percussion(redirected from threshold percussion)
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a method of medical examination of internal organs. It gained acceptance in medical practice at the beginning of the 19th century, after the publication of works by L. Auen-brugger (1761) and J. N. Corvisart (1808). The theoretical basis for percussion was provided by J. Skoda in 1839, and various modifications of the method were proposed by V. P. Obraztsov and others.
Percussion is based on the fact that when the surface of the body is tapped, vibratory motions arise in the underlying organs, producing sounds of definite volume, duration, pitch, and resonance. For example, the lungs contain air and produce a loud, distinct sound, whereas the heart, liver, and muscles, being solid organs, produce a soft, dull sound.
Percussion may be topographic, determining the boundaries of an organ, or comparative, revealing changes in an organ. An area of dulled sound in a lung may indicate pneumonia or pleurisy, while a metallic sound indicates increased pneumatiza-tion of lung tissue (pulmonary emphysema) or the presence of cavities (caverns, cysts) in the lung. The presence of free fluid in the abdominal cavity (ascites) is indicated by a dull sound, and excessive accumulation of gases in the intestine (meteorism) by a metallic sound.
REFERENCESChernorutskii, M. V. Diagnostika vnutrennikh boleznei, 4th ed. [Leningrad] 1959.
Miasnikov, A. L. Propedevtika (diagnostika i chastnaia patologiia) vnutrennikh boleznei, 4th ed. Moscow, 1957.
A. Z. CHERNOV
In veterinary medicine, percussion is most often used to examine the heart, respiratory organs, and digestive organs. Various types of percussion hammers and pleximeters are used. Percussion makes it possible to detect changes in organs of animals at depths of 6–7 cm from the examined surface.