The Epi-logical approach
Knowledge structures in the form of clinical mind maps, which are architecturally aligned with a cognitive strategy, are intended to help facilitate transformation of declarative to procedural transformation.
The cognitive strategy that is being used with these clinical mind maps is called the Epi-logical approach. This approach has the following 4 steps:
Building probable diagnoses
Addressing urgent or emergent situations
Removing anchor bias
Below is an illustration of the Epi-logical approach
The Epi-logical approach is transferable across various patient presentations, but the clinical mind maps are specific to the problem at hand. In addition to providing readers with a cognitive strategy, the Epi-logical approach, this book offers knowledge structures in the form of clinical mind maps to be used with the approach. Each clinical mind map is built around one patient problem or a chief complaint and the components include
Differential diagnoses or probable diagnoses
Key symptoms or risk factors associated with each differential diagnosis
Physical exam findings pertinent to each differential diagnosis
Labs/diagnostic tests/imaging relevant to each diagnosis
Key symptoms, risk factors, physical exam findings and lab/diagnostic tests/ imaging relevant to each diagnosis are collectively called illness scripts, and these scripts can be recalled when matching diagnoses with patient presentations.
Steps of the Epi-logical Approach
Step 1 involves “building probable diagnoses.” Probable diagnoses are evoked from memory/declarative knowledge of a list of differentials that cause a symptom or problem with which the patient presents. This involves recall, and if this recall is elaborate, the list of probable diagnoses will be more conducive for use within the framework of this 4-step cognitive strategy, called the Epi-logical approach.
Step 2 is “checking for urgent/emergent situations.” This step involves looking at a patient’s overall appearance (evoking system 1 mode), specifically looking for symptoms or signs which may lead to acute death or disability. Examples include the presence of stridor in a patient whose initial complaint was shortness of breath, or a fist sign on the chest accompanied by sweating in a middle or old age male whose initial complaint was chest pain or looking at a hemoglobin of 4 gm/ dl in a patient who was seen recently for fatigue. Thankfully, only a few patient presentations are urgent/emergent situations. Examples include an altered mental status, trauma to vital organs, features of shock, and gangrene of a body part. In these cases, the patient needs to be stabilized, and intervention needs to occur, regardless of how well a cognitive strategy is being used for diagnostic reasoning.
Step 3 is “weighing.” Weighing involves some degree of conscious or subconscious knowledge of frequency of symptoms and/or signs associated with the differentials under consideration. Generally, the more experienced a clinician is, the more efficient this process should be. Weighing is analytic reasoning (system 2 mode). After asking the patient about differentiating features for each diagnosis that is being considered, a student can decide that one diagnosis is more likely than the other diagnoses. Although no human expert places an exact numerical value on relevant disease features, the human mind goes through a rapid, computational process ascribing weights to these features, and arrives at a conclusion that a certain diagnosis is more likely or less likely than the other diagnoses. The more experienced the clinician, the more subconscious this computational process may be. Since most textbooks do not or cannot describe frequency estimates of disease features with certainty, how experienced doctors ascribe weights to these features remains an enigmatic phenomenon. There are reasons to believe that past experiences which lead to automatic frequency encoding, cognitive architecture, and the context of the situation at hand largely make this determination. That being said, the frequencies of occurrence of several symptoms and signs associated with several diseases have been entered in the book "Clinical Mind Maps - Using the Epi-logical Approach" in the form of “frequency estimates” tables. These estimates have been extracted from an extensive literature search of observational studies. However, not all studies represent generalizable population/demographics. Therefore, these frequency estimates must be used in conjunction with the context, individual patient circumstances, and the gestalt feeling of the clinician involved in the patient evaluation. In other words, a holistic approach, as opposed to an inflexible and scripted approach, must be used.
The Epi-logical approach suggests that weighing be incorporated as a mindful,
analytic, and conscious step in the process of diagnostic reasoning. This weighing is especially important for novices such as students in their pre-clinical years, students in clinical rotations, and clinicians in training in their early years of practice, or even late years of practice when patient presentation is not clear, because they have not gone through sufficient number of experiences to develop reliable frequency encoding. Although very useful, weighing comes with some caveats. 1) The clinician involved in the weighing process may be relying on past experiences that built a disproportionately higher than actual frequency estimates of certain features in their mind. 2) Similarly, a clinician might not have seen certain features in a disease and/or might not recall these features from declarative knowledge, and therefore may not ascribe any weight to these features when considering relevant diagnoses. 3) The context or situation may prompt a clinician to place a higher weight on certain features than merited, thus leading to an incorrect conclusion. 4) A patient may perceive certain features to be more bothersome than others, and highlight these accordingly, thus causing yet another challenge in the process of diagnostic reasoning. Weighing involves first asking high yield questions to able to narrow the differentials or probable diagnoses list, and then asking medium yield questions which are focused follow-up questions that are specific to the individual diagnoses.
Examples of questions for the process of weighing include 1) Duration of the chest pain. If the chest pain is acute, a certain set of differentials ought to be considered far more than if the chest pain is chronic. 2) The location of a headache. In this case, both the duration and the location related questions are considered high yield questions. If a headache is unilateral, a certain set of diagnoses is more likely than others. Following high yield questions, a clinician can start asking medium yield or focused follow up questions. Choosing high and medium yield questions to ask for various types of patient presentations, such that a clinician can group differential diagnoses appropriately, requires a well aligned knowledge structure such as a clinical mind map.
Step 4 is “removing anchor bias.” Essentially all cognitive biases are an anchor bias or a pre-mature closure bias. Any cognitive bias, if it leads to an unsuccessful diagnosis, means that by definition, the diagnostic process had ended at that time, thus making it a pre-mature closure or an anchor at an incorrect diagnosis. Caveats in the weighing process, as described above, are highly likely to lead to cognitive biases. Removing an anchor bias by looking for symptoms/signs for diseases that have not been thoroughly considered is intended to remedy this situation. According to the Epi-logical approach, only one or a few symptoms/ signs need to be checked for unexplored differentials. Therefore, a clinician may
consider looking for the most frequently present symptom/sign, or the second most frequent symptom/sign if the initial patient presentation happens to be the first most frequently present symptom/sign. This process improves efficiency and involves the notion of automatic frequency encoding for experienced clinicians and declarative knowledge of some form of estimates of features present in diseases for novices.
The physical exam is listed here after history-related questions for simplicity reasons. In real-life encounters, most clinicians can and do perform a physical exam simultaneously, and there may be situations when a certain physical exam sign may be the patient’s initial presentation. To keep things simple, the task of taking a history is listed prior to and separate from performing a physical exam. Lab/diagnostic tests are also listed after taking a history and doing a physical exam for simplicity purposes, but tests can occur simultaneously or beforehand in real-life scenarios.
The definition of diagnostic success includes efficiency. In urgent/emergent situations when the patient is unstable, a clinician may prefer to actively follow a system 1 mode (pattern recognition, rules of thumb, gut feeling, and heuristics) instead of following a more analytical system 2 mode -based weighing process. The most important task is to recognize an urgent/emergent situation. A well- built knowledge structure in the form of a clinical mind map can facilitate that recognition.
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