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

Contextual factors associated with neonatal pain responses: clinical observational study

Objectives

This study aimed to identify the contextual factors of neonatal pain responses and provide clinical medical staff with evidence regarding effective means of evaluating neonatal pain and strengthen clinical pain management.

Methods

Two trained nurses independently used the Neonatal Infant Pain Scale (NIPS) to assess the pain scores of 198 neonates after they underwent painful medical procedures. Univariate linear regression analysis was performed to analyze the correlation between contextual factors and NIPS scores. Variables with statistically significant differences (p < 0.2) after univariate linear regression analysis were selected as independent variables, and the NIPS score was used as the dependent variable. Multiple linear regression was used to determine the salient factors associated with neonatal pain responses. This study was registered at the Chinese Clinical Trial Registry (ChiCTR2300074086).

Results

Univariate linear regression analysis showed that the NIPS scores were associated with days after birth, types of painful procedures, Apgar scores at 1 min after birth, and gestational age (GA) (p < 0.2). Multiple regression analysis showed that Apgar score at 1 min after birth (β = 0.272, p < 0.001) and GA (β = 0.503, p < 0.001) were independent associated factors of neonatal pain responses. Neonates with low Apgar scores at 1 min after birth and younger GA had less pronounced pain responses.

Conclusions

The Apgar score at 1 min after birth and GA affected the neonatal pain responses. In this regard, the current clinical method of pain assessment solely through observation of neonatal pain responses is occasionally inaccurate. The Apgar score at 1 min after birth and GA should be considered in determining the neonatal pain status and hence enhance the quality of neonatal pain management.

Pain-related changes in crSO2 among premature infants undergoing PICC insertion

OBJECTIVE

To evaluate the effectiveness of cerebral regional oxygen saturation (crSO₂) values, measured using near-infrared spectroscopy (NIRS), in assessing pain associated with the peripherally inserted central catheter (PICC) in premature infants.

METHODS

NIRS was used to measure the crSO₂ levels of 48 premature infants with gestational age (GA) of < 32 weeks or a birth weight of < 1500 g. Premature infant pain profile (PIPP) scores, vital signs, transcutaneous oxygen tension (TcpO₂), transcutaneous carbon dioxide tension (TcpCO₂), and crSO₂ values were monitored. One-way repeated measure analysis of variance was used to compare heart rate (HR), respiratory rate (RR), blood pressure (BP), peripheral oxygen saturation (SpO₂), TcpO₂, TcpCO₂, and crSO₂ values before (Time 1), during (Time 2), and after (Time 3) PICC insertion. The correlation between the PIPP scores at Time 2 and the fluctuations (values detected at Time 2 minus those at Time 1) of SpO_2, TcpO_2, and crSO₂ were also analyzed.

RESULTS

The PIPP score at Time 2 was significantly higher than those at Times 1 and 3. HR, RR, and BP values increased (p < .05), and SpO₂ and crSO₂ levels decreased at Time 2 (p < .05) compared with those at Time 1. Stratified analysis based on GA revealed significant differences in HR, RR, and crSO₂ values between Times 1 and 2 in infants with a GA of ≥ 32 weeks. In infants with a GA < 32 weeks, significant differences were observed in HR, RR, SpO₂, BP, and crSO₂ values between Times 1 and 2. The fluctuation of the crSO₂ level was strongly correlated with the PIPP score at Time 2 (r = -0.829, p < .001). A weak correlation was observed between the PIPP score at Time 2 and TcpO₂ level fluctuation (r = 0.375, p = .009). No correlation was observed between the PIPP score at Time 2 and SpO₂ level fluctuation (r = 0.242, p = .097).

CONCLUSION

The fluctuation of crSO₂ levels strongly correlates with PICC procedural pain. Hence, crSO₂ levels measured using NIRS may be used as an indicator for pain assessment in premature infants.

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

ABSTRACT

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

Pain Scales in Neonates Receiving Mechanical Ventilation in Neonatal Intensive Care Units - Systematic Review

INTRODUCTION

Recently, interest in the problem of proper prevention and monitoring of pain, especially acute, has been increasing in relation to various age groups. Greater awareness of the problem prompts discussion about the purpose of analgesia in newborns treated with mechanical ventilation.

AIM

The purpose of the systematic review was to analyze current research on the use of pain scales in newborns treated with mechanical ventilation in the Neonatal Intensive Care Unit.

METHODS

Medline databases: PubMed, OVID, EBSCO, Web of Science and Cochrane Library were traced using the appropriate keywords. The search was limited to studies in English. The review took into account the years 2006-2019. Considering the criteria, 12 articles were included in further analysis, to which full access was obtained.

RESULTS

The analyzed scientific research showed differences in beliefs about the validity and credibility of the scales used. Researchers indicated that staff with practical experience in using scales in their daily practice was very skeptical of the results obtained on their basis.

CONCLUSION

Based on this review, no explicit evidence can be obtained to support the use of one proper scale in pain assessment. It can be inferred that the COMFORT and N-PASS scales are effective for pain assessment and for determining the need for analgesics in mechanically ventilated neonates. These scales may be equally effective in assessing chronic pain, especially in mechanically ventilated children. On the other hand, the PIPP and CRIES scales are most commonly recommended for assessing acute and postoperative pain.

Methodological Issues in the Study of the Development of Pain Responsivity in Preterm Neonates: A Systematic Review

The study of the development of neonatal pain responses is of key importance, both for research and for clinical reasons, with particular regard to the population of preterm neonates, given the amount of painful procedures they are exposed to on a daily basis. The aim of this work was to systematize our knowledge about the development of pain responses in prematurely born neonates by focusing on some key methodological issues. Studies on the impact of age variables, namely gestational age (GA), postmenstrual age (PMA) and chronological age (CH), on pain responsivity in premature neonates were identified using Medline and Scopus. Studies (N = 42) were categorized based on terminological and methodological approaches towards age variables, and according to output variables considered (facial, nonfacial behavioral, physiological). Distinct multidimensional developmental patterns were found for each age-sampling strategy. Overall, each of the three age variables seems to affect pain responsivity, possibly differently across age windows. Targeted as well as integrated approaches, together with a renewed attention for methodological consistency, are needed to further our knowledge on this topic.

Acute pain measured with the modified Bernese Pain Scale for Neonates is influenced by individual contextual factors

BACKGROUND

Individual contextual factors like gestational age (GA) or previous painful experiences have an influence on neonates' pain responses and may lead to inaccurate pain assessment when not appropriately considered.

OBJECTIVES

We set out to determine the influence of individual contextual factors on variability in pain response in neonates, measured with the modified Bernese Pain Scale for Neonates (BPSN), and, if necessary, to incorporate relevant individual factors into a revised version of the BPSN.

METHODS

We videotaped 154 full-term and preterm neonates of different GAs during 1-5 capillary heel sticks in their first 14 days of life. For each heel stick, we produced three video sequences: baseline, heel stick, and recovery. The randomized sequences were rated on the BPSN by five blinded nurses. Individual contextual factors were retrospectively extracted from patient charts and from the video recordings. We analysed the data in single and multiple linear mixed models.

RESULTS

Premature birth (b = -0.721), caffeine (b = -0.302), and the behavioural states quiet and awake (b = -0.283), active and asleep (b = -0.158), and quiet and asleep (b = -0.498) were associated with changes in behavioural pain scores. Premature birth (b = -0.232), mechanical ventilation (b = -0.196), and duration of the heel stick procedure (b = 0.0004) were associated with changes in physiological pain scores. Premature birth (b = -0.907), Caffeine (b = -0.402), the behavioural states quiet and awake (b = -0.274), and quiet and asleep (b = -0.459), and duration of the heel stick procedure (b = 0.001) were associated with changes in the modified BPSN total scores.

CONCLUSIONS

Postmenstrual age, behavioural state, caffeine, and ventilation status have an influence on neonates' pain response and should be incorporated in the revised BPSN to enhance clinical pain assessment in neonates with different GAs.

SIGNIFICANCE

We identified individual contextual factors associated with dampened pain response in neonates and will incorporate them into a revised version of the Bernese Pain Scale for Neonates to provide clinicians with a tool they can use to more accurately assess and manage pain in this vulnerable population.

Effectiveness of Sucrose Used Routinely for Pain Relief and Neonatal Clinical Risk in Preterm Infants: A Nonrandomized Study

BACKGROUND

Preterm infants (PI) requiring the neonatal intensive care unit are exposed to early repetitive pain/distress. Little is known about how pain relief strategies interact with infants' clinical health status, such as severity of illness with pain responses. This study aimed to examine main and interactive effects of routine sucrose intervention and neonatal clinical risk (NCR) on biobehavioral pain reactivity-recovery in PI during painful blood collection procedures.

METHODS

Very low birth weight PI (<1500 g; n=104) were assigned to low and high clinical risk groups, according to the Clinical Risk Index for Babies. Sucrose group (n=52) received sucrose solution (25%; 0.5 mL/kg) 2 minutes before the procedures and control group received standard care. Biobehavioral pain reactivity-recovery was assessed according to the Neonatal Facial Coding System, sleep-wake state scale, crying time, and heart rate at 5 phases (baseline, antisepsis, puncture (P), recovery-dressing, and recovery-resting [R]). Repeated measure ANOVA with mixed-design was performed considering pain assessment phases, intervention group, and NCR.

RESULTS

Independent of NCR, sucrose presented main effect in decreasing neonates' facial activity pain responses and crying time, during P and R. Independent of NCR level or routine sucrose intervention, all neonates displayed activated state in P and decreased biobehavioral responses in R phase. Although no sucrose or NCR effects were observed on physiological reactivity, all neonates exhibited physiological recovery 10 minutes after P, reaching the same heart rate patterns as the baseline.

CONCLUSIONS

Independent of NCR level, sucrose intervention for pain relief during acute painful procedures was effective to reduce pain intensity and increase biobehavioral regulation.

The influence of gestational age in the psychometric testing of the Bernese Pain Scale for Neonates

BACKGROUND

Assessing pain in neonates is challenging because full-term and preterm neonates of different gestational ages (GAs) have widely varied reactions to pain. We validated the Bernese Pain Scale for Neonates (BPSN) by testing its use among a large sample of neonates that represented all GAs.

METHODS

In this prospective multisite validation study, we assessed 154 neonates between 24 2/7 and 41 4/7 weeks GA, based on the results of 1-5 capillary heel sticks in their first 14 days of life. From each heel stick, we produced three video sequences: baseline; heel stick; and, recovery. Five blinded nurses rated neonates' pain responses according to the BPSN. The underlying factor structure of the BPSN, interrater reliability, concurrent validity with the Premature Infant Pain Profile-Revised (PIPP-R), construct validity, sensitivity and specificity, and the relationship between behavioural and physiological indicators were explored. We considered GA and gender as individual contextual factors.

RESULTS

The factor analyses resulted in a model where the following behaviours best fit the data: crying; facial expression; and, posture. Pain scores for these behavioural items increased on average more than 1 point during the heel stick phases compared to the baseline and recovery phases (p < 0.001). Among physiological items, heart rate was more sensitive to pain than oxygen saturation. Heart rate averaged 0.646 points higher during the heel stick than the recovery phases (p < 0.001). GA increased along with pain scores: for every additional week of gestation, the average increase of behavioural pain score was 0.063 points (SE = 0.01, t = 5.49); average heart rate increased 0.042 points (SE = 0.01, t = 6.15). Sensitivity and specificity analyses indicated that the cut-off should increase with GA. Modified BPSN showed good concurrent validity with the PIPP-R (r = 0.600-0.758, p < 0.001). Correlations between the modified behavioural subscale and the item heart rate were low (r = 0.102-0.379).

CONCLUSIONS

The modified BPSN that includes facial expression, crying, posture, and heart rate is a reliable and valid tool for assessing acute pain in full-term and preterm neonates, but our results suggest that adding different cut-off points for different GA-groups will improve the BPSN's clinical usefulness.

TRIAL REGISTRATION

The study was retrospectively registered in the database of Clinical Trial gov. Study ID-number: NCT 02749461 . Registration date: 12 April 2016.

Assessment of the intensity of procedural pain in newborns treated in the intensive care unit measured by the Neonatal Infant Pain Scale (NIPS)

<b>Introduction:</b> Newborns born prematurely and treated in intensive care units are at greater risk of experiencing pain than patients treated in other units. <b>Purpose:</b> To evaluate the severity of pain perceived by children during the performance of medical procedures related to the treatment and care process. <b>Materials and methods:</b> The study was conducted at one of the Intensive Care Units in Opole. The study group consisted of 100 newborns, 60% of the subjects were prematurely born newborns, and 40% - were full-term. The degree of procedural pain associated with blood collection, peripheral puncture insertion, upper respiratory tract suction, gastric tube insertion and ophthalmic examination was assessed by an observation method using the standard Neonatal Infant Pain Scale Form (NIPS). <b>Results:</b> Out of the analysed medical procedures, 100% of children experienced acute, severe pain over the course of suction and ophthalmological examination. The highest perception of pain was experienced by 88.3% of premature newborns and 71.8% of full-term newborns. Over the course of medical procedures, 84% of male and 79.6% female newborns experienced acute pain. It was shown that the degree of pain perception was determined by the type of performed medical procedure (p=0.001) and the gestational age of the newborn (p=0.037). On the other hand, there was no correlation between the sex of the newborn child and the degree of pain perception (p=0.758). <b>Conclusions:</b> Based on the foregoing study result, bearing in mind the need to minimise the effects of pain stimulation, it seems important to use standardised tools to assess the severity of pain in newborns treated in Intensive Care Units on a larger scale.

Non-pharmacological management of neonatal pain: Research and clinical practice in the Neonatal Intensive Care Unit

Abstract According to the World Health Organization and the International Association for the Study of Pain, pain is a relevant worldwide problem in the healthcare field. The present study aimed to describe the definition of pediatric pain and the main characteristics, and to examine the findings regarding the impact of pain on the development of the child. The best clinical practices in Neonatal Intensive Care Units should include developmental care and specifically implement pain management, aiming to protect the health and development of the infants. The efficacious non-pharmacological management of neonatal pain includes breastfeeding, skin-to-skin, non-nutritive sucking, facilitated-tucking and swaddling. Sweet solutions also have pain relief effects. Psychologists could actively participate in the implementation of non-pharmacological interventions and in the whole process to sensitize and train the professional teams, to alert parents to protection against pain and to support policymakers in the implementation of pain guidelines in the hospital.

Co-bedding in neonatal nursery for promoting growth and neurodevelopment in stable preterm twins

BACKGROUND

The increased birth rate of twins during recent decades and the improved prognosis of preterm infants have resulted in the need to explore measures that could optimize their growth and neurodevelopmental outcomes. It has been postulated that co-bedding simulates twins' intrauterine experiences in which co-regulatory behaviors between them are observed. These behaviors are proposed to benefit twins by reducing their stress, which may promote growth and development. However, in practice, uncertainty surrounds the benefit-risk profile of co-bedding.

OBJECTIVES

We aimed to assess the effectiveness of co-bedding compared with separate (individual) care for stable preterm twins in the neonatal nursery in promoting growth and neurodevelopment and reducing short- and long-term morbidities, and to determine whether co-bedding is associated with significant adverse effects.As secondary objectives, we sought to evaluate effects of co-bedding via the following subgroup analyses: twin pairs with different weight ranges (very low birth weight [VLBW] < 1500 grams vs non-VLBW), twins with versus without significant growth discordance at birth, preterm versus borderline preterm twins, twins co-bedded in incubator versus cot at study entry, and twins randomized by twin pair versus neonatal unit.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group (CNRG). We used keywords and medical subject headings (MeSH) to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2), MEDLINE (via PubMed), EMBASE (hosted by EBSCOHOST), the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and references cited in our short-listed articles, up to February 29, 2016.

SELECTION CRITERIA

We included randomized controlled trials with randomization by twin pair and/or by neonatal unit. We excluded cross-over studies.

DATA COLLECTION AND ANALYSIS

We extracted data using standard methods of the CNRG. Two review authors independently assessed the relevance and risk of bias of retrieved records. We contacted the authors of included studies to request important information missing from their published papers. We expressed our results using risk ratios (RRs) and mean differences (MDs) when appropriate, along with 95% confidence intervals (95% CIs). We adjusted the unit of analysis from individual infants to twin pairs by averaging measurements for each twin pair (continuous outcomes) or by counting outcomes as positive if developed by either twin (dichotomous outcomes).

MAIN RESULTS

Six studies met the inclusion criteria; however, only five studies provided data for analysis. Four of the six included studies were small and had significant limitations in design. As each study reported outcomes differently, data for most outcomes were effectively contributed by a single study. Study authors reported no differences between co-bedded twins and twins receiving separate care in terms of rate of weight gain (MD 0.20 grams/kg/d, 95% CI -1.60 to 2.00; one study; 18 pairs of twins; evidence of low quality); apnea, bradycardia, and desaturation (A/B/D) episodes (RR 0.85, 95% CI 0.18 to 4.05; one study; 62 pairs of twins; evidence of low quality); episodes in co-regulated states (MD 0.96, 95% CI -3.44 to 5.36; one study; three pairs of twins; evidence of very low quality); suspected or proven infection (RR 0.84, 95% CI 0.30 to 2.31; three studies; 65 pairs of twins; evidence of very low quality); length of hospital stay (MD -4.90 days, 95% CI -35.23 to 25.43; one study; three pairs of twins; evidence of very low quality); and parental satisfaction measured on a scale of 0 to 55 (MD -0.38, 95% CI -4.49 to 3.73; one study; nine pairs of twins; evidence of moderate quality). Although co-bedded twins appeared to have lower pain scores 30 seconds after heel lance on a scale of 0 to 21 (MD -0.96, 95% CI -1.68 to -0.23; two studies; 117 pairs of twins; I(2) = 75%; evidence of low quality), they had higher pain scores 90 seconds after the procedure (MD 1.00, 95% CI 0.14 to 1.86; one study; 62 pairs of twins). Substantial heterogeneity in the outcome of infant pain response after heel prick at 30 seconds post procedure and conflicting results at 30 and 90 seconds post procedure precluded clear conclusions.

AUTHORS' CONCLUSIONS

Evidence on the benefits and harms of co-bedding for stable preterm twins was insufficient to permit recommendations for practice. Future studies must be adequately powered to detect clinically important differences in growth and neurodevelopment. Researchers should assess harms such as infection, along with medication errors and caregiver satisfaction.

The Effect of Mother's Voice on Arterial Blood Sampling Induced Pain in Neonates Hospitalized in Neonate Intensive Care Unit

Background and Objective:

Due to devastating effects of pain in neonates, it is very important to ease it though safe and feasible methods. This study was to determine the effect of familiar auditory stimuli on the arterial blood sampling (ABS) induced pain in term neonates.

Research Method:

This study was done on 30 newborns hospitalized in neonate intensive care unit (NICU) of a hospital in Tehran. Research samples were selected by using convenience sampling and randomly divided into two groups of control and test. In the test group, the recorded mothers’ voices were played for the newborns before and after blood sampling procedure. Then, pain measures were recorded 10 minutes before, during and 10 minutes after blood collection based on Neonatal Infant Pain Scale (NIPS); then the pain level changes were reviewed and studied.

Findings:

The findings showed significant differences between the control and test groups that indicating the effect of mother’s voice on reducing the pain of neonates during the ABS (p<0.005).

Conclusion:

Research findings demonstrate that mother’s voice reduces ABS induced pain in the term neonates.

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.

Salivary biomarkers are not suitable for pain assessment in newborns

BACKGROUND AND AIMS

Newborns admitted to the neonatal intensive care unit are repeatedly subjected to painful or stressful procedures; therefore, objective assessment of their pain is essential. An increasing number of scales for neonatal pain assessment have been developed, many of which are based on physiological and behavioral factors. Recently, salivary biomarkers have been used to assess stress in adults and older infants. This study aimed to determine whether salivary biomarkers can be useful objective indices for assessing newborn pain.

STUDY DESIGN

A total of 47 healthy newborns were enrolled 3-4days after birth. Heel lancing was performed to collect blood for a newborn screening test. Before and after heel lancing, saliva was collected to analyze hormone levels, a video was recorded for behavioral observations, and heart rate was recorded. Two investigators independently assessed newborn pain from the video observations using the Neonatal Infant Pain Scale (NIPS). Salivary chromogranin (sCgA) and salivary amylase (sAA) levels were measured using an enzyme-linked immunosorbent assay kit and a dry chemistry system, respectively.

RESULTS

No definite changes in salivary biomarkers (sCgA or sAA) were detected before and after heel lancing. However, newborn sCgA levels were markedly higher than reported adult levels, with large inter- and intra-subject variability, whereas newborn sAA levels were lower than adult levels. NIPS score and heart rate were dramatically increased after heel lancing.

CONCLUSIONS

NIPS score (behavioral assessment) and heart rate are useful stress markers in newborns. However, neither sCgA nor sAA is suitable for assessing newborn pain.

Role of sucrose in reducing painful response to orogastric tube insertion in preterm neonates

OBJECTIVES

To study whether orogastric tube (OGT) insertion elicits a painful response in preterm neonates, and the role of oral sucrose in reducing this pain.

METHODS

This double blinded, randomized control trial was conducted in the neonatal intensive care units of Kalawati Saran Children's Hospital. Clinically stable preterms within the first 7 postnatal days, who had not received painful stimulus 30 min prior to intervention, and who required routine OGT insertion were included. Lingual 24 % sucrose or distilled water (1 ml) was administered 2 min before OGT insertion. The primary outcome was painful response assessed by Premature Infant Pain Profile scale (PIPP), while the secondary outcomes were heart rate and SpO2 changes. The trial is registered with ClinicalTrials.gov (

REGISTRATION NUMBER

NCT 00949104) RESULTS: Sixty preterms were randomized in each group. Final analysis was carried out on 52 subjects in the placebo group and 53 in the sucrose group. The mean intra-procedure PIPP scores were significantly higher than the mean pre-procedure PIPP scores, in the gestational age groups of more than 34 wk, and 32 wk to 33 wk, 6 d, in both the placebo (7.25 vs. 3, and 8.14 vs. 3.14, respectively) and sucrose arm (8.06 vs. 3.21, and 7.18 vs. 4.18, respectively). The mean PIPP scores assessed at 30 s post procedure in the sucrose group were significantly lower than the placebo group (4.32 vs. 5.6, p = 0.014). No significant adverse events were seen.

CONCLUSIONS

OGT insertion causes pain in preterms and single dose lingual 24 % sucrose may alleviate this pain.

Update on pain assessment in sick neonates and infants

This article describes developments in pain assessment in critically ill neonates and infants during the last 5 to 6 years. Pain assessment instruments show a redundancy of items and a lack of profound psychometric background. Although most research focuses primarily on acute pain, in clinical practice there is also the challenge of assessing prolonged and/or persisting pain. The effectiveness of pain assessment is still a matter of debate and has recently been challenged as a primary end point in analgesia-related trials. Integration of observation of behavior with reliable and specific neurobiology-based parameters remains a challenge.

Contextual factors associated with pain response of preterm infants to heel-stick procedures

BACKGROUND

Evidence indicates that medical and demographic contextual factors (cFs) impact pain responses in preterm neonates, but the existing evidence is very heterogeneous.

AIM

To explore the effect of cFs on pain responses to heel-stick procedures of preterm infants.

METHODS

This study was a secondary analysis of data collected during a randomized controlled trial examining pain response to non-pharmacological interventions across repeated heel sticks. Five heel sticks across the first 14 days of life were videotaped. Pain response was rated with the Bernese Pain Scale for Neonates (BPSN) by four raters blinded to the heel-stick phases (baseline, heel stick, recovery). Demographic and medical cFs were extracted from medical charts. Mixed single and multiple regression analyses were performed controlling for the intervention group, site and heel-stick phase.

RESULTS

Apgar scores at 1 min were negatively associated with behavioural (p = 0.002) BPSN scores, while Apgar scores at 5 min after birth were positively associated with behavioural (p = 0.006) scores. Accumulated number of painful procedures (p = 0.002) and gender (p = 0.02) were positively associated with physiological scores while continuous positive airway pressure CPAP (p = 0.009) and mechanical ventilation (p = 0.005) were negatively associated.

CONCLUSION

Higher exposure to painful procedures, male infants and having CPAP or mechanical ventilation were cFs associated with physiological response. The only variables significantly associated with behavioural BPSN scores were Apgar scores but these relationships were inconsistent.

Assessing pain in preterm infants in the neonatal intensive care unit: moving to a 'brain-oriented' approach

Preterm infants in the neonatal intensive care unit undergo repeated exposure to procedural and ongoing pain. Early and long-term changes in pain processing, stress-response systems and development may result from cumulative early pain exposure. So that appropriate treatment can be given, accurate assessment of pain is vital, but is also complex because these infants' responses may differ from those of full-term infants. A variety of uni- and multidimensional assessment tools are available; however, many have incomplete psychometric testing and may not incorporate developmentally important cues. Near-infrared spectroscopy and/or EEG techniques that measure neonatal pain responses at a cortical level offer new opportunities to validate neonatal pain assessment tools.

Contextual factors influencing pain response to heelstick procedures in preterm infants: what do we know? A systematic review

Major efforts to develop objective measurement tools for neonatal pain assessment have been made. However, the challenge of measuring pain in neonates remains suggesting that contextual factors (cFs) might alter their responses to pain. Although the role of cFs is increasingly discussed as crucial for pain assessment, they are not well described in the literature and are rarely considered in the clinical setting despite their importance.

AIM

To systematically examine studies investigating the impact of cFs on pain response in preterm infants.

METHOD

A literature search was undertaken for the period from 1990 to 2009. Studies reporting the relation between one or more cFs and pain response in preterm infants during a heelstick procedure were considered for inclusion.

RESULTS

Twenty-three studies satisfied inclusion criteria. The studies varied relative to their design, sample, analysis procedures, and variables examined. Six categories of cFs emerged: age, pain exposure, health status, therapeutic interventions, behavioral status, and demographic factors. The examined cFs varied in the strength of their association with pain response, although none were invariably related, as evidenced by contradictory findings. In some cases the inconsistencies appeared attributable to methodological limitations in studies. Behavioral and physiological pain responses were not always in agreement as would be expected.

CONCLUSION

This review supports the influence of some cFs on pain response. However, the results remain inconclusive which may be, in part, related to the heterogeneity of the studies. Contextual factors need further investigation for a better understanding of the magnitude of their effect on pain response.

Heart rate variability in response to pain stimulus in VLBW infants followed longitudinally during NICU stay

The objective of this longitudinal study, conducted in a neonatal intensive care unit, was to characterize the response to pain of high-risk very low birth weight infants (<1,500 g) from 23 to 38 weeks post-menstrual age (PMA) by measuring heart rate variability (HRV). Heart period data were recorded before, during, and after a heel lanced or wrist venipunctured blood draw for routine clinical evaluation. Pain response to the blood draw procedure and age-related changes of HRV in low-frequency and high-frequency bands were modeled with linear mixed-effects models. HRV in both bands decreased during pain, followed by a recovery to near-baseline levels. Venipuncture and mechanical ventilation were factors that attenuated the HRV response to pain. HRV at the baseline increased with post-menstrual age but the growth rate of high-frequency power was reduced in mechanically ventilated infants. There was some evidence that low-frequency HRV response to pain improved with advancing PMA.