Noise pollution in the NICU Stephanie Olbrych MPH Candidate MPHP 429 Dr McCoy 8 April 2010 NICU Noise Olbrych 2 Background Neonatology is a relatively new field in medicine tracing its roots to 1878 and the invention of the incubator Daz Floyd 2005 Although this device revolutionized care given to these premature babies by keeping them warm it still did not have much impact on survival rates Survival rates were so low that from 1896 to 1939 these preterm babies were treated more as artifacts than human lives used throughout the world as exhibits for thousands to view the World Exposition in Berlin Coney Island etcetera Daz Floyd 2005 Around 1939 survival rates began increasing due to the treatment regimen of separation from mother attentive care by nurses and wet nurses prohibited visits by children and limited visiting time yet care still open for public viewing in open multi patient wards with large windows Daz Floyd 2005 Although public patient viewing was not the norm for patient care the use of multipatient wards was during this time period In the late 1970s multi patient rooms were phased out in favor of private or semi private rooms Daz Floyd 2005 Yet neonatal intensive care units NICUs remained preserved in the past trends of multi patient wards due to the desire to maintain status quo the spatial needs due the large influx of patients due to infant mortality rates plummeting dropping 22 1990 2000 the severe shortage of nurses and the desire to have the babies monitored constantly to note any physiological changes Daz Floyd 2005 Dureau 2005 Technological advances in equipment including monitors and alarms that did not demand the constant vigilance of caregivers prompted the first published recommendation for private rooms in the NICU in 1992 Daz Floyd 2005 Even though the first private room NICU was built in 1997 by 2005 there were only 12 facilities with designs for private and semiprivate rooms from the hundreds of NICUs nationwide Daz Floyd 2005 As survival rates continued to increase so did the angst of intact survival or survival without disabilities Daz Floyd 2005 Thus more focus was placed on maximizing the quality of care in the NICU environment A primary focus of this move was an aim to reduce the level of noise in the NICU Sound is defined as a vibration that travels through a given medium and can be measured in decibels Byers et al 2006 Lai Bearer 2008 Noise more specifically is defined as unwanted sound Byers et al 2006 Lai Bearer 2008 Recognized by the Joint Committee on Infant Hearing as an important environmental factor noise pollution was investigated Trapanotto et al 2004 This organization founded in 1969 brings together fields such as audiology pediatrics and nursing in the interest of the patients JCIH The Committee declared noise as one of the most polluting physical agents in neonatal intensive care such that hospitalization in intensive care can be considered in itself a risk factor for preverbal deafness Trapanotto et al 2004 Efforts to minimize noise in the NICU therefore conjunctly promote sleep healthy neonatal physiologic stability and reduce harmful effects of auditory and neurological development since sound both agitates the mood and complicates the medical condition of the child Nagorski Johnson 2003 Research dating back to the early 1970s has shown sound levels in the NICU to range from 45 to 135 dBA with a mean generally between 54 and 80 dBA Chang et al 2006 Nagorski Johnson 2003 These levels are astounding giving that workplace standard determines that workers should not spend more than 8 hours at 90 dBA 4 hours at 95 dBA 2 hours to 100 dBA and no continuous exposure to levels over 115 dBA AAP 1997 Frequently noise levels within isolettes exceed 90 dB the level at which the Occupational Safety and Health Administration OSHA requires adults to wear ear protection to defend against NICU Noise Olbrych 3 hearing loss Daz Floyd 2005 This constant high sound level is partially due to the isolettes themselves contributing 50 to 80 dB of noise newer isolette models have capped noise at 50 dB Lai Bearer 2008 Daz Floyd 2005 However the babies themselves cause much of the noise with accompaniment by staff care providing staff and family conversations and additional equipment like respiratory control In 1974 the American Academy of Pediatrics AAP suggested noise in the NICU be below 58 dB since 1997 the recommendation was lowered to 45 dB after additional research had been conducted Chang et al 2006 Toxicology The goal for NICUs is to provide an environment that promotes sleep supports neonatal physiologic stability and reduces potential adverse effects on the auditory development of premature infants Brandon et al 2007 Unfortunately noise disturbs sleep causes physiologic stress and leads to complications with hearing and comprehension Byers et al 2006 The auditory system develops in utero in weeks 22 to 24 with the development of cochlear function peripheral sensory end organs and first hearing capacities Brandon et al 2007 Lai Bearer 2008 Krueger et al 2005 Blink startle responses to vibroacoustic stimulation begin at 24 to 25 weeks and are consistent after 28 weeks illustrating a fetus s ability to detect and process sounds AAP 1997 The womb provides fetuses with rhythmic familiar acoustical signals over a range of low frequencies which developing ears can tolerate Brandon et al 2007 Daz Floyd 2005 The fetus hears the mother s voice as a unique clear sound against the background uterine sounds this maternal voice recognition in utero is essential to train the baby to pay attention to the mother s speech after birth and is strongly influential in developing the baby s own future speech patterns Brandon et al 2007 Furthermore the uterine environment serves as a protection against other low mid and high frequency unwanted sounds other than the mother s voice and the uterine environment itself Brandon et al 2007 At weeks 27 to 29 the child hears a 40 dB threshold of sound decreasing to roughly the adult threshold level of 13 5 dB at 42 weeks illustrating the essential auditory development occurring postnatal AAP 1997 Premature babies may spend this time crucial for outer ear middle ear and cochlear development in the NICU lacking the protection of the uterus for this development occurring in the last trimester Lai Bearer 2008 Krueger et al 2005 These NICU babies are exposed to sounds that move through the air rather than through the liquid