Anatomy of a Stethoscope: Everything You Need to Know
Posted by Stethoscope.com on Aug 29th 2022
Stethoscopes are inarguably one of the most critical tools for heart monitoring. With roots dating back to 1816, the first stethoscope was nothing more than a monaural (meaning ‘one ear’) wooden tube. Fortunately, its technological advancements over the last 200 years have far exceeded this initial prototype.
Now, we even have digital stethoscopes featuring bluetooth auscultation. This modern format allows doctors to auscultate their patients remotely – a concept that, even a decade ago, would have been difficult to conceive.
As stethoscopes evolve into new iterations, with advanced capabilities, one thing that remains the same is the familiar build with its tried and true functionalities.
How Stethoscopes Work
Before diving into the overall anatomy of a stethoscope, it’s important to understand how this anatomy allows it to perform the task of auscultation. Basically, it comes down to two important phenomena: vibrations and sound waves.
When the diaphragm (also known as the chestpiece) of the stethoscope is placed against the patient’s chest, their breathing and heartbeat produces soundwaves that cause the surface of the chestpiece to vibrate. These vibrations then travel up the mechanism, through its hollow tubing, all the way to the earpieces.
From here, the doctor can hear the heartbeat and a variety of breath sounds:
- Tracheal: Heard over the trachea; harsh and loud.
- Bronchial: Heard in the anterior chest; loud and hollow.
- Vesticular: Heard throughout most of the lung fields; soft, low, and rustling.
A standard Lub-Dub rhythm is also indicative, generally, of a healthy heartbeat. Turbulence and unusual sounds between heartbeats can indicate a heart murmur or other condition, which is why physicians are trained to notice even the slightest auscultative nuances.
Additionally, there are four common breathing sounds that also point to potential problems, such as:
- Rales: Clicking, bubbling, or rattling sounds upon inhaling.
- Ronchi: Gurgling sounds that resemble snoring.
- Stridor: Noisy, high-pitched, almost creaking sound.
- Wheeze: High-pitched whistling, particularly when exhaling.
The modern-day stethoscope is able to detect all of these sounds and more. The device as we know it is the product of Harvard Medical School professor and cardiologist Dr. David Littmann in 1961. He envisioned a contraption with an open and closed chestpiece for assessing different pitches, strong tubing in a minimal length, and a spring to hold the earpieces together.
“A high-quality stethoscope is so important so you can avoid misinterpretation of the readings,” says Dr. Faith Alex of National TASC.
Today, the 3M Littmann stethoscope lineup is one of the most reputable, and trusted by healthcare professionals around the globe.
Parts of a Stethoscope
Stethoscopes come in a variety of models, often geared toward different medical specialties, meaning the best stethoscope for doctorsmight be different from the best stethoscope for respiratory therapists or pediatricians.
“One big feature that you need to consider when choosing a good stethoscope is the acoustics,” explains Dr. Kyle Burton. “A good stethoscope should be able to amplify the sounds of the patient, such as blood pressure, pulse, lung sounds, and others. This is why you need a good stethoscope that delivers stellar sound quality for them. There are different types of stethoscopes available out there, such as a binaural stethoscope, dual membrane chamber stethoscope, and others.”
Still, all stethoscopes share the same general build, starting from the top.
With a self-explanatory name, you can immediately deduce that this is the part of the stethoscope that is placed against a patient’s chest. It consists of three parts: the diaphragm, the bell, and the stem.
The diaphragm can be either two-sided, two-sided and tunable, or one-sided and tunable. Tunable diaphragms work by adjusting the pressure so you can capture different frequencies. Low-pressure allows you to hear low-frequency sounds, while applying more pressure allows you to hear higher-frequency sounds.
The bell is the smaller, circular end and also detects low-frequency sounds. It is ideal for pediatric patients or just smaller patients in general.
The stem is what connects the chestpiece to the tubing, providing an acoustic path to the eartips for maximum functionality.
Soft, flexible, and hollow, the tubing transmits the sounds picked up by the chestpiece all the way to the physician’s ears. Most modern-day stethoscopes, such as those by 3M Littmann, feature double-lumen tubing, which creates two sound paths.
Tubing is usually made of highly durable polyvinylchloride (PVC), which is fairly resistant to the skin oils and weathering that can occur from being worn around the neck and from heavy usage.
Much like the chestpiece, this part of the stethoscope consists of multiple components – primarily the aural tubes and earpieces. The aural tubes, or ear tubes, are hollow metal tubes that connect the acoustic tube to the earpieces. They are typically made of steel or an aluminum alloy for maximum durability and strength, while remaining lightweight.
These tubes lead into the earpieces, or ear tips, which are typically made of rubber or silicone. By positioning them comfortably in the ear canal, the doctor can hear all that they need to make a diagnosis. They create a seal within the ear, providing essential noise cancellation, so that sound can flow most efficiently.
How to Clean & Maintain a Stethoscope
The key to keeping your stethoscope’s performance high is to maintain it properly. Cleaning and maintaining your stethoscope is a fairly easy task, so long as you remain diligent.
“Just as we wash hands between each patient, clinicians should disinfect their stethoscopes after every patient assessment,” emphasizes Dr. Alex.
Keep 70% isopropyl alcohol wipes handy for between patients. With these, you can wipe down the earpieces, tubing, chestpiece – everything. A mild soap and water mixture can also be used for the tubing, but be mindful to never submerge any part of your stethoscope. Also, avoid cleaners with any sort of harsh chemicals or hand sanitizer.
Of course, the biggest factor in proper stethoscope care is prevention. By keeping your stethoscope out of direct exposure with the sun or other elements, you will extend its lifespan significantly.
Finding the Right Stethoscope
Feel like you understand the ins and outs of this device and are ready to make the move on purchasing one? Our Stethoscope Selector guide will help you find the best stethoscope to complete your medical toolkit.
Whether you’re a new medical student, a practicing nurse, or a seasoned physician seeking out a deeper understanding of this day-to-day tool, knowing the intricate functionalities of a stethoscope can serve as a valuable reminder of its usefulness. Furthermore, it can encourage us to research new and improved models, with groundbreaking features and applications. No matter how this powerful device evolves, it will always remain the core fixture of the medical community.