How it began
René Laënnec, a French physician, became chief of service at the Necker Hospital in Paris in 1816. That fall he was to examine a young woman with symptoms of heart disease. By the best-known account, he had seen children in the courtyard of the Louvre sending sounds to each other along a piece of wood. In the patient's room he rolled a quire of paper into a cylinder, placed it against her chest, and heard the heart more clearly than he ever had with his ear alone.
Before it existed
Physicians listened to breath sounds by placing an ear directly against the patient's chest, a practice referred to as far back as Hippocrates, and used percussion, striking the chest with the fingertips. Neither satisfied Laënnec's demand for precision. He criticized the difficulty of hearing sounds in the chest of an obese person and objected to the hygiene of patients who were unwashed or lice-ridden.
How it works
Laënnec wrote that the invention drew on acoustics, in particular the fact that sound is conveyed through solid bodies. Between 1816 and 1819 he experimented with hollow tubes made of cedar or ebony, arriving at a model about 1 foot long and 1.5 inches in diameter with a quarter-inch central channel. He named it the stethoscope, from the Greek stethos, chest, and skopein, to observe or explore.
Who pushed back
Laënnec's two-volume book on the stethoscope, De l'Auscultation Médiate, was published on August 19, 1819. According to the medical historian Howard Markel, it caused hardly a stir in the medical world, even at 13 francs, with a stethoscope included for an extra 3 francs. By the late 1820s the book had been reprinted and translated into other languages. That success, together with the gradual acceptance of the instrument by practicing physicians, allowed Laënnec's method to change clinical medicine.
What lasted
Using the instrument, Laënnec matched the sounds he heard with findings at autopsy. He became the first physician to distinguish reliably among conditions such as bronchiectasis, emphysema, pneumothorax, and pleurisy, and he described heart sounds and murmurs. He is considered the father of clinical auscultation and introduced clinical terms still used today.
