Rev Thomas Bayes (1701- 1761)
Likelihood Assessments
Within the realm of Emergency Medicine, patients present with problems that can be:
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subjective (e.g. chest pain)
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objective (e.g. fever)
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potential (e.g. suspected poisoning, potential post-traumatic fracture or hemorrhage)
One of the main competences of emergency physicians is to determine whether patients are suffering from time-sensitive conditions whereby mortality and morbidity are reduced through early measures. Ruling-out time-sensitive conditions with 100% certainty is not achievable. Rather, emergency physicians estimate the likelihoods of time-sensitive conditions based on bedside information (from the history, physical examination, bedside blood tests, EKG, point-of-care ultrasound, urinalysis) and decide thereafter whether further investigations are warranted.
The EMCC teaches a Bayesian approach to likelihood assessment based on:
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estimating the pre-test probability of conditions based on the patient’s risk factors
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estimating the post-test probability by understanding how bedside information affects the pre-test probability
Decision-Making
After acquiring bedside information, the emergency physician needs to decide whether
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further investigations are warranted
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further treatments (beyond those that might already have been provided) are warranted
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the patient needs to be admitted to undergo investigations and receive treatments
These decisions are based on
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the likelihoods that the patient is suffering from time-sensitive conditions
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patient-related factors: prognosis with vs without investigations/treatments, patient wishes and values
The EMCC teaches the concepts of test-threshold and treat-threshold related to the individual patient.
Diagnostic Errors
Diagnostic errors stem from three sources:
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lack of information
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lack of knowledge
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not considering the actual diagnosis
The EMCC provides checklists and clinical decision tools to mitigate the risk of diagnostic errors. These checklists provide
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key bedside information that should be acquired from patients with a given problem (e.g. chest pain, hyperkalemia)
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key time-sensitive diagnoses to consciously consider
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clinical decision tools, or lacking these, key clinical findings relating to these time-sensitive diagnoses
Likelihood Assessment and Decision-Making Scenarios
Course participants take turns acquiring bedside information from patients presenting with a variety of problems, estimating the likelihoods of time-sensitive conditions, and discussing the risk-benefits of various investigation-treatment strategies.
The Likelihood Assessment & Decision-Making stations focus on assessing the likelihood of dangerous conditions through a focused history, physical examination, and the use of bedside tests such as the EKG, bedside blood tests (blood gases, electrolytes, lactate, glucose) and ultrasound. The stations also focus on further management (i.e. further investigations, treatments, out-patient follow-up vs admission) from a risk-benefit perspective.