Sound Levels and Neonates, Level of Noise Generated in the NICU - Essay Example

Sound Levels and Neonates   Literature Review While there have been a number of articles about noise levels in the neonatal intensive care unit and the effect on patients’ health, most of the articles have been qualitative, and have not achieved results on a statistically-significant enough population in order to draw valid clinical conclusions. The evidence is highly suggestive, however, of the damage which can be caused by noise in the NICU. The articles reviewed cover two main topics: the effect of noise in the NICU on the patients, and measures which can be put in place in order to reduce such noise. Level of Noise Generated in the NICU There is no doubt that the amount of noise generated in the NICU can be significant. A study at the University of Padova established noise levels within and outside the incubator. It divided those noises into significant ‘white’ noise, and specific noises, which can be used by voluntary and involuntary noises generated when workers touched the plexiglass surface of the incubator, or connected or disconnected to the incubator. It appears that the background noise was less harmful than the sudden and unexpected noises, which tended to generate levels above 80 dB (Benini, 1997). A literature review discovered a good deal of evidence of neonatal stress from noise, with the most common measures being cardiovascular and respiratory response. The authors list the key stimuli, including sound intensity, and the effect that they have on the infant’s behavioral state. Some articles have differentiated the neonates by gestational age and infant maturity. As one of the co-authors found, however, the sample sizes were small, and the variables were not well controlled in most studies (Morris, 2000) Measurement of Noise Effects on Neonates in the NICU Noise has been measured and reported upon in the NICU since the 1970’s. At that time, noise levels were reported in the 70-117 dB range, which is clearly above currently-acceptable levels (Peltzman, 1970) (Long, 1980) (Satish M. a.-S., 1993) (Satish M. S., 1991) . These studies suggested that continuous and elevated noise levels resulted in significant deterioration in healing and levels of nervousness in neonates. Early work on the effects of noise in the NICU concentrated on noise within the incubator itself; these led to improvements in incubator noise reduction, and resulted in a general emphasis on NICU noise reduction (Bess, 1979). It is always difficult to find accurate, reproducible responses of newborns to stimuli. One effect which can be reproduced is that of reduced noise on sleeping times for infants. Strauch et al led a study which analyzed the amount of sleep experienced by VLBW (very low birth weight) babies (Strauch, 1993). In addition to monitoring total sleep, the study also included infant sleep states, such as deep sleep state. The study found a significant increase in deep sleep (84 versus 34 percent) and less crying (2 versus 14 percent). While the study noted this improvement during a “Quiet Hour,” the actual average and peak noise levels were not noted. In addition, the measurement of VLBW babies may have skewed the results in a way different than it would have been done for older or heavier pre-term neonates. One of the few studies found which measured the influence of noise on the neonate in a reproducible fashion was a study done at the University of Iowa by Quinonez and Crawford (Quinonez, 1997). This study related response to amplitudes of various levels with infants at different ages. In general, the amplitude of response increased as a function of gestational age. This study suggests that the developing auditory system creates a greater response to noise as the neonate approaches full gestational maturity. As with many such studies, however, the number of infants tested (n=18) was low, and the results therefore suggestive rather than conclusive. MK Philbin conducted a literature review of clinical studies performed on the effect of noise on preterm newborns. She found that the studies were generally flawed. The general concerns were that the studies failed to connect the type of noise with specific and reproducible physiologic signs and behavior. Few of the studies focused on length of exposure, nor did they indicate a longer-term effect of high noise in the NICU. In the absence of specific, measurable criteria, the author was left with the conclusion that general reductions in noise level through process changes would result in an improvement in newborns’ outcomes (Philbin M. , 2000). If excess NICU noise causes physiological distress, what is the impact of a designated quiet period? An Irish study examined 10 preterm infants (average gestational age 28.7 weeks) (Sleven, 2000). The study reduced a series of stimuli, including light, noise, handling and activity. They found that when infants were exposed to these quiet periods, there was a reduced diastolic blood pressure and mean arterial pressure, as well as a reduction in infant movements. As this study was performed on only 21 babies, the reactions measured were qualitative in nature. It would have been useful to track babies for a longer period of time who had been in a noisy environment, to see if there were other longer-term physiological changes. While noise has been demonstrated as a stressor in many NICU studies, it is not the only stressor. A study of 55 premature infants measured the crying response of neonates to handling and to noise in 5-minute intervals. It was found that either the nursing activities (19 commonly-performed activities on neonates) or noise alone contributed to increased crying, but the effects of the two were not cumulative; that is, the crying response was equally great with one or both stimuli (Zahr, 1995) Changes in Procedures, Recommendations A literature review helped a Department of Pediatrics to develop standards for noise levels for newly-renovated NICU’s (Philbin, 1999). They recommended a maximum noise level average limit of 50dB and a maximum noise level not to exceed 55 dB for more than 6 minutes in any hour. They also differentiated on 1-second noises, which should not exceed 70 dB. A similar study, performed in 1998, found that neonatal outcomes, measured by physiologic and neurobehavioral signs, was improved with a sound-modified NICU (Blackburn, 1998). The American Academy of Pediatrics’ Committee on Environmental Health is sufficiently concerned about NICU noise that they published a position paper on the hazards of noise to the fetus and newborns, including pre-term babies (Etzel, 1997). This helpful article reviews the physiology of hearing, and the effects that noise has on pre-term babies after the 25th week. In addition, it provides human and animal evidence of birth defects and neural problems with fetuses exposed to noise in the womb. The article encourages pediatricians to determine the health effects of noise on their patients, and to screen babies for the possibility of noise-induced hearing loss. Of particular relevance to this paper, the AAP encouraged noise monitoring in the NICU and within incubators, in order to assure that noise levels remained below 45dB. Higher levels were called a ‘concern.’ As with the above nursing article, it encouraged staff to change procedures in simple ways that can reduce noise, such as less-noisy shoes and careful closing of doors. Bibliography Ballberg, D. (1991). The Effect of Neonatal Intensive Care Unit Noise on the Habituation of Neonatal Chicks. Dayton: Air Force Institute of TEchnology, Wright-Patterson Air Force Base. Benini, F. M. (1997). Evaluation of Noise in the Neonatal Intensive Care Unit. American Journal of Perinatology , 37-41. Bess, F. P. (1979). Further observations on noise levels in infant incubators. Pediatrics , 100-106. Blackburn, S. (1998). Environmental impact of the NICU on developmental outcomes. Journal of Pediatric Nursing , 279-289. Bremmer, P. B. (2003). Noise and the Premature Infant: Physiological Effects and Practice Implications. Journal of Obstetric, Gynecologic & Neonatal Nursing , 447-454. Etzel, R. e. (1997). Noise: A Hazard for the Fetus and Newborn. Elk Grove, IL: American Academy of Pediatrics. Johnson, A. (2003). Adapting the Neonatal Intensive Care Environment to Decrease Noise. Journal of Perinatal and Neonatal Nursing , 280-288. Long, L. L. (1980). Noise and hypoxemia in the intensive care nursery. Pediatrics , 143-145. Morris, B. P. (2000). Physiological effects of sound on the newborn. Journal of Perinatology , 555-560. Peltzman, P. K. (1970). Effects of incubator noise on human hearing. Journal of Auditory REsearch , 335-339. Philbin, M. R. (1999). Recommended Permissible Noise Criteria for Occupied, Newly Constructed or Renovated Hospital Nurseries. Journal of Perinatology , 559-563. Philbin, M. (2000). The influence of auditory experience on the behavior of preterm newborns. Journal of Perinatology , 577-587. Quinonez, R. a. (1997). Electrophysiologic changes in preterm neonates: auditory brain stem response and distortion product otoacoustic emissions. Ann Otol Rhinol Laryngol. , 721-728. Satish, M. a.-S. (1993). Elevated sound levels increase desaturation episodes in sick preteens. Pediatric Research , 1389. Satish, M. S. (1991). Sound levels and sleep states in preterm infants,. Pediatrics REsearch , 1563. Sleven, M. F. (2000). Altering the NICU and measuring infants responses. Acta Paediatrica , 577-581. Strauch, C. B.-B. (1993). Implementation of a quiet hour: effect on noise levels and infant sleep states. Neonatal Network , 31-35. Trapanotto, M., Benini, F., Farina, M., Gobber, D., & Magnavita, V. Z. (2004). Behavioural and physiological reactivity to noise in the newborn. Journal of Paediatrics and Child Health , 275-281. Zahr, L. a. (1995). Responses of premature infants to routine nursing interventions and noise in the NICU. Nursing Research , 179-185. Read More