If you're a nursing student or home caregiver you don't have to be too picky when purchasing a stethoscope. A good reasonably-priced, all-purpose stethoscope is great for monitoring blood pressure and heart/breath sounds.
Most standard models are made with stainless steel or a comparable alloy as well as natural rubber latex, dry natural rubber, or PVC (poly vinyl chloride). There are also electronic stethoscopes that use a microphone and low-noise amplifiers that are specially designed to pick up many inaudible sounds.
Stethoscope Types
Stethoscopes will vary in style and quality from one manufacturer to another but most will have similar components. Here are a few of the standard stethoscopes we've found.
Electronic Stethoscopes
Double-Sided - Double Head - Dual Head (Combination) Stethoscopes - Consist of a bell and a diaphragm. With the double sided stethoscope, the user should open (or index) the bell or diaphragm by rotating the chest piece. When the diaphragm is open, the bell will be closed, preventing sound from coming in through the bell and vice-versa.
Triple Sided - Triple Head Stethoscopes - Both the double head and triple head stethoscopes have a diaphragm and bell. The triple head also utilizes a corrugated diaphragm for additional auscultatory capabilities.
Tunable Diaphragm Stethoscopes - A stethoscope equipped with a tunable diaphragm allows the user to hear high and low frequency sound without rotating the device.
Disposable Stethoscopes - Disposable stethoscopes allow the user to throw them away after use. They prevent cross-contamination.
Stethoscope Response
Many factors contribute to acoustic response. Make sure to check your stethoscope regularly. Normal wear and tear, like keeping it in your pocket, may cause obstructions. Stethoscopes rely on airtight seals o transmit sound. Loose parts or cracked tubing can prevent this seal. The proper headset alignment and the fit of the ear tips are also major factors. There are also differences in hearing from one individual to another, we at TheMedSupplyGuide.com recommend trying different stethoscope models before purchasing.
Stethoscope Components
The Ear Pieces - There are three types of ear pieces. There are the older threaded ear tips, snap-tight ear tips, and newest soft-sealing ear tips. Proper fitted ear tips are necessary to achieve optimal acoustic performance.
The Tubing - The two most popular tube designs are dual tube design and the single lumen design. The dual tube design consists of two internal tubes, each one going to a separate ear. The single lumen design allows sound to be carried to both ears through a single tube. It is said sound quality is better carried in the dual tube design.
The Bell - When indexed the bell allows the user to listen to low frequency sound.
The Diaphragm - When indexed the diaphragm allows the user to listen to high frequency sound.
The Chest Piece - The chest piece contributes to the sound quality in a stethoscope. The weight and width of this component will contribute to the sound intensity.
Long tube vs Short tube
Many stethoscope users have questions regarding the length of the tubing. It has been said that a shorter tube will provide for a better acoustic response. Instructors in some medical programs recommend their students buy the shortest tubing possible. Is this a myth? Consider this. As tubing length increases, resonant frequency decreases and lower frequency sounds increase. Heart sounds normally are considered to have a lower frequency. So what's the verdict? According to 3M, who did testing on there Littmann series, found that "there is only a small difference in sound between a short tube and long tube stethoscopes". It is so small that the human ear can't tell the difference. A longer tube may actually pickup low frequency sounds better. Longer tubing will also give the individual more freedom when working with patients and may relieve back pain. So its a toss up. The manufacturer and style of your stethoscope will ultimately determine the quality of sound regardless of tube length.
Keep it Clean
In one study, 80% of 200 stethoscopes from four different hospitals and clinics were found to be contaminated with at least one microbe. Staphylococcus accounted for 83% of the microbes cultured--and 58% of those organisms were methicillin-resistant. The study also found that 90% of the stethoscopes owned by physicians were contaminated. Nurses' stethoscopes came in a close second. 79% of the ones they owned were found to be contaminated. So disinfect your stethoscope regularly.
Stethoscope
The stethoscope is an instrument for listening to sounds produced by organs in the human body, including the heart and lungs. One end of the stethoscope is placed against the body, and the other end is placed in or at the ear, a method called direct auscultation. The sounds are then interpreted by an experienced listener.
Auenbrugger Invents Percussion
In the late 1700s Leopold Auenbrugger (1722-1809), a Viennese doctor, developed a technique called percussion. Auenbrugger tapped on his patient's chest and then analyzed the different sounds he heard. He published his findings in a pamphlet in 1761. The pamphlet was ignored by the medical profession until the early 1800s. At that time, Jean Nicholas Covisart (1755-1821) adopted Auenbrugger's percussion technique. Covisart translated Auenbrugger's pamphlet into French and encouraged Rene Theophile Laennec (1781-1826), one of his students, to study acoustic diagnosis.
Designing the Stethoscope
Laennec invented the stethoscope in 1816 during an examination of a young woman with a heart affliction. Laennec was unable to put his ear to the woman's chest to evaluate her condition. This was both because the patient was a very large woman and because moral standards of the day considered such an examination to be immodest (indecent). In a burst of inspiration, Laennec rolled a sheaf of paper tightly into a tube. He placed one end of the tube over the patient's heart and listened from the other end. The doctor later wrote, "I was both surprised and gratified at being able to hear the beating of the heart with much greater clarity and distinctness than I had ever done before by direct application of my ear."
Laennec made a later stethoscope from a wooden tube. In 1819 Laennec wrote a book describing his instrument and the diagnoses to be made with it. To help promote the book, the publisher gave a stethoscope with each book purchase.
Skoda Promotes the Stethoscope
Austrian doctor Joseph Skoda (1805-1881) promoted the use of the stethoscope. He was very instrumental in popularizing its use for diagnostic purposes. Various improvements were made to the device over the years, including the use of pliable (flexible) tubing, introduced in 1850. In 1852 American doctor George P. Cammann developed a binaural stethoscope, a stethoscope with an earpiece for each ear.
The Electronic Stethoscope
The next major development in stethoscope design came 100 years later, when the electronic stethoscope appeared in 1980. One application of an electronic stethoscope is the fetal monitor, which is used to listen to a unborn baby's heart rate. With the "external" monitor, the heart rate is heard through belts placed around the mother's abdomen (stomach). With the "internal" monitor, the heart rate is heard through a wire that is attached to the baby's scalp.
A modern stethoscope. The stethoscope is an instrument for listening to sounds produced by organs in the human body, including the heart and lungs. One end of the stethoscope is placed against the body and the other end is placed in or at the ear.
The advantage of electronic monitoring of the heart rate is that the monitor provides continuous listening and can pick up uncommon patterns, then can sound an alert so that medical personnel can take immediate action. That action is almost always to deliver the baby by Cesarean section (abdominal surgery), then to guard against oxygen starvation, which may occur with a faulty heartbeat and ultimately result in brain damage.
Electronic stethoscopes are also being studied for their usefulness in areas where the patient is remote (distant) from the physician, a form of diagnosis called telediagnosis. The quality of the information obtained from the electronic stethoscope compared very well with direct, or conventional, auscultation. The method brought the information, or data, to the physician using a modern and a standard telephone line.
When pitted against direct auscultation, the electronic stethoscope missed some faint heart murmurs, so the standard stethoscope-—which doesn't need electricity to work-—remains valuable and widely used. Its portability, low cost, and ready availability make the stethoscope an ideal basic tool.
