Differences in pain expression between male and female newborn infants

An Analgesic Technique for Orogastric Tube Insertion in Newborns: DOLATSONG, a Randomized Multicentric Controlled Trial

BACKGROUND

Gastric tube insertion is necessary to support early enteral feeding of newborns during their neonatal intensive care stay. This frequent and invasive procedure is known to be painful. Very few analgesic techniques (sweet solutions, sucking, swaddling, and skin-to-skin contact) are available to reduce the pain caused by orogastric tube insertion procedure. Objective: To determine whether a new orogastric tube insertion technique modifies the pain response in newborns, we hypothesize that inserting an orogastric tube through the nipple of a bottle reduces pain caused by this procedure.

DESIGN

Prospective, controlled, randomized, multicentered and open label study.

SETTINGS

Three neonatal intensive care units in France (2 level 3 units and 1 level 2B).

PARTICIPANTS

Full-term or premature newborns at 32 weeks of gestation or more, postnatal age between 48 hours and 21 days, not ventilated and requiring enteral feeding, were randomized into 2 groups: usual technique ( n = 36) and experimental technique ( n = 35).

METHODS

Our experimental technique was to insert the orogastric tube through a modified nipple of a bottle. This method was compared with the usual technique of inserting the tube directly into the newborn's mouth without a support to guide it accompanied by a nipple encouraging sucking with a nonnutritive solution. An association of nonnutritive sucking and orally administered 30% glucose was given to all children for analgesic purposes. Pain during the orogastric tube insertion was assessed on video recordings by 2 independent experts, using a heteroassessment behavioral scale for pain (DAN- Douleur Aiguë du Nouveau-né ; APN-Acute Pain in Newborns). The primary outcome was an Acute Pain in Newborns score of less than 3 at the time of the procedure. Comparisons were made using Fisher exact test or Mann-Whitney U test. Factors associated with an Acute Pain in Newborns score of 3 and greater were explored using univariable and multivariable regression models.

RESULTS

All but 1 video recording in each group were analyzed. Among the 34 neonates in the experimental group, 71.4% (95% CI: [53.7-85.4]) had an Acute Pain in Newborns score of less than 3 during orogastric tube insertion versus 41% (95% CI: [27.9-61.9]) in the control group ( P = .031). Gagging was frequent and nonsignificantly different between the 2 groups (69% in the control group, 51% in the experimental group, P = .13). In multivariable analysis, the experimental technique was an independent factor of pain prevention compared with the usual technique (odds ratio = 0.21 [0.06-0.71], P = .015).

CONCLUSIONS

This study suggests that a simple, inexpensive, and feasible technique of orogastric tube insertion through the nipple of a bottle limits pain associated with this procedure in newborns.

Minding the gap: a sex difference in young infants' mental rotation through thirty degrees of arc

Mental rotation (MR) is an important feature of spatial cognition invoking mental imagery of an object's appearance when viewed from a new orientation. Prior studies have revealed evidence of MR in infants, including a sex difference similar to that detected in older populations. Some of these studies used visual habituation methods whereby infants were familiarized with an object rotating through a 240° angle, followed by test trials showing either the habituation object or a mirror image object rotating through the previously unseen 120° angle. Significantly longer looking at either of these objects was taken to reflect infants' ability to recognize the habituation object even when seen from a novel viewpoint, suggesting the capacity for MR. However, these infants' responses could, in theory, be explained with reference to perceptual discrimination rather than MR, because the views of the habituation and test objects were very similar in some video frames. In the current study, we observed a diverse population of 5-month-olds (24 females, 24 males) for evidence of MR through 30° of arc. In this more challenging test, our stimuli left a 30° gap angle between critical video frames representing the habituation and test objects. Consistent with earlier reports, we found that relative to female infants, male infants looked significantly longer at the mirror image test stimulus immediately following habituation. These results add to an emerging consensus that some young infants are capable of MR, and that male and female infants on average behave differently in this type of MR task.

Analgesic Potential Comparison Between Piperine-Combined Curcumin Patch and Non-Piperine Curcumin Patch: A Pragmatic Trial on Post-Cleft Lip/Palate Surgery Pediatric Patients

Purpose

Despite its well-acknowledged analgesic potential, curcumin's low bioavailability has been recognized. Piperine, a substance naturally contained in pepper, has been known for its effect on increasing curcumin bioavailability. To investigate the analgesic potential of curcumin and piperine addition to curcumin patch used as adjuvant therapy in the management of acute postoperative orofacial pain.

Patients and Methods

This pragmatic trial recruited 75 patients that underwent oromaxillofacial surgery at Unpad Dental Hospital, Bandung, Indonesia. Research participants were randomly assigned to three different groups: the first group that did not receive any intervention other than the post-operative standard treatment (POST), the second group that received POST and non-piperine curcumin patch, and the third group that received POST and piperine-combined curcumin patch. Participants' pain intensity was evaluated by using the face, leg, activity, cry, and consolability (FLACC) pain scale and salivary prostaglandin-E2 (PGE2) level for two-time points, which were eight hours apart. All data were gathered and analyzed to compare the within and between-group differences.

Results

Within groups comparison of the FLACC scores for two evaluation points showed significant differences for all groups (p < 0.01). For salivary PGE2 analysis, a comparison of the non-piperine group to the piperine group also showed significant results. Yet, when all three groups were compared, regardless of the differences, the results were not statistically significant.

Conclusion

Despite of the proven efficacy of curcumin patch, the addition of piperine to the curcumin patch in the current study did not provide any significant effects. Further investigation is of importance.

Caregiver Ratings of Toddler Pain: The Role of Caregiver Psychological Predictors

INTRODUCTION/AIM

Young children's limited ability to self-report pain necessitates an understanding of the factors that influence pain ratings. The current paper examines the relative prediction of caregiver psychological factors and toddler pain behaviors on caregiver pain ratings post-vaccination.

METHODS

One hundred fifty-six parent-toddler dyads were video recorded during pediatric vaccinations. Child pain behaviors were coded before, during, and after the needle using the Face, Legs, Activity, Cry, Consolability Scale and the Neonatal Facial Coding System). Caregivers rated their child's pain after the needle, reported pre- and post-needle worry during the visit, and completed rating scales assessing other areas of psychological functioning within 2 weeks after the appointment. Regression models were estimated to examine the relative contribution of child and caregiver factors to the prediction of caregiver pain ratings.

RESULTS

The regression model predicting caregiver pain ratings from the toddlers' pain-related distress (facial activity immediately after the needle, overall pain-related behavior immediately after, 1-min and 2-min post-needle) and caregiver worry were significant (adjusted R-square = 0.21), with caregiver pre- and post-needle worry being the only significant predictors of caregiver pain ratings.

CONCLUSIONS

This study outlines that although child distress behavior remains a significant influence on pain ratings during toddlerhood, when caregiver worry (pre- and post-needle) was entered into the model, they were the only significant predictors of caregiver pain ratings.

Artificial Intelligence Based Pain Assessment Technology in Clinical Application of Real-World Neonatal Blood Sampling

Background: Accurate neonatal pain assessment (NPA) is the key to neonatal pain management, yet it is a challenging task for medical staff. This study aimed to analyze the clinical practicability of the artificial intelligence based NPA (AI-NPA) tool for real-world blood sampling. Method: We performed a prospective study to analyze the consistency of the NPA results given by a self-developed automated NPA system and nurses’ on-site NPAs (OS-NPAs) for 232 newborns during blood sampling in neonatal wards, where the neonatal infant pain scale (NIPS) was used for evaluation. Spearman correlation analysis and the degree of agreement of the pain score and pain grade derived by the NIPS were applied for statistical analysis. Results: Taking the OS-NPA results as the gold standard, the accuracies of the NIPS pain score and pain grade given by the automated NPA system were 88.79% and 95.25%, with kappa values of 0.92 and 0.90 (p < 0.001), respectively. Conclusion: The results of the automated NPA system for real-world neonatal blood sampling are highly consistent with the results of the OS-NPA. Considering the great advantages of automated NPA systems in repeatability, efficiency, and cost, it is worth popularizing the AI technique in NPA for precise and efficient neonatal pain management.

The predictors, barriers and facilitators to effective management of acute pain in children by emergency medical services: A systematic mixed studies review

We aimed to identify predictors, barriers and facilitators to effective pre-hospital pain management in children. A segregated systematic mixed studies review was performed. We searched from inception to 30-June-2020: MEDLINE, CINAHL Complete, PsycINFO, EMBASE, Web of Science Core Collection and Scopus. Empirical quantitative, qualitative and multi-method studies of children under 18 years, their relatives or emergency medical service staff were eligible. Two authors independently performed screening and selection, quality assessment, data extraction and quantitative synthesis. Three authors performed thematic synthesis. Grading of Recommendations Assessment, Development and Evaluation and Confidence in the Evidence from Reviews of Qualitative Research were used to determine the confidence in cumulative evidence. From 4030 articles screened, 78 were selected for full text review, with eight quantitative and five qualitative studies included. Substantial heterogeneity precluded meta-analysis. Predictors of effective pain management included: 'child sex (male)', 'child age (younger)', 'type of pain (traumatic)' and 'analgesic administration'. Barriers and facilitators included internal (fear, clinical experience, education and training) and external (relatives and colleagues) influences on the clinician along with child factors (child's experience of event, pain assessment and management). Confidence in the cumulative evidence was deemed low. Efforts to facilitate analgesic administration should take priority, perhaps utilising the intranasal route. Further research is recommended to explore the experience of the child. Registration: PROSPERO CRD42017058960.

Gender Biases in Estimation of Others' Pain

Caregiving and other interpersonal interactions often require accurate perception of others' pain from nonverbal cues, but perceivers may be subject to systematic biases based on gender, race, and other contextual factors. Such biases could contribute to systematic under-recognition and undertreatment of pain. In 2 experiments, we studied the impact of perceived patient sex on lay perceivers' pain estimates and treatment recommendations. In Experiment 1 (N = 50), perceivers viewed facial video clips of female and male patients in chronic shoulder pain and estimated patients' pain intensity. Multi-level linear modeling revealed that perceivers under-estimated female patients' pain compared with male patients, after controlling for patients' self-reported pain and pain facial expressiveness. Experiment 2 (N = 200) replicated these findings, and additionally found that 1) perceivers' pain-related gender stereotypes, specifically beliefs about typical women's vs. men's willingness to express pain, predicted pain estimation biases; and 2) perceivers judged female patients as relatively more likely to benefit from psychotherapy, whereas male patients were judged to benefit more from pain medicine. In both experiments, the gender bias effect size was on average 2.45 points on a 0-100 pain scale. Gender biases in pain estimation may be an obstacle to effective pain care, and experimental approaches to characterizing biases, such as the one we tested here, could inform the development of interventions to reduce such biases. Perspective: This study identifies a bias towards underestimation of pain in female patients, which is related to gender stereotypes. The findings suggest caregivers' or even clinicians' pain stereotypes are a potential target for intervention.

[Parental responses to child pain : The role of parental and child somatic and anxiety symptoms]

Hintergrund

Elterliche kognitiv-affektive und verhaltensbezogene Reaktionen können die Chronifizierung von kindlichen Schmerzen beeinflussen. Unklar ist, ob Mütter und Väter unterschiedlich reagieren und inwieweit Top-down- (elterliche Somatisierung, Angstsymptome) und Bottom-up-Variablen (kindliche schmerzbezogene Beeinträchtigung, Angstsymptome) die elterlichen Reaktionen modulieren.

Ziele der Arbeit

(1) Vergleich der Somatisierung, Angstsymptome und elterlichen Reaktionen (Katastrophisieren, Zuwendung) von Müttern und Vätern chronisch schmerzkranker Kinder und (2) Untersuchung des Einflusses von Top-down- und Bottom-up-Variablen auf die elterlichen Reaktionen.

Methode

Eltern-Kind-Triaden (Kind, Mutter, Vater; je N = 21, Gesamt‑N = 63; Kinder: 50 % weiblich, 11–19 Jahre, ∅15,14 Jahre) wurden während einer kinder- und jugendpsychiatrischen Behandlung ihrer chronischen Schmerzen hinsichtlich der kindlichen Schmerzen und Angstsymptome, elterlicher Somatisierung und Angstsymptome und elterlichen Reaktionen mit validierten Fragebögen erfasst.

Ergebnisse

Mütter und Väter unterschieden sich nicht in Somatisierung, Angstsymptomen und Reaktionen. Eltern katastrophisierten stärker, wenn ihre Kinder sowohl unter Angstsymptomen als auch unter stärkerer schmerzbezogener Beeinträchtigung litten. Elterliche Zuwendung war verstärkt, wenn Eltern selbst Angstsymptome angaben. Jüngere Kinder und Mädchen erhielten mehr Zuwendung.

Diskussion

Im Einklang mit vorherigen Studien zeigt sich, dass elterliche und kindliche Angstsymptome, nicht aber das elterliche Geschlecht als modulierende Faktoren der elterlichen maladaptiven Reaktionen eine Rolle spielen. Dies sollte in Prävention und Therapie von Kindern mit chronischen Schmerzen und deren Bezugspersonen berücksichtigt werden.

Analgesic effects of breast- and formula feeding during routine childhood immunizations up to 1 year of age

BACKGROUND

Data on analgesic effects of breast/formula milk sucking while receiving routine childhood immunizations are available only in early infancy, have rarely been compared in the same study, and are not accompanied by information on mothers' satisfaction/acceptance. Here we aimed to compare the analgesic effect of both methods vs. held-only controls up to 1 year of age, and verify mothers' satisfaction.

METHODS

Two to 12 months children subjected to vaccine were allocated into three groups: breastfed, formula-fed, and held-only controls. A video recording was performed to analyze pain parameters: crying latency/duration and specific scales [FLACC (Face, Legs, Activity, Cry, and Consolability), NIPS (Neonatal Infant Pain Scale)]. After the procedure, mothers filled in a satisfaction questionnaire.

RESULTS

One-hundred and sixty-two children were recruited: 54 breastfed, 35 formula fed, and 73 controls. Breastfed showed the longest crying latency, and together with formula fed, had the shortest duration and lowest pain scores. Most mothers appreciated not only the respective feeding-mediated pain mitigation method used, but also the simply-holding procedure. In all cases, they felt reassured, with an unexpected frequent underestimation of their child's pain during the shot.

CONCLUSIONS

The analgesic effect of breastfeeding during vaccination extends also to children >6 months old, and is obtained by formula too. Embracing the child may help to reassure mothers.

IMPACT

We confirmed the analgesic effect of breastfeeding during the vaccination procedures in early infancy. We show for the first time that this effect is extended also to children up to 1 year of age, and it may be obtained by formula feeding as well. Most mothers appreciated pain mitigation not only through feeding, but also the simply-holding procedure. In all cases, mothers felt reassured, with an unexpected frequent underestimation of their child' pain during the shot. The promotion of these easily feasible and well-accepted strategies should be further encouraged within health professionals during vaccination procedures.

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

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

Cortical Pain Response of Newborn Infants to Venepuncture: A Randomized Controlled Trial Comparing Analgesic Effects of Sucrose Versus Breastfeeding

OBJECTIVE

Sucrose administration and breastfeeding decrease behavioral expressions of pain in neonates. However, recent studies indicated that there is a persistent cortical response with sucrose. This study compared the efficacy of sucrose administration versus breastfeeding to decrease cortical responses to pain during venepuncture.

PATIENTS AND METHODS

A randomized, prospective, controlled trial was conducted in a tertiary level maternity ward. Healthy, 3-day-old term neonates, undergoing venepuncture for neonatal screening, were randomly assigned to receive sucrose solution or be breastfed before venepuncture. Variations in the total hemoglobin concentration [HbT] in the contralateral somatosensory cortex were assessed with near infrared spectroscopy. The Neonatal Facial Coding System (NFCS) was used to assess reactions.

RESULTS

There were 114 term neonates included, with 102 included for the primary outcome (breastfed group: 48; sucrose group: 54). Similar maximum increases in [HbT] were observed in both groups (mean±SD: sucrose group: 31.2±58.1 μmol/L; breastfed group: 38.9±61.4 μmol/L; P=0.70). Breastfed neonates presented more behavioral expressions that indicated pain compared with sucrose-administered neonates (46.8% vs. 26.8% of NFCS ≥1, P=0.04). The maximum increase in [HbT] was persistent, although newborn infants who did not express behavioral signs of pain had lower concentrations than neonates who did (mean±SD: 21.2±29.1 vs. 60.0±89.8 μmol/L, P<0.01).

DISCUSSION

There was no difference in the cortical responses to pain during venepuncture in newborn infants who were administered sucrose versus those who were breastfed.

Nociception and the neonatal brain

Measuring brain activity in infants provides an objective surrogate approach with which to infer pain perception following noxious events. Here we discuss different approaches which can be used to measure noxious-evoked brain activity, and discuss how these measures can be used to assess the analgesic efficacy of pharmacological and non-pharmacological interventions. We review factors that can modulate noxious-evoked brain activity, which may impact infant pain experience, including gestational age, sex, prior pain, stress, and illness.

Geometric morphometrics for the study of facial expressions in non-human animals, using the domestic cat as an exemplar

Facial expression is a common channel for the communication of emotion. However, in the case of non-human animals, the analytical methods used to quantify facial expressions can be subjective, relying heavily on extrapolation from human-based systems. Here, we demonstrate how geometric morphometrics can be applied in order to overcome these problems. We used this approach to identify and quantify changes in facial shape associated with pain in a non-human animal species. Our method accommodates individual variability, species-specific facial anatomy, and postural effects. Facial images were captured at four different time points during ovariohysterectomy of domestic short haired cats (n = 29), with time points corresponding to varying intensities of pain. Images were annotated using landmarks specifically chosen for their relationship with underlying musculature, and relevance to cat-specific facial action units. Landmark data were subjected to normalisation before Principal Components (PCs) were extracted to identify key sources of facial shape variation, relative to pain intensity. A significant relationship between PC scores and a well-validated composite measure of post-operative pain in cats (UNESP-Botucatu MCPS tool) was evident, demonstrating good convergent validity between our geometric face model, and other metrics of pain detection. This study lays the foundation for the automatic, objective detection of emotional expressions in a range of non-human animal species.

Sex-specific airway hyperreactivity and sex-specific transcriptome remodeling in neonatal piglets challenged with intra-airway acid

Acute airway acidification is a potent stimulus of sensory nerves and occurs commonly with gastroesophageal reflux disease, cystic fibrosis, and asthma. In infants and adults, airway acidification can acutely precipitate asthma-like symptoms, and treatment-resistant asthma can be associated with gastroesophageal reflux disease. Airway protective behaviors, such as mucus secretion and airway smooth muscle contraction, are often exaggerated in asthma. These behaviors are manifested through activation of neural circuits. In some populations, the neural response to acid might be particularly important. For example, the immune response in infants is relatively immature compared with adults. Infants also have a high frequency of gastroesophageal reflux. Thus, in the current study, we compared the transcriptomes of an airway-nervous system circuit (e.g., tracheal epithelia, nodose ganglia, and brain stem) in neonatal piglets challenged with intra-airway acid. We hypothesized that the identification of parallel changes in the transcriptomes of two neutrally connected tissues might reveal the circuit response, and, hence, molecules important for the manifestation of asthma-like features. Intra-airway acid induced airway hyperreactivity and airway obstruction in male piglets. In contrast, female piglets displayed airway obstruction without airway hyperreactivity. Pairwise comparisons revealed parallel changes in genes directly implicated in airway hyperreactivity ( scn10a) in male acid-challenged piglets, whereas acid-challenged females exhibited parallel changes in genes associated with mild asthma ( stat 1 and isg15). These findings reveal sex-specific responses to acute airway acidification and highlight distinct molecules within a neural circuit that might be critical for the manifestation of asthma-like symptoms in pediatric populations.

Factors Associated With Infant Pain Severity Undergoing Immunization Injections

PURPOSE

Factors influencing infants' behavioral and vocal (cry) response to painful stimuli are explored to improve pain management plans for infants undergoing immunizations.

DESIGN AND METHODS

An observational study design was used. Pain responses of 60 to 75 days-old infants (44% male vs 56% female) undergoing two-month immunization injections were videotaped and coded using the Modified Behavioral Pain Scale (MBPS), and duration of total crying time during injection was recorded. The influences of five factors (gender, caregiver attendance, previous experience of nociception (circumcision), mode of delivery), and weight (birth and current) were examined at baseline, during and post-immunization.

RESULTS

Higher birth weight was the most significant factor that reduced pain responses during (p = 0.001) and post-immunization (p = 0.03). A higher birth weight reduced full lung crying (p = 0.04), which reflects crying during injection as compared to total crying time. Vaginal delivery had a significant effect on behavioral pain responses of infants only post-immunization (p = 0.006). Parent's presence in the immunization room significantly reduced total crying time (p = 0.03). Uncircumcised male infants had a significant reduction in behavioral pain responses during immunization (p = 0.01) compared to circumcised infants.

CONCLUSIONS

The literature well supports the acknowledgement of early pain experience and its psychological consequences. Knowing and controlling for each of mentioned factors early in life during every painful procedure could improve coping mechanisms of infants for any painful procedures later in life.

PRACTICE IMPLICATIONS

Control of certain factors during early life experiences can modify pain of immunization.

The distribution of pain activity across the human neonatal brain is sex dependent

In adults, there are differences between male and female structural and functional brain connectivity, specifically for those regions involved in pain processing. This may partly explain the observed sex differences in pain sensitivity, tolerance, and inhibitory control, and in the development of chronic pain. However, it is not known if these differences exist from birth. Cortical activity in response to a painful stimulus can be observed in the human neonatal brain, but this nociceptive activity continues to develop in the postnatal period and is qualitatively different from that of adults, partly due to the considerable cortical maturation during this time. This research aimed to investigate the effects of sex and prematurity on the magnitude and spatial distribution pattern of the long-latency nociceptive event-related potential (nERP) using electroencephalography (EEG). We measured the cortical response time-locked to a clinically required heel lance in 81 neonates born between 29 and 42 weeks gestational age (median postnatal age 4 days). The results show that heel lance results in a spatially widespread nERP response in the majority of newborns. Importantly, a widespread pattern is significantly more likely to occur in females, irrespective of gestational age at birth. This effect is not observed for the short latency somatosensory waveform in the same infants, indicating that it is selective for the nociceptive component of the response. These results suggest the early onset of a greater anatomical and functional connectivity reported in the adult female brain, and indicate the presence of pain-related sex differences from birth.

Gene regulatory mechanisms underlying sex differences in brain development and psychiatric disease

The sexual differentiation of the mammalian nervous system requires the precise coordination of the temporal and spatial regulation of gene expression in diverse cell types. Sex hormones act at multiple developmental time points to specify sex-typical differentiation during embryonic and early development and to coordinate subsequent responses to gonadal hormones later in life by establishing sex-typical patterns of epigenetic modifications across the genome. Thus, mutations associated with neuropsychiatric conditions may result in sexually dimorphic symptoms by acting on different neural substrates or chromatin landscapes in males and females. Finally, as stress hormone signaling may directly alter the molecular machinery that interacts with sex hormone receptors to regulate gene expression, the contribution of chronic stress to the pathogenesis or presentation of mental illness may be additionally different between the sexes. Here, we review the mechanisms that contribute to sexual differentiation in the mammalian nervous system and consider some of the implications of these processes for sex differences in neuropsychiatric conditions.

Factors Associated With Adherence to Nasoalveolar Molding (NAM) by Caregivers of Infants Born With Cleft Lip and Palate

OBJECTIVE

Identify factors associated with adherence to nasoalveolar molding (NAM) therapy.

DESIGN

Retrospective case-control study.

SETTING

Tertiary referral center.

PATIENTS, PARTICIPANTS

Infants with cleft lip, with or without cleft palate, referred for NAM. One hundred thirty-five patients met criteria.

MAIN OUTCOME MEASURE(S)

Adherence to NAM therapy, defined as continuous use of the appliance and attendance of NAM adjustment visits.

RESULTS

Female sex (OR = 2.85, 95% CI 1.21-6.74), bilateral cleft (OR = 2.88, 95% CI 1.29-6.46), and travel distance (OR = 1.01, 95% CI 1.00-1.01) were independent predictors of nonadherence. Bilateral clefts (OR = 8.35, 95% CI 2.72-25.64) and public-payer insurance (OR = 3.67, 95% CI 1.13-11.91) for male patients were significantly associated with nonadherence, in our sex-stratified multivariate model. The majority of the families (58%) had public health insurance. Males comprised 77.0% of the cohort.

CONCLUSIONS

NAM treatment adherence is impaired by bilateral clefts, female sex, increased travel distance, and public insurance. Further studies are warranted to investigate how these factors affect adherence, and to develop interventions to improve adherence in families at risk due to economic or psychosocial barriers.

Withdrawal Assessment Tool-1 Monitoring in PICU: A Multicenter Study on Iatrogenic Withdrawal Syndrome

OBJECTIVES

Withdrawal syndrome is an adverse reaction of analgesic and sedative therapy, with a reported occurrence rate between 17% and 57% in critically ill children. Although some factors related to the development of withdrawal syndrome have been identified, there is weak evidence for the effectiveness of preventive and therapeutic strategies. The main aim of this study was to evaluate the frequency of withdrawal syndrome in Italian PICUs, using a validated instrument. We also analyzed differences in patient characteristics, analgesic and sedative treatment, and patients' outcome between patients with and without withdrawal syndrome.

DESIGN

Observational multicenter prospective study.

SETTING

Eight Italian PICUs belonging to the national PICU network Italian PICU network.

PATIENTS

One hundred thirteen patients, less than 18 years old, mechanically ventilated and treated with analgesic and sedative therapy for five or more days. They were admitted in PICU from November 2012 to May 2014.

INTERVENTIONS

Symptoms of withdrawal syndrome were monitored with Withdrawal Assessment Tool-1 scale.

MEASUREMENTS AND MAIN RESULTS

The occurrence rate of withdrawal syndrome was 64.6%. The following variables were significantly different between the patients who developed withdrawal syndrome and those who did not: type, duration, and cumulative dose of analgesic therapy; duration and cumulative dose of sedative therapy; clinical team judgment about analgesia and sedation's difficulty; and duration of analgesic weaning, mechanical ventilation, and PICU stay. Multivariate logistic regression analysis revealed that patients receiving morphine as their primary analgesic were 83% less likely to develop withdrawal syndrome than those receiving fentanyl or remifentanil.

CONCLUSIONS

Withdrawal syndrome was frequent in PICU patients, and patients with withdrawal syndrome had prolonged hospital treatment. We suggest adopting the lowest effective dose of analgesic and sedative drugs and frequent reevaluation of the need for continued use. Further studies are necessary to define common preventive and therapeutic strategies.

Validity of the Child Facial Coding System for the Assessment of Acute Pain in Children With Cerebral Palsy

The purpose of the current study was to examine the concurrent and discriminant validity of the Child Facial Coding System for children with cerebral palsy. Eighty-five children (mean = 8.35 years, SD = 4.72 years) were videotaped during a passive joint stretch with their physiotherapist and during 3 time segments: baseline, passive joint stretch, and recovery. Children's pain responses were rated from videotape using the Numerical Rating Scale and Child Facial Coding System. Results indicated that Child Facial Coding System scores during the passive joint stretch significantly correlated with Numerical Rating Scale scores (r = .72, P < .01). Child Facial Coding System scores were also significantly higher during the passive joint stretch than the baseline and recovery segments (P < .001). Facial activity was not significantly correlated with the developmental measures. These findings suggest that the Child Facial Coding System is a valid method of identifying pain in children with cerebral palsy.

Effects of Open and Closed Suctioning Systems on Pain in Newborns Treated with Mechanical Ventilation

This experimental study was conducted to compare the effects of open and closed suctioning systems on pain in newborns receiving ventilation support. The study sample consisted of 42 babies (23 female, 16 male) hospitalized in the unit between December 2010 and December 2011 who met the selection criteria established for the study. Using the random sampling method, 20 of the babies were included in the closed suctioning system group and the remaining 22 were analyzed in the open suctioning system group. The data collection tools of the study were intervention monitoring form, data collection form, and documentation of the personal information on the babies; and the Neonatal Pain, Agitation, and Sedation Scale (N-PASS) evaluated the babies' pain responses. The data were evaluated using SPSS 15 software. Most neonates were born preterm (≤37 weeks' gestation at birth; 69% [n = 29]). The mean (SD) birth weight, gestational age, and intensive care unit stay were 1.82 kg (1.1 kg), 31.9 (5.3) weeks, and 25.3 (2.9) calendar days, respectively. Results of the study revealed no statistically significant difference between the open suctioning and closed suctioning groups (p = .194). However, the N-PASS pain scores obtained before and during the suctioning processes were significantly different (p < .001). In conclusion, babies seem to experience pain during the suctioning process, according to N-PASS scores, and although not significant statistically, the level of pain felt during open suctioning was observed to be slightly higher compared with closed suctioning.

The effects of olfactory stimulation and gender differences on pain responses in full-term infants

AIM

Studies have reported conflicting findings on whether different smells can reduce distress when infants undergo painful procedures. Our study assessed the impact of vanilla on infants' responses to a painful toe lance, including possible gender differences.

METHODS

We measured the pain responses of 69 full-term infants - 34 girls and 35 boys - during toe lance, using two multidimensional scales - the Neonatal Facial Coding System and Behavioural Indicators of Infant Pain - together with crying duration and hand movements. Three sets of data were collected during baseline, toe lance and recovery, while the babies were exposed to the odour of vanilla (n = 39) or odourless water (n = 30).

RESULTS

Pain responses increased significantly during toe lance, then declined during recovery. Crying duration correlated significantly with finger splaying/fisting and both pain scale scores, with boys displaying higher pain scores than girls. Vanilla had no impact on pain levels.

CONCLUSION

Crying and finger splaying/fisting were observable responses that may be useful for screening pain or distress in healthy neonates. Increased pain reactions by boys may reflect higher irritability. Exposure to an unfamiliar odour did not have a calming effect on full-term neonates.

No pain, no social gains: A social-signaling perspective of human pain behaviors

In this review article, we describe a social-signaling perspective of human pain and pain empathizing behaviors which is based on the premise that pain percepts evolved to serve both intrapersonal as well as interpersonal, communicative functions. This perspective offers a generative framework for understanding the natural origin and proximate expression of felt pain and pain empathizing behaviors. The basic thesis is that humans evolved sensory-behavioral heuristics for perceiving and inhibiting exogenous and endogenous pain sensations as part of more general expressive styles characterized by the demonstration of vulnerability gestures (i.e., trustworthiness cues) versus empowerment gestures (i.e., capacity cues), and these styles ultimately facilitate broader self-protection and social novelty-seeking life-history behavior strategies, respectively. We review the extant literature on how social contextual factors (e.g., audience characteristics) and how structural and functional components of individual’s social network appear to influence the expression of pain behaviors in ways that support basic predictions from the social-signaling perspective. We also show how the perspective can be used to interpret conventional findings of sex differences in pain percepts and pain empathizing behaviors and for predicting how the situational context and individual’s peer networks modulate these differences in vitro and in vitro. We conclude the article by describing how pain researchers may better understand how varying levels and divergent directions of changes in affect tend to co-occur with systematic changes in internal vs external pain sensitivities, and thus why, from an evolutionary perspective, pain may occur in the presence and absence of physical tissue damage.

Gender expression, sexual orientation and pain sensitivity in women

BACKGROUND

Despite a growing body of literature investigating sex differences with regard to pain, surprisingly little research has been conducted on the influence of various aspects of self-identity, including gender expression and sexual orientation, on pain sensitivity within each sex, particularly among women. In men, dispositional femininity is linked to greater clinical pain and trait masculinity is associated with higher pain thresholds.

OBJECTIVES

To examine whether gender expression and sexual orientation are associated with within-sex differences in ischemic pain sensitivity in healthy young women.

METHODS

A convenience sample of 172 females (mean age 21.4 years; range 18 to 30 years of age; 56.0% white, 89% heterosexual) performed an ischemic pain task in counterbalanced order. Desired levels of dispositional femininity for a preferred romantic partner and self-described levels of personal dispositional femininity were measured.

RESULTS

Compared with heterosexual women, lesbian and bisexual women reported lower pain intensity ratings early in the discomfort task. Irrespective of sexual orientation, attraction to more feminine romantic partners and dispositional masculinity were correlated with lower pain intensity, and with higher pain thresholds and tolerance levels.

DISCUSSION

These preliminary findings suggest that within-sex differences in sexual orientation and other aspects of identity, irrespective of biological sex, may be important to consider when examining experimental pain performance and clinical pain experiences.

CONCLUSION

Larger investigations of the psychophysiological relationships among sexual orientation, gender expression and pain sensitivity are warranted. These findings may have implications for differences in clinical pain sensitivity of lesbian and bisexual women compared with heterosexual women.

Pain assessment and measurement in neonates: an updated review

Pain assessment and measurement are the cornerstones of pain management. Pain assessment connotes a comprehensive multidimensional description. Conversely, pain measurement provides a numeric quantitative description of each factor illustrating pain qualities. Pain scales provide a composite score used to guide practice and research. The type of infant pain instrument chosen is a significant factor in guiding pain management practice. The purpose of this review was to summarize current infant pain measures by introducing a conceptual framework for pain measurement. Although more than 40 infant pain instruments exist, many were devised solely for research purposes; several of the newly developed instruments largely overlap with existing instruments. Integration of pain management into daily practice remains problematic. Understanding how each instrument measures infant pain allows clinicians to make better decisions about what instrument to use with which infant and in what circumstances. In addition, novel new measurement techniques need further testing.

Sex-related long-term behavioral and hippocampal cellular alterations after nociceptive stimulation throughout postnatal development in rats

Early noxious stimuli may alter the neurogenesis rate in the dentate gyrus and the behavioral repertoire of adult rats. This study evaluated the long-term effects of noxious stimulation, imposed in different phases of development, on nociceptive and anxiety-like behaviors, hippocampal activation, cell proliferation, hippocampal BDNF and plasma corticosterone levels in 40 day-old male and female adolescents. Noxious stimulation was induced by intra-plantar injection of Complete Freund's adjuvant (CFA), on postnatal days (P) 1 (group P1), 8 (P8) or 21 (P21). Control animals were not stimulated in any way. On P21 a subset of animals from each group received BrdU and was perfused on P40 for identification of proliferating cells in the granule cell layer of the dentate gyrus. Another subset of rats was subjected to behavioral testing on P40 and one week later, to magnetic resonance imaging (MRI) acquisition. Noxious stimulation evoked hypoalgesia in adolescents, mainly in females (P < 0.02), reflected by greater latency to withdraw the paw and less paw lickings in the hot plate test than controls (P < 0.001). It also resulted in more time spent in the open arms, e.g., less anxiety-like behavior than controls (P < 0.01), especially in females (P < 0.01, compared with males). Proliferative cell rate in the dentate gyrus was the highest in P8 males and females (P < 0.001), with males exhibiting more proliferation than females on P1 and P8, which was directly related to the hippocampal levels of BDNF and inversely related to plasma corticosterone. Sex differences were also detected in manganese-enhanced MRI signal, which was more prominent in P1 females than males (P < 0.01). This study represents the first step of investigation on the cellular basis of the sex-dependent long-term consequences of nociceptive stimuli in newborns.

Pain prevalence, intensity, assessment and management in a hospitalized pediatric population

New research, regulatory guidelines, and practice initiatives have improved pain management in infants, children, and adolescents, but obstacles remain. The aim of this study was to identify the prevalence and demographics of pain, as well as pain management practice patterns in hospitalized children in a tertiary-care university hospital. We prospectively collected data including patient demographics, presence/absence and location of pain, pain intensity, pain assessment documentation, analgesic use, side effects of analgesic therapy, and patient/family satisfaction. Two hundred male (58%) and female, medical and surgical (61%) patients, averaging 9 ± 6.2 years were studied. Pain was common (86%) and often moderate to severe (40%). Surgical patients reported pain more frequently when enrolled than did medical patients (99% vs. 65%). Female gender, age ≥ 5 years, and Caucasian race were all associated with higher mean pain scores. Furthermore, females and Caucasian children consumed more opioids than males and non-Caucasians. Identified obstacles to optimal analgesic management include lack of documented physician pain assessment (<5%), a high prevalence of "as needed" analgesic dosing, frequent opioid-induced side effects (44% nausea and vomiting, 27% pruritus), and patient/family dissatisfaction with pain management (2%-7%). The data demonstrated that despite a concentrated focus on improving pain management over the past decade, pain remains common in hospitalized children. Identification of patient populations and characteristics that predispose to increased pain (e.g., female, Caucasian, postoperative patient) as well as obstacles to analgesic management provide a focus for the development of targeted interventions and research to further improve care.

Does past pain influence current pain: biological and psychosocial models of sex differences

Previous studies have generally indicated sizeable sex differences for both laboratory pain reactivity and clinical pain reports. Numerous biological and psychosocial models have been invoked to account for these findings, but the laboratory and clinical findings have generally been examined in isolation. This paper reviews data which show a relationship between past clinical pain experiences and current responses to experimentally induced pain. Individuals with a greater pain history tend to show lower pain tolerance. Since women often have high pain experience levels and lower pain tolerance, one might ask whether the two factors are related. We review several models, based upon concepts of neonatal differences in pain reactivity, hypervigilance following early pain experiences, and concepts of peripheral and central sensitization or plasticity which might help to bridge the gap between clinical and experimental findings.

Current states of opinion and future directions on the epidemiology of sex differences in human pain

One of the most commonly neglected findings in the human pain literature is the observation of sex differences in the mechanisms that support the phenotypic expression of pain. The present commentary describes an assessment of the prevalence of observed sex differences in various pain processes, and of how expert pain researchers interpret the epidemiology and, hence, the proximate and ultimate causes of such differences. Forty-two pain investigators completed an anonymous survey on the epidemiology of sex differences in the human pain experience. Investigator responses indicated that sex differences are pervasive across various areas of pain research, that sex differences are particularly pronounced in the area of situational influences on pain behaviors, and that contemporary pain researchers largely disagree on the epidemiology of, and hence, proximate and ultimate causes of the differences. The relevance of social situational factors on sex differences in pain behaviours is discussed in the context of evolutionary, developmental, social psychology and pain sensory systems that may function, in part, for regulating interpersonal intimacy.

Fatores que influenciam a prática do profissional de saúde no manejo da dor do recém-nascido

OBJETIVO: Apresentar revisão sobre as principais variáveis que podem influenciar as ações e as atitudes dos profissionais de saúde no manejo adequado da dor no período neonatal. FONTES DOS DADOS: Pesquisa bibliográfica, nas bases de dados Medline, SciELO e Lilacs, entre 1995 e 2009, restrita aos artigos escritos em inglês e português. Foram utilizados os seguintes descritores: "dor", "Terapia Intensiva Neonatal" e "profissional de Saúde". Avaliaram-se 88 artigos, sem seleção pelo desenho, sendo incluídos os 55 mais relevantes e recentes. SÍNTESE DOS DADOS: Os estudos confirmaram que o manejo da dor no neonato pelos profissionais de saúde é inadequado. Essa prática pode estar relacionada aos seguintes fatores: conhecimento insuficiente quanto à fisiopatologia da dor; não utilização de métodos de avaliação; falta de normatização sistemática ou protocolos; e falha na comunicação e incorporação da teoria na prática diária por parte da equipe multiprofissional. São acrescidos ainda os fatores subjetivos, pessoais e profissionais, que podem interferir na avaliação e no tratamento da dor no recém-nascido. CONCLUSÕES: Os obstáculos para um manejo adequado da dor são multifatoriais e o conhecimento das atitudes e crenças das equipes de saúde que trabalham com neonatos é muito importante. Há necessidade de investimentos na capacitação, formação e sensibilização dos profissionais acerca do controle e do tratamento da dor, com o intuito de proporcionar um cuidado mais humanizado ao neonato.

Assessment of acute pain in children: development of evidence-based guidelines

AIM

Detecting children's pain in a healthcare setting can be improved by facilitating pain expression in ways that are appropriate to the child's cognitive development and that can be recognised by their carers. To ensure up-to-date guidance on assessing pain in children, the Royal College of Nursing undertook an evidence-based update of pain assessment guidelines, initially published in 2000.

METHODS

Following systematic review of the psychometric testing literature, a two-stage critical appraisal process was developed to derive a list of robust tools that could be recommended for use in a variety of settings to assess the intensity of a child's acute pain. Studies were appraised on the basis of their relevance to this topic and according to prespecified quality criteria. Tools were assessed for inclusion in guideline recommendations according to minimum validity and reliability thresholds.

RESULTS

Overall the quality of literature was poor, limited by small samples, lack of control groups, unblinded raters and convenience sampling. Twenty-four tools are recommended for use with infants and verbal children without cognitive impairment, 11 of which are purely self-report tools. Eight tools are recommended for use with neonates, some of which require concurrent physiological measures. Four tools are considered valid for use in children with cognitive impairment. All of these tools had shown reliability and validity according to the criteria established for this review.

CONCLUSION

The tools are presented in user-friendly tables that include a guide to their key features and the setting and age groups in which they have been validated. They are accompanied by good practice recommendations from experts and recommendations relating to timing and triggers for pain assessment. These outputs are some of those associated with the full guidelines and supporting material published on the Royal College of Nursing website (http://www.rcn.org.uk/childrenspainguideline).

Effect of gender and hand laterality on pain processing in human neonates

BACKGROUND

Previous studies in adults have reported that handedness and gender can affect pain perception. However, it is currently unclear when these differences emerge in human development. Therefore, we examined prefrontal responses to pain stimulation among newborns during their first acute pain experience after birth.

METHODS

Forty newborns at 4-6 days postnatal age were observed during clinically required blood sampling while prefrontal activation was measured with near infrared spectroscopy. Blood sampling in this study was the first experience of a procedure involving skin breaking for these infants. We divided subjects into a right-hand stimulation group (n=21) and a left-hand stimulation group (n=19), depending on whether blood was sampled from the right or the left hand. A three-way analysis of variance (ANOVA) was conducted to examine the effects of several variables on the magnitude of the oxy-Hb value in response to pain stimulus, including stimulus side (right hand or left hand), gender (male or female), recording side (right prefrontal area or left prefrontal area) and interactions between these variables.

RESULTS

The data revealed a significant effect of stimulus side (F (1, 72)=9.892, P=0.002), showing that the right-hand stimulation induced a greater prefrontal activation than the left-hand stimulation. No significant gender difference or interactions were found.

CONCLUSION

Our findings suggest that hand laterality affects pain perception even in neonates. However, gender differences in pain perception did not appear to occur during the neonatal period. Further investigations using brain-imaging techniques are required to identify laterality- or gender-related differences in pain processing in humans.

Oral glucose solution as pain relief in newborns: results of a clinical trial

BACKGROUND

It was long believed that newborns could not experience pain. As it is now documented that newborns have all the necessary systems to perceive pain, pain management can no longer be ignored. The objective of this study is to investigate which concentration of glucose is most effective in reducing pain for venipuncture in the newborn.

METHODS

This double-blind clinical trial of 304 newborns was conducted on a maternity and neonatal ward (neonatal medium intensive care unit). During at least 1 month, one of the four selected solutions (10, 20, 30% glucose, and placebo) was administered orally, 2 minutes before the venipuncture was performed. The pain from the skin puncture was scored using a validated pain scale (the "Leuven Pain Scale").

RESULTS

This study showed a significantly lower average pain score in the 30 percent glucose group (3.99) when compared with the placebo group (8.43). The average pain scores in the 20 percent glucose group (5.26) and the 10 percent glucose group (5.92) were also significantly lower than those in the placebo group.

CONCLUSION

Oral administration of 2 mL of 30 percent glucose 2 minutes before the venipuncture provides the most effective pain reduction in newborns.

Tolerance and withdrawal from prolonged opioid use in critically ill children

OBJECTIVE

After prolonged opioid exposure, children develop opioid-induced hyperalgesia, tolerance, and withdrawal. Strategies for prevention and management should be based on the mechanisms of opioid tolerance and withdrawal.

PATIENTS AND METHODS

Relevant manuscripts published in the English language were searched in Medline by using search terms "opioid," "opiate," "sedation," "analgesia," "child," "infant-newborn," "tolerance," "dependency," "withdrawal," "analgesic," "receptor," and "individual opioid drugs." Clinical and preclinical studies were reviewed for data synthesis.

RESULTS

Mechanisms of opioid-induced hyperalgesia and tolerance suggest important drug- and patient-related risk factors that lead to tolerance and withdrawal. Opioid tolerance occurs earlier in the younger age groups, develops commonly during critical illness, and results more frequently from prolonged intravenous infusions of short-acting opioids. Treatment options include slowly tapering opioid doses, switching to longer-acting opioids, or specifically treating the symptoms of opioid withdrawal. Novel therapies may also include blocking the mechanisms of opioid tolerance, which would enhance the safety and effectiveness of opioid analgesia.

CONCLUSIONS

Opioid tolerance and withdrawal occur frequently in critically ill children. Novel insights into opioid receptor physiology and cellular biochemical changes will inform scientific approaches for the use of opioid analgesia and the prevention of opioid tolerance and withdrawal.

A socio-relational framework of sex differences in the expression of emotion

Despite a staggering body of research demonstrating sex differences in expressed emotion, very few theoretical models (evolutionary or non-evolutionary) offer a critical examination of the adaptive nature of such differences. From the perspective of a socio-relational framework, emotive behaviors evolved to promote the attraction and aversion of different types of relationships by advertising the two most parsimonious properties of reciprocity potential, or perceived attractiveness as a prospective social partner. These are the individual's (a) perceived capacity or ability to provide expedient resources, or to inflict immediate harm onto others, and their (b) perceived trustworthiness or probability of actually reciprocating altruism (Vigil 2007). Depending on the unique social demands and relational constraints that each sex evolved, individuals should be sensitive to advertise "capacity" and "trustworthiness" cues through selective displays of dominant versus submissive and masculine versus feminine emotive behaviors, respectively. In this article, I introduce the basic theoretical assumptions and hypotheses of the framework, and show how the models provide a solid scaffold with which to begin to interpret common sex differences in the emotional development literature. I conclude by describing how the framework can be used to predict condition-based and situation-based variation in affect and other forms of expressive behaviors.

Expressive dimensions of pain catastrophizing: An observational study in adolescents with chronic pain

Investigated was the relationship between pain catastrophizing and pain intensity in adolescents suffering from chronic pain (n = 38) and the extent to which they expressed communicative pain and pain-related protective behaviours. Adolescents were observed on video performing a 2-Min Walk Test (2MWT). Behaviours were coded on videotape. The adolescents' verbalizations about the 2MWT were also rated by their parents. Analyses revealed that higher levels of catastrophic thinking about pain were associated with higher levels of facial pain expressions and verbalizations about their pain experience, beyond the effects of age, gender, pain duration and pain intensity. Pain-related protective behaviours did not vary with the adolescents' level of pain catastrophizing, but varied with pain intensity. The findings corroborate the functional distinctiveness of different types of pain behaviours. The results are discussed in terms of the processes linking (1) catastrophizing to communicative pain behaviours and (2) pain to pain-related protective behaviours.

The behavioral pain response to heelstick in preterm neonates studied longitudinally: description, development, determinants, and components

OBJECTIVES

Preterm infants often experience multiple painful procedures during their stay in neonatal intensive care units (NICUs). The objectives of this study were to evaluate behavioral responses to heelstick in preterm newborns, characterize developmental changes and the effects of other demographic and clinical variables on the pain response, and estimate the contributions of individual Neonatal Infant Pain Scale (NIPS) behaviors to the summary pain score.

METHODS

A longitudinal study was conducted to evaluate the behavioral responses of 35 preterm newborns to multiple heelstick procedures during their stay in the NICU. Sixty-one video recordings of blood collection by heel lance were evaluated for behavioral pain response using the NIPS. Generalized linear mixed models were calculated to address the study objectives.

RESULTS

The increases in NIPS scores from the baseline to the blood draw were highly significant (mean baseline score=3.34, mean blood draw score=5.45, p<0.001). The newborns' pain responses increased an average of 0.23 points on the NIPS scale each week (p=0.002). Lower NIPS scores during the heelstick procedure were associated with four clinical variables: younger post-menstrual age at birth, lower birthweight, mechanical ventilation, and longer length of stay in the NICU. Crying, arousal state, and facial grimace contributed more than 85% of the increase in NIPS scores during the heelstick procedure.

DISCUSSION

While behavioral responses to pain are attenuated in young, severely ill preterm newborns, they can be reliably detected. The most robust pain behaviors are crying, changes in arousal state, and facial grimacing.

Developmental changes in the responses of preterm infants to a painful stressor

The purpose of this investigation was to examine longitudinally gestational age and developmental differences in preterm infants' self-regulatory abilities in response to a painful stressor, as well as associations between behavioral and cardiovascular responses. Participants included 49 healthy premature infants. Behavioral and cardiovascular responses to a heel stick blood draw were compared between infants of 28-31 and 32-34 weeks' gestation age at birth. Both gestational age groups displayed behavioral and cardiovascular indications of stress in response to the blood draw. However, both shortly after birth and several weeks later, infants born at younger gestational ages (28-31 weeks) were more physiologically reactive. Evidence that the behavioral stress responses of 28-31 weeks' gestation age group preterm infants do not reflect their physiological responses suggests that evaluation of preterm infants' experiences and risk require assessments of both physiology and behavior. The greater stress vulnerability of the 28-31 weeks' gestation group relative to the 32-34 weeks' gestation group and the implications of this for subsequent development are discussed.

Studying sex and gender differences in pain and analgesia: a consensus report

In September 2006, members of the Sex, Gender and Pain Special Interest Group of the International Association for the Study of Pain met to discuss the following: (1) what is known about sex and gender differences in pain and analgesia; (2) what are the "best practice" guidelines for pain research with respect to sex and gender; and (3) what are the crucial questions to address in the near future? The resulting consensus presented herein includes input from basic science, clinical and psychosocial pain researchers, as well as from recognized experts in sexual differentiation and reproductive endocrinology. We intend this document to serve as a utilitarian and thought-provoking guide for future research on sex and gender differences in pain and analgesia, both for those currently working in this field as well as those still wondering, "Do I really need to study females?"