PPSU in Novel Stethoscope for Noisy Environments

The front face of what is said to be first stethoscope that can detect heart/lung activity in high ambient noise (above 90 dbA), including combat casualty and civilian emergency medical environments, features Radel PPSU (polyphenylsulfone) from Solvay Specialty Polymers, Alpharetta, Ga. Radel resin forms the injection molded front flat face of the new A Scope noise-immune stethoscope that comes into contact with a patient’s skin. It requires biocompatibility, toughness, and strong chemical resistance. The 2-in.-wide, 0.10-in.-thick part has reinforcing ribs and ultrasonically welded bosses around the circumference. PPSU provides better toughness than polycarbonate and its chemical resistance enables the device to withstand harsh cleaning agents, alcohol, and chlorinated solvents. Its strong dimensional stability permits the front face to mate tightly to the aluminum housing.

 

This novel stethoscope was developed by manufacturer Active Signal Technologies Inc., Linthicum Heights, Md., in cooperation with the U.S. Army’s Aeromedical Research Laboratory (USAARL) in Ft. Rucker, Ala. It was 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 stethoscope.Without that capability, patients can potentially expire from undetected collapsed lungs or loss of intubation integrity. The new device uses a combination of highly sophisticated sensors, signal conditioning, and Dopler technology to detect physiologic activity. The device has passed a comprehensive series of MIL-STD 810F environmental tests, is FDA approved, and was deployed to Afghanistan for field evaluation in late 2011.