A stethoscope is a medical device with which it is possible to conduct auscultation, that is, listen to sounds that are present in the heart, blood vessels, lungs, intestines, bronchi and other internal organs of a person. The most famous areas of application of this device are listening to Korotkov tones in the process of measuring blood pressure, as well as determining the location of the probe inside the stomach during its washing or enteral nutrition.
The head, which must be applied to the surface of the human body in the place necessary for listening and which has the ability to pick up various sounds in the organs, serves as a working part of the stethoscope. Other parts of the device are flexible sound tubes, through which sound enters a specialist’s auditory canals for analysis.
Non-medical models of stethoscopes exist, the purpose of which lies in the technical diagnosis of the functioning of various mechanisms - a crank mechanism, bushings, components and parts. In a technical stethoscope, sensitivity is given to the device by a thin rod of metal, which is leaned against the place of study.
History of occurrence
Back in 1816, the French physician Rene Laennec, the progenitor of the diagnostic auscultation technique and the entire scientific diagnostic method, invented the first stethoscope. In those days, to listen to the internal organs of patients, it was customary to put an ear to their body, which the innovating doctor categorically did not want to do, and therefore used folded paper for this purpose, which perfectly conducted sound, making it even clearer than when listening directly with ear attachment. Since that time, the stethoscope has been modified and improved, however, the principle of its operation and physical characteristics remained the same.
In 1894, an advanced stethoscope was proposed to be called the phonendoscope professors of physics and preparatory clinical medicine A. Bianchi and G. Bazzi. The stethoscope acquired its modern form in the 1940s, when it was improved by Sprag and Rappaport, creating a new example of the standard for this device. Today it is called in the scientific community - the Sprag-Rappaport stethoscope.
A modern device called a stethophonendoscope helped to combine a stethoscopic funnel and a phonendoscopic membrane in the design of a bilateral head. The term "stethoscope" today means both a phonendoscope and a stethophonendoscope.
The design of a modern stethoscope is necessarily present:
- membrane and funnel;
- sound duct;
The head of a stethoscope is the part that must be applied directly to the patient's body in order to catch and amplify auscultatory sounds inside the organ under investigation. Heads are two-sided and one-sided. On one-sided heads there are either funnels or membranes (in most cases). On bilateral on both sides of the head, there is one and the other, or on different sides of the head are multidiameter membranes. With double-sided heads, to switch them, it is enough to turn the nozzle 180 degrees, which is structurally connected to the sound duct.
To capture high-frequency auscultatory sounds, it is more rational to use a membrane that is more sensitive in this case, and a funnel is better for low-frequency sounds. By a membrane is meant a flat or slightly convex outward, by analogy with a glass watch, a plate mounted on the head of a stethoscope. It can usually be changed over time or, if necessary, easily. Epoxy membranes reinforced with fiberglass are hypersensitive, while polyvinyl chloride membranes are less sensitive.
A sound pipe is a flexible elastic hose with which sound is conducted from the head of the device into the hearing aid (in other words, the ears) of a specialist. Sometimes the head is connected to one, and sometimes to two sound ducts. But even in the case of a single sound pipe in front of the arms, it is necessarily divided into 2 parts.
The stethoscope is called the pair of metal tubes that connect to the sound duct. The springs of the arms ensure a tight fit of the olives to the auricles. The tips of the arches can be positioned forward so that the olives can be inserted into the ears at an angle with respect to the ear canals.
And finally, olives mean two rounded tips on the arches of hard or soft texture, providing a comfortable fit of the stethoscope in the external auditory course of the specialist examining with the device. Olives differ in size, they must be individually selected in accordance with the size of their own auditory passages. Olives, as well as membranes, can be easily replaced in the structure of this device with new or more comfortable ones. Ideally, the olives comfortably fit to the researcher’s ears, not pressing too hard, but not falling out of them. This ensures that the sound system is closed, which avoids the appearance of empty space between the olive and the ear and ensures high quality of auscultation.
Types of instrument
A stethoscope can be divided in medical practice into categories of patients for whom it is used in medical practice. Thus, a therapeutic stethoscope is designed to listen to adult patients, neonatal - to newborn babies under the age of 28 days, and pediatric pediatric auscultation is performed. The last 2 varieties of the device differ from the therapeutic one in the smaller head size for listening.
In the practice of doctors, a rappaport stethoscope is widely used, which is distinguished by its versatility with respect to patients of any age. Its distinctive feature is a massive double-sided head, on which it is possible to install different nozzles - 3 types of funnels and 2 varieties of membranes, as well as equipping two independent sound ducts to ensure sound quality. The only disadvantage of this device is its high weight.
Also, stethoscopes are divided into types, depending on the specifics of the specialist. Cardiological stethoscopes are distinguished by increased acoustic characteristics, which provides a much greater sound spectrum when listening to heart sounds. A pinar fetoscope or stethoscope is used in gynecology to listen to the heart sounds of the fetus during pregnancy. It is most similar in design to the first devices that were invented 2 centuries ago. This is a stiff tube-shaped stethoscope with a double-ended bell. When measuring blood pressure in patients, a simple device is used, equipped with a single head with a membrane.
In modern medical practice, an electronic stethoscope is also widely used, which contains a microphone in its own head, which is capable of converting the sounds perceived by the device into an electronic signal that must be processed and output to the speakers that are built into the device's olives. With its help, auscultation can be performed with a double conversion of the received sound in the adult category of patients.