The Noise Immune Stethoscope

By Catherine Davis, USAARLMarch 30, 2012

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(Photo Credit: U.S. Army) VIEW ORIGINAL

In collaboration with Active Signal Technologies, a Small Business Innovation Research partner, the U.S. Army Aeromedical Research Laboratory developed a stethoscope in 2007 that can be used to listen to heart and lung sounds in high-noise environments such as medical evacuation vehicles. The Noise Immune Stethoscope uses a traditional acoustic listening mode similar to classic acoustic stethoscopes, but it also adds ultrasound-based technology that is "noise immune" to amplify heart and lung sounds. This technology has the capability for users to switch easily from Doppler to acoustic mode. Both modes immediately turn body sounds into electrical signals for enhanced performance. The Communications Earplug, currently used by aviators, attaches to the NIS and allows auscultation while wearing the flight helmet.

Heart and lung sounds are a necessary component of casualty triage and ongoing care, although hearing and assessing these sounds with traditional acoustic stethoscopes is very difficult on the battlefield. It is vitally important that military medical care providers have the necessary tools to identify the diagnosis and course of treatment. The NIS enables medical personnel to assess abnormalities of the cardiopulmonary system in high-noise environments such as within medical evacuation aircraft and on the battlefield, and within busy intensive care units.

"The dual-mode stethoscope is specifically designed for high-noise conditions," said Maj. Tim Cho, M.D., chief of the Aeromedical Factors Branch of USAARL's Warfighter Health Division. "As a result, the fight surgeon or flight medic will be able to make more accurate decisions while en route to higher echelons of care during flight."

After the development of the NIS at USAARL, research began to assess the utility and durability of the new stethoscope under field conditions and in patients with cardiopulmonary pathology. During 2011, the development of the NIS accomplished numerous significant milestones. The NIS received U.S. Food and Drug Administration 510(k) clearance, and through a series of rigorous laboratory and field tests conducted by USAARL, the NIS received an airworthiness release for use on board the Black Hawk helicopter. A 2011 USAARL research study conducted on board the USS Vinson highlighted clinicians' ease of use of the NIS acoustic mode for identifying patients' heart and lung sounds during high-noise operations. Currently, a second study is being conducted by USAARL at Madigan Army Medical Center in Tacoma, Wash., for which data is being collected to identify cardiopulmonary pathology using the NIS. This study is scheduled to be completed in fiscal year 2013.

Scott Brady, a biomedical engineer at the U.S. Army Medical Materiel Agency, anticipates that within the next year, final steps will be underway to assign the NIS to the appropriate sets, kits, and outfits so the device can be used on patients in real-world operational environments.

Related Links:

U.S. Army Aeromedical Research Laboratory

U.S. Army Medical Materiel Agency

U.S. Army Medical Research and Materiel Command