auscultation

auscultation is the act of listening to sounds generated within the body, generally for the purpose of diagnosis of disease. It may be done directly with the unaided ear (immediate auscultation) or with a stethoscope (mediate auscultation).

Immediate auscultation was practised in ancient times. In both the Hindu and the Greek medical traditions, physicians listened carefully to the sounds which could be heard emanating from within the thorax. The Sanskrit medical texts mention the use of the sense of hearing to determine whether the contents of an abnormal cavity were gaseous. The Hippocratic writings describe the technique of succussion — shaking the patient to ascertain whether splashing noises could be elicited within the chest. Aretaeus the Cappadocian, in the second century ad, described how, in ascites, fluid could be heard fluctuating in the abdomen as the patient shifted position, whereas tympanites (gas in the abdomen) could be distinguished by the drum-like sound produced if the abdomen was struck with the hand.

In the eighteenth century, the great Italian physician/anatomist, Giovanni Morgagni, valued auscultation, pointing out that attending to the noises made by fluid fluctuating in the abdomen or thorax was useful in the identification of dropsy. The precise location and character of the noises could enable differentiation between the various forms of dropsy. For instance, the otherwise difficult diagnosis of ‘dropsy of the pericardium’ could be made confidently when the physician could ‘distinctly hear the agitation of the water itself in the pericardium’. In 1761, Leonard Auenbrugger, a Viennese physician, published a pioneering account of the related technique of thoracic percussion. The character of the sound elicited when the chest wall was tapped with a finger was indicative of the pathological condition of the underlying tissues.

At the end of the eighteenth century and the beginning of the nineteenth, in a series of developments principally associated with the Paris School, a new approach to internal disease was developed. The holistic, humoral pathology of earlier centuries was gradually replaced by a conception which localized disease in the solid structures of the body. The ‘anatomico-clinical’ perspective was based, as its name suggests, upon the twin pillars of pathological anatomy, which revealed the structural features of disease after death, and clinical observation, which sought to comprehend the structural features of disease in the living patient. Within this conceptual framework, techniques of physical examination were revived and their diagnostic potentialities systematically explored. A notable pioneer of the clinical use of the ear was the French physician, Jean-Nicolas Corvisart

, whose Essay on the Diseases of the Heart contained much that was new in the understanding of cardiac and aortal disorders.

Corvisart's preferred diagnostic technique was percussion, but both he and his Parisian colleague, Gaspard Bayle, experimented with applying the ear directly to the patient's chest. In 1816, Rene Laennec, who had been a student of Corvisart and who knew of Bayle's work, invented the stethoscope, which made examination of the chest much more convenient for both physician and patient. In 1819, Laennec published his great treatise On Mediate Auscultation. It has been fairly said that virtually everything that Laennec wrote on auscultation was new at the time, but is now familiar to every medical student. Laennec painstakingly described the normal sounds of the lungs and then identified a large number of abnormal sounds — bronchophony, pectoriloquy, egophony, the metallic tinkling, the cracked pot sound, a variety of ‘râles’, and so on. The most substantial section of the work is on tuberculosis, which provided him with ideal clinical material upon which to display the utility of auscultation of the lungs. Laennec also investigated the sounds of the heart in health and disease, describing, for the first time, the file, rasp, and bellows sounds, and a variety of murmurs. He showed, among much else, that valvular disease of the heart could be diagnosed by ear in the living patient. Applications for the new instrument were also found in the diagnosis of fractures, of bladder stones, and of liver abscesses. Laennec's investigations with the stethoscope, correlated always with post-mortem findings, laid the foundations of the modern procedures of physical diagnosis.

Laennec's innovation was adopted widely and quickly. The remainder of the nineteenth century saw considerable refinement of stethoscopic technique and design, and improved understanding of the pathological basis of abnormal sounds. Further applications were found for the instrument in the monitoring of pregnancy, of bowel function, and in the measurement of blood pressure. In the twentieth century, however, the ear has been displaced, to some extent, by the eye in physical examination. The invention of radiographic imaging demoted the stethoscope from its place of supreme authority in lung disorders; the ultrasonic scanner threatens the same in disorders of the heart. Blood flow can also now be visualized using Doppler ultrasound. Other imaging modalities provide clear, detailed pictures of all the body's cavities. Yet a trained sense of hearing remains an indispensable aid to the examining physician, and all medical students still have to strive to educate their ears along the lines first set out by Rene Laennec.

Malcolm Nicolson

See also diagnosis; heart sounds; lungs.