Auscultation

Auscultation is the medical term for listening to the sounds inside the body during a medical exam. The most familiar type of auscultation is that of a medical practitioner using a stethoscope to listen to a person's heart sounds. However, medical professionals also listen to the lungs or intestines as well as the heart sounds of an unborn baby with a stethoscope. The professional may also listen to the sound of blood flowing through an arm or leg. Devices other than a stethoscope may be used, such as Doppler ultrasound. Auscultation is an important procedure because it provides a non-invasive way for a medical practitioner to search for potential health problems in the cardiac, respiratory, and digestive systems.

Background

For centuries, medical practitioners knew that listening to the sounds made inside the body could provide clues to a patient's health. Evidence indicates the practice was used by the ancient Egyptians. By placing an ear directly against the patient's body, the healer could hear the sounds made by the beating of the heart, hear how air flowed in and out of a patient's lungs, and listen to the gurgles of the bowels. Through experience and training, these health practitioners learned how the healthy heart, lungs, and intestines sounded. They also learned what sounds indicated a problem, and what problem was the most likely cause of a certain type of sound. This allowed the doctor to determine what might be wrong with a person and how to begin treatment. The practice was called immediate auscultation after the Latin word auscultare, which means "to listen."

In 1816, a French doctor named Rene Theophile Hyacinthe Laënnec (1781 – 1826) was treating a young woman with suspected heart disease. His ability to diagnose her was complicated by two things. First, the woman was significantly overweight, which made it difficult to accurately hear her heart sounds. Second, the sense of modest behavior at the time made it embarrassing to both Laënnec and his patient to press as closely together as was necessary for him to hear her heart.

Laënnec solved this problem by applying a principle he had seen as part of a children's game. He had observed a child press his ear to a piece of wood and listen to the sounds made when another child scratched against the other end of the wood, and realized sound could be transmitted through an object. Laënnec rolled a piece of paper into a cone shape and pressed one end against the woman's chest and the other to his ear. He discovered that not only could he hear her heart sounds but they were also louder and clearer than the sounds heard by placing an ear directly against a chest. Laënnec named his invention a stethoscope; stethos is Greek for "chest" or "breast" and skopien is a Greek word that means "explore." He called his new technique mediate auscultation.

Laënnec would soon devise a more permanent instrument made of wood and refine the technique for using it as a diagnostic tool. He spent several years making careful notes of his observations based on body sounds and confirmed his findings by performing autopsies when possible. Three years after he invented the stethoscope, Laënnec published the first comprehensive manual about his findings, On Mediate Auscultation or Treatise on the Diagnosis of the Diseases of the Lungs and Heart. As a result, he is considered the father of auscultation.

Overview

In the more than two centuries since Laënnec established the first tools and techniques of mediate auscultation, it has become a standard part of most medical exams. During the most basic exam, a medical practitioner will listen to the sounds made by the heart and lungs. They follow an established format for doing this, moving the stethoscope around to various regions of the chest and back to listen to the sounds in each area. When possible, the patient will be asked to breathe in and out several times, and may be asked to change positions, bending forward and even lying down. The medical practitioner is listening to learn several things about the sounds, such as how often they occur, how loud or soft they are, how long they last, how many sounds there are, and the quality of the sounds as compared to those known to be normal.

During an auscultation examination of the heart, the medical practitioner can determine if the patient has a heart murmur. A murmur is an unusual extra sound heard when the heart beats. As the professional listens to the different parts of the heart by moving the stethoscope around on the body, the frequency, intensity, duration, and other characteristics of the murmur can help determine what might be wrong with the patient's heart.

While performing an auscultation exam of the respiratory system, the medical practitioner is listening for how easily air is flowing in and out of the lungs. The frequency, intensity, and length of time for each breath to be taken in and out all provide important clues about the health of the lungs. By having the patient breathe normally, then more deeply, the professional can determine if the respiratory system is functioning properly or if the patient has an illness, obstruction, or other breathing problem.

Auscultation of the heart and lungs are fairly routine elements of a medical exam. The technique can also be applied to listening to the sounds of the intestines. In this case, the patient is generally lying down while the stethoscope is moved about on the abdomen. The type and quality of sounds heard or the absence of bowel sounds can tell a medical professional a great deal about a person's health.

The technique is also often used to listen to the heartbeat of unborn babies by pressing the stethoscope to the mother's abdomen. Other tools can be used for this as well, such as a Doppler ultrasound that electronically detects and enhances the baby's heartbeat. Ultrasound is also used in the auscultation of limbs to check for impaired blood flow that may indicate a clot or other obstruction.

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