Pierre-Adolphe Piorry was a French physician and invented the pleximeter in 1826. This instrument consisted of a small plate which was interposed between the skin of the patient and the percussing finger of the physician for mediate percussion. Piorry believed that the method of pleximetry was superior to immediate or direct percussion.
Piorry was a prolific writer and described his invention and new method of percussion in his book, "De la percussion mediate," in 1828. Piorry was obviously greatly inspired by the invention of the stethoscope in 1816 by Laennec and the publication of his celebrated monograph, "De l'auscultation mediate," in 1819. He dedicated his book to Auenbrugger, Corvisart and Laennec.
Piorry used various materials such as leather, lead, and wood for the construction of the plates. He finally used ivory to make small plates of 5-cm diameter. Piorry described specific sound for each organ in normal and pathologic conditions. He referred to them as cardiac sound ("son cardial"), pulmonary sound, gastric sound, intestinal sound, etc. Applying this methodology, he introduced the concept of organographism to outline the limits of each organ in the abdomen and thorax.
Pierre-Adolphe Piorry used the technique of pleximetry to estimate the thickness of the heart, to delineate its right and left borders and to determine its size. He also applied this technique for the diagnosis of pericardial effusion, aortic aneurysms, and cardiac enlargement in patients with valvular disease. In his analysis, he also correlated the findings of mediate percussion with those of cardiac auscultation.
The method of pleximetry did not obtain broad acceptance among physicians and was progressively abandoned. In 1830's, James Hope and William Stokes used the finger as pleximeter and until today, the finger-to-finger method remains the preferred technique of percussion.