All you need to know about electronic stethoscopes

From their humble beginning 200 years ago, the stethoscopes have come a long way. Learn all you need to know about electronic stethoscopes.

electronic stethoscope

The stethoscope is the symbol of medicine. But, during the last two hundred years, they did not evolve dramatically.

The first one was invented by the French doctor Rene Theophile Hyacinthe Laënnec (1781–1826). It just consisted of a wooden hollow tube, but this tube revolutionized cardiology. The digital stethoscopes are now jewels of technology.

They have far more capabilities that amplify the sounds. With user interfaces, Bluetooth technology, ambient noise-canceling technologies, performance, and ease of use dramatically improved during the last fifteen years. Here is all you need to know about electronic stethoscopes and how to choose the best ones.

History of the stethoscopes

Puritanism during the 19th century was at the core of the invention of the stethoscope. René Laënnec was a devout catholic physician working at the Necker-Enfants Malades Hospital in Paris.

In the 1800s, doctors used direct auscultation to listen to the heart and chest sounds. The physicians had to put their ears directly on the skin of the patient. Not only were the sounds not amplified in any way, but this method was also very hygienically debatable.

Laennec and the first stethoscope
Dr. Henri Laennec, with one of the first stethoscopes he invented in 1816 to avoid direct auscultation on the skin of a young patient.

Dr. Laennec was 35 years old when he had to go to the bed of a young female child suffering from what was thought of as heart disease. Reluctant to perform direct auscultation on the young patient, he tightly rolled a sheet of paper and listened to the child’s heart. Using this paper tube, he was amazed by the hearing quality improvement that far surpassed direct auscultation.

He spent the next 3 years testing various types of materials to make tubes, perfecting his design. After careful experimenting on patients suffering from pneumonia, Laënnec decided upon a hollow tube of wood, 3.5 cm in diameter and 25 cm long. The stethoscope was born. Little improvements were made ever since.

In 1925, two physicians from Massachusetts, Bowles, and Sprague developed a stethoscope with a combination of a bell, a rigid diaphragm chest piece, and flexible tubing. This model was very close to the ones General Practitioners are still using today.

The electronic stethoscope as a game-changer for clinicians

Most heart diseases are recognizable by the sounds the heart produces. Therefore, despite the development of echocardiograms, electrocardiograms, Computer tomography, and cardiac magnetic resonance imaging, heart auscultation is always a valuable first step in any clinical examination. Heart auscultation refers to listening to the sounds of the heart.

Detecting such pathologies using a standard stethoscope somehow requires good hearing and a wealth of clinical expertise. It can be a difficult path to follow for young doctors. It takes years of practice to train the ear to detect abnormal heart sounds.

Anatomy of an electronic stethoscope?

One of the main issues of acoustic stethoscopes is that heart sounds are shallow. They also contain a mixture of low-frequency and high-frequency sounds.

Image: Leng et al., 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4496820/

Most of the electronic stethoscopes comprise three main modules:

  • The data acquisition module records, filters, and amplifies the sounds and converts them to digital signals. The data-acquisition module of an electronic stethoscope can classically be divided into three components: the electronic stethoscope sensor, the amplifier and filter, and the analog-to-digital converter.
  • The pre-processing module removes the sound artifacts, normalizes, and segments the signals. This module contains a signal denoising unit, and the normalization module will normalize the heart sounds to a certain scale.
  • The signal processing module that analyses the events extracts the waveforms to help the clinical diagnostic decision. The raw data will be converted to parametric representations for further analysis. The classifier will then categorize the data to assist the physician during his clinical diagnostic decision-making process.

Are the apps useful?

In addition, most of the high-end stethoscopes now come with an associated app. but are they beneficial?

No app will replace ever going next to the patient’s bedside. Apps may help identify a diastolic rumble, but we agree that recording the heart sounds is useful for the tech-savvy medical student. Therefore, we consider the app. as a good to have but not as a must-have. Eko platform can be accessed using the 3M Littman CORE and DUO electrocardiogram digital stethoscopes.

The digital health revolution is more about putting the patient at the center of his medical journey. Patients nowadays want to understand what they are suffering from. As with endo-buccal cameras for dentists, the electronic stethoscopes’ apps can help in diagnostics. The EKO platform combines FDA-approved artificial intelligence algorithms to detect murmurs and atrial fibrillation in real-time.

Considerations for choosing an electronic stethoscope

Electronic stethoscopes do not come cheap. Be ready to spend at least $400 for one coming from a reputable maker. To choose the right, you must think about your budget and the environment you are working in. Do you suffer from hearing loss? Do you want to share the recordings with colleagues for a second opinion? Do you have an analog stethoscope that you cherish for a long time but would like to upgrade with digital capabilities? All of these questions will have an impact on your choice.

For pediatric specialists or ER doctors, an important element to consider is the associated ambient noise reduction technologies. For example, electronic stethoscopes amplify sound, but they also amplify the ambient noise, making them useless when working in noisy wards.

Veterinarians will also appreciate the ability to reduce the bell’s frictional noise on the animal’s fur.

The best stethoscope is the one you always have with you. It would help if you considered not only the weight of the stethoscope but also the battery life. There is nothing more frustrating than owning an expensive piece of equipment and not using it because the battery is not long-lasting.

Some of the newest electronic stethoscopes use either a standard battery that can be replaced or recharged via a USB connector.

To wrap up

In the last couple of years, more and more medical students, physicians, nurses, and veterinarians have made the jump from acoustic stethoscopes to their digital counter-part. To know more about the models offered by 3M Littman, Cardionics, Eko, and many more, check our guide on the models we consider the best digital stethoscopes for 2022.

More than a fashion, electronic stethoscopes offer numerous advantages and are useful to train residents’ ears not to forget older physicians who may have hearing loss issues. They capture more sounds and offer a greater range of sound wave frequencies. In all of these cases, these new instruments can be handy. They integrate so much technology and offer a new way to practice auscultation.

Stethoscopes have come a long way from the paper tube of Laennec. Still, with the rise of telemedicine, we argue that they will soon become an essential instrument in any medical connected practice.

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