Noise levels in neonatal intensive care unit and use of sound absorbing panel in the isolette

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.

Preventing Excessive Noise Exposure in Infants, Children, and Adolescents

Noise exposure is a major cause of hearing loss in adults. Yet, noise affects people of all ages, and noise-induced hearing loss is also a problem for young people. Sensorineural hearing loss caused by noise and other toxic exposures is usually irreversible. Environmental noise, such as traffic noise, can affect learning, physiologic parameters, and quality of life. Children and adolescents have unique vulnerabilities to noise. Children may be exposed beginning in NICUs and well-baby nurseries, at home, at school, in their neighborhoods, and in recreational settings. Personal listening devices are increasingly used, even by small children. Infants and young children cannot remove themselves from noisy situations and must rely on adults to do so, children may not recognize hazardous noise exposures, and teenagers generally do not understand the consequences of high exposure to music from personal listening devices or attending concerts and dances. Environmental noise exposure has disproportionate effects on underserved communities. In this report and the accompanying policy statement, common sources of noise and effects on hearing at different life stages are reviewed. Noise-abatement interventions in various settings are discussed. Because noise exposure often starts in infancy and its effects result mainly from cumulative exposure to loud noise over long periods of time, more attention is needed to its presence in everyday activities starting early in life. Listening to music and attending dances, concerts, and celebratory and other events are sources of joy, pleasure, and relaxation for many people. These situations, however, often result in potentially harmful noise exposures. Pediatricians can potentially lessen exposures, including promotion of safer listening, by raising awareness in parents, children, and teenagers. Noise exposure is underrecognized as a serious public health issue in the United States, with exposure limits enforceable only in workplaces and not for the general public, including children and adolescents. Greater awareness of noise hazards is needed at a societal level.

Concept and considerations of a medical device: the active noise cancelling incubator

Background

An increasingly 24/7 connected and urbanised world has created a silent pandemic of noise-induced hearing loss. Ensuring survival to children born (extremely) preterm is crucial. The incubator is a closed medical device, modifying the internal climate, and thus providing an environment for the child, as safe, warm, and comfortable as possible. While sound outside the incubator is managed and has decreased over the years, managing the noise inside the incubator is still a challenge.

Method

Using active noise cancelling in an incubator will eliminate unwanted sounds (i.e., from the respirator and heating) inside the incubator, and by adding sophisticated algorithms, normal human speech, neonatal intensive care unit music-based therapeutic interventions, and natural sounds will be sustained for the child in the pod. Applying different methods such as active noise cancelling, motion capture, sonological engineering. and sophisticated machine learning algorithms will be implemented in the development of the incubator.

Projected Results

A controlled and active sound environment in and around the incubator can in turn promote the wellbeing, neural development, and speech development of the child and minimise distress caused by unwanted noises. While developing the hardware and software pose individual challenges, it is about the system design and aspects contributing to it. On the one hand, it is crucial to measure the auditory range and frequencies in the incubator, as well as the predictable sounds that will have to be played back into the environment. On the other, there are many technical issues that have to be addressed when it comes to algorithms, datasets, delay, microphone technology, transducers, convergence, tracking, impulse control and noise rejection, noise mitigation stability, detection, polarity, and performance.

Conclusion

Solving a complex problem like this, however, requires a de-disciplinary approach, where each discipline will realise its own shortcomings and boundaries, and in turn will allow for innovations and new avenues. Technical developments used for building the active noise cancellation-incubator have the potential to contribute to improved care solutions for patients, both infants and adults.Code available at: 10.3389/fped.2023.1187815.

Living in a box: Understanding acoustic parameters in the NICU environment

Background

In the last years, a significant body of scientific literature was dedicated to the noisy environment preterm-born infants experience during their admission to Neonatal Intensive Care Units (NICUs). Nonetheless, specific data on sound characteristics within and outside the incubator are missing. Therefore, this study aimed to shed light on noise level and sound characteristics within the incubator, considering the following domain: environmental noise, incubator handling, and respiratory support.

Methods

The study was performed at the Pediatric Simulation Center at the Medical University of Vienna. Evaluation of noise levels inside and outside the incubator was performed using current signal analysis libraries and toolboxes, and differences between dB_A and dB_SPL values for the same acoustic noises were investigated. Noise level results were furthermore classed within previously reported sound levels derived from a literature survey. In addition, sound characteristics were evaluated by means of more than 70 temporal, spectral, and modulatory timbre features.

Results

Our results show high noise levels related to various real-life situations within the NICU environment. Differences have been observed between A weighted (dB_A) and unweighted (dB_SPL) values for the same acoustic stimulus. Sonically, the incubator showed a dampening effect on sounds (less high frequency components, less brightness/sharpness, less roughness, and noisiness). However, a strong tonal booming component was noticeable, caused by the resonance inside the incubator cavity. Measurements and a numerical model identified a resonance of the incubator at 97 Hz and a reinforcement of the sound components in this range of up to 28 dB.

Conclusion

Sound characteristics, the strong low-frequency incubator resonance, and levels in dB_SPL should be at the forefront of both the development and promotion of incubators when helping to preserve the hearing of premature infants.

Prenatal auditory experience and its sequelae

Towards the end of the second trimester of gestation, a human fetus is able to register environmental sounds. This in utero auditory experience is characterized by comprising strongly low-pass-filtered versions of sounds from the external world. Here, we present computational tests of the hypothesis that this early exposure to severely degraded auditory inputs serves an adaptive purpose-it may induce the neural development of extended temporal integration. Such integration can facilitate the detection of information carried by low-frequency variations in the auditory signal, including emotional or other prosodic content. To test this prediction, we characterized the impact of several training regimens, biomimetic and otherwise, on a computational model system trained and tested on the task of emotion recognition. We find that training with an auditory trajectory recapitulating that of a neurotypical infant in the pre-to-postnatal period results in temporally extended receptive field structures and yields the best subsequent accuracy and generalization performance on the task of emotion recognition. This strongly suggests that the progression from low-pass-filtered to full-frequency inputs is likely to be an adaptive feature of our development, conferring significant benefits to later auditory processing abilities relying on temporally extended analyses. Additionally, this finding can help explain some of the auditory impairments associated with preterm births, suggests guidelines for the design of auditory environments in neonatal care units, and points to enhanced training procedures for computational models.

Negative Effects of Noise on NICU Graduates' Cochlear Functions

To evaluate the adverse effects of noise on hearing. Methods: Thirty-two infants that had been admitted to neonatal intensive care unit (NICU) and 25 healthy controls were included in this study. Noise levels were recorded continously during the hospitalization period. Results: All healthy controls passed the hearing screening tests before discharge and on the sixth-month follow up. Hospitalized infants had lower "Distortion Product Auto Acoustic Emission Signal Noise Ratio" (DPOAE SNR) amplitudes (dB) at five frequencies (1001, 1501, 3003, 4004, 6006 Hz in both ears). DPOAE fail rates at 1001 Hz and 1501 Hz were higher than in hospitalized infants (81.8% and 50.0% vs 20.0% and 4.0%). Infants who failed the test at 1001 and 1501 Hz were exposed to noise above the recommended maximum level for longer periods of time. Conclusion: Hearing tests performed at sixth-months of life were adversely affected in NICU graduates.

Mothers' voices and white noise on premature infants' physiological reactions in a neonatal intensive care unit: A multi-arm randomized controlled trial

BACKGROUND

A few positive effects of mothers' voice on physiological outcomes have been studied and limited studies have focused on the level of cortisol. In addition, white noise has recently been found to be beneficial for human sleep, but studies in premature infants were limited and no study has compared the effects of mothers' voice and white noise on premature infants.

OBJECTIVE

To examine the effects of mothers' voice and white noise on sleep-wake patterns, salivary cortisol levels, weight gain, heart rate, and oxygen saturation of premature infants in a neonatal intensive care unit (NICU).

METHODS

This was a three-group randomized controlled trial. A total of 103 medically stable premature infants in incubators were recruited from the NICU of a women's and children's hospital in China between March and December 2017 and were randomized into three groups: the mothers' voice group (n = 34), the white noise group (n = 34), and the routine care group (n = 35). Mothers' voice, white noise, and no voice were provided to the three groups for 20 min at a time, three times a day for four consecutive days. The sound levels of the mothers' voice and white noise were controlled between 50 and 55 dB. Sleep-wake patterns, salivary cortisol level, and weight were measured at pre-test and post-test whereas heart rate and oxygen saturation were measured every five-minute at 11am, 2pm, 5pm for four-consecutive days.

RESULTS

A group difference was found only in weight gain (p = 0.003), with weight gain in the white noise group being significantly higher than the mothers' voice group (Z=-3.447, p = 0.001). Significant declines in total sleep time and sleep efficiency and increases in wake time after sleep onset and average awakening time were only found in the routine-care group between the pre-test and post-test (p<0.05). No significant differences were found in the salivary cortisol levels, heart rates, and oxygen saturation levels among the three groups (p>0.05). A significant increase in oxygen saturation during the 20-min intervention was found in white noise group. Non-significant decreases in the heart rate during the 20-min intervention and salivary cortisol levels at post test were noted in all the three groups.

CONCLUSION

White noise is more useful for encouraging weight gain in preterm infants compared with mothers' voices. White noise might be introduced for use in the care of premature infants in NICUs, and more high-quality randomized controlled trials are needed to confirm these findings. Trial Registration No: ChiCTR-INR-17012755.

The "Sound of Silence" in a Neonatal Intensive Care Unit-Listening to Speech and Music Inside an Incubator

Background: The intrauterine hearing experience differs from the extrauterine hearing exposure within a neonatal intensive care unit (NICU) setting. Also, the listening experience of a neonate drastically differs from that of an adult. Several studies have documented that the sound level within a NICU exceeds the recommended threshold by far, possibly related to hearing loss thereafter. The aim of this study was, first, to precisely define the dynamics of sounds within an incubator and, second, to give clinicians and caregivers an idea about what can be heard “inside the box.”

Methods: Audio recordings within an incubator were conducted at the Pediatric Simulation Center of the Medical University Vienna. They contained recorded music, speech, and synthesized sounds. To understand the dynamics of sounds around and within the incubator, the following stimuli were used: broadband noise with decreasing sound level in 10 steps of 6 dB, sine waves (62.5, 125, 250, 500, 1000, 2000, 4000, 8000, and 16,000 Hz), logarithmic sweep (Chirp) over the frequency band 20 Hz to 21 kHz, singing male voice, singing, and whispering female voice.

Results: Our results confirm a protective effect of the incubator from noises above 500 Hz in conditions of “no-flow” and show almost no protective effect of an incubator cover. We, furthermore, observed a strong boost of low frequencies below 125 Hz within the incubator, as well as a notable increase of higher frequency noises with open access doors, a significant resonant effect of the incubator, and a considerable masking effect of the respiratory support against any other source of noise or sound stimulation even for “low-flow” conditions.

Conclusion: Our study reveals high noise levels of air supply at high flow rates and the boost of low frequencies within the incubator. Education of medical staff and family members as well as modifications of the physical environment should aim at reducing noise exposure of preterm infants in the incubator. Audiovisual material is provided as Supplementary Material.

Environmental noise levels in hospital settings: A rapid review of measurement techniques and implementation in hospital settings

BACKGROUND

Hospitals provide treatment to improve patient health and well-being but the characteristics of the care environment receive little attention. Excessive noise at night has a negative impact on in-patient health through disturbed sleep. To address this hospital staff must measure night-time environmental noise levels. Therefore, an understanding of environmental noise measurement techniques is required. In this review, we aim to 1) provide a technical overview of factors to consider when measuring environmental noise in hospital settings; 2) conduct a rapid review on the equipment and approaches used to objectively measured noise in hospitals and identify methodological limitations.

DESIGN

: A rapid review of original research articles, from three databases, published since 2008. Studies were included if noise levels were objectively measured in a hospital setting where patients were receiving treatment.

RESULTS

1429 articles were identified with 76 included in the review. There was significant variability in the approaches used to measure environmental noise in hospitals. Only 14.5% of studies contained sufficient information to support replication of the measurement process. Most studies measured noise levels using a sound level meter positioned closed to a patient's bed area in an intensive care unit.

CONCLUSION

: Unwanted environmental noise in hospital setting impacts negatively on patient and staff health and well-being. However, this literature review found that the approaches used to objectively measure noise level in hospital settings have been inconsistent and poorly reported. Recommendations on best-practice methods to measure noise levels in hospital environments are provided.

Noise level in neonatal incubators: A comparative study of three models

BACKGROUND

Preterm infants usually have to spend a long time in an incubator, excessive noise in which can have adverse physiological and psychological effects on neonates. In fact, incubator noise levels typically range from 45 to 70 dB but differences in this respect depend largely on the noise measuring method used. The primary aim of this work was to assess the extent to which noise in an incubator comes from its own fan and how efficiently the incubator can isolate external noise.

METHODS

Three different incubator models were characterized for acoustic performance by measuring their internal noise levels in an anechoic chamber, and also for noise isolation efficiency by using a pink noise source in combination with an internal and an external microphone that were connected to an SVAN958 noise analyzer.

RESULTS

The incubators studied produced continuous equivalent noise levels of 53.5-58 dB and reduced external noise by 5.2-10.4 dB.

CONCLUSIONS

A preterm infant in an incubator is exposed to noise levels clearly exceeding international recommendations even though such levels usually comply with the limit set in the standard IEC60601-2-19: 2009 (60 dBA) under normal conditions of use.

Sound levels in a neonatal intensive care unit significantly exceeded recommendations, especially inside incubators

AIM

This study measured sound levels in a 2008 built French neonatal intensive care unit (NICU) and compared them to the 2007 American Academy of Pediatrics (AAP) recommendations. The ultimate aim was to identify factors that could influence noise levels.

METHODS

The study measured sound in 17 single or double rooms in the NICU. Two dosimeters were installed in each room, one inside and one outside the incubators, and these conducted measurements over a 24-hour period. The noise metrics measured were the equivalent continuous sound level (L_eq ), the maximum noise level (L_max ) and the noise level exceeded for 10% of the measurement period (L₁₀ ).

RESULTS

The mean L_eq , L₁₀ and L_max were 60.4, 62.1 and 89.1 decibels (dBA), which exceeded the recommended levels of 45, 50 and 65 dBA (p < 0.001), respectively. The L_eq inside the incubator was significantly higher than in the room (+8 dBA, p < 0.001). None of the newborns' characteristics, the environment or medical care was correlated to an increased noise level, except for a postconceptional age below 32 weeks.

CONCLUSION

The sound levels significantly exceeded the AAP recommendations, particularly inside incubators. A multipronged strategy is required to improve the sound environment and protect the neonates' sensory development.

Preterm behavioral epigenetics: A systematic review

Behavioral epigenetics is revealing new pathways that lead individuals from early adversity exposures to later-in-life detrimental outcomes. Preterm birth constitutes one of the major adverse events in human development. Preterm infants are hospitalized in the Neonatal Intensive Care Unit (NICU) where they are exposed to life-saving yet pain-inducing procedures and to protective care. The application of behavioral epigenetics to the field of preterm studies (i.e., Preterm Behavioral Epigenetics, PBE) is rapidly growing and holds promises to provide valid insights for research and clinical activity. Here, the evidence of the epigenetic correlates of prenatal adversities, NICU-related environment and development of preterm infants is systematically reviewed. The findings suggest that a number of prenatal adverse (e.g., maternal depression and stress) and post-natal (e.g., NICU-related pain-related stress) events affect the developmental trajectories of preterm infants and children via epigenetic alterations of imprinted and stress-related genes. Nonetheless, the potential epigenetic vestiges of early care and protective interventions in NICU have not been investigated yet and this represents a fascinating challenge for future PBE research.

Sound as a supportive design intervention for improving health care experience in the clinical ecosystem: A qualitative study

PURPOSE

Most prior hospital noise research usually deals with sound in its noise facet and is based merely on sound level abatement, rather than as an informative or orientational element. This paper stimulates scientific research into the effect of sound interventions on physical and mental health care in the clinical environment.

METHODS

Data sources comprised relevant World Health Organization guidelines and the results of a literature search of ISI Web of Science, ProQuest Central, MEDLINE, PubMed, Scopus, JSTOR and Google Scholar.

RESULTS

Noise induces stress and impedes the recovery process. Pleasant natural sound intervention which includes singing birds, gentle wind and ocean waves, revealed benefits that contribute to perceived restoration of attention and stress recovery in patients and staff.

CONCLUSIONS

Clinicians should consider pleasant natural sounds perception as a low-risk non-pharmacological and unobtrusive intervention that should be implemented in their routine care for speedier recovery of patients undergoing medical procedures.

Noise in the Neonatal Intensive Care Unit: What Does the Evidence Tell Us?

BACKGROUND

In 2014, more than 10% of all births in the United States were preterm (born at <37-weeks' gestation). These high-risk infants will often spend weeks to months within the neonatal intensive care unit (NICU), where noise levels can easily reach 120 decibels adjusted (dBA) on a regular and sometimes consistent basis. The American Academy of Pediatrics recommends that NICU sound levels remain below 45 dBA to promote optimal growth and development.

PURPOSE

The purpose of this evidence-based brief is to critically appraise the literature concerning preterm infant response to noise within the NICU as well as the use of noise interventions to improve health outcomes for the vulnerable preterm infant population.

METHODS/SEARCH STRATEGY

Systematic searches of databases included the Cochrane Library, CINAHL, PubMed, and Science Direct. Included studies were appraised and then synthesized into a narrative summary.

FINDINGS/RESULTS

Twenty studies met inclusion criteria for this review. While there are numerous methods that have been shown to reduce noise levels within the NICU, most NICU noise levels remain consistently above the American Academy of Pediatrics recommendations. Studies that assessed interventions found that staff reeducation was critical to sustaining appropriate noise levels.

IMPLICATIONS FOR PRACTICE

Implementing interventions with rigorous attention to initial and continued staff education with engagement and ownership is recommended. This review identifies gaps in intervention studies targeting vulnerable NICU populations.

IMPLICATIONS FOR RESEARCH

While noise interventions show promise in the NICU, additional focused research is needed to further strengthen the evidence and inform clinical practice.

Noise Reduction in the Neonatal Intensive Care Unit: A Quality Improvement Initiative

Exogenous noise has deleterious effects on the developing fetus and infant. The aim of this quality improvement project was to lower the mean ambient noise level within a level IV neonatal intensive care unit (NICU) by 10% from the baseline in one year. Multiple noise reduction strategies were tested through Plan-Do-Study-Act cycles based on the Institute for Healthcare Improvement model for improvement. Strategies targeted environmental and behavioral modifications. Noise levels were recorded continuously; means and peaks were calculated. The mean noise level decreased from 62.4 dB to 56.1 dB, and peak noise level decreased from 115 dB to 76 dB within 12 months. Day shift noise level decreased by 7.7 dB; night shift noise level decreased by 4.9 dB from baseline. Targeted education, behavioral, and environmental modifications decreased the noise level in the NICU as per the study aim. To create a change in culture, constant dialogue between the project champions and the NICU staff is necessary.

Effect of peer education on the noise management in Iranian neonatal intensive care unit

Background:

Advancements in neonatal intensive care unit (NICU) science and technology have increased the survival rate of preterm infants. Despite these advances, they are still facing with neurobehavioral problems. Noise level in NICU is a potential source of stress for preterm infants. It should be decreased to the standard level as much as possible. The purpose of this study was to evaluate the effect of peer education on the performance of staff in noise management in the NICU.

Materials and Methods:

A pre-post test quasi-experimental design was used. Fifty-eight staff members (nurses and physicians) participated in this study. Sound pressure levels were measured before and after the intervention. Peer education program formed the intervention. The staff performance in noise management was evaluated before and after the intervention by using a questionnaire. Data analysis was done by using t-test.

Results:

The results of the study showed that the mean sound level in different environments significantly decreased after the intervention. It reached from 86.7 to 74.9 dB in the center of unit and from 68.2 to 48.50 dB in the infants' bedside (P < 0.0001). The mean score of the staff performance in noise management significantly increased after the intervention, compared to the pre-intervention score. It increased from 74.6 to 83.4 (P < 0.0001).

Conclusions:

Peer education was found to be successful in noise management because behavioral changes were done to avoid generating unnecessary noise by the staff.

Sustaining a "culture of silence" in the neonatal intensive care unit during nonemergency situations: a grounded theory on ensuring adherence to behavioral modification to reduce noise levels

The aim of this study was to generate a substantive theory explaining how the staff in a resource-limited neonatal intensive care unit (NICU) of a developing nation manage to ensure adherence to behavioral modification components of a noise reduction protocol (NsRP) during nonemergency situations. The study was conducted after implementation of an NsRP in a level III NICU of south India. The normal routine of the NICU is highly dynamic because of various categories of staff conducting clinical rounds followed by care-giving activities. This is unpredictably interspersed with very noisy emergency management of neonates who suddenly fall sick. In-depth interviews were conducted with 36 staff members of the NICU (20 staff nurses, six nursing aides, and 10 physicians). Group discussions were conducted with 20 staff nurses and six nursing aides. Data analysis was done in line with the reformulated grounded theory approach, which was based on inductive examination of textual information. The results of the analysis showed that the main concern was to ensure adherence to behavioral modification components of the NsRP. This was addressed by using strategies to “sustain a culture of silence in NICU during nonemergency situations” (core category). The main strategies employed were building awareness momentum, causing awareness percolation, developing a sense of ownership, expansion of caring practices, evolution of adherence, and displaying performance indicators. The “culture of silence” reconditions the existing staff and conditions new staff members joining the NICU. During emergency situations, a “noisy culture” prevailed because of pragmatic neglect of behavioral modification when life support overrode all other concerns. In addition to this, the process of operant conditioning should be formally conducted once every 18 months. The results of this study may be adapted to create similar strategies and establish context specific NsRPs in NICUs with resource constraints.

How caregivers view patient comfort and what they do to improve it: a French survey

Background

Intensive care unit (ICU) patients are exposed to many sources of discomfort. Most of these are related to the patient’s condition, but ICU design or how care is organized also can contribute. The present survey was designed to describe the opinions of ICU caregivers on sources of patient discomfort and to determine how they were dealt with in practice. The architectural and organizational characteristics of ICUs also were analyzed in relation to patient comfort.

Methods

An online, closed-ended questionnaire was developed. ICU caregivers registered at the French society of intensive care were invited to complete this questionnaire.

Results

A total of 915 staff members (55% nurses) from 264 adult and 28 pediatric ICUs completed the questionnaire. Analysis of the answers reveals that: 68% of ICUs had only single-occupancy rooms, and 66% had natural light in each room; ICU patients had access to television in 59% of ICUs; a clock was present in each room in 68% of ICUs. Visiting times were <4 h in 49% of adult ICUs, whereas 64% of respondents considered a 24-h policy to be very useful or essential to patients’ well-being. A nurse-driven analgesia protocol was available in 42% of units. For caregivers, the main sources of patient discomfort were anxiety, feelings of restraint, noise, and sleep disturbances. Paramedics generally considered discomfort related to thirst, lack of privacy, and the lack of space and time references, whereas almost 50% of doctors ignored these sources of discomfort. Half of caregivers indicated they assessed sleep quality. A minority of caregivers declared regular use of noise-reduction strategies. Twenty percent of respondents admitted to having non-work-related conversations during patient care, and only 40% indicated that care often was or always was provided without closing doors. Family participation in care was planned in very few adult ICUs.

Conclusions

Results of this survey showed that ICUs are poorly equipped to ensure patient privacy and rest. Access by loved ones and their participation in care also is limited. The data also highlighted that some sources of discomfort are less often taken into account by caregivers, despite being considered to contribute significantly.

Intervention minimizing preterm infants' exposure to NICU light and noise

Neonatal intensive care unit (NICU) light and noise may be stressful to preterm infants. This research evaluated the physiological stability of 54 infants born at 28- to 32-weeks' gestational age while wearing eye goggles and earmuffs for a 4-hour period in the NICU. Infants were recruited from four NICUs of university-affiliated hospitals and randomized to the intervention-control or control-intervention sequences. Heart rate (HR), heart rate variability (HRV), and oxygen saturation (O2 sat) were collected using the SomtéTM device. Confounding variables such as position and handling were assessed by videotaping infants during the study periods. Results indicated that infants had more stress responses while wearing eye goggles and earmuffs since maximum HR was found to be significantly higher and high-frequency power of HRV significantly lower during the intervention as compared with the control period. Therefore, this intervention is not recommended for the clinical practice.

Neonatal incubators: a toxic sound environment for the preterm infant?*

BACKGROUND

High sound pressure levels may be harmful to the maturing newborn. Current guidelines suggest that the sound pressure levels within a neonatal intensive care unit should not exceed 45 dB(A). It is likely that environmental noise as well as the noise generated by the incubator fan and respiratory equipment may contribute to the total sound pressure levels. Knowledge of the contribution of each component and source is important to develop effective strategies to reduce noise within the incubator.

AIMS

The objectives of this study were to determine the sound levels, sound spectra, and major sources of sound within a modern neonatal incubator (Giraffe Omnibed; GE Healthcare, Helsinki, Finland) using a sound simulation study to replicate the conditions of a preterm infant undergoing high-frequency jet ventilation (Life Pulse, Bunnell, UT).

METHODS

Using advanced sound data acquisition and signal processing equipment, we measured and analyzed the sound level at a dummy infant's ear and at the head level outside the enclosure. The sound data time histories were digitally acquired and processed using a digital Fast Fourier Transform algorithm to provide spectra of the sound and cumulative sound pressure levels (dBA). The simulation was done with the incubator cooling fan and ventilator switched on or off. In addition, tests were carried out with the enclosure sides closed and hood down and then with the enclosure sides open and the hood up to determine the importance of interior incubator reverberance on the interior sound levels

RESULTS

With all the equipment off and the hood down, the sound pressure levels were 53 dB(A) inside the incubator. The sound pressure levels increased to 68 dB(A) with all equipment switched on (approximately 10 times louder than recommended). The sound intensity was 6.0 × 10(-8) watts/m(2); this sound level is roughly comparable with that generated by a kitchen exhaust fan on high. Turning the ventilator off reduced the overall sound pressure levels to 64 dB(A) and the sound pressure levels in the low-frequency band of 0 to 100 Hz were reduced by 10 dB(A). The incubator fan generated tones at 200, 400, and 600 Hz that raised the sound level by approximately 2 dB(A)-3 dB(A). Opening the enclosure (with all equipment turned on) reduced the sound levels above 50 Hz by reducing the revereberance within the enclosure.

CONCLUSION

The sound levels, especially at low frequencies, within a modern incubator may reach levels that are likely to be harmful to the developing newborn. Much of the noise is at low frequencies and thus difficult to reduce by conventional means. Therefore, advanced forms of noise control are needed to address this issue.

Auditory brain development in premature infants: the importance of early experience

Preterm infants in the neonatal intensive care unit (NICU) often close their eyes in response to bright lights, but they cannot close their ears in response to loud sounds. The sudden transition from the womb to the overly noisy world of the NICU increases the vulnerability of these high-risk newborns. There is a growing concern that the excess noise typically experienced by NICU infants disrupts their growth and development, putting them at risk for hearing, language, and cognitive disabilities. Preterm neonates are especially sensitive to noise because their auditory system is at a critical period of neurodevelopment, and they are no longer shielded by maternal tissue. This paper discusses the developmental milestones of the auditory system and suggests ways to enhance the quality control and type of sounds delivered to NICU infants. We argue that positive auditory experience is essential for early brain maturation and may be a contributing factor for healthy neurodevelopment. Further research is needed to optimize the hospital environment for preterm newborns and to increase their potential to develop into healthy children.

Noise at the Neonatal Intensive Care Unit and inside the incubator

The goal was to identify sound pressure level (SPL) at the neonatal intensive care unit (NICU) and inside the incubator of a teaching hospital of a public university from São Paulo - SP, Brazil. SPL inside the NICU and the incubator were measured using four dosimeters in January/2010. SPL at the NICU varied from 52.6 dBA to 80.4 dBA and inside the incubator, from 45.4 dBA to 79.1 dBA. SPL both at the NICU and inside the incubator are above the recommended values, but levels were higher at the NICU than inside the incubator. Although there are some specific factors related to SPL inside the incubator, the NICU and incubator acoustic features present a system: an increase/decrease in SPL at the NICU usually tends to increase/decrease SPL inside the incubator. The study points to the need for simultaneous monitoring of SPL at the NICU and inside the incubator.