Lukasz Nowak a Karolina Nowak b a Institute of Fundamental Technological Research Polish Academy of Sciences Poland b Centre of Postgraduate Medical Education Poland ID: 784586
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Slide1
Discovering new facts and revealing existing myths about the acoustic stethoscope 200 years after its invention
Lukasz Nowak(a), Karolina Nowak(b)
(a) Institute of Fundamental Technological Research,
Polish
Academy
of
Sciences
,
Poland
(b) Centre of Postgraduate Medical Education,
Poland
Slide2Research project: „New Methods and Technologies for Acoustic Medical Diagnotics”Aim of the project: to develop a new generation of methods and technologies for acoustic medical diagnosticsMultidisciplinary team of scientists and physicians combining clinical knowledge and strong background in acoustics, electronics and signal processing2Introduction
Slide3Theoretical and experimental investigations on the physical phenomena underlying the auscultation examinationsState of the art revisionAuscultation signals database: heart, breath, and other soundsSignal analysis and processing: algorithms and softwareElectronic stethoscopes: development, construction, measurements3What do we do?
Slide4Invented 200. years ago, in 1816, by French physician, Rene LaennecThe first non-lethal instrument for exploring internal anatomy1850s: binaural stethoscopeThe symbol of healthcare professionalsThe most widespread and commonly used medical diagnostic device4Stethoscope - facts
Slide5David Littmann, An approach to the ideal stethoscope, Journal of the American Medical Association, Vol 178 (5), 1961, pp :504-505.basic assumptions concerning the construction and theory of operation of the modern acoustic stethoscopes – „desireable features”5Modern acoustic stethoscopesTwo chest
pieces (bell and diaphragm), tubing, binaural and earpieces
Single-
chestpiece
stethoscopes
with „
tunable
”
diaphragm
Slide6Just a few silmple components…6Stethoscope – mythsSimplest diagnostic device you can imagine?chestpiecetubing
binauralearpieces
Slide7Patient -> stethoscope -> Physician: coupled acoustic system7Stethoscope – factsUnderlying phenomena still not really well understood…chestpiece
tubingbinauralearpiecesPATIENTPHYSICIAN
Slide88Auscultation soundsreal world vs. ideal world
Slide9BELL:„amplifying low-pitched sounds”skin as a diaphragmheart auscultation„lower natural resonances” [large chestpiece]DIAPHRAGM:„attenuating low-pitched sounds”stiff diaphragmlung auscultation9Bell vs. diaphragm
facts or myths?
Slide1010Bell vs. diaphragmexperimental methodologyErtel P. Y., Lawrence M., Brown R. K. and Stern A. M. Stethoscope Acoustics II.Transmission and Filtration Patterns, Circulation, Vol 34 (5), 1966, pp 899-909.Welsby P. D., Parry G. and Smith D. The stethoscope: some preliminary investigations, Postgraduate Medical Journal, Vol 79 (938), 2003, pp 695-698.
Slide1111Bell vs. diaphragmmeasurements and results
Lung auscultation sounds spectra
Slide12Heart auscultation sounds spectra12Bell vs. diaphragmmeasurements and results cont’d
Slide1313Tunable diaphragmsfacts or myths?
Slide1414Hollow tubesfacts & measurements
Slide15Stethoscope is a simple acoustic device, but mechanisms and phenomena underlying auscultation are very complex and not yet properly understoodMany common theses concerning stethoscope have no proper scientific justification……and some of them seem to be just wrongMuch of a scientific effort in the field is devoted to Computer Aided Auscultation
systems……but can it really repleace the physician on the other side of the stethoscope?15Summaryfuture of auscultation?
Slide1616Thank you for your attentionemail: lnowak@ippt.pan.pl
The authors would like to acknowledge the financial support from the Polish National Centre for Research and Development (NCBiR), grant no.LIDER/034/037/L-5/13/NCBR/2014