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

Classification of Individual Pain Response Trajectories Following Medically Indicated Heel Lances in Preterm Infants During Their NICU Admission

OBJECTIVES

Infants born preterm are exposed to repeated painful procedures during neonatal intensive care unit admission. Particularly in preterm infants, trajectories of pain response are not well understood. The aim of this study was to classify pain response trajectories over 2 minute following medically indicated heel lances in preterm infants.

MATERIALS AND METHODS

This study used existing clinical trial data (NCT01561547) that evaluated the efficacy of kangaroo care and sucrose for infant pain control. Pain was measured using the Premature Infant Pain Profile at 30, 60, 90, and 120 seconds following a heel lance. Group-based trajectory modeling was used to classify pain response in this 2 minute period.

RESULTS

A total of 236 infants with median gestational age of 33 weeks contributed 610 procedures. A model with 5 trajectory classes best fit the data. Three trajectories were stable over time at different levels of intensity from low-mild to low-moderate pain. One trajectory reflected a linear reduction from high-moderate to low-moderate pain. The final trajectory showed variable moderate-high pain. At all times points, 3 classes were at least 1-point different from the overall sample mean pain score. Only 21 (9%) infants maintained the same class for all 3 procedures.

DISCUSSION

In this sample of preterm infants receiving pain relief, most pain trajectories reflected mild to low-moderate pain that was stable over 2 minute after heel lance initiation. Trajectories were not consistent over multiple procedures within infants, and an overall mean pain score for the sample may misrepresent subgroups of pain response.

Pain in Preterm Infants: Different Perspectives

In the last decades, there has been a tremendous change in approaching and managing neonates' pain. These changes began with rebutting the previous misconception about neonates' , particularly preterm infants' , pain. The development in neuroimaging has revealed that by 24 weeks of gestation the peripheral nervous system is mature and function fully. Researchers now know that neonates experience pain and premature infants have even lower pain thresholds. Since that time, a mounting amount of literature has addressed the issue of neonatal pain. Many pharmacological and non pharmacological pain reduction strategies have been investigated for their safety and analgesic effectiveness. Many interventions such as nonnutritive sucking (NNS), skin-to-skin contact (SSC), and facilitated tucking are effective in controlling neonates pain.

Factors influencing the occurrence of neonatal procedural pain

OBJECTIVES

The objective of this study was to describe the occurrence of neonatal procedural pain and explore the factors that influence the frequency of painful procedures.

DESIGN

A descriptive prospective epidemiologic study.

SETTING

NICU at a general hospital in China.

METHODS

A demographic and diagnosis or illness information questionnaire and an occurrence of procedural pain questionnaire specifically designed for this study were used to record the current status of neonatal procedural pain. The neonatal infant pain scale (NIPS) was used to measure pain intensity. A multiple linear regression model was used to explore the factors influencing the frequency of painful procedures.

RESULTS

One hundred and twenty neonates experienced a total of 16,840 painful procedures. Each neonate was exposed to a median (IQR) of 66.5(27,154.75) painful procedures during hospitalization and a median (IQR) of 13(11, 19) painful procedures. All 27 different procedures were considered painful, and 70.37% (19/27) of these procedures caused severe pain. Overall, the mean NIPS score of the 27 procedures was 5.04 ± 1.52 with a range from 0 to 7. Respiratory support, age, and length of hospital stay were factors influencing the frequency of painful procedures.

CONCLUSIONS

NICU neonates experience pain at a high frequency and intensity during hospitalization. Respiratory support, age, and length of hospital stay were factors influencing the frequency of painful procedures. Strategies are needed to bridge the gap between practice and the evidence-based guidelines.

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.

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.

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.

Dimensioning of painful procedures and interventions for acute pain relief in premature infants

Objective:

to dimension the exposure of premature infants to painful procedures, relating the distribution of the exposure to contextual factors, as well as to describe the pharmacological and non-pharmacological interventions health professionals use during the first two weeks of the infant’s hospitalization at two neonatal services.

Method:

descriptive-exploratory study in which the professionals registered the painful procedures and pain relief interventions on a specific form in the patient file.

Results:

the daily average of the 89 premature infants was 5.37 painful procedures, corresponding to 6.56 during the first week of hospitalization and 4.18 during the second week (p&lt;0.0001). The most frequent procedures were nasal/oral (35.85%) and tracheal aspirations (17.17%). The children under invasive ventilation were the most exposed to painful procedures (71.2%). Only 44.9% of the painful procedures received some intervention for the purpose of pain relief, the most frequent being sucrose (78.21%) and continuing sedation (19.82%).

Conclusion:

acute pain was undertreated at these neonatal services, recommending greater sensitization of the team for the effective use of the existing protocol and implementation of other knowledge transfer strategies to improve neonatal pain management.

Individual contextual factors in the validation of the Bernese pain scale for neonates: protocol for a prospective observational study

Background

The Bernese Pain Scale for Neonates (BPSN) is a multidimensional pain assessment tool that is already widely used in clinical settings in the German speaking areas of Europe. Recent findings indicate that pain responses in preterm neonates are influenced by individual contextual factors, such as gestational age (GA), gender and the number of painful procedures experienced. Currently, the BPSN does not consider individual contextual factors. Therefore, the aim of this study is the validation of the BPSN using a large sample of neonates with different GAs. Furthermore, the influence of individual contextual factors on the variability in pain reactions across GA groups will be explored. The results will be used for a modification of the BPSN to account for individual contextual factors in future clinical pain assessment in neonates.

Methods and design

This prospective multisite validation study with a repeated measures design will take place in three university hospital neonatal intensive care units (NICUs) in Switzerland (Bern, Basel and Zurich). To examine the impact of GA on pain responses and their variability, the infants will be stratified into six GA groups ranging from 24 0/7 to 42 0/7. Among preterm infants, 2–5 routine capillary heel sticks within the first 14 days of life, and among full-term infants, two heel sticks during the first days of life will be documented. For each heel stick, measurements will be video recorded for each of three phases: baseline, heel stick, and recovery. The infants’ pain responses will be rated according to the BPSN by five nurses who are blinded as to the number of each heel stick and as to the measurement phases. Individual contextual factors of interest will be extracted from patient charts.

Discussion

Understanding and considering the influence of individual contextual factors on pain responses in a revised version of the BPSN will help the clinical staff to more appropriately assess pain in neonates, particularly preterm neonates hospitalized in NICUs. Pain assessment is a first step toward appropriate and efficient pain management, which itself is an important factor in later motor and cognitive development in this vulnerable patient population.

Trial registration

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

Development of Accumulated Pain/Stressor Scale (APSS) in NICUs: A National Survey

High-risk neonates experience numerous painful/stressful procedures daily in neonatal intensive care units (NICUs). Accumulated pain and stress have a detrimental impact on infants' neurodevelopment. Few valid tools are available to measure accumulated pain/stressors among NICU infants. The aim of this study was to obtain nurses' perceptions about severity and acuity levels regarding each painful/stressful procedure that infants may experience in the NICU. The data will support developing a new instrument, the Accumulated Pain/Stressor Scale (APSS) in NICUs. A nationwide online survey was conducted through the U.S. National Association of Neonatal Nurses membership. Respondents were asked to rate the perceived severity of pain/stress associated with 68 procedures using a 5-point Likert scale and to categorize pain/stress as acute or chronic. Modal values were used to determine summary rankings among the procedures. Eighty-four neonatal nurses completed the survey. Among 68 procedures, nearly all were rated as painful/stressful to some degree. Five procedures (7%) had a modal value of five (extremely painful/stressful), nine (14%) had a value of four, 20 (29%) had a value of three, 30 (44%) a value of two, and four (6%) had a value of one (not painful/stressful). Forty-four procedures (65%) were perceived as acute, six (9%) as chronic, and 18 (26%) as both acute and chronic. Nurses' perceptions of pain severity and acuity regarding procedures in NICUs varied somewhat. Further studies are needed in developing and validating the scale. The development of the APSS can quantitatively measure the accumulated neonatal pain/stress.

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.