The Stethoscope

Before the stethoscope, understanding the inner workings of the human body meant physically going inside. If you have ever experienced the discomfort of the cold pad of a stethoscope moving around your skin, lead by an unfamiliar human, feel comfort not only from the framed certificates on the wall, but also by the history and incredible advancements made in the medical industry. Before the stethoscope, a good reading on the heart included more blood, more tools and much more discomfort.

The original stethoscope, born in 1816 Paris, France by Rene Laennec, was made of a wooden tube, allowing just enough room for one ear to listen to the music of one body. There was no mobility and no comfort, but the tool was the key that began a medical revolution. 1840 brought upgrades in the form of the flexible tube, but there was still just enough room for only one ear to listen in and connect, read, and learn about the body. Not long after, in 1851, Arthur Leared tweaked the tool and constructed the binaural stethoscope, allowing for better listening and better understanding. Finally, a year later, the stethoscope was ready for commercial production. Today, advancements continue, as stethoscopes fall into three categories: traditional acoustic, amplifying, and digitizing.

Traditional Acoustic Stethoscopes

Traditional acoustic stethoscopes are made up of three classic components: the chest piece, tubing, and an ear piece.The chest piece, made up of the bell (or the hollow cup) and the diaphragm (or the disc) allow for a combination of frequency input into the device. While the bell transmits sounds that fall under lower frequency, the diaphragm transmits sounds that are of a higher frequency. The body produces vibrations that reach the diaphragm, which lead to acoustic pressure waves which travel through the device to the listener. It’s a clinical orchestra in there. Hollow tubes act as the messenger, allowing for the transmission of sound from the chest piece to be delivered to the ear piece. The length of the tube affects the information received on the other end, as an increase in length will decrease the pressure at the end of the tube. Typically, tubes are found to be 18-26 inches in length, and the audible difference between lengths is not easily detected by the human ear. The combination of the ear piece, the listener, the tool, and the patient creates a circuit that allows the flow of sound energy, where a break or air leak in the circuitry could alter the sound quality, and in effect, the information. Pressure, ear tip seal, and ear tip insertion angle are a few factors that may alter the reading of sound flow. However, even when all the pieces line up appropriately, the sound level is still typically very low.

Electronic Stethoscopes

Sure, everyone knows the traditional acoustic stethoscope. It is so much a symbol of medicine that is is the singular prop to complete a medical monster halloween costume. Although they get the job done, we now have a new advancement that just gets the job done better. In the age of the upgrade, consider upgrading the stethoscope, too. Simply put, electronic stethoscopes hear better. By electrically amplifying sounds produced by the body, electronic stethoscopes are able to overcome complications found in traditional acoustic stethoscopes. Since sounds are transmitted electronically, stethoscopes often allow for features such as audio or serial data output in real time to an accompanying software application. Audio output can be saved and transferred for assessment and diagnosis, making the medical analysis simpler and more efficient. Some stethoscopes that have audio data output options are also able to be hooked up to a videoconferencing unit’s audio input. Currently, the only three models that can transmit serial data for real time transmission include the Littmann 3200, the Telehealth Technologies TR1-EF, and the CareTone.

If the battery is running low, the auto-shut off power saving feature can come into play. To give power to digitizing stethoscopes, however, an AC 120 V power cord is needed instead of batteries. Whether the tool is on or off depends on if it is plugged in.

Electronic stethoscopes convert the acoustic sound energy from the chest piece into electrical energy. As the voltage travels through the circuitry, it encounters an amplifier component, which converts small amounts of energy to increase the sound output. Some stethoscopes, such as the ViScope MD, even have visual audio indicators to reveal the level at use.

Ear tips are generally the same in acoustic stethoscopes as well as electronic stethoscopes. Instead of using ear tips, some models of the electronic stethoscope use headphones for heightened sound output quality. Typically, ambient noise enters the stethoscope through the patient’s body, air, and other surrounding disturbances. With electronic stethoscopes, ambient noise is canceled out. When ambient noise is generated, because the device is recorded by microphone, this then connects to the noise-canceling circuit. By creating waves opposite the incoming disturbance, the ambient noise is effectively canceled. Call it what you want– magic, science, technology. Better is better.

With the help of electronic stethoscopes, murmurs are more easily caught and tracked. According to Andrew J Schuman, MD, FAAP, “I have been an avid user of the Littmann 3200 stethoscope for many years and I will never go back to using a traditional stethoscope. Chief advantages of going electronic are the reduction or elimination of external sounds that interfere with optimal auscultation, as well as amplification of sounds across selected frequency ranges. Despite poor hearing, I can detect murmurs and lung sounds with my Littmann Model 3200 that colleagues using standard stethoscopes sometimes miss.”

In any case, consider all the factors at play. When picking a stethoscope, and specifically an electronic stethoscope, there are a few options to choose from, so consider the program, the user, existing systems, equipment available for adjunct use, and the specialties that will use the equipment.

References:

Schuman, Andrew J. “Electronic Stethoscopes: What’s New for Auscultation.” Contemporary Pediatrics. Modern Medicine Network, 1 Feb. 2015. Web. 20 Jan. 2016. <http://contemporarypediatrics.modernmedicine.com/contemporary-pediatrics/news/electronic-stethoscopes-what-s-new-auscultation?page=0%2C1>.