What is a stethoscope and how does a stethoscope work?
A stethoscope is a diagnostic instrument used by various health care professionals to listen to or auscultate a patient’s heart, lungs, various pulse points and abdomen. Health care providers (HCP) use a stethoscope as part of a non-invasive examination. Commonly, physicians and nurse practitioners will listen for congestion in the lungs and for irregular heartbeats and murmurs. In addition, stethoscopes are used to check blood pressure (BP) by listening for the restored blood flow as pressure is released from the BP cuff.
In 1816, Dr. Rene Theophile Hyacinthe Laennec invented the first stethoscope. Dr. Laennec fashioned a cylinder from several sheets of paper and used it to examine a young female patient. He discovered that internal sounds could be isolated and amplified through a tube, making examinations less intrusive and easier to interpret. Prior to Dr. Laennec’s discovery, physicians would literally place their ears directly on a patient’s chest or back to heart the heart and lung sounds. This technique of “immediate or direct auscultation” had been well know from ancient times but was little used as it was as uncomfortable for the physician as it was for the patient.
The original stethoscope, a rigid wooden cylinder with a funnel, has evolved into the modern instrument which typically has two chest pieces connected to the ear pieces by tubing. Dr. Laennec perfected his listening device using wooden tubes turned on a lathe. Colleagues convinced Dr. Laennec to name his invention the stethoscope, after the Greek words for chest (stethos) and ‘to view’ (scope).
Modern stethoscopes consist of a shallow bell-shaped device with a clear stiff diaphragm, connected to the ear pieces by flexible tubing and a hollow metal headset. The chest piece is placed directly on the patient’s skin. As the patient takes deep breaths or the heart beats, sounds are amplified through the diaphragm or bell. These amplified sounds travel through the hollow flexible tubing and headset, finally reaching the examiner’s ears through the tight-fitting earpieces. At this point the examiner can describe and assess the sounds they heard and apply them to their diagnoses and treatment.
K Schunk, BS, MS, MSEd, APN, CNP, FNP