Stethoscopes Print

The stethoscope – an evergreen in medicinal diagnostics

Since the stethoscope was invented in 1816 by the Frenchman Th. H . Laennec, the use of further developed medical diagnostic products has been indispensable. Even today the stethoscope cannot be replaced by any other technique in primary cardiovascular diagnostics.

The application versatility of this instrument is illustrated by the large number of its different user groups: internal specialists (cardiologists, pulmonologists etc.), anaesthesiologists, paediatricians, general medical practitioners, rescue teams, nursing staff, medical students, veterinarians.

The performance requirements of a stethoscope change according to the type of examination being performed. While a simple stethoscope is sufficient for a Riva Rocci blood pressure measurement, internal specialists (cardiologists, pulmonologists) need a high-capacity stethoscope with a wide frequency area and very good amplification.

During an auscultation, heart and lung noises, intestinal noises (peristalsis etc.), and the blood flow in the arteries (stenosis) are examined. During a birth as well the baby’s heart rate and the Korotkow sounds during the blood pressure measurement are evaluated.

All classic stethoscopes in use today operate according to the same principle. Through certain physical characteristics they serve to make noises in the body more audible. They consist of a “head” or chest piece, a tube and a head piece with so-called “ear tips” that seal the auditory canals of the examiner.

The type and material of the stethoscope determine with which intensity the air column in the tube is made to oscillate through certain bodily noises, and thereby determine the volume of the noise that reaches the examiner.

KaWe is one of the leading manufacturers of stethoscopes. We have been producing products to meet every kinds of requirement for generations. Our selection for different special fields attests to the amazing variety that can always be expected of KaWe.

Auscultation of the heart

The heart is a muscular hollow organ, the contractions of which ensure the blood supply to the human body. The anatomy of the heart with its right and left atrium and right and left chamber (ventricle) between which the so-called “valve area“, the four decisive heart valves (mitral valve, tricuspidal valve, aortic valve and pulmonal valve) are situated, enables a well-regulated pumping operation and determines the direction of blood flow in the heart, which normally can only flow in one direction.

The rhythmic contraction of the heart is called systole. In this period of the cardiac cycle, the aortic and the pulmonary valves open and the blood flows into the large and the small blood circuit. Due to the subsequent relaxing of the heart with the opening of the mitral and the tricuspidal valves, the heart chambers are once again filled with blood. This process is called diastole. The heart rate is determined by the number of pumps per minute. The first and second heart sounds are created by the closing valves and the flow condition of blood. The mitral and the tricuspidal valve closure create the first heart sound, whereas the aortic and the pulmonal valve closure create the second heart sound. Turbulence in the bloodstream, e.g. pathological changes of the valves (stenosis, insufficiency) or vasoconstrictions of the large blood vessels (e.g. aortic and pulmonal stenosis) cause the development of typical cardiac murmurs. Heart sounds and cardiac murmurs are recognized through auscultation with a stethoscope. The frequency of the sound waves, their intensity (amplitude), sound characteristics and duration all give necessary information for a correct diagnosis.

Therefore, the frequency range and the possible amplification are crucial for the determination of the quality of a stethoscope. In the high-frequency area the auscultation with the diaphragm part of the stethoscope is recommended, whereas the bell side should be used in the low-frequency area.

The figures show the results of a frequency analysis of the sonic characteristics of the Rapport, Planet and Prestige stethoscopes. The measurements were taken using a wave band from 15 Hz up to 3000 Hz. The frequency range of the healthy heart is between 50 Hz and approx. 200 Hz. Pathological heart murmurs are in the high-frequency area of greater than 450 Hz up to 1000 Hz.

KaWe stethoscopes excellently measure the required frequency area, and the natural heart sounds as well as the pathological noises are amplified so that an excellent auscultation result is attained.

KaWe has been manufacturing stethoscopes for more than 80 years and disposes of expert knowledge in this area. This enables us to offer you in this field of application a cost-oriented, quality product.

All KaWe stethoscopes are latex-free.

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