Thread by @Acute_Pulmo_Med

The promised #Tweetorial on validation of #COVIDー19 phenotypes that we published @AnnalsATS

But before we start.

Disclosures:
- I'm a splitter and 💕 phenotypes
- If physiology can teach us; I'm all for it!
- But, data and physiology should converge

https://twitter.com/ColinRCooke/status/1260274955125698563?s=20

What we know:
- #ARDS can be split into #phenotypes
- But, uncertain therapeutic implications

https://twitter.com/Acute_Pulmo_Med/status/1254779302639398912?s=20

- #COVID-19 might be split into phenotypes as well
- But, ☝️based on #physiology with little data to back it up.

Remember:
- H phenotype = ⬆️elastance (=⬇️compliance) + ⬆️ lung weight + ⬆️shunt + ⬆️recruitability. What we consider ARDS.
- L phenotype is opposite - not resembling most ARDS cases.. Would not benefit ⬆️PEEP, ⬆️TV?

Lung morphology is explained here:

https://twitter.com/Acute_Pulmo_Med/status/1254779350450270211?s=20

Methods:
38 pt with proven #COVID-19 needing IMV.
6mL/kg
Around 10cmH2O PEEP
Crs measured
CT scan was performed in all - aeration was measured by classifying <-500 HU as poorly/non-aerated tissue, as by the famous Gattinoni paper @NEJM in 2006

nejm.org/doi/full/10.10…

Main result:
- Most pt 50% or more poorly/non-aerated lung tissue.
- Mean Crs ~40
- No relation CT and Crs
- 2 Pt show L-phenotype
- >50% discordant phenotypes
- Most patient show non-focal morphology
- Non-focal morphology more extensive consolidations

We concluded that compliance and an estimation of lung weight do not correlate in patients with COVID-19 related ARDS. Most patients could not be classified as either “H” or “L” subphenotype, but showed mixed features.

That does NOT mean that #COVID19 is not a particular etiological subphenotype of #ARDS that may respond to specific interventions.
- Antivirals
- Anticoagulation
- Specific immunomodulation

And this is NO discouragement of better phenotyping these patients.

We need data-driven approaches to evaluate the existence of treatable traits to improve patient-tailored care. Until these data become available, an evidence-based approach extrapolating data from ARDS not related to COVID19 is the most reasonable approach for ICU care.

In future studies we will assess:
- Lung perfusion defects
- Lung recruitability
- Alveolar and systemic inflammation, coagulation and epi/endothelial injury

To better understand the pathophysiology and heterogeneity that we encounter.

Fin