Work-related noise exposure in a neonatal intensive care unit

Abstract

Premature infants are children born before the 37th week of gestation. They often need to be cared for in neonatal intensive care units (NICUs) after birth, where they are continuously exposed to noise that can affect sleep patterns and lead to growth and developmental delays. To date, there are no unified limits for the prevention of noise exposure in NICUs. Recommendations for maximal continuous sound levels vary - depending on the professional society - between 35 and 60 dB(A) for daytime values and 20 to 60 dB(A) for nighttime values. They span a range from quiet whispering to normal road traffic noise. Existing studies of noise measurements in NICUs indicate that these recommendations are generally not met. A limitation of previous work is their short time periods that noise measurements were made for, usually one or two hours. As a result, it is not possible to make statements about the diurnal cyclic change in noise exposure, which may have an influence on the circadian rhythm of premature infants, for example. The present work aims to determine the intensity and diurnal cyclic differences of noise exposure in a NICU. In addition, particularly noisy work activities are identified in order to derive suggestions for prevention.For this purpose, the continuous sound levels are recorded for 22 work shifts in a German level 1 perinatal center. Measurements are made in the patient room and the inside of an infant incubator. The mean daily noise exposure levels (LEX,8h) of the early, late and night shifts are calculated and the peak sound level (LpCpeak) is recorded. To test for a day-night rhythm, these are compared using one-factor ANOVA. Using the Contextual Inquiry method, work analyses are performed for 12 work shifts and the early, late and night shifts with the highest equivalent continuous sound level (LAeq) are examined for noise-intensive work activities as examples. The measurement results in LEX,8h and LpCpeak values of up to 49.7 dB(A) and 124.4 dB(C) inside the infant incubator and 55.4 dB(A) and 110.3 dB(C) in the patient room. A day-night rhythm of noise exposure could not be demonstrated. The most noise-intensive work activities included the suctioning of patients and the conversations conducted in the process, with an LAeq of 63 dB(A). In addition, numerous very high impulsive noise events are identified which contribute to the noise exposure of premature infants. The presented study proves that the noise exposure is too high, which is very likely to affect the sleep behavior of premature infants. The results correspond with the statements of comparable studies. It is remarkable that especially the high peak noise levels are mainly due to trivial causes, which can be avoided by simple preventive measures.