Active Signal Technologies Inc, Linthicum Heights, Md, a leading contract research firm specializing in electromechanical devices, has developed the first stethoscope, A SCOPE, that can detect heart/lung activity in high ambient noise (above 90 dBA) including combat casualty and civilian emergency medical environments. The A SCOPE dual-mode noise immune stethoscope features a front face made of Radel polyphenylsulfone (PPSU) resin from Solvay Specialty Polymers USA, LLC, which provides biocompatibility, toughness, and strong chemical resistance.
Active Signal Technologies developed the A SCOPE in cooperation with the U.S. Army’s Aeromedical Research Laboratory (USAARL) in Ft. Rucker, Ala., and the stethoscope has been tested in simulated Blackhawk helicopter environments up to 110 dBA, the limit of USAARL’s acoustic reverberation chamber. The noise can be from rotary and fixed wing aircraft as well as ambulances where the prevailing sound levels preclude auscultation (listening to internal body sounds) with standard stethoscopes. Without this capability, patients can potentially expire from undetected collapsed lungs or loss of intubation integrity, according to the company.
Radel PPSU is a super-tough thermoplastic with high heat resistance, exceptional hydrolytic stability, and excellent chemical resistance. The material is also compliant with ISO 10993-1 for limited exposure, non-implantable applications. Besides, it provides better toughness than polycarbonate and its chemical resistance enables the device to withstand harsh medical substances including cleaning agents, alcohol, and chlorinated solvents.
Radel PPSU’s documented biocompatibility is a key feature for the stethoscope’s injection molded front flat face which comes in contact with the patient’s skin, according to Arthur Cooke, president of Active Signal Technologies. The two-inch wide, 0.10-inch thick part has reinforcing ribs and ultrasonically welded bosses around the circumference. The front face attaches to internal screws in the stethoscope’s aluminum housing.
In addition, the material’s strong dimensional stability also permits the front face to mate tightly to the aluminum housing. The injection molding process allows for higher production rates and more cost-effective manufacturing on a per part basis. The device has passed a comprehensive series of MIL-STD 810F environmental tests, is FDA approved (510(k) Number K103499), and was deployed to Afghanistan for field evaluation in late 2011.
The device also uses a combination of highly sophisticated sensors, signal conditioning, and Doppler technology to detect physiologic activity. Solvay Specialty Polymers is one of the leading global suppliers of high-performance thermoplastics for implantable and non-implantable medical devices.