Name That Tune: An Introduction to Auscultating, Differentiating and Assessing Lung Sounds

It’s a hot summer night, and your unit has been working nonstop when a call comes in

It’s a hot summer night, and your unit has been working nonstop when a call comes in: “Unit 172, respond to 3317 Court Street, 1st floor; 62-year-old male, chest pain, difficulty breathing.” On arrival, you and your partner find an obese gentleman in the tripod position, gasping for breath. He has a nasal cannula on, with 30 feet of tubing going to an oxygen tank in an adjacent room. On the table beside him, you notice three different types of inhalers and an ashtray full of cigarette butts. Your partner begins to place the bell of his stethoscope in various places around the man’s expansive, fat-padded chest. Just as you are beginning to doubt that he is hearing anything, a perplexed look crosses his face, and he asks: “Does this sound like rales to you, or rhonchi?”

One of the most important and difficult skills that an EMS provider must learn and master is assessment of lung sounds. This includes not only becoming skilled at knowing where to place a stethoscope to listen correctly to the lungs and identify the various sounds, but also what potential problems they indicate and how to properly address their presence in the field. Correct recognition of lung sounds and the subsequent appropriate treatment can make all the difference in managing patients with respiratory compromise.

From the early 1800s, when René T. H. Laënnec invented the first crude stethoscope, medical providers have used auscultation of the chest to enhance their ability to properly examine patients.1 Prior to that, doctors placed their ears directly on patients’ chests to hear lung sounds.

EMS providers now have access to cutting-edge technology to help them better recognize and differentiate lung sounds. Stethoscopes have advanced significantly since the early days of Laënnec. Current models are available with enhanced acoustics and built-in microphones designed to amplify sounds several times louder than traditional scopes. Bell-head configurations allow the user to alternate between low, middle and high tones by simply adjusting the pressure used to hold the scope to the skin. In addition to enhanced equipment, EMS providers are also armed with advanced resources to better train themselves in lung sound recognition. A wide variety of sample breath sounds can be found on media ranging from audio CDs distributed with textbooks to Internet-based downloadable WAV files. As computer-programmable training manikins become more affordable, greater numbers of prehospital providers can gain invaluable practice locating and identifying critical changes in patients’ respiratory patterns in a classroom setting.

Appropriate Placement

Webster defines auscultation as “the act of listening to sounds arising within organs [as the lungs] as an aid to diagnosis and treatment.” The stethoscope not only amplifies sounds, it also filters out unwanted noise, if positioned correctly. Of primary importance in properly auscultating a patient’s lung sounds is the placement of the stethoscope on the chest wall. If it is incorrectly placed, you may hear body processes other than breath sounds, such as gastrointestinal activity, or nothing at all, especially if it is placed over bone.

Knowing your way around the thoracic cavity and its organs is most helpful in remembering the locations to best assess lung function. Some fundamentals of anatomy to remember include:

• Although of similar size, the right lung has three lobes and the left has two.

• From the anterior (front) perspective, the lungs extend from the top of the rib cage, just above the clavicle (collarbone), down to about the level of the sixth intercostal space (6th ICS).

• The diaphragm defines the bottom of the thoracic cavity. To allow for the space needed by the abdominal organs, the shape of this muscular wall is normally concave when relaxed, pressing up against the lungs.

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