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Stethoscope Evolution: From Wooden Tube to Smartphone App

Stethoscope-EvolutionThe Hindu Vedas, the primary texts of Hinduism, date back to 1500 BC. These ancient texts note the importance of body sounds in the diagnosis of disease. The Ebers Papyrus, again from around 1500 BC, also makes note of the importance of breath sounds in the diagnosis and treatment of many ailments. Hippocrates, who lived in the fourth century BC, expanded on the work of his forebears, and devised a complex system whereby diseases could be diagnosed from lung sounds alone.

It wasn’t until over a thousand years later, in the early 1800s, when the French doctor René Théophile Hyacinthe Laënnec created a device that could amplify sounds generated in the chest cavity. There are many stories that attempt to explain the source of his inspiration. One such story has it that the doctor witnessed children speaking to one another from the opposite ends of a long wooden tube, and that he went to his laboratory right away to create a smaller wooden tube that could better amplify sound. What really fueled his passion, however, was likely exasperation. In that time period, doctors had two options when attempting to listen in on the body: they could perform what was known as “percussion,” or they could place their ears directly against a patient’s body.

Percussion, which involved placing the middle finger of the right hand on the body of the patient and then tapping it with the middle finger of the left hand, was the preferred method of the era. However, while percussion could reveal fluid buildup around organs and other signs of poor health, it could not detect issues with the heart. For that, doctors had to make direct contact with patients, but this practice came with a cost. People were often plagued with lice, as well as diseases such as tuberculosis. Doctors could easily fall ill themselves after coming into close contact with patients. Worse yet, since they saw so many patients, they became vectors of disease themselves.

Laënnec, tired of pressing his head against unwashed bodies, devised the stethoscope as a method of listening in on the organs of the body from a distance. The doctor was also critical of the ear-to-body technique because it didn’t work well on obese patients. His device, however, was able to transmit and slightly amplify body sounds, which made it easier to listen to the heart of any patient.

Essential Medical Diagnostic Tool

According to medical historian Jacalyn Duffin, Laënnec’s invention marked the birth of modern medicine. Laënnec’s stethoscope, however, was only slightly more sophisticated than the ear trumpets of the era. Over the next hundred years, many other doctors would tweak the design until the device came to resemble the stethoscope of today. The first major improvement came when it was fitted with two flexible tubes. Each tube acted as a separate channel, which helped doctors make out faint sounds.

In the 1960s, Harvard Medical School professor David Littman created what many consider to be the first modern stethoscope. Littman’s model was lighter than any stethoscope before it, and it was capable of detecting sounds that earlier models could not. Even before Littman released his version of the diagnostic tool, the stethoscope had become an essential tool in the doctor’s kit. For the first time, it allowed physicians to explore the inner workings of a patient while they were still alive. Modern stethoscopes can detect irregular heart rhythms and murmurs that if undetected and untreated can lead to premature death. Physicians around the world also use it to detect lung infections such as pneumonia in young children.

The Digital Age

As 3D printers, smartphone apps and custom electronics become cheaper and easier to produce, many innovators are giving the stethoscope a digital makeover. For instance, the StethIO, an iPhone case that contains a plastic diaphragm, is a mobile stethoscope that uses a dedicated iPhone app to detect heartbeat irregularities. The StethoCloud, on the other hand, is a device that allows physicians to connect a traditional stethoscope to their smartphone, where sophisticated software detects the tell-tale breathing pattern associated with pneumonia. Its inventors hope that it will allow doctors in Africa and elsewhere to diagnose the illness sooner, which could save hundreds of thousands of lives each year.

Professor T. Varagunan of the University of Peradeniya believes that the traditional stethoscope will no longer exist by 2020. Indeed, ultrasound technology is already doing what the stethoscope can’t: allowing doctors to see their patients’ internal body structure. Many other experts have expressed doubts as to whether the stethoscope as it has existed for roughly 100 years will be used at all in the coming decades. The device still has many supporters, however. After all, it is a simple device that doesn’t rely on a power source, and it isn’t prone to failure.

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