What is the biomedical model #2

A couple of weeks ago, I posted the first of a series of short critical summaries of the biomedical model.

The biomedical model is perhaps one of the most important theories underpinning physiotherapy, and yet it is rarely taught overtly in the physiotherapy curriculum. Clinicians don’t see it hiding behind their assessments and diagnoses. They don’t see it underpinning most of the treatments. And they don’t recognise it as a key driver of the kind of knowledge we accept to be true and false. So having a better understanding of how the biomedical model works would seem like a good idea.

In the first post of the series, I briefly wrote about specific aetiology and the idea that one of the most important tasks in medical practice is to find the specific cause – or aetiology – for the patients presenting signs and symptoms. In this post I want to focus on germ theory.

Today it is hard to imagine that a profession as established and powerful as medicine might have been built around a concept of health and illness that had nothing to do with germs. But this is of course true. For centuries, doctors believed in the idea of humors and miasmas. Humors derived from Ancient Greek and Roman physicians who envisaged a kind of chemical flow of fluids through the body related to the fundamental elements of water, air, earth and fire. Popularised by the Roman physician Galen, humors persisted as a guiding influence in medicine until the 19th century.

Miasmas, or foul air, were a source of much anxiety and inspiration in Victorian times

Similarly, the idea of miasmas - or foul air - was equally ancient and it too survived until the late 19th century. People thought that the presence of foul smelling air indicated disease, and so miasmas became a driving force behind a lot of social innovation, particularly in the 19th century. Modern nursing, for instance, owes its formation to miasmas because Florence Nightingale believing that foul air was the cause of so much disease and illness in the Crimean War. Her answer was to open the doors and windows to let the wind blow the foul smelling air away; to burn stinking dressings; and to practice scrupulous cleanliness. Little did she realise that what she was doing was ridding the environment of its pathogens. (Some have said that Nightingale died in 1910 still believing in miasmas, more than two decades after the discovery of germs). Miasma theory also influenced the placing of new hospitals on hill tops and out of towns to prevent the diseased air of the patients blowing over the town.

But the developments of modern scientific practice 19th century led to growing arguments for the existence of germs – or some form of small organism that might invade the body of a person or animal and cause disease. The history of the discovery of germs is well known, but perhaps what is less well understood is how it influenced the status of doctors. With the discovery of germs, doctors began to invest more time in public health and insisted on the creation of large centres of practice and learning, breaking with a centuries long tradition of the doctor visiting the patient at home. Now, with the discovery of germs, doctors took on an unprecedented degree of professional autonomy and power.

With the discovery of germs, the search was on to isolate the specific pathogens causing some of the diseases that had decimated civilisation in previous centuries. Smallpox, cholera, tuberculosis, typhoid, polio, herpes and hepatitis were all targeted, and with the discovery of antibiotics, medical power in the early part of the 20th century became almost absolute.

It is perhaps not surprising then that professions like nursing, physiotherapy, occupational therapy, podiatry, and midwifery tried to associate themselves closely to the medical profession. But in doing so, it became necessary to not only accept medical understandings of disease causality, but also the hierarchies that had been created by the medical profession. Thus, physiotherapists willingly accepted a patho-centric understanding of disease causality and ensured that students learnt that illness, suffering, impairment, and disability had their roots in pathology. Only in the last decade or so have physiotherapists followed many of the other professions allied to medicine to explore some of the other reasons why people experience health and illness the way they do, much of which lies in people’s lived experience and social relations rather than in the presence of a pathogen.

In recent years interest in pathogens has resurfaced in areas like the micro-biome, where our host bacterial colony is seen as necessary and important for our health and not just something to be managed and eliminated. And while few physiotherapists work directly to eliminate pathogens, it has still played a significant role in defining how physiotherapy has been structured and defined in the past.

Next: Cartesian dualism.