Infants born very preterm react to variations of the acoustic environment in their incubator from a minimum signal-to-noise ratio threshold of 5 to 10 dBA

Continuous white noise exposure during sleep and childhood development: A scoping review

BACKGROUND

White noise machines are widely used as a sleep aid for young children and may lead to poor hearing, speech, and learning outcomes if used incorrectly.

OBJECTIVE

Characterize the potential impact of chronic white noise exposure on early childhood development.

METHODS

Embase, Ovid MEDLINE, the Cochrane Central Register of Controlled Trials, Scopus, and Web of Science were searched from inception through June 2022 for publications addressing the effects of chronic noise exposure during sleep on early development in animals and children. PRISMA-ScR guidelines were followed. Among 644 retrieved publications, 20 met inclusion criteria after review by multiple authors. Seven studies evaluated animal models and 13 studies examined pediatric subjects, including 83 animal and 9428 human subjects.

RESULTS

White noise machines can exceed 91 dB on maximum volume, which exceeds the National Institute for Occupational Safety and Health noise exposure guidelines for a 2-h work shift in adults. Evidence suggests deleterious effects of continuous moderate-intensity white noise exposure on early development in animal models. Human subject data generally corroborates these models; however, studies also suggest low-intensity noise exposure may be beneficial during sleep.

CONCLUSIONS

Existing data support the limitation of maximal sound intensity and duration on commercially available white noise devices. Further research into the optimal intensity and duration of white noise exposure in children is needed.

Defining the Concept of Acoustic Neuroprotection in the Neonate: A Concept Analysis

BACKGROUND

It has long been understood and acknowledged that the Neonatal Intensive Care Unit (NICU) environment and the transport environments are extremely loud, with both long- and short-term sequelae to the neonate, being well over the recommended amount of noise by the American Academy of Pediatrics (AAP). This problem has yet to be properly addressed. The purpose of this manuscript is to define and explain the concept of acoustic neuroprotection. While we cannot change the internal structures of the neonates' auditory system, we could change the acoustics of the environment to be support neuroprotection of these sensitive patients.

EVIDENCE ACQUISITION

Walker and Avant's concept analysis steps were followed to create and define the idea of acoustic neuroprotection, as it has not had a definition before. A total of 45 articles from multiple search engines were chosen. A combination of 2 concepts were used: acoustic protection and neurodevelopmental protection/support. The search was expanded past 20 years for lack of research and importance of seminal works.

RESULTS

To achieve acoustic neuroprotection, a neonate should not be exposed to sound greater than 45 decibels (dBa) for longer than 10 s, and exposure to sound above 80 dBa should never occur. Appropriate interventions need to include supporting the neurodevelopment of the neonate through therapeutic sound, while decreasing the amount of toxic noise exposure to safe levels.

IMPLICATIONS FOR PRACTICE AND RESEARCH

By further understanding and having a quantifiable goal of acoustic neuroprotection for neonates, neonatal clinicians can work together to create new interventions for how to better protect and support the care of our tiniest patients.

[Towards an ideal environment in neonatology]

The establishment of sensory systems occurs gradually along a transnatal continuum. During premature birth, hospitalization in neonatology, through its atypical sensory stimulations, can disrupt the development of the baby's still immature brain. To promote harmonious development in children, caregivers and parents must learn to take into account their sensory expectations in order to create the most suitable environment possible for their development.

Oxytocin Levels Increase and Anxiety Decreases in Mothers Who Sing and Talk to Their Premature Infants during a Painful Procedure

(1) Background: Preterm infants spend their first weeks of life in the hospital partially separated from their parents and subjected to frequent potentially painful clinical procedures. Previous research has found that early vocal contact reduces infant pain perception while simultaneously increasing oxytocin (OXT) levels. The current study aims to assess the effect of maternal singing and speaking on mothers. (2) Methods: During a painful procedure over two days, twenty preterm infants were randomly exposed to their mother's live voice (speaking or singing). Maternal OXT levels were measured twice: before and after singing, as well as before and after speaking. The anxiety and resilience responses of mothers were studied before and after the two-day interventions, regardless of the speaking/singing condition. OXT levels in mothers increased in response to both singing and speech. Concurrently, anxiety levels decreased, but no significant effects on maternal resilience were found. (3) Conclusions: OXT could be identified as a key mechanism for anxiety regulation in parents, even in sensitive care situations, such as when their infant is in pain. Active involvement of parents in the care of their preterm infants can have a positive effect on their anxiety as well as potential benefits to their sensitivity and care abilities through OXT.

Noise and Critical Sound Levels During Non-Invasive Ventilation of a Preterm Infant in the Incubator

Background Preterm birth and the subsequent necessary treatment in neonatal intensive care units (NICU) subjects the preterm infant to non-physiological noise exposure with potentially adverse consequences for short- and long-term development. Adjusters to improve the acoustic environment for the preterm infant need to be defined.

Methods Sound pressure level measurements during routine procedures in a NICU were performed by ¼” microphones placed inside and outside the incubator. The microphones need to be suitably positioned to measure sound pressure levels that are representative for the sound field inside and outside the incubator. The sound pressure level spectra generated by respiratory support and corresponding monitor alarms were compared.

Results Inside the incubator, higher sound level pressures (in dBA) were generated primarily by the use of the system components of the incubator itself than outside, whereas when the incubator was closed, it had an insulating effect on sounds generated in the NICU. Non-invasive ventilation resulted in an increase in sound pressure levels from 50 to 60 dBA in the neonate’s environment, with sound pressure levels increasing particularly in the frequency range above 1 kHz.

Conclusion Preterm infants are exposed to high sound levels, especially in the non-physiological high-frequency range, particularly during non-invasive ventilation. The continuous sound exposure could be further reduced to some extent by an optimized design of the incubator.

Sensory-based interventions in the NICU: systematic review of effects on preterm brain development

BACKGROUND

Infants born preterm are known to be at risk for abnormal brain development and adverse neurobehavioral outcomes. To improve early neurodevelopment, several non-pharmacological interventions have been developed and implemented in the neonatal intensive care unit (NICU). Sensory-based interventions seem to improve short-term neurodevelopmental outcomes in the inherently stressful NICU environment. However, how this type of intervention affects brain development in the preterm population remains unclear.

METHODS

A systematic review of the literature was conducted for published studies in the past 20 years reporting the effects of early, non-pharmacological, sensory-based interventions on the neonatal brain after preterm birth.

RESULTS

Twelve randomized controlled trials (RCT) reporting short-term effects of auditory, tactile, and multisensory interventions were included after the screening of 1202 articles. Large heterogeneity was identified among studies in relation to both types of intervention and outcomes. Three areas of focus for sensory interventions were identified: auditory-based, tactile-based, and multisensory interventions.

CONCLUSIONS

Diversity in interventions and outcome measures challenges the possibility to perform an integrative synthesis of results and to translate these for evidence-based clinical practice. This review identifies gaps in the literature and methodological challenges for the implementation of RCTs of sensory interventions in the NICU.

IMPACT

This paper represents the first systematic review to investigate the effect of non-pharmacological, sensory-based interventions in the NICU on neonatal brain development. Although reviewed RCTs present evidence on the impact of such interventions on the neonatal brain following preterm birth, it is not yet possible to formulate clear guidelines for clinical practice. This review integrates existing literature on the effect of sensory-based interventions on the brain after preterm birth and identifies methodological challenges for the conduction of high-quality RCTs.

Body size measuring techniques enabling stress-free growth monitoring of extreme preterm infants inside incubators: A systematic review

Introduction

Growth monitoring of preterm infants is essential for assessing the nutritional effects on their growth. The current growth monitoring techniques are too stressful, however, for the smallest preterm infants. We performed a systematic review to summarize studies on stress-free techniques for measuring the body size of preterm infants inside incubators other than the traditional calliper and tape measure-based instruments.

Methods

We searched four online literature databases: Embase, Medline, Web of Science Core Collection, and Cochrane, using search terms related to patients (neonates, infants, children) and body size measuring techniques. By means of expert judgement we assessed the techniques’ suitability for stress-free body size measurement of an infant lying in an incubator. As a criterion for suitability, we used an imaginary ideal technique.

Results

Twenty-six studies were included in this review. In 24 studies, the technique for body size measurement was related to 3D technology, and the majority of these studies acknowledged clinical superiority of 3D over 2D data. Two 3D techniques were assessed as suitable for stress-free measurement of preterm infants inside incubators. The first technique used a commercially available 3D handheld scanner which needed 3D postprocessing to derive measurement data. The second technique used a self-developed stereoscopic vision system.

Conclusions

3D volumetric parameters have higher clinical value for growth monitoring than 2D. In addition, contactless 3D measurements enable stress-free growth monitoring of even the smallest preterm infants. However, the time-consuming 3D postprocessing challenges the usability of 3D techniques. Regrettably, none of the identified suitable 3D techniques met all our requirements of an ideal all-in-one body size measuring technique for extreme preterm infants. Handheld 3D scanning might have the best properties for developing this ideal technique.

Pain Behavioural Response to Acoustic and Light Environmental Changes in Very Preterm Infants

Noise and high light illumination in the neonatal intensive care unit (NICU) are recognized as stressors that could alter the well-being and development of vulnerable preterm infants. This prospective observational study evaluated the pain behaviours of very preterm infants (VPIs) to sound peaks (SPs) and light levels variations (LLVs) in the NICU. We measured spontaneously occurring SPs and LLVs in the incubators of 26 VPIs over 10 h. Their behavioural responses were analysed through video recordings using the "Douleur Aigue du Nouveau-né" (DAN) scale. We compared the maximum DAN scores before and after environmental stimuli and the percentage of VPIs with a score ≥ 3 according to the type of stimuli. A total of 591 SPs and 278 LLVs were analysed. SPs of 5 to 15 dBA and LLVs significantly increased the maximum DAN scores compared to baseline. The occurrence of DAN scores ≥ 3 increased with both stressors, with a total of 16% of SPs and 8% of LLVs leading to quantifiable pain behaviour. Altogether, this study shows that VPIs are sensitive to SPs and LLVs, with a slighter higher sensitivity to SPs. The mechanisms leading to pain behaviours induced by noise and light changes should be evaluated further in the context of VPIs brain development. Our results provide further arguments to optimize the NICU sensory environment of neonatal units and to adapt it to the expectations and sensory abilities of VPIs.

Comparing light and noise levels before and after a NICU change of design

OBJECTIVE

To compare light and sound levels before and after a change of design and evaluate these levels considering recommended NICU standards.

STUDY DESIGN

A pre-test/post-test design. Light and sound levels were compared between the former open ward (OW) NICU of 34 beds and the current 40-bed unit composed of both pods and single-family rooms (SFR).

RESULT

Light levels were significantly higher in the pod/SFR unit for all levels of care, days of the week and time of the day. These findings could be attributed to the number and configuration of windows in the new pod/SFR unit allowing for more daylight entry compared to the OW. Sound levels were significantly lower in the current NICU (pod/SFR) compared to the former OW.

CONCLUSION

Following the change of design, the pod/SFR unit are less noisy than the OW, although light levels are higher indicating the necessity to measure light levels.

Maternal speech decreases pain scores and increases oxytocin levels in preterm infants during painful procedures

Preterm infants undergo early separation from parents and are exposed to frequent painful clinical procedures, with resultant short- and long-term effects on their neurodevelopment. We aimed to establish whether the mother's voice could provide an effective and safe analgesia for preterm infants and whether endogenous oxytocin (OXT) could be linked to pain modulation. Twenty preterm infants were exposed to three conditions-mother's live voice (speaking or singing) and standard care-in random order during a painful procedure. OXT levels (pg/mL) in saliva and plasma cortisol levels were quantified, and the Premature Infant Pain Profile (PIPP) was blindly coded by trained psychologists. During the mother's live voice, PIPP scores significantly decreased, with a concomitant increase in OXT levels over baseline. The effect on pain perception was marginally significant for singing. No effects on cortisol levels were found. The mother's live voice modulated preterm infants' pain indicators. Endogenous OXT released during vocal contact is a promising protective mechanism during early painful interventions in at-risk populations.

The Soundscape of Neonatal Intensive Care: A Mixed-Methods Study of the Parents' Experience

Parents who have infants hospitalised in neonatal intensive care units (NICUs) experience high levels of stress, including post-traumatic stress disorder (PTSD) symptoms. However, whether sounds contribute to parents’ stress remains largely unknown. Critically, researchers lack a comprehensive instrument to investigate the relationship between sounds in NICUs and parental stress. To address this gap, this report presents the “Soundscape of NICU Questionnaire” (SON-Q), which was developed specifically to capture parents’ perceptions and beliefs about the impact that sound had on them and their infants, from pre-birth throughout the NICU stay and in the first postdischarge period. Parents of children born preterm (n = 386) completed the SON-Q and the Perinatal PTSD Questionnaire (PPQ). Principal Component Analysis identifying underlying dimensions comprising the parental experience of the NICU soundscape was followed by an exploration of the relationships between subscales of the SON-Q and the PPQ. Moderation analysis was carried out to further elucidate relationships between variables. Finally, thematic analysis was employed to analyse one memory of sounds in NICU open question. The results highlight systematic associations between aspects of the NICU soundscape and parental stress/trauma. The findings underscore the importance of developing specific studies in this area and devising interventions to best support parents’ mental health, which could in turn support infants’ developmental outcomes.

Parental Perception of Vocal Contact with Preterm Infants: Communicative Musicality in the Neonatal Intensive Care Unit

In this study, we evaluate mothers’ subjective experience of speaking and singing to their infants while they are in their incubators. We also discuss the relevance of the theoretical framework of Communicative Musicality for identifying the underlying mechanisms that may help explain its beneficial effects, both for parents and infants. Nineteen mothers talked and sung to their stable preterm infants in the incubators, for 5 min each, in three sessions over a period of 6 days. After each session, mothers were asked to assess in a self-report questionnaire the ease and the effectiveness of addressing their infants by speaking and singing and their prior musical experience. Perceived ease and effectiveness in communication were found to increase progressively from one session to the next. Mothers rated the speech to be increasingly more effective. This intuitive mean of interaction between parents and infants could be encouraged and supported by the nurses and the medical staff. Furthermore, individual musical experience affects perceived ease of communicating vocally with infants after a premature birth and should thus be encouraged during pregnancy.

Effects of Early Vocal Contact in the Neonatal Intensive Care Unit: Study Protocol for a Multi-Centre, Randomised Clinical Trial

Preterm infants are at risk for developing altered trajectories of cognitive, social, and linguistic competences compared to a term population. This is mainly due to medical and environmental factors, as they are exposed to an atypical auditory environment and simultaneously, long periods of early separation from their parents. The short-term effects of early vocal contact (EVC) on an infant’s early stability have been investigated. However, there is limited evidence of its impact on the infant’s autonomic nervous system maturation, as indexed by heart rate variability, and its long-term impact on infant neurodevelopment. Our multi-centric study aims to investigate the effects of EVC on a preterm infant’s physiology, neurobehaviour, and development. Eighty stable preterm infants, born at 25–32 weeks and 6 days gestational age, without specific abnormalities, will be enrolled and randomised to either an intervention or control group. The intervention group will receive EVC, where mothers will talk and sing to their infants for 10 min three times per week for 2 weeks. Mothers in the control group will be encouraged to spend the same amount of time next to the incubator and observe the infant’s behaviour through a standard cluster of indicators. Infants will be assessed at baseline; the end of the intervention; term equivalent age; and 3, 6, 12, and 24 months corrected age, with a battery of physiological, neurobehavioral, and developmental measures. Early interventions in the neonatal intensive care unit have demonstrated effects on the neurodevelopment of preterm infants, thereby lowering the negative long-term effects of an atypical auditory and interactional environment. Our proposed study will provide new insight into mother–infant early contact as a protective intervention against the sequelae of prematurity during this sensitive period of development. Early intervention, such as EVC, is intuitive and easy to implement in the daily care of preterm infants. However, its long-term effects on infant neurodevelopment and maternal sensitivity and stress are still unclear. Trial Registration: NCT04759573, retrospectively registered, 17 February 2021.

The burden of early life stress on the nociceptive system development and pain responses

For a long time, the capacity of the newborn infant to feel pain was denied. Today it is clear that the nociceptive system, even if still immature, is functional enough in the newborn infant to elicit pain responses. Unfortunately, pain is often present in the neonatal period, in particular in the case of premature infants which are subjected to a high number of painful procedures during care. These are accompanied by a variety of environmental stressors, which could impact the maturation of the nociceptive system. Therefore, the question of the long-term consequences of early life stress is a critical question. Early stressful experience, both painful and non-painful, can imprint the nociceptive system and induce long-term alteration in brain function and nociceptive behavior, often leading to an increase sensitivity and higher susceptibility to chronic pain. Different animal models have been developed to understand the mechanisms underlying the long-term effects of different early life stressful procedures, including pain and maternal separation. This review will focus on the clinical and preclinical data about early life stress and its consequence on the nociceptive system.

Smartphone monitoring of in-ambulance vibration and noise

Transferring sick premature infants between hospitals increases the risk of severe brain injury, potentially linked to the excessive exposure to noise, vibration and driving-related accelerations. One method of reducing these levels may be to travel along smoother and quieter roads at an optimal speed, however this requires mass data on the effect of roads on the environment within ambulances. An app for the Android operating system has been developed for the purpose of recording vibration, noise levels, location and speed data during ambulance journeys. Smartphone accelerometers were calibrated using sinusoidal excitation and the microphones using calibrated pink noise. Four smartphones were provided to the local neonatal transport team and mounted on their neonatal transport systems to collect data. Repeatability of app recordings was assessed by comparing 37 journeys, made during the study period, along an 8.5 km single carriageway. The smartphones were found to have an accelerometer accurate to 5% up to 55 Hz and microphone accurate to 0.8 dB up to 80 dB. Use of the app was readily adopted by the neonatal transport team, recording more than 97,000 km of journeys in 1 year. To enable comparison between journeys, the 8.5 km route was split into 10 m segments. Interquartile ranges for vehicle speed, vertical acceleration and maximum noise level were consistent across all segments (within 0.99 m . s^-1, 0.13 m · s^-2 and 1.4 dB, respectively). Vertical accelerations registered were representative of the road surface. Noise levels correlated with vehicle speed. Android smartphones are a viable method of accurate mass data collection for this application. We now propose to utilise this approach to reduce potential harmful exposure, from vibration and noise, by routing ambulances along the most comfortable roads.

The Importance of Reverberation for the Design of Neonatal Incubators

Low frequency noises are predominant in neonatal intensive care units (NICUs). Some studies affirm that neonates can perceive noises from 113 Hz, and can therefore be affected by sound sources with high spectral content at low frequencies (e.g., incubator engine, air fan). Other studies suggest that reverberation amplifies noise within incubators. In this paper, the reverberation time (T, T ₃₀) within an incubator with standard dimensions was measured in one-third octave bands. To get reliable results, the T was measured in 15 positions at the neonate's ear height, in a room with low T values (to reduce the influence of the room in the results), using an impulsive sound method. Results show a heterogeneous T distribution at the neonate's ear height, with maximum average T differences between positions of 1.07 s. The highest average T of all microphone positions is 2.27 s at 125 Hz, an extremely high mean value for such a small space. As the frequency of electrical devices in America is 60 Hz, some harmonics lay within the one-third octave band of 125 Hz, and therefore may create a very reverberant and inappropriate acoustic environment within the audible spectrum of neonates. As the acoustic environment of the incubator and the room are coupled, it is expected that the results are higher in the NICUs than in the room where the measurements were conducted, as NICUs are more reverberant. Therefore, it is recommended that the T will be limited in the international standards, and that incubator designers take it into account.

The lived experiences of critically ill infants hospitalised in neonatal intensive care: A scoping review

BACKGROUND

Neonatal intensive care saves lives, but the environment in which this occurs is complex and has been shown to negatively disrupt some aspects of an infant's early development. Identifying these negative effects has relied on measuring physiological and behavioural responses. Little research has sought to understand and learn from what an individual infant can communicate about their lived experience.

AIM

To examine what is known of the lived experiences of infants hospitalised in neonatal intensive care.

STUDY DESIGN

A scoping review using the revised Arksey and O'Malley framework was undertaken. Relevant studies, exploring an infant's experience of hospitalisation were identified through a comprehensive, systematic literature search.

RESULTS

4955 articles were retrieved, 88 full texts reviewed, and 23 studies included. We identified no studies that assessed the experience from the infant's perspective. The infant experience was explored using quantitative methodology, characterising, and describing the experience in measurable physiological, behavioural, and neurodevelopmental terms or through the lens of medical outcomes. The environment is described as too loud and too bright and infants are exposed to high levels of medical handling, impacting on physiology, behaviour, sleep, feeding, and both short- and longer-term outcomes.

CONCLUSION

The studies captured in this review focused on quantitative, measurable outcomes as a proxy for the experience as it might be felt, interpreted, and processed by an infant. Medical focus has been crucial to advance the field of neonatology, but the review highlights an important gap; the need to explore and better understand the infant's experience through their eyes.

Influence of the NICU on the Acoustic Isolation of a Neonatal Incubator

The neonatal intensive care unit (NICU) is a very noisy place as compared to the intrauterine environment. To protect the neonate's health, international guidelines suggest avoiding noise levels above 45 dB in NICUs, but this recommendation is not normally met. The incubator acoustic isolation and the acoustic features of the NICU play important roles in determining the noise measured inside the incubator. In this study, the influence of two types of rooms, one with sound-absorbent covering and the other with reverberant surfaces, on the acoustic isolation of a neonatal incubator was evaluated using three acoustic isolation indexes: the level difference, the apparent sound reduction index, and the standardized level difference. Results show that the acoustic isolation of the incubator is very poor, with a level difference below 11 dBA at all frequencies. At 62.5 Hz, the level difference measured in both rooms exhibits a negative value, indicating that the incubator amplifies the noise coming from the NICU. Isolation of the incubator is poor, and the reverberation time (RT) of the containing room influences RT of the incubator, which is consequently higher when the containing room is reverberant; for example, the incubator RT in the reverberant NICU is 0.72 s higher at 500 Hz than that in a room with sound-absorbent covering.

Exposure and reactivity of the preterm infant to noise in the incubator

PURPOSE

To evaluate preterm infants' exposure and reactions to intense noise during incubator care.

METHODS

An observational and prospective study was performed in the intermediary care unit of a hospital in Ribeirão Preto (SP). Thirty-five preterm infants participated in the first stage of the study (measuring noise) and 20 in the second (analysis of responses to intense noise). Noise was measured for two hours using a dosimeter, and the responses were video recorded by three cameras connected to a computer. The preterm infants' responses to an Lmax higher than 65 decibels were analyzed.

RESULTS

Every preterm infant presented Leq above the limit recommended by international organizations, and more than half of the babies had a mean Leq above the limit permitted by the Brazilian standard. Regarding the babies' responses to the intense noise, the majority of them showed blink reflex, startle reflex, facial mimics, changed bodily activities or changed sleep and wake state, all with statistically significant differences.

CONCLUSION

The sound levels measured were intense. The noises that preterm infants are exposed to while being cared for in incubators constitute a stressor event. Sudden, intense noises change their behavioral state and causes reflexive and bodily responses, facial manifestations and changes in their sleep and wake state.

Risk of Severe Intraventricular Hemorrhage in the First Week of Life in Preterm Infants Transported Before 72 Hours of Age

OBJECTIVES

Evaluate the risk of severe intraventricular hemorrhage, in the first week of life, in preterm infants undergoing early interhospital transport.

DESIGN

Retrospective cohort study.

SETTING

Tertiary neonatal centers of the Trent Perinatal Network in the United Kingdom.

PATIENTS

Preterm infants less than 32 weeks gestation, who were either born within and remained at the tertiary neonatal center (inborn), or were transferred (transported) between centers in the first 72 hours of life.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Multivariable logistic regression models adjusting for key confounders were used to calculate odds ratios for intraventricular hemorrhage with 95% CIs for comparison of inborn and transported infants. Cranial ultrasound findings on day 7 of life. Secondary analyses were performed for antenatal steroid course and gestational age subgroups. A total of 1,047 preterm infants were included in the main analysis. Transported infants (n = 391) had a significantly higher risk of severe (grade III/IV) intraventricular hemorrhage compared with inborns (n = 656) (9.7% vs 5.8%; adjusted odds ratio, 1.69; 95% CI, 1.04-2.76), especially for infants born at less than 28 weeks gestation (adjusted odds ratio, 1.83; 95% CI, 1.03-3.21). Transported infants were less likely to receive a full antenatal steroid course (47.8% vs 64.3%; p < 0.001). A full antenatal steroid course significantly decreased the risk of severe intraventricular hemorrhage irrespective of transport status (odds ratio, 0.33; 95% CI, 0.2-0.55). However, transported infants less than 28 weeks gestation remained significantly more likely to develop a severe intraventricular hemorrhage despite a full antenatal steroid course (adjusted odds ratio, 2.84; 95% CI, 1.08-7.47).

CONCLUSIONS

Preterm infants transported in the first 72 hours of life have an increased risk of early-life severe intraventricular hemorrhage even when maternal antenatal steroids are given. The additional burden of postnatal transport could be an important component in the pathway to severe intraventricular hemorrhage. As timely in-utero transfer is not always possible, we need to focus research on improving the transport pathway to reduce this additional risk.

Pain, Parental Involvement, and Oxytocin in the Neonatal Intensive Care Unit

Preterm infants (PTI) typically experience many painful and stressful procedures or events during their first weeks of life in a neonatal intensive care unit, and these can profoundly impact subsequent brain development and function. Several protective interventions during this sensitive period stimulate the oxytocin system, reduce pain and stress, and improve brain development. This review provides an overview of the environmental risk factors experienced by PTI during hospitalization, with a focus on the effects of pain, and early maternal separation. We also describe the long-term adverse effects of the simultaneous experiences of pain and maternal separation, and the potential beneficial effects of maternal vocalizations, parental contact, and several related processes, which appear to be mediated by the oxytocin system.

The human newborn's umwelt: Unexplored pathways and perspectives

Historically, newborns, and especially premature newborns, were thought to "feel nothing." However, over the past decades, a growing body of evidence has shown that newborns are aware of their environment, but the extent and the onset of some sensory capacities remain largely unknown. The goal of this review is to update our current knowledge concerning newborns' perceptual world and how ready they are to cope with an entirely different sensory environment following birth. We aim to establish not only how and when each sensory ability arises during the pre-/postbirth period but also discuss how senses are studied. We conclude that although many studies converge to show that newborns are clearly sentient beings, much is still unknown. Further, we identify a series of internal and external factors that could explain discrepancies between studies, and we propose perspectives for future studies. Finally, through examples from animal studies, we illustrate the importance of this detailed knowledge to pursue the enhancement of newborns' daily living conditions. Indeed, this is a prerequisite for assessing the effects of the physical environment and routine procedures on newborns' welfare.

Correlation of Premature Infant Sleep/Wakefulness and Noise Levels in the Presence or Absence of "Quiet Time"

BACKGROUND

Peak sound levels during sleep can compromise the development of hospitalized infants. Quiet time is a strategy implemented in neonatal units to promote the sleeping of neonates by reducing noise levels, luminosity, and handling during particular periods of the day.

PURPOSE

To determine the impact of quiet time on reducing sound levels and increasing total sleep time.

METHODS

This longitudinal study was conducted at a neonatal intermediate care unit with a convenience sample of 12 premature infants. Four times per day, 60-minute quiet times were provided in the neonatal unit. Sleep-awake states and sound levels were evaluated during quiet times as well as 60 minutes before and afterward. Polysomnography was used for sleep-awake state assessment, and a noise dosimeter was used to check sound levels every 24 hours.

RESULTS

The preterm infants had a corrected gestational age of 35.0 ± 1.5 weeks and weighed 1606.0 ± 317.8 g. Total sleep time was highest during quiet time (P = .005). Premature infants remained awake for longer following quiet times (P = .005). There was also a reduction in sound level during quiet times compared with the other time frames (P = .006). No statistically significant relationship was found between total sleep time and sound levels more than 24 hours.

IMPLICATIONS FOR PRACTICE

Quiet time is a nursing intervention that should be implemented in all neonatal units.

IMPLICATIONS FOR RESEARCH

Future research should use a greater sample size and other factors that influence sleep should be further investigated.

Exposure to human voices has beneficial effects on preterm infants in the neonatal intensive care unit

We reviewed the literature up to March 2016 on the effects of nonmaternal voices on preterm infants' clinical outcomes. Of the 11 studies that met the inclusion criteria, 10 focused on short-term outcomes and one looked at long-term effects. The studies mainly showed that vocal stimuli increased preterm infants' stability in terms of heart rate, respiratory rate, oxygen saturation and behavioural measures. Improvements in feeding skills were also reported. The methods and the measures used in the studies were heterogeneous, making it difficult to draw reliable conclusions.

CONCLUSION

Vocal stimuli increased preterm infants' stability, but further studies are needed.

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Effects on Sleep

To evaluate the quality of available evidence on the effects of environmental noise exposure on sleep a systematic review was conducted. The databases PSYCINFO, PubMed, Science Direct, Scopus, Web of Science and the TNO Repository were searched for non-laboratory studies on the effects of environmental noise on sleep with measured or predicted noise levels and published in or after the year 2000. The quality of the evidence was assessed using GRADE criteria. Seventy four studies predominately conducted between 2000 and 2015 were included in the review. A meta-analysis of surveys linking road, rail, and aircraft noise exposure to self-reports of sleep disturbance was conducted. The odds ratio for the percent highly sleep disturbed for a 10 dB increase in Lnight was significant for aircraft (1.94; 95% CI 1.61-2.3), road (2.13; 95% CI 1.82-2.48), and rail (3.06; 95% CI 2.38-3.93) noise when the question referred to noise, but non-significant for aircraft (1.17; 95% CI 0.54-2.53), road (1.09; 95% CI 0.94-1.27), and rail (1.27; 95% CI 0.89-1.81) noise when the question did not refer to noise. A pooled analysis of polysomnographic studies on the acute effects of transportation noise on sleep was also conducted and the unadjusted odds ratio for the probability of awakening for a 10 dBA increase in the indoor Lmax was significant for aircraft (1.35; 95% CI 1.22-1.50), road (1.36; 95% CI 1.19-1.55), and rail (1.35; 95% CI 1.21-1.52) noise. Due to a limited number of studies and the use of different outcome measures, a narrative review only was conducted for motility, cardiac and blood pressure outcomes, and for children's sleep. The effect of wind turbine and hospital noise on sleep was also assessed. Based on the available evidence, transportation noise affects objectively measured sleep physiology and subjectively assessed sleep disturbance in adults. For other outcome measures and noise sources the examined evidence was conflicting or only emerging. According to GRADE criteria, the quality of the evidence was moderate for cortical awakenings and self-reported sleep disturbance (for questions that referred to noise) induced by traffic noise, low for motility measures of traffic noise induced sleep disturbance, and very low for all other noise sources and investigated sleep outcomes.

A Knowledge-Based Approach to Automatic Detection of Equipment Alarm Sounds in a Neonatal Intensive Care Unit Environment

A large number of alarm sounds triggered by biomedical equipment occur frequently in the noisy environment of a neonatal intensive care unit (NICU) and play a key role in providing healthcare. In this paper, our work on the development of an automatic system for detection of acoustic alarms in that difficult environment is presented. Such automatic detection system is needed for the investigation of how a preterm infant reacts to auditory stimuli of the NICU environment and for an improved real-time patient monitoring. The approach presented in this paper consists of using the available knowledge about each alarm class in the design of the detection system. The information about the frequency structure is used in the feature extraction stage, and the time structure knowledge is incorporated at the post-processing stage. Several alternative methods are compared for feature extraction, modeling, and post-processing. The detection performance is evaluated with real data recorded in the NICU of the hospital, and by using both frame-level and period-level metrics. The experimental results show that the inclusion of both spectral and temporal information allows to improve the baseline detection performance by more than 60%.

Systematic review of maternal voice interventions demonstrates increased stability in preterm infants

We systematically reviewed how effectively maternal voice interventions supported the clinical outcomes and development of preterm infants. A total of 512 preterm infants were included in 15 studies with different designs, from January 2000 to July 2015. Live and recorded maternal voice interventions were associated with the physiologic and behavioural stabilisation of preterm infants, with fewer cardiorespiratory events, but the evidence was insufficient to evaluate the long-term effects. Well-defined determinants and clear setting conditions are needed for such interventions.

CONCLUSION

Further research that investigates the long-term efficacy and effects of live maternal voices on preterm infant development is needed.

Eight principles for patient-centred and family-centred care for newborns in the neonatal intensive care unit

Despite the recent improvements in perinatal medical care leading to an increase in survival rates, adverse neurodevelopmental outcomes occur more frequently in preterm and/or high-risk infants. Medical risk factors for neurodevelopmental delays like male gender or intrauterine growth restriction and family sociocultural characteristics have been identified. Significant data have provided evidence of the detrimental impact of overhelming environmental sensory inputs, such as pain and stress, on the developing human brain and strategies aimed at preventing this impact. These strategies, such as free parental access or sleep protection, could be considered 'principles of care'. Implementation of these principles do not require additional research due to the body of evidence. We review the scientific evidence for these principles here.

Conhecimentos e práticas de manuseio de incubadoras neonatais por profissionais de enfermagem

Resumo Objetivo Comparar conhecimentos e práticas de manuseio de incubadoras neonatais por enfermeiras e técnicas/auxiliares de enfermagem. Métodos Estudo transversal, realizado em unidade neonatal de hospital de referência, com dados obtidos por questionário sobre conhecimentos e observação direta, estruturada e não participante, das práticas da equipe de enfermagem no manuseio de incubadoras. Criou-se escore de adequação de práticas realizadas. Resultados Não houve diferença entre os dois grupos estudados, quanto aos conhecimentos sobre manuseio de incubadoras, exceto para o benefício de umidificação, mais citado entre enfermeiras (p=0,040). Comparando-se escores de práticas obtidos isoladamente e considerando o escore total, também não se constatou diferença (p=0,723). Técnicas/auxiliares de enfermagem e enfermeiras realizaram 70% de práticas adequadas ao manusearem a incubadora, proporção baixa, visto tratar-se de hospital de alta complexidade. Conclusão Em geral, não houve diferença entre os componentes da equipe de enfermagem com relação aos conhecimentos e práticas estudadas.

Transition to a New Neonatal Intensive Care Unit: Positive Effects on Staff Working Environment and How the Physical Environment Facilitates Family-Centered Care

To optimize family-centered care and the staff working environment, the physical care environment should be designed to meet the needs of the infants, their families, and staff. It is important to evaluate the effects of a purpose-built neonatal ward on staff perceptions of job strain, the psychosocial climate, and the appropriateness of the physical environment. This study collected information from staff at a neonatal intensive care unit (NICU), before and after the ward was relocated to a new NICU. Effects were measured using the following variables: job strain, person-centered climate and appropriateness-of-the-physical-environment questionnaires. Data were analyzed using repeated-measures generalized estimating equations and factor analysis. After staff began to work in the new NICU, their job strain significantly increased. At the 2-year follow-up, staff stress levels had returned to preintervention levels. Participating staff perceived the purpose-built neonatal ward as being a significantly more appropriate physical environment for family-centered care of the infants and their families. The staff also perceived the psychosocial climate of the new NICU as significantly more person-centered in terms of having a more homey, comfortable, and everyday ambience and thus experienced as being more supportive. An NICU built according to recommended standards optimized the physical care environment for family-centered care and increased the staff working climate.

Characterising the ambient sound environment for infants in intensive care wards

AIM

The purpose of this study is to characterise ambient sound levels of paediatric and neonatal intensive care units in an old and new hospital according to current standards.

METHODS

The sound environment was surveyed for 24-h data collection periods (n = 80) in the Neonatal and Paediatric Intensive Care Units (NICUs and PICUs) and Special Care Nursery of the old and new Royal Children's Hospital Melbourne. The ambient sound environment was characterised as the proportion of time the ongoing ambient sound met standard benchmarks, the mean 5-s sound levels and the number and duration of noise events.

RESULTS

In the old hospital, none of the data collection periods in the NICU and PICU met the standard benchmark for ongoing ambient sound, while only 5 of the 22 data collection periods in the new hospital met the recommended level. There was no change in proportion of time at recommended Leq between the old and the new Special Care Nursery. There was strong evidence for a difference in the mean number of events >65 dBA (Lmax ) in the old and new hospital (rate ratio = 0.82, 95% confidence interval: 0.73 to 0.92, P = 0.001). The NICU and PICU were above 50 dBA in 75% of all data collection periods, with ventilatory equipment associated with higher ongoing ambient sound levels.

CONCLUSIONS

The ongoing ambient sound suggests that the background sound environment of the new hospital is not different to the old hospital. However, there may be a reduction in the number of noise events.

Very preterm infants can detect small variations in light levels in incubators

AIM

This prospective observational study was designed to improve our understanding of the responses of very preterm infants to light level variations in incubators and to evaluate what determined those reactions.

METHODS

The physiological responses of 27 very preterm infants were analysed following variations in the light level environments of their incubators over 10 hours. Heart and respiratory rates, systemic oxygen saturation and regional cerebral oxygen saturations were recorded using near-infrared spectroscopy, and the variation of each parameter was analysed.

RESULTS

We analysed 332 light level changes. Heart rate increased by 3.8 beats per minute (range -2.6 to 12.6), respiratory rate by six cycles per minute (-1.5 to 26) and regional cerebral oxygen saturation by 1.1% (-0.5% to 3.9%) (p < 0.05 each) when delta lux was over 50. Only respiratory rate decreased significantly, by -8.4 cycles per minute (-28 to -0.4), when delta lux was 50 or lower (p < 0.05). The initial level of illumination altered the very preterm infants' responses, with higher reactivity for higher ambient light levels.

CONCLUSION

Very preterm infants reacted to moderate variations in illumination in their incubator, within recommended ranges of light levels, suggesting that they may detect even small light level variations.

Constructing optimal experience for the hospitalized newborn through neuro-based music therapy

Music-based intervention for hospitalized newborn infants has traditionally been based in a biomedical model, with physiological stability as the prime objective. More recent applications are grounded in other theories, including attachment, trauma and neurological models in which infant, parent and the dyadic interaction may be viewed as a dynamic system bound by the common context of the neonatal intensive care unit (NICU). The immature state of the preterm infant’s auditory processing system requires a careful and individualized approach for the introduction of purposeful auditory experience intended to support development. The infant’s experience of an unpredictable auditory environment is further compromised by a potential lack of meaningful auditory stimulation. Parents often feel disconnected from their own capacities to nurture their infant with potentially life-long implications for the infant’s neurobehavioral and psychological well-being. This perspectives paper will outline some neurological considerations for auditory processing in the premature infant to frame a premise for music-based interventions. A hypothetical clinical case will illustrate the application of music by a music therapist with an infant and family in NICU.

Maternal sounds elicit lower heart rate in preterm newborns in the first month of life

BACKGROUND

The preferential response to mother's voice in the fetus and term newborn is well documented. However, the response of preterm neonates is not well understood and more difficult to interpret due to the intensive clinical care and range of medical complications.

AIM

This study examined the physiological response to maternal sounds and its sustainability in the first month of life in infants born very pretermaturely.

METHODS

Heart rate changes were monitored in 20 hospitalized preterm infants born between 25 and 32 weeks of gestation during 30-minute exposure vs. non-exposure periods of recorded maternal sounds played inside the incubator. A total of 13,680 min of HR data was sampled throughout the first month of life during gavage feeds with and without exposure to maternal sounds.

RESULTS

During exposure periods, infants had significantly lower heart rate compared to matched periods of care without exposure on the same day (p<.0001). This effect was observed in all infants, across the first month of life, irrespective of day of life, gestational age at birth, birth weight, age at testing, Apgar score, caffeine therapy, and requirement for respiratory support. No adverse effects were observed.

CONCLUSION

Preterm newborns responded to maternal sounds with decreased heart rate throughout the first month of life. It is possible that maternal sounds improve autonomic stability and provide a more relaxing environment for this population of newborns. Further studies are needed to determine the therapeutic implications of maternal sound exposure for optimizing care practices and developmental outcomes.

Impact of NICU design on environmental noise

For neonates requiring intensive care, the optimal sound environment is uncertain. Minimal disruptions from medical staff create quieter environments for sleep, but limit language exposure necessary for proper language development. There are two models of neonatal intensive care units (NICUs): open-bay, in which 6-to-10 infants are cared for in a single large room; and single-room, in which neonates are housed in private, individual hospital rooms. We compared the acoustic environments in the two NICU models. We extracted the audio tracks from video-electroencephalography (EEG) monitoring studies from neonates in an open-bay NICU and compared the acoustic environment to that recorded from neonates in a new single-room NICU. From each NICU, 18 term infants were studied (total N=36; mean gestational age 39.3±1.9 weeks). Neither z-scores of the sound level variance (0.088±0.03 vs. 0.083±0.03, p=0.7), nor percent time with peak sound variance (above 2 standard deviations; 3.6% vs. 3.8%, p=0.6) were different. However, time below 0.05 standard deviations was higher in the single-room NICU (76% vs. 70%, p=0.02). We provide objective evidence that single-room NICUs have equal sound peaks and overall noise level variability compared with open-bay units, but the former may offer significantly more time at lower noise levels.

Quantitative sleep stage analyses as a window to neonatal neurologic function

OBJECTIVE

To test the hypothesis that neonatal sleep physiology reflects cerebral dysfunction, we compared neurologic examination scores to the proportions of recorded sleep/wake states, sleep depth, and sleep fragmentation in critically ill neonates.

METHODS

Newborn infants (≥35 weeks gestation) who required intensive care and were at risk for seizures were monitored with 8- to 12-hour polysomnograms (PSGs). For each infant, the distribution of sleep-wake states, entropy of the sequence of state transitions, and delta power from the EEG portion of the PSG were quantified. Standardized neurologic examination (Thompson) scores were calculated.

RESULTS

Twenty-eight infants participated (mean gestational age 39.0 ± 1.6 weeks). An increased fraction of quiet sleep correlated with worse neurologic examination scores (Spearman rho = 0.54, p = 0.003), but the proportion of active sleep did not (p > 0.1). Higher state entropy corresponded to better examination scores (rho = -0.43, p = 0.023). Decreased delta power during quiet sleep, but not the power at other frequencies, was also associated with worse examination scores (rho = -0.48, p = 0.009). These findings retained significance after adjustment for gestational age or postmenstrual age at the time of the PSG. Sleep stage transition probabilities were also related to examination scores.

CONCLUSIONS

Among critically ill neonates at risk for CNS dysfunction, several features of recorded sleep-including analyses of sleep stages, depth, and fragmentation-showed associations with neurologic examination scores. Quantitative PSG analyses may add useful objective information to the traditional neurologic assessment of critically ill neonates.

Moderate acoustic changes can disrupt the sleep of very preterm infants in their incubators

AIM

To evaluate the impact of moderate noise on the sleep of very early preterm infants (VPI).

METHODS

Observational study of 26 VPI of 26-31 weeks' gestation, with prospective measurements of sound pressure level and concomitant video records. Sound peaks were identified and classified according to their signal-to-noise ratio (SNR) above background noise. Prechtl's arousal states during sound peaks were assessed by two observers blinded to the purpose of the study. Changes in sleep/arousal states following sound peaks were compared with spontaneous changes during randomly selected periods without sound peaks.

RESULTS

We identified 598 isolated sound peaks (5 ≤ SNR < 10 decibel slow response A (dBA), n = 518; 10 ≤ SNR < 15 dBA, n = 80) during sleep. Awakenings were observed during 33.8% (95% CI, 24-43.7%) of exposures to sound peaks of 5-10 dBA SNR and 39.7% (95% CI, 26-53.3%) of exposures to sound peaks of SNR 10-15 dBA, but only 11.7% (95% CI, 6.2-17.1%) of control periods. The proportions of awakenings following sound peaks were higher than the proportions of arousals during control periods (p < 0.005).

CONCLUSIONS

Moderate acoustic changes can disrupt the sleep of VPI, and efficient sound abatement measures are needed.

Decreased right temporal activation and increased interhemispheric connectivity in response to speech in preterm infants at term-equivalent age

Preterm infants are at increased risk of language-related problems later in life; however, few studies have examined the effects of preterm birth on cerebral responses to speech at very early developmental stages. This study examined cerebral activation and functional connectivity in response to infant-directed speech (IDS) and adult-directed speech (ADS) in full-term neonates and preterm infants at term-equivalent age using 94-channel near-infrared spectroscopy. The results showed that compared with ADS, IDS increased activity in larger brain areas such as the bilateral frontotemporal, temporal, and temporoparietal regions, both in full-term and preterm infants. Preterm infants exhibited decreased activity in response to speech stimuli in the right temporal region compared with full-term infants, although the significance was low. Moreover, preterm infants exhibited increased interhemispheric connectivity compared with full-term controls, especially in the temporal and temporoparietal regions. These differences suggest that preterm infants may follow different developmental trajectories from those born at term owing to differences in intrauterine and extrauterine development.

Spontaneous cries can alter the physiological well-being and cerebral oxygenation of very preterm infants

INTRODUCTION

Infant crying is a major expression of distress and can occur without any exogenous stimulation. Little is known, however, about the effects of crying on physiological homeostasis in very preterm infants (VPIs).

METHODS

Environmental, behavioral (video and audio recording) and physiologic (heart rate [HR], respiratory rate [RR], and systemic [SaO(2)] and regional cerebral oxygenation [rSO(2)]) parameters were prospectively evaluated over 10h in 18 VPIs (median gestational age, 28 [27-31] weeks). Only episodes of "spontaneous" and isolated cries were analyzed. Changes in parameters were compared over 5-second periods between baselines and 40s following the onset of crying. Two periods were distinguished: 0-20s (a) and 20-40s (b). Minimal and/or maximal values in these periods were also compared to the baseline.

RESULTS

Of the 18 VPIs initially studied, 13 (72%) presented crying episodes (CE). They experienced 210 "spontaneous" and isolated CE, with a median of 9 [range, 1-63] CEs per child. Physiological values varied significantly from the baseline with mainly a mean decrease in HR of -4.8±5.3 beats/min (b) after an initial mean increase of +2.6±2.0 beats/min (a); a mean decrease in RR of -3.8±4.8 cycles/min (a), followed by a mean increase of +5.6±7.3 cycles/min (b) and mean unidirectional decreases in SaO(2) and rSO(2) (minimal values) of -1.8±2.3% and -2.5±3.0%, respectively.

CONCLUSION

Spontaneous cries can alter the homeostasis of VPIs. Their possible adverse consequences and high occurrence emphasize the need for better prevention and response to them.

Neonatal nursery noise: practice-based learning and improvement

OBJECTIVES

To study the impact of interrupted loud noise in Neonatal Intensive Care Unit (NICU) on neonatal physiologic parameters, and apply methods to alleviate noise sources through teaching NICU's staff.

METHODS

Noise level measured at different day times and during different noisy events in the NICU. Changes in the heart rate, respiratory rate and oxygen saturation were recorded just before and immediately after providing noisy events for 36 preterm and 26 full-term neonates. Focused training, guided by sound-level-meter, was provided to the NICU's staff to minimize noise.

RESULTS

The highest mean baseline noise level, 60.5 decibel (dB), was recorded in the NICU critical care area at 12:00 am. The lowest level, 55.2 dB was recorded at 10:00 pm. Noise level inside the incubators was significantly lower than outside, p < 0.001. Noisy events resulted in a significant increase in heart and respiratory rates in preterm neonates as compared to full-terms, p < 0.05.

CONCLUSION

Noise in our NICU exceeded the international permissible levels. Noisy events are numerous, which altered the neonates' physiologic stability especially preterm infants. Staff education is mandatory in ameliorating noise pollution with its deleterious effects on neonatal physiologic homeostasis.