1.1 THE BONES OF THE BOOK
Clinical reasoning is an enigma that has been the subject of research over the last few decades. It pertains to how physicians not only arrive at a diagnosis, but then use their clinical judgement to decide the next best course of action. This could be ordering another test, initiating treatment or the most curious course of just observing and not acting at all.
Current thinking revolves around the dual processing theory, which is an amalgamation of all the research thus far. It incorporates analytic and nonâanalytic strategies of clinical reasoning, which interact at different phases of the patient encounter and are called into play when needed. Nonâanalytic strategies (unconscious/reflexive) include pattern recognition, heuristics, illness scripts, and semantic qualifiers. Analytic strategies (conscious) include causal reasoning and probabilistic reasoning, where logic and critical thinking are given importance. Metaâcognition, an awareness of one's own thinking, overarches the analytic and nonâanalytic processes of cognition directing the clinician to the diagnosis.
An example in action:
An 82 year old lady presents with acute confusion. The doctor, using pattern recognition and heuristics (mental shortcuts) thinks this is likely to be a urinary tract infection (UTI), because he has seen this all too often. He notes the lady was on warfarin, so wonders if he is missing something (metaâcognition). He telephones her carers querying any recent falls with head injuries (analytic strategies). It turns out she had a head injury a week ago, following which she became increasingly confused and drowsy. This leads him to a working diagnosis of subdural haematoma, which gets confirmed on a CT scan.
If he had not been consciously aware of his own thinking (metaâcognition) he would have settled on the diagnosis of a UTI and ascribed a raised white cell count and lowâgrade temperature as confirmatory â thereby missing a significant diagnosis that carried a greater burden on the patient concerned.
You could argue that an experienced clinician would have got this diagnosis right first time. However, there are several contextual factors at play, which can easily mitigate inâdepth analysis. Patient factors, such as an acutely confused person unable to give a clear story; environmental factors such as a busy A&E department and physician factors such as fatigue and sleep deprivation can all impact the decisionâmaking process, leading to an unpleasant outcome for all concerned. Remember that experience does not equate with expertise.
Norman (2005) has suggested that clinical reasoning can only be imbibed by âdeliberate practiceâ wherein the learner encounters a plethora of examples, rather than just learning the strategies of clinical reasoning. In other words, practice, practice, and more practice will develop you into a skilful clinician. You can read this book to master the strategies of clinical reasoning, but unless you put them into practice, it will continue to remain an enigma.
This book has been divided into sections relating to the clinical placements you may find yourselves in. This allows you to work with the book whilst on your placements, transferring knowledge into practice. The topics include those often felt to be poorly covered, and are a treasure trove of common conditions that you will encounter.
The book does not claim to be an exhaustive resource on clinical medicine, but rather a route map, showing the intricacies of clinical reasoning. I shall start with a personal perspective of some rulesâofâthumb for diagnostic reasoning, followed by rulesâofâthumb for decision making to guide investigations and treatments. This will be followed by a unique way of approaching patients that should make your life a lot easier.
If there is one thing I would like you to take from this book, it is to always be open to diagnostic possibilities, ensuring that the thinking process never stops.
Rules of Thumb for Diagnostic Reasoning â A Personal Perspective:
- Commit to a diagnosis
âCollapse query(?) causeâ is a common colloquial term in UK practice amongst junior doctors and is touted as the diagnosis for someone presenting with collapse. This is not a diagnosis. All you are doing is elaborating the fact you do not know the cause of their collapse. The first step in learning to diagnose is to commit to a diagnosis. We all make mistakes along the way, but not committing to a diagnosis is cognitively far more dangerous than making one and learning from it â as long as it does not put a patient at risk. If in doubt, ask a senior clinician for help in making those mental connections, but make sure you at least have a working diagnosis. Occasionally, a diagnosis maybe elusive, in which case a plan of action still needs to be formulated whilst acknowledging uncertainty and ensuring followâup. Often, diagnoses emerge in the fullness of time, hence adequate followâup is essential. - Link to the past medical history
When trying to make a diagnosis, remember that any presentation in medicine is usually linked to the past medical history or medication list. When that train of thought does not yield a diagnosis, a new diagnosis should be entertained. If someone is known to have ischemic heart disease, they are likely to be breathless because of that than due to say, âChurgâStrauss syndrome.â - Common things are common
Use disease prevalence as a yardstick to know what is common. Epidemiologically speaking, a middleâaged male smoker in the developed world is likely to have vascular risk factors such as hypertension, hypercholesterolemia, and diabetes mellitus, predisposing him to ischemic heart disease and strokes. - Explain the symptoms
Patients seek help because they are having symptoms not because they have an abnormal electrocardiogram, test result, or radiograph. Hence always try to explain the symptom/âs, and you'll hit the diagnosis. - Explain all the findings
Can you explain all the findings (history, clinical examination, and investigations) with the diagnosis you have made (Kassirer and Kopelman 1991)? If there are any unexplained findings, reâvisit the diagnosis. - Think of all the alternatives
Always pause just be...