Teddy Hla Profile picture
Oct 25 10 tweets 7 min read
Day 2. Starting on pitfalls in leveraging EHR by Stephanie HYLAND @ESICM #criticalcare #ehr #datascience #ai #LIVES2022
This problem is mainly for ML engineers who may not have talked to domain expert or clinicians / end users.
Pitfall 1 : sampling bias
"whos included in the analysis"
"who in your EHR"?
- e.g., - COVID prediction dataset where missing all blood tests were removed, but this missingess has a meaning. Thus not generalisable.
e.g., yesterday I mentioned about females < 6% of sample popn
Other pitfall: Inability to "time-travel"
e.g., using length of stay outcomes for example.
Pitfall 4: Hazards of measurement frequency
- icu data collected continuously. this is not random!!
- sicker patients got CVP and more frequent ABG
-measurement frequency is informative!
This means if you build a model based on frequency of lactate modelling, are you telling the clinicians anything 'new' - they know its sick hence doing frequent ABG.
Pitfall 5: overinterpretation of findings
-causal inference from observational data is DOABLE
- but WITH CARE!
e.g., if predicted risk according to predictive model increases with blood pressure, it does NOT necessarily imply that reducing blood pressure reduces risk.

(this is what we discussed yesterday about mechanistic effects)
@_hylandSL
@ESICM #criticalcare #ai #ML
@_hylandSL @ESICM Pitfall 6: implementation challenges
-just because you used EHR to build a model doesnt mean it can be implemented on EHR.
- where does the model live?
- how are you going to host?
- what data model ingest and how?
- need informatics team and infrastructure restricted ennviron.
@_hylandSL @ESICM Summary:
1. sample selection bias
2. imprecision in variable definitions
3. reliance on data not yet collected
4. informative measurement and missingness
5. overinterpreation of findings
6. implementation and EHR integration.
and many more :P
@_hylandSL @ESICM What can you do?
- be careful
- ask many questions
- follow STROPE/ TRIPOD guidelines
-have right team - interdisciplinary, statisticians, ML experts, epidemiologists, people familiar with EHR databae
-DONT DO EVERYTHING YOURSELF !
what an insightful talk @_hylandSL @ESICM #ai

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More from @teddyhla

Oct 25
Carolyn Calfee Clinical and Biological phenotypes of ARDS
- what do they have in common?

ARDS : subgrouping since the begining
- sepsis vs. non sepsis
- hyper vs. hypoinflamm
- reactive vs uninflamed
#ventilation #ards #phenotypes #LIVES2022
Are clinical phenotypes biologically distinct?
looking at Trauma vs. Non trauma

ICAM-1 , SP-D, vWF, sTNFr-1 are different.
What about in "Direct" vs. "indirect"
or "Diffuse" vs "focal" -- sRAGE comes up again.

pubmed.ncbi.nlm.nih.gov/17944012/
#ventilation #ARDS #LIVES2022
Image
Read 13 tweets
Oct 25
Mariangela PELLEGRINI
Uppsala- Sweden
"Do we Need a biological definition of ARDS"

- Berlin definition has NO Diffuse alveolar damage .
- the Berlin defn does not capture well
Frohlich - different definitions specificity of 0.63, 0.42, 0.31 even!
#ventilation #ards #LIVES2022
academic.oup.com/bja/article/11…
The BJA article by Frohlich.
Fibrosis only starts after 7 days
Thille article : atsjournals.org/doi/full/10.11…
In essence, different disease processes are happening to the lung at different times in the "ARDS"
pubmed.ncbi.nlm.nih.gov/24429204/
Read 14 tweets
Oct 25
ARDS - new definition or phenotypes by @GicoBellani refreshing with Kigali definition of ARDS - useful not just low resource but during pandemic in supposedly high income settings and only draw back is no PEEp requirement #ards #ventilation #LIVES2022 @ESICM
@GicoBellani @ESICM Resolved versus confirmed ARDS
- prospectively applying Berlin definition did work but if ya wait 24 hrs and re-measure P/F ratio, you end up stratifying much better.
- Better separation of groups

pubmed.ncbi.nlm.nih.gov/29632996/
#ventilation #LIVES2022
@GicoBellani @ESICM Whichever definition - american european consensus or Berlin or Kigali -- all goes back to Ashbaugh original paper in 1967

thelancet.com/journals/lance…

Why are we so confused when it comes to ARDS definition ?

#ards #ventilation #LIVES2022 @ESICM
Read 11 tweets
Oct 25
Next : Mypinder SEKHON on cardiac arrest in COVID-19 era.

Works in Vancouver
COVID 19 era cardiac arrest ARE a lot less sexy with all the PPE. #als #covid19 #resuscitation #LIVES2022
@ESICM
@ESICM Let's look at epidemiology. Northern Italy, Manhattan - COVID hit hard and has impact on other diseases.

e.g., OHCA in Italy during COVID 19 massive spike.
ImageImageImage
Read 9 tweets
Oct 25
NEXT Speaker : VA ecmo for which patients?
Alain COMBES

Severe cardiogenic shock has different phenotypes
1. medical cardiogenic shock(AMI, end stage dilated CM, myocarditis, septic shock)
2. Post cardiotomy refractory CS (post CABG)
#LIVES2022
@ESICM #ecmo #resuscitation #ALS
@ESICM 2022 what do the guidelines say
- ESC recommends short term MCS should be considred in cardiogenic shock.
IABP may be considered but not routinely recommended in post MI
#LIVES2022
Image
Read 18 tweets
Oct 25
what about in refractory cardiac arrest?
ERC - ESICM guidelines 2021
- timing of CAG if no evidence ofr ST segment evaluation.

which means we will end up treating a lot of patients with stent and anticoagulation
TOMAHAWK trial : delayed or early invasive angiography -- no effec.

#LIVES2022
- immediate catheterisation for non ST elevationrr
Read 4 tweets

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