‘Medical Principles: Part 1’
CAERS Substack Article #52
Knowing which keys identify which notes on a piano is central to learning to play piano well. Similarly, practising specific drills in a sport is fundamental to playing the sport skilfully. But in both instances, knowledge of the basics alone does not guarantee competent performance; it is the deeper understanding of how the notes relate to one another, or how the drills should be incorporated into the game, that define one’s proficiency. Otherwise, it will be obvious that you don’t really ‘get it’; your play will be mechanical and shallow.
The same is true in medical practice. It is not enough to simply know facts and data, the mechanics; you have to develop a deeper understanding of the human body and know how things relate in order to put the pieces together into a useful format. You can search for medical information on the internet, but without a feel for how it all flows it can be tough to make sense of it.
With that in mind, the next few articles will explore some basic medical principles which will help to connect the dots, so to speak. Think of them as tricks of the trade.
Let’s start off with the terms ‘symptom’ and ‘sign’. A symptom is something subjective that a patient is experiencing, and the best way for us to know that is for the patient to share that with us. When someone cannot communicate with us, like an infant or someone in a coma, we miss out on a lot of vital information. A sign is something objective, like a rash or a tremor. We learn about symptoms by taking a history from a patient; we discover signs by examining a patient. Sometimes we can try to infer what a patient is experiencing by observing them, but misinterpretation is always possible. If we want to gain more information, we do investigations like blood tests or x-rays. To the surprise of many, taking a good history is by far the most important process for figuring out how to help a patient, and tests are usually the least important.
At the risk of stating the obvious, you are more likely to provide a useful treatment for someone if you know what is wrong with them first, something known as a diagnosis. What many lay people don’t realize, however, is how often the actual diagnosis is more difficult to discover than one might think. It requires taking a good history, if we can, then doing a thorough examination. Once we have done that, we then develop what is referred to as a ‘differential diagnosis’, a list of the most likely possible diagnoses. We need to do that for two reasons: 1) there are very few symptoms or signs that are caused by one disease only (we refer to those signs or symptoms as pathognomonic for that disease; 2) we can then decide on what tests, if any, will be necessary to rule in or rule out diagnoses until we have just one option left, the final diagnosis.
As the old expression says, if the only tool you have is a hammer, then everything looks like a nail. It’s easy to fall into that trap not only as a lay person but as a physician as well when dealing with disease. In order not to put on blinders and miss uncommon or even rare diagnoses, we must use our entire toolbox and keep an open mind by developing a good differential diagnosis. That’s why just looking stuff up on the internet can lead you down the garden path if you are not careful, either because you develop tunnel vision, or you don’t have a deeper understanding of how to put the pieces together.
One of the most difficult parts of medical practice is that no patient wants to be given a horrible diagnosis, and no doctor enjoys providing it either. The problem is, such diagnoses exist and the moral duty of a physician is to search for the true diagnosis irrespective of how tragic it may be. It is perfectly understandable that patients want to minimize the severity of their symptoms and use denial and avoidance to allay their fear. But doctors do a disservice to patients if they do the same; as said earlier, the proper treatment will be hard to discover if we don’t first make an accurate diagnosis, even if it is an unpleasant one.
It is important to remember that any tool can cause harm, and the more powerful the tool, the more potential for greater harm. You can accidentally cut yourself with a handsaw; but you can accidentally lop off your hand with a gas-powered chainsaw. The same is true in medicine; as they say, there are no free lunches. Every intervention, be it a test or a treatment, always carries with it some potential for harm, and the more powerful it is, the more potential for a more severe adverse event. For example, in general, tests that provide more information usually come with more risks. A CT scan tells us more than an ordinary x-ray, but it also exposes the patient to much more radiation. A biopsy of your heart entails more potential for harm than a blood test.
The same is true for treatments. A surgical procedure is riskier than applying a topical cream; a powerful medication that controls a serious disease like cancer usually has more serious side effects as well. So, it is always wise to be skeptical of anyone offering an intervention, especially a powerful one, who claims that there are no downsides or risks. There are more than seven billion people on the planet, each unique, and all of them will not respond identically, good and bad, to every intervention. Beware the promise of no-risk miracles.
Do you feel that you could have been better educated about medical principles during the pandemic? If so, would that have aided your understanding of the medical information that was presented to you? In the next articles I will continue to share some principles that might help.
J. Barry Engelhardt MD (retired) MHSC (bioethics)
CAERS Health Intake Facilitator
•