Screening newborn infants for hearing loss is a relatively new practice that didn’t become common in the United States until the mid-to-late 1990s.
Before its introduction, children often weren’t diagnosed with congenital hearing loss until they were three years of age or older. Late hearing impediment identification can translate into delayed speech and language development.
Approximately 25 years ago, Natus Medical identified these problematic statistics and sought to develop hearing screeners for newborns. Currently, about 97% of all newborns in the U.S. are screened for hearing loss. Formerly, only babies with high risk were screened.
“Although the incidence of hearing loss or deficits in newborns is about [0.3%], the impact on a baby’s life is tremendous,” says Lisa Burque, Natus Medical senior marketing director. “If you catch hearing loss in the newborn period of a baby’s life, you could start intervention early, and that child could have the vocabulary equivalent to a normal hearing baby.”
Since its inception, the company has expanded its portfolio of newborn medical devices; however, research and development of newer, safer hearing screeners is still important. In late 2013, engineers at Natus Medical were preparing to launch the Echo-Screen III newborn hearing screener. The screener incorporates transiently evoked otoacoustic emissions (TEOAE), distortion product otoacoustic emissions (DPOAE), and auditory brainstem response (ABR) capabilities.
The otoacoustic emissions (OAE) technology delivers clicks or tone bursts through the newborn’s ear canal via a probe inserted into his or her ear. The child’s cochlear will then create sound waves in response to the noises, which are measured and recorded by the ear probe.
Both OAE and ABR technologies are fully automated in the Echo-Screen III, meaning the device will provide automatic pass or refer results and fixed screening parameters. A refer result indicates that further testing is needed.
Similarly, the ABR technology sends soft clicking sounds to the newborn’s ears through an ear probe or headphones, but sensors placed on the child detect responses to the sound from his or her brain and send them to the device for analysis. Typically, each test mode takes two minutes.
Just as Natus Medical prepared for the product’s launch, its marketing team requested that the product be free of Bisphenol A (BPA), the chemical that has been used to make lightweight, hard polycarbonate plastics and epoxy resins since the 1960s. Today, more than a billion pounds of BPA are produced annually in the United States.
Despite its widespread use in food and drink packaging, medical devices, and automotive parts, there has been concern among hospitals and clinics that BPA may have unwanted health and environmental risks. Around 1996, BPA gained significant public notoriety as a suspected endocrine disruptor – a chemical that may interfere with the production of hormones in the human endocrine system.
Based on its most current safety assessment, the U.S. Food and Drug Administration (FDA) considers BPA safe at the present levels occurring in foods. However, due to heightened scientific interest in the safety of ingesting low levels of BPA, the FDA’s National Center for Toxicology Research has partnered with the National Toxicology Program (NTP) to carry out in-depth studies on the topic.
While food and beverage account for the majority of BPA exposure to humans, air, dust, and water are other possible sources, according to the National Institute of Environmental Health Sciences. In many neonatal units, polycarbonate plastics are used in incubators, medical devices, and housings for heating lamps due to their easy sterilization, high heat resistance, and durable structure. According to the NTP, the highest exposures to BPA occur in infants and children.
The Echo-Screen III was originally designed and tooled using a polycarbonate /acrylonitrile butadiene styrene (PC/ABS) alloy, which, by its chemical definition, uses BPA. Finding a replacement for PC/ABS was a daunting task for the engineering team at Natus Medical.
According to Kenneth Pawlak, Natus Medical senior mechanical engineer, most medical device engineers use PC/ABS due to its high temperature resistance and flame retardant qualities.
“When marketing told us to change the material, we thought we would have to throw away all the new tooling we had made for this product and replace it with another set of tools that would have [added] 40 to 50 percent in cost,” explains Pawlak. “To use the one or two BPAfree and flame-retardant materials available would have delayed the project by another year.”
Pawlak contacted Eastman Chemical to see if they had a BPA-free, flame retardant material with properties similar to PC/ABS that was not listed in their database. After finding out what Natus Medical required, Eastman revealed that they had a polymer close to launch that matched both of Pawlak’s requests. It was also free of halogens and ortho-phthalate plasticizers.
“They told me the shrinkage factor of the material was within 1/1,000th of polycarbonate,” Pawlak recalls. “By that time, I was ready to stand on my desk to find out how I could get some.”
Echo-Screen III was originally designed to last up to seven years in a hospital environment, so Eastman had to perform a number of tests to make sure the new opaque Tritan copolyester MXF121 material was suitable.
After an engineering drop test matched up with PC/ABS, and a disinfectant test which proved better than PC/ ABS, Eastman knew the material would be a perfect addition to the hearing screener. Moreover, Eastman was able to custom color the material to match Natus Medical’s original design.
“The material doesn’t start cracking and become brittle,” explains Kenneth Breeding, Eastman sales specification associate. “Traditional PC/ABS will become brittle when it’s going up against some of the more aggressive disinfectants used in hospitals.”
Not only was Eastman’s Tritan copolyester BPA-free with an all-color UL 94 V2 flame rating at 1.5 mm, but because the material had a shrinkage rate within the parameters of PC/ABS, Natus Medical could use their existing tools. “We had to make some modifications to the tools, but they were minor adjustments,” explains Pawlak. “We agreed with our marketing team to delay the project to convert to the material, modify the tools, and run the validations.”
The change to Eastman’s copolyester only added four and a half months to the project schedule – primarily due to material trials, cycle development, and minor mold modifications. The Echo-Screen III commercially launched in Europe in the spring of 2014 and was cleared by the FDA in August 2014.
Aside from its BPA-free quality, the Echo-Screen III has an integrated hook, barcode scanner, ABR test fixture, probe test chamber, and docking station for charging the device/spare battery and data transfer. Its keyboard and touchscreen provide two methods of data entry, while integration with audible LITE data management software enables configurable data management. Additionally, conflict resolution assists in identifying and correcting data entry errors.
The company believes its updated, BPA-free Echo-Screen technology will not only help newborns in the U.S., but also internationally. “Natus Medical hearing screeners have been used to screen more than 40 million babies,” says Burque. “Even though 90 percent of infants in developed nations are screened, it’s still not everywhere in the world. There are millions of infants who could benefit from this technology.”