The triumphs of medical microbiology tend to overshadow another important aspect of nineteenth-century medicine that grew out of what we might think of as the unhappy intersection between clinical medicine practiced at the patient’s bedside and pathological investigations con- ducted in the autopsy room. Achieving a more precise understanding of the nature and seats of disease within the dead body was eventually coupled with more precise diagnosis of disease in living patients. Symp- toms were correlated with internal localized lesions, but, until the devel- opment of instruments such as the stethoscope, the lesions could only be detected at the postmortem.
The gradual development and recent enthusiastic reception of the
technological aids used in the diagnosis of disease represent remarkable aspects of the evolution of medical practice over the course of the last two hundred years. Beyond their obvious role in transforming the art of diagnosis, medical instruments have profoundly affected the relation- ship between patient and physician, the education and practical training of physicians, the demarcation between areas of medical specialization, the locus of medical practice, and even the ﬁnancial structure of medical care and treatment. From the time of Hippocrates until well into the nineteenth century, the average physician relied on essentially subjective information, such as the patient’s own account of the course of illness and the physician’s observations of notable signs and symptoms. Which signs and symptoms were considered notable was determined by prevail- ing medical philosophy, tempered by the experience of the individual physician. In general, physical examinations that involving touching the patient were extremely limited, except for some attention to the quality of the pulse. Under these circumstances, the physician could diagnose and prescribe by letter without even seeing the patient. Indeed, the fee for advising the patient by letter was often higher than that for an ofﬁce visit.
During the nineteenth century, even the average physician was being encouraged to follow the path marked out by the great clinicians and morbid anatomists of the previous century towards a more active role in obtaining objective information concerning signs and symptoms of illness by direct physical examination. In 1761, the year in which Giovanni Battista Morgagni (1682–1771) published his monumental ﬁve-volume examination of The Seats and Causes of Diseases, Leopold Auenbrugger (1722–1809) of Vienna published another landmark in the history of medicine entitled Inventum Novum. In little more than 20 pages, Auenbrugger set forth an account of a new diagnostic method called ‘‘chest percussion.’’ Using this method, the physician could gain insight into the internal state of the chest cavity by carefully evaluating the sounds produced by tapping or thumping the patient’s chest. Of course a great deal of experience was needed before a doctor learned to distinguish between the sounds of a healthy chest and those which betrayed the earliest signs of tuberculosis or pneumonia produced by a ‘‘morbid chest.’’
Auenbrugger, who was considered a gifted amateur musician and composer, presumably had a better-trained ear than most physicians. Chest percussion, which depends on the differences in sound trans- mitted through air and ﬂuid, is rather like tapping a wine cask or beer barrel to determine whether it is empty or partially full. Because his father was a tavern keeper, Auenbrugger was probably quite familiar with this phenomenon. Although Auenbrugger considered his method revolutionary, some physicians saw little difference between percussion and other methods of diagnosis by auscultation (listening) dating back to the time of Hippocrates, such as shaking the patient and listening for the sound of ﬂuid sloshing about in the chest, or placing the physician’s ear on the patient’s chest. Indeed, Auenbrugger’s teacher had employed percussion of the abdomen in cases of ascites (ﬂuid accumulation in the peritoneal cavity).
Few physicians expressed any interest in Auenbrugger’s work until
Jean-Nicolas Corvisart (1755–1821) published a translation and com- mentary in 1808. By this time, thanks to the work of the so-called Paris school of morbid anatomy, humoralism had been essentially eclipsed by the concept of localized pathological anatomy. Corvisart’s disciples, especially Rene´ The´ophile Hyacinthe Lae¨nnec (1781–1826), established the value of direct (immediate) and indirect (mediate) auscultation and transformed the art and science of physical examination. Working at the Necker Hospital and the Charite´, Lae¨nnec adopted the goals and methods of the Paris school of hospital medicine. Eventually, his inven- tion of the stethoscope would make him one of the most famous exem- plars of this school, and a symbol of French science, but during his rather brief lifetime, his peers generally treated him with indifference and hostility.
Proponents of early nineteenth-century ‘‘hospital medicine’’ tended to see themselves as disciples of Hippocrates, because of their emphasis on clinical observation, but the context in which they worked, as well as their methods were very different from those of the ancients. Leaders of the French Revolution had imagined a new era in which hospitals, medical schools, and doctors would disappear. Instead, in the aftermath of the Revolution, new hospitals, medical schools, and professional standards emerged. In the major hospitals of Paris, clinicians could see thousands of cases and carry out many hundreds of autopsies. American students ﬂocked to the great hospitals of France to sup- plement their limited education and gain clinical experience. Becoming disciples of French masters, they translated their writings into English. A note of envy for the extensive opportunities for the observation of dis- ease found only in Europe often crept into their introductory remarks. Somewhat later in the century, schools and hospitals in Germany and Great Britain overtook those of France as centers of clinical studies and laboratory research.
The large scale of nineteenth-century hospital medicine provided the ‘‘clinical material’’ for more active and intrusive methods of physical examination and diagnosis, statistical evaluation of various therapeutic interventions (sometimes known as the numerical method of Pierre Charles Alexandre Louis, 1787–1872), and conﬁrmation of correlations among symptoms, lesions, and remedies by means of investigations con- ducted in the autopsy room. Although immediate auscultation and chest percussion were becoming valuable aids to diagnosis and research into what Corvisart called ‘‘internal medicine,’’ many physicians were reluctant to practice these methods. Given the great abundance of ﬂeas and lice on many patients, and the general neglect of personal hygiene, a certain reluctance to put one’s ear on the patient’s chest was under- standable. The stethoscope not only provided some distance between physicians and patients, it improved the quality of the sounds that could be heard within the chest. The name stethoscope was coined from the Greek for ‘‘chest’’ (stethos) and ‘‘to view’’ (skopein). It was the ﬁrst of many ‘‘scopes’’ that gave researchers access to the interior of the body and allowed them to ‘‘anatomize’’ the living before they dissected the deceased.
In On Mediate Auscultation (1819), Lae¨nnec described the difﬁcul- ties he encountered when examining a young woman with signs of heart disease. Discreet percussion with a gloved hand did not reveal anything about the state of the inside of her chest, because of the rather stout state of the outside of her chest. Considerations of propriety precluded immediate auscultation, but in a ﬂash of inspiration, Lae¨nnec took a sheaf of paper and rolled it into a cylinder. When he applied one end of the cylinder to her chest and the other to his ear, he could hear the heartbeat with remarkably clarity. Improvements in the basic cylinder
Stethoscopes for sale in 1869.
of Lae¨nnec made it possible to listen to many sounds and movements within the chest. Through changes in materials and conﬁguration, and the introduction of stethoscopes that transmitted sound to both ears, doctors tried to improve the stethoscope. The instrument has remained fairly consistent in appearance since the 1920s. The classical stethoscope has been relegated to the status of a ‘‘triage tool’’ to detect obviously suspicious sounds that lead to more sophisticated and expensive tests, such as the echocardiogram.
Lae¨nnec warned physicians not to neglect Auenbrugger’s methods
when using the stethoscope, because the physician should use as many aids to diagnosis as possible. More important, it was essential to realize
that a great deal of practice was required before the instrument could be used effectively. To learn the technique, the young physician should work in a hospital where he had access to many kinds of patients and expert guidance. Moreover, large numbers of postmortems were needed to conﬁrm diagnostic accuracy. Like many of his colleagues, Lae¨nnec succumbed to tuberculosis, the disease that was so often the object of his research. France, which had contributed so much to the study of tuberculosis, had the highest mortality rate from consumption in west- ern Europe well into the twentieth century, perhaps largely due to lin- gering beliefs that heredity was more signiﬁcant than contagion and general indifference to public health measures.
Sir John Forbes (1787–1861), who translated excepts of Lae¨nnec’s nine hundred-page treatise on auscultation and diseases of the chest into English in 1821, noted that the stethoscope was extremely valuable, but he doubted that mediate auscultation would ever come into general use among English doctors, because its use required too much time and trouble. His most serious objection was that the instrument was totally foreign in character and incompatible with British traditions. Its use could be imposed on patients in the army and navy, and in hospitals, but not on private patients. Like many of his colleagues, Forbes saw something ludicrous about a digniﬁed physician listening to the patient’s chest through a long tube. In other words, instruments were associated with surgeons and manual labor, not with the philosophical habits of English physicians. Many physicians believed that the advan- tages of objective aids to diagnosis were small and uncertain compared to the threat that instruments might disrupt the bond that was sup- posed to exist between physician and patient.
Obviously, Dr. Forbes proved to be a very poor prophet. The stethoscope soon became the very symbol of medicine and a necessary part of the doctor’s wardrobe. Few doctors were able to match Lae¨nnec’s extraordinary skill at auscultation, but many learned that it was possible to use the instrument to gain objective information about the nature of a patient’s condition and to distinguish between different diseases, such as tuberculosis and pleurisy. The stethoscope made it possible for physi- cians to ‘‘anatomize’’ the living body, but it was only in the autopsy room that the diagnosis could be conﬁrmed. Even the most selﬂess patient was unlikely to sympathize with a physician who referred to the postmortem as the best ways to diagnose disease, because a few autopsies shed more light on pathology than 20 years spent observing symptoms.
It is interesting that the thermometer was not accepted into diag-
nostics as quickly as the stethoscope, although Santorio Santorio had introduced the clinical thermometer in the seventeenth century. The concept of localized pathology is generally given credit for the accept- ance of physical aids to diagnosis, as well as advances in surgery, but
the thermometer, which reﬂected a general condition of bodily heat, did not ﬁt the pattern of a pathology of solids.
The stethoscope was, of course, only the ﬁrst of the many ‘‘scopes’’
that allowed physicians to view every nook and cranny of the interior of the body. It is obviously a long way from Lae¨nnec’s cylinder to comput- erized axial tomography (CAT scans), nuclear magnetic resonance imaging (MRI), and positron emission tomography (PET scans), but it is a brief interval compared to the many centuries that separated Hippocrates from Lae¨nnec. From the patient’s point of view, advances in diagnostics that were not associated with progress in therapeutics were of dubious value. Although increasingly sophisticated and expen- sive new instruments have contributed to the power and prestige of medicine, and may have saved many patients from the burden of uncer- tainty, they do not necessarily improve the treatment of disease or the healing of wounds.
One of the persistent complaints issued against the great hospitals of Paris and Vienna was that their physicians were too interested in diagnosis and pathology, but too little interested in therapy. A nineteenth-century cynic assessing the battle between practitioners who favored active interventions and researchers who relied on a passive or expectative approach could conclude that Viennese hospital doctors no longer killed their patients, they just let them die. In the Parisian hos- pitals, a variety of approaches to therapy competed for attention. Some physicians favored bleeding, others relied on antimony or other chemi- cal remedies, while some remained loyal to complex ancient remedies derived from plants, animals, and minerals. Even the standard deﬁnition of therapeutics as the art of curing diseases was called into question by those who claimed that the term referred to the most convenient means of treating disease. Oliver Wendell Holmes suggested that patients might be better off if the entire materia medica, except for quinine and opium, was thrown into the sea. Most doctors, however, agreed that it was better to try something doubtful than do nothing. Moreover, advances in chemistry were providing new drugs—such as morphine, emetine, strychnine, codeine, and iodine—that were unquestionably powerful, even if their safety and efﬁcacy remained in doubt.
An accurate diagnosis at an early stage of a disease like tubercu- losis, which was made possible by tuberculin and chest X-rays, could be interpreted as simply increasing the length of time in which the patient brooded on the inevitability of death. Nevertheless, the develop- ment of sophisticated diagnostic instruments has become fundamental to the health-care enterprise and is often blamed for the escalating costs of medical care. Although the stethoscope and similar devices intro- duced the fundamental concept of studying the interior structures and functions of the living body, the trend to ever more sophisticated and expensive diagnostic techniques can be traced to Wilhelm Konrad
Roentgen’s (1845–1923) discovery of X-rays in 1895. Roentgen was investigating the properties of cathode rays when he observed a new kind of ray that was able to pass through opaque objects, including clothing, hair, and ﬂesh. Bones, however, stopped the rays, leaving a picture of their shadow on a photographic plate. Roentgen’s prelimi- nary report to the Physico-Medical Society of Wurzburg, ‘‘On a New Kind of Ray,’’ included several radiographs, including the well-known picture of Frau Roentgen’s skeletal hand. When the popular press published stories about X-rays, Roentgen’s ﬁndings caused worldwide speculation about their potential role in medicine. In 1901, Roentgen, already a universal celebrity, was awarded the ﬁrst Nobel Prize in Physics.
X-rays gave physicians a new diagnostic tool, as well as a means of
investigating the interior of the body. Just as the microscope and tele- scope made it possible to look at the microcosm and macrocosm in new ways, by making the ﬂesh that clothed the bones essentially trans- parent X-rays created a new way of looking at the human body. After the initial period of enthusiastic and uncritical use, researchers realized that prolonged exposure to X-rays might cause tissue damage and cancer, in addition to the burns that were more quickly noted.
By the late 1960s, new medical instruments made it possible to
visualize interior aspects of the body that had been impossible to see with ordinary X-rays. The methods called the ‘‘second wave of imaging tech- nology’’ included computerized tomography, MRI, ultrasound, mam- mography, and PET. Sir Godfrey Hounsﬁeld (1919–2004), a British electrical engineer, and Allan Macleod Cormack (1924–1998), a South African physicist, shared the 1979 Nobel Prize in Physiology or Medicine for their independent contributions to the development of computer- assisted tomography. (The brightness of images that appear on the CAT scanner is measured in Hounsﬁeld units.) Neither man had a background in medicine or a doctoral degree, but, according to the Nobel Prize Committee, their revolutionary work ‘‘ushered medicine into the space age.’’
Computed axial tomography allows computers to analyze and pro-
duce a series of cross-sectional images from X-rays that are taken from many different angles. Although the original scanner was designed to examine the head, the instrument was adapted to study every organ sys- tem in the body. Despite the enormous cost of the device, about seven thousand CAT scanners were in use in American hospitals by 2000. Magnetic resonance imaging (originally called nuclear magnetic reso- nance or NMR) can create thin-section images of any part of the body from any angle, generating biomedical and anatomical information. MRI has been particularly valuable for diagnosing diseases of the brain and central nervous system. Physicists and chemists used NMR
technology in the 1940s, but it became a diagnostic tool, referred to as
MRI, in the 1980s.
In less than two hundred years, diagnostic and therapeutic technol- ogies have become central and enormously expensive components of medicine. Technological success has created an avalanche of expec- tations and questions about the actual risks and beneﬁts associated with this transformation of medical practice. Faith in the diagnostic power of medical instruments led to decreased interest in the procedure that the pioneers in this ﬁeld thought so fundamental: conﬁrmation at the postmortem.
Autopsies were once routinely performed in a majority of hospital deaths, but since the 1980s, the number of such procedures in the United States and several other countries has dropped sharply. Before 1970, the Joint Commission on Accreditation of Healthcare Organizations man- dated autopsies in at least 20 percent of all hospital deaths, but by 1995, the National Center for Health Statistics stopped collecting national autopsy statistics. In most wrongful-death cases against hospitals or physicians, an autopsy is critical to establishing negligence. Doctors and hospital administrators, afraid of being sued over mistaken diag- noses, increasingly avoid autopsies. Attempts to quantify the incidence of medical errors suggest that autopsies uncover missed or incorrect diagnoses in up to 25 percent of hospital deaths. In many cases, the cor- rect diagnoses might have led to changes in therapy or other procedures. Autopsies revealed that many systemic bacterial, viral, and fungal infections had not been diagnosed prior to death. Whatever the cause of death in a particular case, such infections might have been a threat to those who had been in contact with the patient. Similar studies of patients who died in intensive-care units found many instances of incor- rect diagnoses, as well as evidence of infections, cancers, and other undiagnosed diseases. Researchers suggested that over-reliance on soph- isticated diagnostic imaging techniques sometimes contributed directly to major diagnostic errors.