Sociologist Roy Porter writes: “By granting access to the body’s noises – breathing, blood pulsing around the heart – the stethoscope changed the approach to internal diseases and, consequently, the doctor-patient relationship. From now on, the living body was no longer a closed book – pathology could be studied directly on it.”.
The stethoscope (Greek *stethos* = chest; *skopein* = to examine), also called a phonendoscope, is an acoustic instrument used in medicine for perceiving normal or pathological sounds from organs (especially the heart and lungs). The manoeuvre is called pulmonary (respiratory and pleural) or cardiac auscultation. It is also used for perceiving vascular (arterial and venous), foetal, intestinal, etc. sounds.
The inventor of the stethoscope was a French doctor, Rene Laennec (1816), who used a wooden tube resembling a trumpet that made contact with the patient's chest and transmitted the sound through the air in this “tunnel” to the doctor's ear.
The simple stethoscope has a sound-receiving diaphragm (applied to the body) which picks up higher frequency sounds, connected via a rubber or plastic tube to the doctor's ear. Most are binaural, except for the monaural obstetric stethoscope used for listening to the fetal heart. The opposite side of the diaphragm may be bell-shaped to better transmit lower frequency sounds. When this part is used, the doctor can vary the pressure of the “bell” on the skin to ”tune” the frequency of vibrations from the skin and better perceive the sounds of the heartbeat.
Over time, improvements have emerged involving sound amplification, background noise reduction, or other features that have been optimised by applying simple physical principles.
In Laennec's time, the doctor would place their ear directly on the patient's chest or back, a technique that was of course uncomfortable, and in the case of women, was often considered an indecent gesture. Later, an “extra-long” stethoscope was also used to treat very poor or flea-ridden patients, whom the doctor did not want to get close to. Besides inventing this device, Doctor Laennec studied in detail the difference between the sounds specific to certain diseases, especially those of pneumonia, tuberculosis, and bronchitis. Ironically, Laennec himself died at the age of 45 from tuberculosis, diagnosed by his colleagues using the stethoscope.
Nowadays, the differential stethoscope is also used to compare sounds from different parts of the body, or the more complex electronic stethoscope with a sound amplification system and selection of high or low frequency tones, or even the possibility of visualisation, recording and comparison with normal sound sequences.
- article written by Dr Ionel Julea for reperemedicale.ro