There is a coming-of-age moment in the life of most medical students when they receive their first stethoscope. With the delivery of a deceptively simple medical instrument comes an implied message; that your primary objective from this point is in the care of sick people. It is very difficult to fathom how medicine was pre-stethoscope. The iconic stethoscope has undergone many changes and evolved with the times to earn its place slung around the neck of a physician.
Past Stethoscope
What led to the discovery of stethoscope?
In the early 19th century, doctors listened to a patient’s heartbeat and breath sounds by placing an ear directly to the patient’s chest or back. This technique however suffered from several drawbacks like physical contact between the physician and the patient , improper placement of the ear , also the sounds observed were not amplified creating the possibility of missing key sounds that might indicate potential illness.
Wooden Tube Stethoscope
In September 1816, during a cool morning, while walking in the courtyard , Dr. Rene Theophile , a 35-year-old French physician, observed two children sending signals to each other using a long piece of solid wood and a pin. With an ear to one end, the child received an amplified sound of the pin scratching the opposite end of the wood. Later that year, Laënnec was called to a young woman with “general symptoms of a diseased heart.” Both application of his hand to the chest and percussion offered little diagnostic assistance. Laënnec was reluctant to start immediate auscultation (placing the doctor’s ear on the patient’s chest) because of the age, sex and plumpness of the patient. In this moment of embarrassment, Dr Theophile of the children’s wood signaling. It was this observation that inspired his invention of the stethoscope. Not only did this solve the problem, but Dr. Laennec realized that it amplified the sounds in the woman’s chest. He called this simple invention a “stethoscope,”( derived from the Greek words stethos (chest) and skopein (to view or see).)
The elementary first design was soon improved, with later versions of the rolled-up tube looking like thin wooden funnels that featured one end that was larger than the other. Doctors who dealt heavily with patients who had contracted highly contagious illnesses were known to have used stethoscopes that were up to 35 cm (13.5 inches) long to keep a distance.
Bi-aural Stethoscope
It wasn’t until 1851 when the Stethoscope had its next major improvement, which was to make the device bi-aural. Invented by Irish physician Arthur Leared, it was refined in 1852 by George Cammann for commercialization. Initially there was some concern that the bi-aural stethoscope could create hearing imbalances which might be problematic during examinations, but by the early 1900’s these concerns had largely subsided and the bi-aural stethoscope was a commonly used diagnostic instrument.
Stethophone
As the popularity of the binaural stethoscope took off, Scottish doctor Somerville Scott Allison designed a similar instrument called a “stethophone” that used two “bells” to listen to different parts of the body at the same time, such as the heart and the lungs.
By the 1940s, the most common style of stethoscope included these two different bells connected to two large, rubber tubes that then attached to metal ear tubes. This design was heavy and difficult to carry around, but it was not until the 1960s that a lighter model would come around.
Present Day Stethoscopes
The present day Stethoscope is the “Bell and the Diaphragm “ version. The bell is used to detect low-frequency sounds and the diaphragm to detect high-frequency sounds. Modern day Stethoscope can listen to lower or higher pitched noises by adjusting the pressure of bell against the patient’s body. Today the doctors around the world use Litmann’s design and this brand is one of the most popular. The stethoscope is a simple tool using basic physics to amplify noise within the body. However, the impact of the tool is great, and there is no doubt that many healthcare professionals throughout history have made diagnoses they otherwise would not have been able to. After the stethoscope came microscopy, then radiography and x-rays. Health professionals quickly adopted these tools into common medical practice. The stethoscope is still evolving and will continue to evolve in the future too .
Future Stethoscopes
At the same time, as Rene Laennec invented the stethoscope, Frederick Koening invented the steam-powered printing press, and Georg Stevenson designed the first steam locomotive. Do we still use these technologies today? Definitely not. Like every coin has two sides even stethoscope has its own pros and cons. We can apply it in many clinical situations and it helps us tremendously in our daily clinical practice. But other modalities are by far superior to the stethoscope. We would rarely rely solely on the stethoscope to make an important medical decision. A major advantage is Portability, while major disadvantage being Probability. It is possible to make mistakes while hearing the sounds .
This thought led a professor of internal medicine and director of UTMB’s Echocardiography Lab, Ahmad to implement new course for second-year medical students in Point of Care Echocardiography. Instead of using a stethoscope to “auscultate,” or listen for heart sounds, students are trained to use a small portable ultrasound device that can get real-time images of the heart right at the bedside. With advancing technology it is important to have devices which weigh less than a pound and can obtain images with accuracy .Handheld ultrasound devices are being used in UTMB hospitals, but not widely—yet. Ahmad hopes there will be a time when all physicians and general practitioners have their own ultrasound devices. This will enable them to see how a heart functions instead of just guessing , and this can be done by training medical students early on in their course Training physicians at an early stage while they are still in medical school so they are comfortable with this new technology. In this case, seeing is better than hearing.”
Another perspective to the Future Stethoscopes is by biochemical engineers who have been working on a type of stethoscope that is very different from what we are used to. It is a foam pad that can simultaneously auscultate 14 chest wall locations using 14 super powerful embedded microphones. The new tool is very accurate, and in a trial of 100 pneumonia patients, they found that 91% of the patients had adventitious lung sounds, with 89% having crackle sounds and 63% having a high-or low-pitched wheeze.
Smartphones are beginning to have a real influence on the way we manage our day-to-day health, and one area they may have a significant impact is in monitoring our hearts. A new study has demonstrated that an app designed to turn smartphones into electronic stethoscopes can capture reliable, quality recordings of user heartbeats across the population, which doctors can then use to remotely monitor progression of heart conditions. The Echoes app is designed to perform the role of a traditional stethoscope. Users simply place the phone’s microphone directly on their skin in a quiet environment, with an onscreen slider enabling them to tune the microphone’s sensitivity to ensure they capture their beating.
Despite all of the improvements and changes, the basic principle behind the stethoscope continues to remain the same; to provide physicians with the means to perform auscultation and identify specific sounds within the body and the dream of every medical student to have it around their neck, also remains constant.
Reference
https://www.adctoday.com/learning-center/about-stethoscopes/history-stethoscope
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1570491/
https://www.cureus.com/articles/103799-the-history-and-evolution-of-the-stethoscope
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