances, experience and concern for neonates is discussed. Examples are used from the literature to support the argument for nurses being in roles and relationships where the neonate's interests are the basis of practice. How nurses classify infants on the basis of their future outcome is used to illustrate how nurses can apply the best interest standard. Ethical approaches of care and cure are used to show the best interest standard as applied to neonates. Caring as an expression of best interests is recommended for nursing decisions and actions using infant outcomes as a focus for caring and best interests.

Behavior, pain perception, and the extremely low-birth weight survivor

This article explores the literature concerning responses to pain of both premature and term-born newborn infants, the evidence for short-term and long-term effects of pain, and behavioral sequelae in individuals who have experienced repeated early pain in neonatal life as they mature. There is no doubt that pain causes stress in babies and this in turn may adversely affect long-term neurodevelopmental outcome. Although there are methods for assessing dimensions of acute reactivity to pain in an experimental setting, there are no very good measures available at the present time that can be used clinically. In the clinical setting repeated or chronic pain is more likely the norm rather than infrequent discrete noxious stimuli of the sort that can be readily studied. The wind-up phenomenon suggests that, exposed to a cascade of procedures as happens with clustering of care in the clinical setting in an attempt to provide periods of rest for stressed babies, an infant may in fact perceive procedures that are not normally viewed as noxious, as pain. Pain exposure during lifesaving intensive medical care of ELBW neonates may also affect subsequent reactivity to pain in the neonatal period, but behavioral differences are probably not likely to be clinically significant in the long term. Prolonged and repeated untreated pain in the newborn period, however, may produce a relatively permanent shift in basal autonomic arousal related to prior NICU pain experience, which may have long-term sequelae. In the long run, the most significant clinical effects of early pain exposure may be on neurodevelopment, contributing to later attention, learning, and behavior problems in these vulnerable children. Although there is considerable evidence to support a variety of adverse effects of early pain, there is less information about the long-term effects of opiates and benzodiazepines on the developing central nervous system. Current evidence reviewed suggests that judicious use of morphine for adjustment to mechanical ventilation may ameliorate the altered autonomic response. It may be very important, however, to distinguish stress from pain. Animal evidence suggests that the neonatal brain is affected differently when exposed to morphine administered in the absence of pain than in the presence of pain. Pain control may be important for many reasons but overuse of morphine or benzodiazepines may have undesirable long-term effects. This is a rapidly evolving area of knowledge of clear relevance to clinical management likely to affect long-term outcomes of high-risk children.

Pain assessment in infants and children

The science of pain assessment for infants and children has grown substantially in the past several decades to the point that valid and reliable methods for pain assessment are available for use in clinical settings. Accurate pain assessment requires consideration of children's developmental level, type of pain experienced, history and context of pain, family influences, and interaction with the health care team. Research is needed to improve the sensitivity, specificity, and generalizability of pain-assessment tools and to more fully incorporate contextual factors into the objective assessment process. Finally, the improvement of pain assessment in the clinical setting can be viewed as a patient care quality issue, and continuous quality improvement methods can be used effectively to incorporate pain assessment as an integral component of every infant's and child's health care.

Office-based pain management. The 15-minute consultation

Pain is a ubiquitous component of pediatric illness and injury. Unfortunately, the treatment of pain has remained secondary to the diagnosis and treatment of the disease state. Clinicians' duty is to relieve suffering, and, as such, the relief of pain should be a primary focus. Presently available modalities, when used appropriately, can significantly reduce the pain associated with medical encounters. Careful attention to such approaches may reduce the anxiety about pain, which is often an undercurrent at most health care visits, and allows clinicians and children to focus on getting well and staying healthy.

Fetal pain?

During the last few years a vivid debate, both scientifically and emotionally, has risen in the medical literature as to whether a fetus is able to feel pain during abortion or intrauterine surgery. This debate has mainly been inspired by the demonstration of various hormonal or motor reactions to noxious stimuli at very early stages of fetal development. The aims of this paper are to review the literature on development of the pain system in the fetus, and to speculate about the relationship between "sensing" as opposed to "feeling" pain and the number of reactions associated with painful stimuli. While a cortical processing of pain theoretically becomes possible after development of the thalamo-cortical connections in the 26th week of gestation, noxious stimuli may trigger complex reflex reactions much earlier. However, more important than possible painfulness is the fact that the noxious stimuli, by triggering stress responses, most likely affect the development of an individual at very early stages. Hence, it is not reasonable to speculate on the possible emotional experiences of pain in fetuses or premature babies. A clinically relevant aim is rather to avoid and/or treat any possibly noxious stimuli, and thereby prevent their potential adverse effects on the subsequent development.

Effects of perinatal pain and stress

Neonatal intensive care exposes preterm neonates to a series of repeated, randomly occurring invasive procedures and handling, resulting in acute pain, chronic pain, and prolonged stress during a critical window associated with epochal brain development. Characteristics of the immature pain system in preterm neonates (such as a low pain threshold, prolonged periods of windup, overlapping receptive fields, immature descending inhibition) predisposes them to greater clinical and behavioral sequelae from inadequately treated pain than older age groups. Evidence for developmental plasticity in the neonatal brain suggests that repetitive painful experiences during this period or prolonged exposure to analgesic drugs may alter neuronal and synaptic organization permanently. Traditionally, clinicians have chosen the perspective that routine use of analgesic or sedative drugs in preterm neonates may create more problems than minimal therapy. However, the immediate and long-term consequences of inadequately treated pain have forced them to reconsider the risk-benefit ratios for such therapy. Whereas the short-term consequences of prolonged analgesic therapy in human neonates are well-known (tolerance, withdrawal, ventilator dependency), long-term consequences are relatively unknown. Advances in the study of repetitive pain associated with routine NICU care have challenged the perspective that prolonged pain and stress were inevitable consequences of premature birth.

Comparing two methods of topical anesthesia used before intravenous cannulation in pediatric patients

INTRODUCTION

The purpose of this study was to compare the efficacy of two methods of topical anesthesia before venipuncture or intravenous cannulation of pediatric patients to assess which type of topical anesthetic would better alleviate pain in the least amount of time with the greatest success rate of cannulation.

METHODS

This study was a randomly controlled trial of 100 preoperative pediatric patients aged 5 to 21 years. The following methods of topical anesthesia were compared: (a) iontophoresis of a topical solution of 2% lidocaine with epinephrine 1:100,000 using a Phoresor Dose Controller (PDC) with Numby Stuff electrodes and a eutectic mixture of local anesthetic and (b) 2.5% lidocaine and 2.5% prilocaine (eutectic mixture of local anesthetics [EMLA] cream).

RESULTS

Children reported less pain with iontophoresis (M = 0.08) compared with EMLA cream (M = 1.88, P < .001). Time to accomplish topical anesthesia was shorter with iontophoresis (13 minutes) compared with EMLA cream (60 minutes, P < .001). Failure to accomplish venipuncture occurred 5 times with the iontophoresis method and 8 times with the EMLA method (not significant). No dermal burns resulted from use of iontophoresis.

DISCUSSION

We conclude that use of iontophoresis in pediatric patients is safe, rapid, and significantly more effective than is EMLA cream in reducing pain associated with venipuncture or intravenous cannulation.

Can adverse neonatal experiences alter brain development and subsequent behavior?

Self-destructive behavior in current society promotes a search for psychobiological factors underlying this epidemic. Perinatal brain plasticity increases the vulnerability to early adverse experiences, thus leading to abnormal development and behavior. Although several epidemiological investigations have correlated perinatal and neonatal complications with abnormal adult behavior, our understanding of the underlying mechanisms remains rudimentary. Models of early experience, such as repetitive pain, sepsis, or maternal separation in rodents and other species have noted multiple alterations in the adult brain, correlated with specific behavioral phenotypes depending on the timing and nature of the insult. The mechanisms mediating such changes in the neonatal brain have remained largely unexplored. We propose that lack of N-methyl-D-aspartate (NMDA) receptor activity from maternal separation and sensory isolation leads to increased apoptosis in multiple areas of the immature brain. On the other hand, exposure to repetitive pain may cause excessive NMDA/excitatory amino acid activation resulting in excitotoxic damage to developing neurons. These changes promote two distinct behavioral phenotypes characterized by increased anxiety, altered pain sensitivity, stress disorders, hyperactivity/attention deficit disorder, leading to impaired social skills and patterns of self-destructive behavior. The clinical important of these mechanisms lies in the prevention of early insults, effective treatment of neonatal pain and stress, and perhaps the discovery of novel therapeutic approaches that limit neuronal excitotoxicity or apoptosis.

Prevention and management of pain and stress in the neonate

This statement is intended for health care professionals caring for neonates (preterm to one month of age). The objectives of this statement are to: increase awareness that neonates experience pain; provide a physiological basis for neonatal pain and stress assessment and management by health care professionals; make recommendations for reduced exposure of the neonate to noxious stimuli and to minimize associated adverse outcomes; and recommend effective and safe interventions that relieve pain and stress.

Biobehavioral pain responses in former extremely low birth weight infants at four months' corrected age

OBJECTIVE

To compare biobehavioral responses to acute pain at 4 months' corrected age between former extremely low birth weight (ELBW) infants and term-born controls.

METHODOLOGY

Measures of facial behavioral and cardiac autonomic reactivity in 21 former ELBW infants (mean birth weight = 763 g) were compared with term-born infants (n = 24) during baseline, lance, and recovery periods of a finger-lance blood collection. Further, painful procedures experienced during neonatal care were quantified in both groups.

RESULTS

Overall, behavioral and cardiac autonomic responses to the lance were similar between groups. However, the ELBW group seemed to have a less intense parasympathetic withdrawal in the lance period and a more sustained sympathetic response during recovery than the control group. Further, in the recovery period, two behavioral patterns (early recovery and a late recovery) were apparent among the ELBW group.

CONCLUSIONS

Biobehavioral pain responses were similar overall between both groups of infants. Subtle differences were observed in cardiac autonomic responses during the lance period and in behavioral recovery among ELBW infants. Whether these findings represent a long-term effect of early pain experience or a developmental lag in pain response remains unclear. The lack of an overall difference runs counter to previously reported findings of reduced behavioral response in former ELBW infants. biobehavioral pain response, premature infants, repetitive pain, heart rate variability.

Validation of the premature infant pain profile in the clinical setting

OBJECTIVE

The Premature Infant Pain Profile (PIPP) is a 7-indicator composite measure developed to assess acute pain in preterm and term neonates. It has been validated in studies using synchronized videotaping of infants undergoing procedures. The purpose of this study was to establish (a) construct validity of the PIPP and (b) inter- and intrarater reliability of the PIPP prospectively in the clinical environment.

DESIGN

A randomized, crossover design was used.

SETTING

The study was conducted in a Level III outborn neonatal intensive care unit.

PARTICIPANTS

A convenience sample of 43 neonates, stratified by gestational age, was studied.

INTERVENTIONS

Each infant experienced three separate, randomly ordered events: baseline, a painful event, and a nonpain event. Infants were videotaped and scored at the bedside using the PIPP by the nurse caring for the infant and the clinical nurse specialist who bad expertise in infant pain. The videotapes were later reviewed by two additional experts; one in real time and one using a second-to-second stop frame technique.

RESULTS

Repeated-measures analysis of the main effects and interactions yielded a statistically significant main effect for event (pain, nonpain, baseline), thus differentiating pain from nonpain and baseline events (F = 48, p = 0.0001) and establishing construct validity. Interrater reliability analysis of individual event scores of the PIPP yielded reliability coefficients of 0.93-0.96. Intrarater reliability coefficients analysis for individual events were equally high at 0.94-0.98.

CONCLUSIONS

This study demonstrates that the PIPP is a pain measure with good construct validity and excellent inter- and intrarater reliability for the assessment of procedural pain of preterm and term infants in clinical settings.

Assessment of pain and agitation in critically ill infants

Critically ill infants are subjected to many painful experiences that, if inadequately treated, can have severe physiological and psychological consequences. Optimal management of pain relies on the adequacy of nurses' assessment; this, however, is complicated by another common condition, agitation. A multidimensional assessment is therefore necessary to adequately identify pain and agitation. The aim of this descriptive study was to identify the cues that nurses caring for critically ill infants use to assess pain and agitation. A questionnaire, developed from the literature, was distributed to all registered nurses (85) working in the neonatal and paediatric intensive care units of an Australian teaching hospital. Questionnaires were completed by 41 nurses (a 57 per cent response rate). Results revealed that, except for diagnosis, there were no significant differences between the cues participants used to assess pain and those to assess agitation. Nurses used numerous cues from various sources: most importantly, their own judgement (99 per cent); the parents' judgement (90 per cent); the infant's environment; documentation (78 per cent), and the infant's cues (70 per cent). These findings demonstrate the relevance of the nurse's role in assessment of pain and agitation in critically ill infants. Nurses used cues specific to the critically ill rather than the less sick infant. Results of this study also show the difficulty of differentiating between pain and agitation. Further research on ways of distinguishing between the construct of pain and agitation needs to be undertaken.

Procedural pain in newborn infants: the influence of intensity and development

OBJECTIVE

Previous reports have shown that pain is managed inadequately in newborn infants. Ironically, clinicians believe that infants can experience pain much like adults, that infants are exposed daily to painful procedures, and that pain protection should be provided. In adults, a close relationship has been shown in how adults behave in response to pain, how painful they sense the stimulus to be, and physical measurements of the intensity of the stimulus. Whether similar parallels exist in newborn infants has not been examined. If these parallels do not exist in infants, it may help explain why clinicians fail to manage procedural pain in infants more effectively. The objective of this study was to determine whether the magnitude of infants' responses to nursing/medical procedures: 1) differs as a function of the invasiveness or intensity of the procedure; 2) differs as a function of intrauterine (gestational age at birth) and/or extrauterine (conceptional age) development; and 3) parallels the subjective pain ratings of clinicians for those procedures.

METHODS

A broad developmental and clinical range of newborn infants was studied shortly before (baseline and preparatory periods), throughout, and shortly after (recovery period) required nursing/medical procedures during hospitalization. Heart rate, oxygen saturation, mean arterial pressure, and behavioral state (percentage of time spent in sleep or in agitation) were measured, and the magnitude of change in each in response to procedures was calculated. Procedures were categorized as mildly, moderately, and highly invasive to examine differences in response magnitude as a function of procedural invasiveness. Responses were compared as a function of prematurity and postnatal age. Clinicians' procedural pain ratings were compared with the magnitude of infants' responses.

RESULTS

Of the original 152 infants, 135 were studied at least two times (range 2-27). Significant changes occurred in physiologic and behavioral measures in response to procedures indicative of pain responses. The magnitude of response generally increased with increased procedural invasiveness although there was considerable overlap of magnitude with invasiveness. Both premature and full-term infants differentiated procedural invasiveness. Very premature infants (<28 weeks' gestational age) exhibited increased increments in response magnitude with increasing postnatal age. Clinician's ratings of procedural painfulness were correlated with and predicted the magnitude of heart rate response to individual procedures.

CONCLUSIONS

Similar to what has been shown in adults, newborn and developing infants show increased magnitude physiologic and behavioral responses to increasingly invasive procedures, demonstrating that even very prematurely born infants respond to pain and differentiate stimulus intensity. However, the considerable overlap of magnitude with invasiveness suggests that there is not a physiologic or behavioral threshold that clearly marks the presence of pain. Inconsistencies in physiologic and behavioral responses make reliance on a pain index difficult. The best approach may be one of universal precaution to provide pain management systematically to reduce the acute and long-term impact of early procedural pain. development, stimulus intensity, pain response.

Modern concepts of paediatric analgesia

Laboratory data, economic pressures, and the wish for humane treatment have been some of the driving forces behind improvements in paediatric pain management. Within the space of 10 years, there have been dramatic changes in the quality of treatment received by children undergoing surgical operations. Moreover, those receiving medical treatment, for example, sickle cell disease, have also benefited from increased experience in pain management. Children receiving care in specialised centres can now expect to benefit from up-to-date techniques of pain management, such as patient-controlled analgesia, nurse-controlled analgesia, and epidural infusions. They will be managed by ward nurses experienced and trained in paediatric pain relief, they will be attended by nurses whose special interest and training is the management of children's pain, and they will be provided with the techniques of analgesia by competent, trained anaesthetic staff. Improved care, with close attention to pain relief, is not only humane, but improves the patient turnaround by enhancing rapid discharge. Further education is required to spread these benefits to children being managed outside highly specialised centres. Not only education, but investment, is needed also to ensure that all children receive a standard of care second to none.

Long-term behavioral effects of repetitive pain in neonatal rat pups

Human preterm neonates are subjected to repetitive pain during neonatal intensive care. We hypothesized that exposure to repetitive neonatal pain may cause permanent or long-term changes because of the developmental plasticity of the immature brain. Neonatal rat pups were stimulated one, two, or four times each day from P0 to P7 with either needle prick (noxious groups N1, N2, N4) or cotton tip rub (tactile groups T1, T2, T4). In groups N2, N4, T2, T4 stimuli were applied to separate paws at hourly intervals;each paw was stimulated only once a day. Identical rearing occurred from P7 to P22 days. Pain thresholds were measured on P16, P22, and P65 (hot-plate test), and testing for defensive withdrawal, alcohol preference, air-puff startle, and social discrimination tests occurred during adulthood. Adult rats were exposed to a hot plate at 62 degrees C for 20 s, then sacrificed and perfused at 0 and 30 min after exposure. Fos expression in the somatosensory cortex was measured by immunocytochemistry. Weight gain in the N2 group was greater than the T2 group on P16 (p < 0.05) and P22 (p < 0.005); no differences occurred in the other groups. Decreased pain latencies were noted in the N4 group [5.0 +/- 1.0 s vs. 6.2 +/- 1.4 s on P16 (p < 0.05); 3.9 +/- 0.5 s vs. 5.5 +/- 1.6 s on P22 (p < 0.005)], indicating effects of repetitive neonatal pain on subsequent development of the pain system. As adults, N4 group rats showed an increased preference for alcohol (55 +/- 18% vs. 32 +/- 21%; p = 0.004); increased latency in exploratory and defensive withdrawal behavior (p < 0.05); and a prolonged chemosensory memory in the social discrimination test (p < 0.05). No significant differences occurred in corticosterone and ACTH levels following air-puff startle or in pain thresholds at P65 between N4 and T4 groups. Fos expression at 30 min after hot-plate exposure was significantly greater in all areas of the somatosensory cortex in the T4 group compared with the N4 group (p < 0.05), whereas no differences occurred just after exposure. These data suggest that repetitive pain in neonatal rat pups may lead to an altered development of the pain system associated with decreased pain thresholds during development. Increased plasticity of the neonatal brain may allow these and other changes in brain development to increase their vulnerability to stress disorders and anxiety-mediated adult behavior. Similar behavioral changes have been observed during the later childhood of expreterm neonates who were exposed to prolonged periods of neonatal intensive care.

Pain in neonate

Anatomical, functional and neurochemical maturation of pain pathways is well developed in fetus and neonates. Various physiological and behavioural responses to painful stimuli in neonates substantiate their ability to feel pain. Biological effects of pain are systematically studied in human fetus and neonates. Pain expressions in the newborn not only reflect tissue damage but are a function of ongoing behavioural state. The ultimate aim should be to keep neonates free from pain and other stressful stimuli as far as possible, by advocating minimal handling protocol, giving comforts after painful procedures, local anesthesia while carrying out painful procedures like cutdown and insertion of chest tubes, and if a baby is ventilated fentanyl and/or midazalam infusion must be carried out during initial periods of ventilation.

Assessment of pain in the neonate

This article critically reviews the measures developed for assessing pain in the human neonate. Information was gathered with a computerized literature search of published articles and abstracts, a manual review of relevant conference proceedings, recently published journals, unpublished reports and manuscripts, and personal files. This identified 16 measures that were critically examined for their psychometric properties (reliability and validity) and clinical use. Special emphasis was placed on the feasibility of using neonatal pain assessment measures for clinical practice to address the research-practice gap. Although considerable progress has been made in the field of neonatal pain assessment, few measures have adequately established psychometric properties and clinical utility. Furthermore, most measures have been developed for research and not for the clinical setting. Issues regarding sensitivity, specificity, and the ability to detect clinically important changes have not been addressed. A sufficient number of infant pain measures have now been developed to assess acute pain. There is a paucity of measures to assess chronic pain in infants, and measures for infants who are low birth weight, critically ill, or ventilated. Future research should be aimed at strengthening the properties of existing measures, and at the development of measures for those infants with chronic pain or special needs.

Practical approach to analgesia and sedation in the neonatal intensive care unit

The anatomic and physiological bases for nociception are present even in very preterm neonates. Neonates show the same behavioral, endocrine, and metabolic responses to noxious stimuli as older subjects. Preterm infants appear to be more sensitive to painful stimuli and have heightened responses to successive stimuli. Infants receiving intensive care are subjected to frequent stressful procedures and also chronic noxious influences related to the environment of care. Inflammatory conditions such as necrotizing enterocolitis may also cause pain. Untreated pain in babies is associated with increased major morbidity and mortality. Nonpharmacological interventions, including environmental modification and comforting during procedures reduce stress. Intravenous opiates are the mainstay of pharmacological analgesia. A pure sedative agent can provide physiological stability in settings in which there are less acutely painful stimuli or when there are adverse effects from, or tolerance to, opiates. Local anesthesia of skin and mucous membranes is helpful for invasive procedures. Antipyretic analgesics such as acetaminophen have a role in inflammatory pain.

The interpretation of infant pain: physiological and behavioral indicators used by NICU nurses

The purpose of this descriptive study was to identify the indicators used by neonatal nurses to interpret the experience of pain in infants in a Neonatal Intensive Care Unit (NICU). A sample of 72 NICU nurses completed a structured questionnaire to identify the physiological and behavioral indicators they used to interpret the experience of pain in the infants entrusted to their care. The 10 pain indicators used by more than 50% of the nurses, listed in decreasing order of frequency, were: fussiness, restlessness, grimacing, crying, increasing heart rate, increasing respirations, wiggling, rapid state changes, wrinkling of forehead, and clenching of fist. These findings are consistent with existing literature, are compatible with the stress cues identified in Als' Synactive Theory of Development, and lend support to the use of such measures for the assessment of infant pain.

Venipuncture is more effective and less painful than heel lancing for blood tests in neonates

OBJECTIVE

Heel lancing has hitherto been the method of choice for screening tests of inborn errors of metabolism in neonates. Eutectic mixture of local anesthetic has little, if any, analgesic effect when applied to the heel of pre- and full-term infants. Today there seems to be no practical method that effectively alleviates the pain caused by heel lancing. The aim of this study was to investigate whether other methods, such as venipuncture of the dorsal side of the hand, are less painful and more efficient than heel lancing in neonates.

METHODS

One hundred twenty healthy, full-term infants who underwent testing for phenylketonuria (PKU) were included in the study. They were randomized into three groups: a venipuncture group (VP) (n = 50), a heel-lance group with a small lancet (SL) (n = 50), or a large lancet (LL) (n = 20). Pain reactions were assessed by the Neonatal Facial Coding System (NFCS). The latency and duration of the first cry as well as the total screaming time was analyzed. The efficacy of the method was assessed by the time taken to complete the PKU test and number of times the skin had to be punctured.

RESULTS

Nociceptive response. The NFCS scores after the first skin puncture were: VP, 247; SL, 333; and LL, 460. The NFCS scores were significantly lower in the VP than in the groups subjected to heel lancing. During the first 60 seconds after skin puncture, 44% of the infants cried in the VP group, compared with 72% and 85% in the SL and LL groups, respectively. Efficacy. A successful PKU test with only one skin puncture was performed in 86% of the VP group, but in only 19% in the SL group and 40% in the LL group. The total time needed to obtain the PKU blood sample was 191 seconds (median) in the VP group, 419 seconds in the SL group, and 279 seconds in the LL group.

CONCLUSION

Venipuncture is more effective and less painful than heel lancing for blood tests in neonates.

Randomised controlled trial of eutectic mixture of local anaesthetics cream for venepuncture in healthy preterm infants

AIM

To assess the safety and efficacy of EMLA cream (eutectic mixture of local anaesthetics) used to induce surface anaesthesia for venepuncture in healthy preterm infants.

METHODS

Nineteen infants, median gestational age 31 weeks (range 26-33 weeks) were assessed in a randomised, double blind, placebo controlled, cross-over trial. Changes in physiological variables (heart rate, blood pressure, oxygen saturation) and behavioural responses (neonatal facial coding system score, crying time) before and after venepuncture with EMLA cream were compared with those obtained with a placebo cream to assess efficacy. Toxicity was assessed by comparing methaemoglobin concentrations at 1 hour and 8 hours after application.

RESULTS

There was no significant difference in efficacy between EMLA and placebo creams in physiological and behavioural responses. There was no significant difference in methaemoglobin concentrations one hour after the cream had been applied. At eight hours, however, concentrations were significantly higher after EMLA than placebo (p = 0.016). There was no evidence of clinical toxicity.

CONCLUSION

This study does not support the routine use of EMLA for venepuncture in healthy preterm infants.

Judging pain in infants: behavioural, contextual, and developmental determinants

Caretakers intuitively use various sources of evidence when judging infant pain, but the relative importance of salient cues has received little attention. This investigation examined the predictive significance for judgements of painful discomfort in preterm and full-term neonates of behavioural (facial activity and body movement), contextual (invasiveness of the procedure), and developmental (gestational age) information. Judges viewed videotapes showing infants varying in the foregoing characteristics undergoing heel incisions for routine blood sampling purposes. Findings indicated all but the contextual information contributed uniquely to judgements of pain, with facial activity accounting for the most unique variance (35%), followed by bodily activity and gestational age, each accounting for 3% and 1% of the judgmental variance, respectively. Generally, 71% of the variance in ratings of pain could be predicted using facial activity alone, compared to 30% of the variance using bodily activity alone, 19% by relying on context alone, and 8% by referring to gestational age alone. Noteworthy was the tendency to judge early preterm infants to be experiencing less pain even though they were subjected to the same invasive procedure as the older infants. This finding also runs counter to evidence from developmental neurobiology which indicates that preterm newborns may be hypersensitive to invasive procedures.

Effect of neonatal circumcision on pain response during subsequent routine vaccination

BACKGROUND

Preliminary studies suggested that pain experienced by infants in the neonatal period may have long-lasting effects on future infant behaviour. The objectives of this study were to find out whether neonatal circumcision altered pain response at 4-month or 6-month vaccination compared with the response in uncircumcised infants, and whether pretreatment of circumcision pain with lidocaine-prilocaine cream (Emla) affects the subsequent vaccination response.

METHODS

We used a prospective cohort design to study 87 infants. The infants formed three groups--uncircumcised infants, and infants who had been randomly assigned Emla or placebo in a previous clinical trial to assess the efficacy of Emla cream as pretreatment for pain in neonatal circumcision. Infants were videotaped during vaccination done at the primary care physician's clinic. Videotapes were scored without knowledge of circumcision or treatment status by a research assistant who had been trained to measure infant facial action, cry duration, and visual analogue scale pain scores.

FINDINGS

Birth characteristics and infant characteristics at the time of vaccination, including age and temperament scores, did not differ significantly among groups. Multivariate ANOVA revealed a significant group effect (p < 0.001) in difference (vaccination minus baseline) values for percentage facial action, percentage cry time, and visual analogue scale pain scores. Univariate ANOVAs were significant for all outcome measures (p < 0.05): infants circumcised with placebo had higher difference scores than uncircumcised infants for percentage facial action (136.9 vs 77.5%), percentage cry duration (53.8 vs 24.7%), and visual analogue scale pain scores (5.1 vs 3.1 cm). There was a significant linear trend on all outcome measures, showing increasing pain scores from uncircumcised infants, to those circumcised with Emla, to those circumcised with placebo.

INTERPRETATION

Circumcised infants showed a stronger pain response to subsequent routine vaccination than uncircumcised infants. Among the circumcised group, preoperative treatment with Emla attenuated the pain response to vaccination. We recommend treatment to prevent neonatal circumcision pain.

Pain management in newborns: how far have we progressed in research and practice?

Compelling research supports the newborn infant's capacity for pain. Yet, pain is frequently underestimated and undertreated. This is a result of limited understanding of pain pathway development, immediate and long-term consequences, measurement tools and approaches, and safety and efficacy of pain-relieving interventions. This paper reviews recent research in relation to management of pain in the newborn, and presents implications for practice and future research.