The effectiveness of earmuffs on the physiologic and behavioral stability in preterm infants☆
Introduction
Development of auditory system has been started from 23 to 24 weeks of gestation and continues shortly after the birth. Around 70% of premature newborns (birth before 37 completed weeks of gestation) need hospitalization in neonatal intensive-care unit (NICU). Neonatal intensive-care units are often characterized by noise pollution from different sources like monitor alarms, medical devices, cellular phones, staff conversations, and sound of infant crying [1], [2].
Preterm newborns because of immature autonomic, auditory, central nervous systems, and low ability of self-adaptation responses are prone to negative effects of environmental stimuli and stresses [3]. Excess auditory stimuli including loud, sharp, and unpredictable sounds create negative developmental and physiological responses [4]. Committee on Environmental Health in 1997 has reported the prevalence of hypoxemia (low level of blood oxygen), behavioral abnormality (in sleep, awake, crying, etc.) and hearing loss related to continuous noise exposure among preterm infants cared in the NICU [5]. It has been shown that the noise reduction enhances the behavioral responses, including the sleep quality and time of quiet sleep in preterm infants [6].
The limiting noise levels (loudness of sound) in NICU was recommended hourly Leq of 45 dB by the American Academy of Pediatrics', however, it is far from baseline noise levels in contemporary NICUs (range between 70 and 80 dB) [6], [7]. In order to achieve this goal, different methods like reduction of environmental noise, behavioral modification, treating infants in private room, incubators with controlled sound levels and prevention of receiving noise by infants were implemented [8], [9].
Earmuffs, earplugs, and sound absorbing foams can protect infants from receiving noise in the NICU. Wearing earmuffs can decline noise level by 7–12 dBA equal to 50% sound pressure [10]. Bott has shown the effectiveness of Earplugs in weight gain of very low birth weight newborns [11]. Li et al. also have revealed that wearing earmuffs may decline the frequency of hearing loss, mental retardation, periventricular hemorrhage intraventricular hemorrhage or periventricular leukomalacia among 100 premature newborns with respiratory distress syndrome [12].
In Iran, there is not any protocol regarding reduction of noise levels in NICUs. Although few Iranian studies [9] have evaluated the effectiveness of the earmuffs on motor or physiological responses in preterm infants, there is a gap for more information. The goal of this study was to evaluate the effects of wearing earmuffs on the physiologic and behavioral responses in preterm infants with a different method which has not been implemented in 2 studies.
Section snippets
Participants
A crossed over controlled trial study was carried out at NICU of Aliasghar Hospital affiliated to Iran University of Medical Sciences (Tehran, Iran) from June up to September of 2014. Thirty-six preterm infants who met the inclusion criteria were crossed over (Simple crossed over) and entered the study. Inclusion criteria were preterm birth (gestational age<37 weeks), age> 1 week to rule out intracranial hemorrhage, NICU hospitalization cared in closed incubator, parents' informed consent, no
Results
Thirty-six preterm infants born with mean gestational age of 30.94 ± 1.47 weeks (28–32 weeks) and birth weight 1364.17 ± 145.76 entered the study. Of all subjects 22 (61.10%) were male. The mean first and 5 min Apgar scores were 8.67 and 9.72, respectively. The first minute Apgar score in 50% of neonates were 9 and 5 min Apgar score in 72% were 10. The demographic data are shown in Table 1.
As infants' physiologic responses are demonstrated in Table 2; analysis of paired t-test showed
Discussion
Various studies have indicated the negative effects of high noise levels on physiologic and neurobehavioral responses in preterm infants admitted in the NICUs [5], [13], [14], [15]. Using earmuff as an individual, safe, comfortable, and infection controlled device protects neonates' hearing from exposure to loud noise and provide a safe environment for neonate's growth and development. The results of the present study showed that noise stress reduction during wearing earmuffs has potentially
Conclusion
We found that noise level reduction in NICUs by using earmuff improved preterm neonates' physiological stability and behavioral states of ABSS; lower heart rate, respiratory rates and higher mean arterial O2 saturation were notable among preterm infants with earmuffs. Moreover, neonates wearing earmuffs experienced more time in quiet sleep. Although further studies are needed to confirm these results, the authors suggest using earmuffs in neonatal intensive care units.
List of abbreviations
Neonatal intensive-care unit: NICU.
Ethics approval and consent to participate
Ethics approval for the study was obtained from the institutional review board of Iran University of Medical Sciences according to Helsinki declaration. Our gathered data were confidential and no extra cost was imposed on our participants. Registration ID of this study in Iranian Registry of Clinical Trials was: RCT2015020817972N6.
Funding
None to declare.
Authors' contributions
NK, NK, AN, ZG, and AK all have the same contribution in data gathering, interpretation, and writing the manuscript.
Competing interests
None to declare.
Disclosure of any prior publications or submissions
There are no prior publications or submissions with any overlapping information, including studies and patients.
Acknowledgements
The authors would like to express our gratitude to Dr. Rastgar for his kindly collaboration. We also thank Dr. Alireza Karimi for his great help and time to read the manuscript and give us their comments to improve the quality of the manuscript.
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Cited by (22)
Effect of a noise reduction program on stress of premature neonates in neonatal intensive care unit
2023, Journal of Neonatal NursingCitation Excerpt :In Iran, studies with noise reduction intervention indicated that teaching the staffs can decrease noise levels in NICU (Biabanakigoortani et al., 2016). Also using earmuffs on preterm neonates decreased the noise that infants receive during their stay in NICU and lead to physiologic stability and improvement in behavioral development (Abdeyazdan et al., 2014; Khalesi et al., 2017). The salivary cortisol level is not evaluated in any of the studies in Iran.
Sleep in the Hospitalized Child: A Contemporary Review
2021, ChestCitation Excerpt :Noise reduction interventions aim to improve sleep quality through various methods, including “quiet hours,” earplugs, earmuffs, and so forth. Ear protection in preterm NICU patients is associated with more time in quiet sleep and improved Anderson Behavioral State Scale score.97,98 Instituting environmental interventions can be challenging while balancing safety and staff expectations.
The value of cardiorespiratory parameters for sleep state classification in preterm infants: A systematic review
2021, Sleep Medicine ReviewsCitation Excerpt :All in all, one could conclude that fetuses spend at least 60–90% of their time asleep. Outside of the protective intrauterine environment, preterm infants are suddenly exposed to excessive light, noise and treatments in the neonatal intensive care unit (NICU), which are all known to disturb sleep [26,27]. Sleep monitoring is thus thought to be very important, as monitoring can increase awareness of sleep duration and quality, give insight in factors negatively influencing sleep, and steer the timing of elective interventions [28].
Active soundproof earmuffs system with passive noise insulation structure compensation
2020, Applied AcousticsCitation Excerpt :So far, it has been proved that, ANC technique is widely and sufficiently used for low-frequency noise reduction [1]. The professional soundproof earmuffs coupled with ANC feature [9–12] or other ANC hearing protection devices (HPDs) including headset [13–19], helmet [20,21] and hearing aids [22–24] can overcome the shortcoming of the passive noise reduction and realize effective noise suppressing on full frequency range. Fig. 1 shows a typical head mounted active soundproof earmuffs system with feedforward ANC subsystem.
Part 1: Narrative overview of developmental care interventions for the preterm newborn
2019, Journal of Neonatal NursingCitation Excerpt :An experimental study concludes that silicone earplugs wore by eight very low birth weight preterm infants’ during their NICU hospitalization appears to favor mental developmental index at 18–22 months of corrected age (Abou Turk et al., 2009). Then, preterm infants who were randomized in crossover trials were physiologically more stable (lower heart and respiratory rates and improved oxygen saturation (Khalesi et al., 2017); and in more quiet sleep state during the 2-hr period they were wearing the earmuffs compared to the period when they were not wearing it (Duran et al., 2012; Khalesi et al., 2017). Findings of other studies with a RCT design also confirm that preterm infants wearing earmuffs 2-hr in the morning and 2-hr in the afternoon were more physiologically stable and had improved motor state (Abdeyazdan et al., 2014a) as well as greater weight gain (Abdeyazdan et al., 2014b) compared to those not wearing earmuffs.
Investigating the Effect of Using Aerogel on Transmission Loss of Earmuff
2024, Iran Occupational Health
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Trial registration information: It has been issued in Iran University of Medical Sciences by a letter number of IRI95/125489/14 on 12 February 2016.