clinical reasoning skills
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Clinical Reasoning Skills. STEPP Course ST1;2011 Peter Macfarlane. intellectual process; leading to a ‘working diagnosis’ & management- discussion some puzzles. sound medical principle;.. ‘diagnosis precedes treatment’.. ...right diagnosis...right treatment - PowerPoint PPT PresentationTRANSCRIPT
Clinical Reasoning Skills
STEPP CourseST1;2011
Peter Macfarlane
• intellectual process; leading to a ‘working diagnosis’ & management- discussion
• some puzzles
• sound medical principle;.. ‘diagnosis precedes treatment’..
• ...right diagnosis...right treatment• ...no diagnosis/wrong diagnosis;..!• APLS/emergency approach vs • classical history/examination/formulation/?
Ix/progress
• Hx /Ex ...the medical student approach, exhaustive data..but no idea what it means!)
• then; hypothesis/analytical/deductive approach
• mental shortcuts (heuristics)• then iterative diagnosis approach...’I know
what’s going on here; ...series of closed questions to check this....
• pattern recognition; ‘ducks’quick: like recognizing a friendslower: patterns/clusters
• Stepwise ‘rule outs’; used to exclude ‘don’t miss’ diagnoses
• probabilistic reasoning; ‘zebras’
‘informal’; e.g. -age -duration illness -’red flags’
• ‘formal’ probabilistic reasoningthe Bayesian approach
• Sensitivity• Specificity• Positive predictive value• Negative predictive value• know the 2X2 table
• SpP IN :
• SnN OUT :
• SpP IN : test(or Sx/Sg) with high Specificity performance, Positive result is a good ‘rule IN’
• SnN OUT : test (or Sx/Sg) with high Sensitivity performance, Negative result is a good ‘rule OUT’
• #
• investigations...beware of pitfalls.-’paralysis by analysis’- treat the child not the numbers-always question whether you know
what the test result means (values,pos,neg), before you start.
-’sometimes the best thing to do for the patient (child) is to spare them the misery of a useless intervention’
• keep it simple; Occam’s Razor (1 diagnosis), but learn how to juggle complex multiple problems..
• Test of treatment• Test of time, beware pressure to act....• ‘don’t just do something, stand there!’• if no diagnosis- keep an open mind, think aloud and
get advice (foster ethos of 2nd opinion)• abandon the ‘diagnosis’ when things don’t go to plan• When the diagnosis is ‘obvious’ ; avoid premature
closure; always ask ‘what else could this be?’ ..........think beyond the obvious; avoid the cognitive trap
• recognize your own biases• #
Test of Treatment
• ‘first do no harm’, Test of Treatment rarely leads to robust diagnosis; nearly always better to use ‘test of time’ (except in critical illness).
• lots of confounders....
‘treatment’ trial
apparent effect
TP FP
uncertain no apparent effect or worse
TN FN?
trial of treatment confounders
• False positives• placebo• spontaneous
improvement/remission• natural fluctuation in
disease process
• False negatives• side effects• wrong
drug/dose/duration• natural fluctuation in
disease process• drug resistant disease
variant
ways to improve test of treatment
• establish the baseline• agree the end point• objective measurement if possible; if not reduce
‘subjectivity’• keep everything else the same• careful thought about drug selection, dose route,
duration• Use the ‘3 step protocol’; multiple trials of n=1• #
• Questions?