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In the 19th century, scientists tried to capture the world with numbers. Anthropologists measured human bodies and physicians recorded bodily functions. Physiologists penetrated the inside of the body and pathologists examined disease processes after death. Systematic measurements identified and explained phenomena such as fever or blood pressure for the first time. In the late 19th century, these scientific measurements found their way into medical practice. This means that subjective assessments lost their importance. Doctors and patients were now guided by measurable and comparable numbers and measurement curves. They are still part of the standard of medical research and practice today.

Thermometers and curves

Physicians have long been interested in body temperature and physiologists occasionally measure it for research purposes. Systematic measurements, however, did not become established in the new hospitals until the 19th century. This is how doctors translate a subjectively perceived condition into a number. At first, it remained open as to what exactly the measured values meant. The breakthrough as a standard diagnostic method was helped by the representation in curves. They made it possible to identify typical fever courses of individual diseases. Shortly before 1900, taking a temperature reached private households and advice literature, thereby becoming commonplace.

From research instrument to everyday object

The first thermometers were long and unwieldy and were mainly used in research. In the 19th century, a 15-centimetre-long thermometer was introduced that worked by expanding a column of mercury. Form and function remained almost unchanged for a long time. In the 20th century, electrical, then digital and finally infrared thermometers appeared. They measured accurately and, especially with the latter, within a few seconds. However, the portable pocket thermometer based on toxic mercury persisted and was used until the 1990s.

Blood pressure in numbers

In the middle of the 19th century, blood pressure became the focus of medical attention: Physiologists developed measuring instruments and begin to record it quantitatively. This laboratory work was representative of a new quantitative understanding of disease and health. However, doctors were reluctant to use the new method. They could do little with the values and feared the loss of their ability to judge a medical situation. When handy instruments and the concept of dangerous high blood pressure became established from 1900 onwards, blood pressure measurement became a self-evident medical diagnostic method: The generated value using instruments allowed the doctor to make a diagnosis independently of the patient's subjective descriptions. Objectifying methods such as blood pressure measurement thus also led to a fundamental change in the doctor-patient relationship.

Arterial movements

Since ancient times, doctors have recorded and interpreted the pulse. But it was not until the 19th century that physiologists used instruments that quantified and displayed the pulse. A first step was the development of the so-called sphygmograph from 1850: The instrument permanently recorded pulse rates. The expanding and contracting artery moves a small plate whose movement is transferred to a strip of paper.

From pulse to blood pressure

In the second half of the 19th century, doctors developed various blood pressure measuring devices. The sphygmomanometer of the Italian doctor Scipione Riva-Rocci was considered a breakthrough. A new feature was an arm cuff. It would be filled with air and its pressure measured by a mercury manometer. When the pressure releases, the mercury falls. The value at which the pulse returns is called the upper blood pressure. The basic principle of the easy-to-use instrument, which at the same time delivers fast and precise results, has endured to this day.

Long-term- and self-measurement

In the 20th century, blood pressure measuring devices and methods were further refined. In 1968, a fully automatic unit was launched on the market for the first time. It enabled 24-hour long-term measurements and thus the differentiation between nocturnal and diurnal blood pressure changes. In the course of the 1970s, easy-to-use electronic self-measuring devices became established. They determined the vibrations of the pulsating blood and calculated the blood pressure from this. Patients were able to use it to take measurements themselves at home and classify the results using the established limit values.

Measuring patients in Bern

In Bern, too, quantitative methods were already standard around 1900. Hermann Sahli, director of the medical university clinic of the Inselspital from 1888, dealt with pulse and blood pressure measurement, among other things. With his main work "Lehrbuch der klinischen Untersuchungsmethoden" (Textbook of Clinical Examination Methods), published in 1894, he aimed to advance precise diagnostics. To this end, he was also developing different, easy-to-use instruments so that not only clinicians but also GPs could use them. Sahli understood the human organism as a unit and was, therefore, an opponent of the increasing specialisation of medicine.

A handy blood pressure monitor

Sahli was an opponent of cuff blood pressure measurement. He preferred to measure with a mercury manometer and a pressure pad, which he revised. Sahli's pocket sphygmomanometer – subject to further development – was intended for outpatient treatment, for example, in the general practitioner's office. It was uncomplicated to use and the patient did not have to undress. It was also handy, it found space in every coat pocket and could thus be easily transported.

Comparative measurement

Modern chemistry and biochemistry opened up the broad field of blood analysis to medicine. Haemoglobin could be used to diagnose anaemia, which was otherwise detected by external symptoms such as a pale skin colour. Sahli wanted a simple and reliable measuring device – and improved the previous so-called haemometers. The device allowed the general practitioner to keep up with medical progress and still work independently. Sahli's model became a bestseller; it was used for decades and often imitated.

Body measurements

In the 19th century, measuring the human condition did not stop at the human body. Medics and anthropologists measured skull and body sizes and compare hair, skin and eye colours. Anthropometry, the science of measuring the human body, played a significant role in this. Anthropometric instruments and methods were used to search for comparable values: Through the systematic surveys of schoolchildren and recruits or on research trips. Anthropologists established typologies and determined what was considered "normal" or abnormal", what was healthy or sick, European and non-European. Such classifications supported the notion of supposed "racial types" and culminated in the devastating racial ideology of National Socialism.

Body size and cranial circumference

Anthropologists used various instruments to measure the body. They used simple measuring rods to record body sizes, for example. The so-called anthropometer consisted of four parts that could be plugged together and could be used in many ways: to determine shoulder width, arm and leg length or chest circumference. The craniometer was used to measure the circumference of the skull. With the collected measurements, anthropologists tried to create typologies and assign them to a gender or ethnicity.

Hair colours and shapes

In the early 20th century, racial anthropologists also recorded the external appearance of humans. For the precise determination of eye and hair colours, they resorted to colour charts. In 1914, for example, the Swiss-German anthropologist Rudolf Martin introduced an eye colour chart, which was constantly developed further and was intended to help determine "human races". The hair colour chart of the German eugenicist Eugen Fischer, who is considered a pioneer of Nazi racial ideology, also worked by matching a series of colour shades.

How much is too much?

In order to be able to classify and compare measured values, limit values are necessary. Like the categories "healthy" and "sick", these are not natural constants. Research is constantly gaining new insights that lead to new assessments of health risks. Accordingly, medicine defines at what level blood pressure, cholesterol levels, bone density or body weight are no longer considered normal but pathological. But this is not just a purely scientific decision. Medical associations, patient organisations, health insurance companies, pharmaceutical companies and social changes also influence which values ultimately prevail.

More patients

In the late 1950s, the first drugs to lower blood pressure were developed. The pharmaceutical industry was lobbying for the lowest possible treatment thresholds to be set. In 1983, the World Health Organisation (WHO) set the limit for blood pressure at 140/90. The American Heart Association corrected it downwards to 130/80 in 2017. This means that millions of people were now considered to have high blood pressure – and were treated accordingly with medication.

Body Mass Index

The body mass index is a measure for evaluating body weight in relation to height (weight per height squared). It has been used since the 1980s. However, it is controversial in terms of which level one should be considered overweight. In 1998, the US health authorities lowered the previous limit of 27.8 for men and 27.3 for women to 25 for both sexes. Many people who were previously considered normal weight were now defined as overweight. The World Health Organisation (WHO) also adopted this value, although it was not clear whether people with a BMI of 25 to 30 have an increased health risk.

Limits of measurement

Not everyone welcomed the advent of quantitative methods. Some rejected them and sought alternatives. Thus, in the last third of the 19th century, naturopathy and alternative medical procedures experienced an upswing. These were based on a different understanding of disease: The human being is seen as a holistic system with the capacity for self-healing. Objectifying technical knowledge, numbers and measurements were only of marginal importance. However, there were also alternative concepts such as the "biorhythm", which rely on measurements. Moreover, even orthodox medicine today is aware that health and illness cannot be fully described with numbers.

Small globules, holistic principle

Homeopathy focuses on the individual human being in its entirety. It does not consider a disease in isolation, but caused by several factors. The diagnosis is not made by measuring methods, but mainly by talking to the patient. The therapy aims at reinforcing symptoms with similarly acting agents so that the organism can heal itself. However, many homeopaths no longer see their practice as a contradiction but as a complement to conventional medicine. In this sense of a complementary procedure, homeopathy has also been researched and applied at the Inselspital in Bern since 1994.

Achieving a balance instead of numbers

Up until the 19th century, medicine was dominated by the so-called theory of the humours, which was not based on a quantitative but on a qualitative system. It is not a question of absolute quantities, but of too much or too little cold, heat, humidity or dryness. The aim of herbal therapy, bloodletting or cupping was to achieve a balance in the nature and circulation of the bodily fluids. Modern biomedicine radically broke with this concept. Nevertheless, the old ideas and forms of therapy continued to find favour for a long time and in some cases even today.

Rhythm of Life

In the 1970s, the electronics company Casio launched the "Biolator". In actually it was a pocket calculator, but it could also be used to calculate the "biorhythm" and display it graphically in curves. First formulated around 1900 and popularised in the 1970s, the idea of "biorhythms" is based on the assumption that every human being, since birth, has three underlying internal clocks that influence mental, physical and emotional states. The "Biolator" used quantitative methods and thus contributed to the hype behind the idea – which is, otherwise, not based on scientific principles – in the following years.

Quality of life

The number of available hospital beds or average life expectancy have long been used todetermine medical progress. Since the 1970s, the concept of quality of life emerged, which was also recorded with figures. The EQ-5D questionnaire, which was also used by the Inselspital, for example, examined the state of health in five dimensions and determined a quality-of-life index between 0 and 100. The quality-of-life measurement instrument was widely used, but not without controversy. This is because there were complex questions about what exactly is meant by 'good' quality of life and whether such measurements allowed conclusions to be drawn about the health status of individuals and the status of medicine.


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