The effects of noise reduction by earmuffs on the physiologic and behavioral responses in very low birth weight preterm infants

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Abstract

Objective

Preterm infants are exposed to loud noises during their stay in the neonatal intensive care unit which can lead to physiologic and behavioral alterations and even hearing loss. The use of earmuffs can reduce sound level and these changes. The objective of the present study is to evaluate the effectiveness of the earmuffs in preterm infants solely cared for in closed incubators.

Methods

A comparative prospective study comprising 20 clinically stable preterm infants weighing less than 1500 g cared in closed incubator was conducted. Preterm infants acted as their own controls whereby they were observed without earmuffs (Group 1) for 2 days and with earmuffs (Group 2) on consecutive 2 days. The preterm infants’ physiologic responses and Anderson Behavioral State Scoring System (ABSS) scores were assessed over 30 s every 2 h for 8 h during daytime for 4 days.

Results

Out of 20 preterm infants, 6 were male and 14 female with a mean birth weight of 1220 ± 209 g, gestational age of 29.9 ± 2.1 weeks. The total number of measurements was 320. The mean ABSS scores of Group 1 and 2 were 3.07 ± 1.1 and 1.34 ± 0.3, respectively. Statistically significant difference was noted between the means of ABSS scores (p < 0.001). Preterm infants with earmuffs (87.5%) were more frequently observed in a quiet sleep state of ABSS compared with those without earmuffs (29.4%).

Conclusions

Noise level reduction was associated with significant improvement in behavioral states of ABSS. We suggest that noise reduction in preterm infants with earmuffs is helpful by improving sleep efficiency and increasing time of quiet sleep.

Introduction

Preterm infants are continuously exposed to loud noises such as alarm, ventilator and phone noises during their stay in the neonatal intensive care unit (NICU) [1]. American Academy of Pediatrics (AAP) recommends noise levels <45 dBA in the NICU, but the noise levels often exceed this level [1], [2]. Earlier studies investigating the effects of loud NICU noises have shown the negative short-term alterations in blood pressure, oxygen saturation, respiratory and heart rates in preterm infants [1]. Inside the incubators, noise levels range from 58 to 75 dbA and preterm infants are not mostly protected from external noise. For example, inside the incubator, the noise level of tapping incubator with fingers is 80 dBA [2]. Previous studies have demonstrated negative synergistic effect of aminoglycosides and noise on hearing in preterm infants cared in an incubator [1], [3]. In addition, Winkel et al. have found that among preterm infants in closed incubator care, 52% had an abnormal audiogram pattern without hearing loss [3]. Studies have shown that reducing the noise level by interventions such as closing the incubator portholes gently and eliminating radios in the NICU result in positive physiologic and behavioral changes [1], [4]. However, a few studies have investigated the benefits of noise reduction by earmuffs in preterm infants [5], [6]. Only one study has demonstrated that when very low birth weight preterm infants in an open warmer or incubator care wore the earmuffs, they had less fluctuation in oxygen saturation and less frequent behavioral state changes [6]. The objective of the present study is to evaluate the effectiveness of the earmuffs in preterm infants solely cared for in closed incubators.

Section snippets

Patients

A comparative prospective design was used, to describe differences related to using the earmuffs in very low birth weight preterm infants. The present study was approved by the Trakya University Local Ethics Committee. Parental consent was obtained from the parents of study patients. The study was conducted in the Neonatal Intensive Care Unit (NICU) of the Trakya University Hospital, where all preterm infants weighing less than 1500 g are routinely nursed in incubators (Air-Shields, Isolette

Results

The present comparative prospective study comprised 20 preterm infants; 6 male and 14 female infants with a mean birth weight of 1220 ± 209 g, a mean gestational age 29.9 ± 2.1 weeks and a mean age at observation 30 ± 2.2 weeks. The first and five minute Apgar scores in preterm infants were 6.6 ± 1.3 and 8.6 ± 1.1, respectively.

The total number of measurements was 320. The means of inside and outside incubator noise levels were 57.83 ± 2.72 and 61.34 ± 3.16 dBA, respectively which was significantly different (p

Discussion

Many NICUs have been built to maintain noise control, using sound absorbing materials, noise-reducing incubators, and separating noisy spaces from patient areas. However, advances in technology have caused more noise sources in the NICU, such as telephones, high-frequency ventilators, and alarms [11], [12]. In this study, the effectiveness of the earmuffs was evaluated for the noise reduction in very low birth weight preterm infants solely cared in closed incubator. We found that noise level

Conflict of interest

The authors do not have any conflict of interest.

Acknowledgements

The residents and nurses in the Trakya University Hospital NICU are gratefully acknowledged for their support and assistance.

References (17)

  • E.M. Wachman et al.

    The effects of noise on preterm infants in the NICU

    Arch Dis Child Fetal Neonatal Ed

    (2011)
  • American Academy of Pediatrics Committee on Environmental Health Noise

    A hazard for the fetus and newborn

    Pediatrics

    (1997)
  • S. Winkel et al.

    Possible effects of kanamycin and incubation in newborn children with low birth weight

    Acta Paediatr. Scand.

    (1978)
  • C. Strauch et al.

    Implementation of a quiet hour: effect on noise levels and infant sleep states

    Neonatal Netw.

    (1993)
  • S. D’Agati et al.

    The effect of noise reduction on behavioral states in newborns

    Pediatr. Res.

    (1994)
  • L.K. Zahr et al.

    Premature infant responses to noise reduction by earmuffs: effects on behavioral and physiologic measures

    J. Perinatol.

    (1995)
  • G.C. Anderson et al.

    Self-regulatory gavage-to-bottle feeding for preterm infants: effects on behavioral state, energy expenditure and weight gain

  • Y. Ahn

    The relationship between behavioral states and pain responses to various NICU procedures in premature infants

    J. Trop. Pediatr.

    (2006)
There are more references available in the full text version of this article.

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