Auscultation in the diagnosis of respiratory disease in the 21st century

Auscultation of the chest via a stethoscope has been an integral part of respiratory examination for the last 200 years. Hippocrates was known to “directly auscultate” the chest by placing an ear to the patient’s chest wall, but this had fallen out of favour until the 1800s, when Laënnec invented the precursor for the modern day stethoscope in 1816. This consisted of a wooden rod, one end of which was placed on to the chest wall and the other to the doctor’s ear. In 1819, Laënnec went on to describe lung sounds and compare them with pathology found at autopsy. He described five types of chest “rattles” (rales), but, in part because of translation problems, there was subsequent confusion around what was meant by dry or wet crepitations and rhonchi.1 Fortunately, owing in large part to the seminal work of Forgacs,2 the sounds heard at auscultation were simplified into breath sounds (normal or bronchial), adventitious sounds (crackles, wheezes and rhonchi) and voice sounds (normal and bronchophony). Various other sounds such as pleural rubs, clicks and squawks may also be heard.2 3

ORIGIN OF THE LUNG SOUNDS

Even today the breath sounds are incompletely understood, but the normal breath sounds are probably the result of turbulent airflow through the larger …