PART II: Connective Tissue & Immune System

In Part I, I briefly discussed (1) potential link b/w hypermobility #EDS and post-viral syndromes like #MECFS & #LongCOVID and (2) acupuncture studies showing anatomical importance of connective tissue (CT)

https://twitter.com/AndrewCAhn2/status/1563164366924439553

1/ Here, in Part II, I will try to bring these seemingly disparate topics together.

These acupuncture-inspired CT studies (by @NCCIH_Director) were one of the earliest studies showing how mechanical forces in CT can modify inflammation.

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PART I: Connective Tissue & Immune System

#LongCOVID is shedding light on long-ignored, physiological aspects of Post-Viral syndromes (e.g. #MECFS)

One fascinating area is the role of connective tissue (and Ehler Danlos Syndrome #EDS) in their pathophysiologies.

1/ Anyone following conversations in the #LongCOVID community might be surprised by the oversized prominence that #EDS plays.

Take @meghanor piece in @TheAtlantic where #EDS community is described working w/ #MECFS #ChronicLyme communities on LongCOVID...

theatlantic.com/magazine/archi…

During med residency in late 1990s, I noticed that patients w/ hypermobile joints ("double jointed") frequently had episodes of unexplained tachycardia, headache/lightheadedness. I suspected Marfan's but never found the classic signs for it (i.e., tall stature, high arched palate, or "thumb sign" [see images below from nature.com/articles/52018… ]).

Plus, for whatever reason, many of these patients were women.

Have you ever wondered how simethicone (e.g. "Gas-X") works?

To my surprise, there is a substantial physico-chemisty mechanism at play.

Simethicone is a mixture of (1) polydimethylsiloxane (PDMS) and (2) silical particles frequently used for flatulence or "gassy" abdomen. PDMS is physiologically inactive, non-toxic when ingested orally.

Its low surface viscosity + hydrophobicity enable it to spread easily over surfaces of gas bubbles. Then its very low surface tension causes the bubble surface to thin and burst -> easier expulsion of gas

Part 6: COVID and Overdispersion

In Part 5, we talked about epidemiological implications of overdispersion.

In this section, we explore potential CAUSES of COVID-19 overdispersion

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https://twitter.com/AndrewCAhn2/status/1344792823204360192

1: VIRAL LOAD
Based on nice system rev by Chen et al, doi.org/10.1101/2020.1…, variability in Resp Viral Load for SARS-CoV-2 >> Influenza A.

Mean VL is actually lower for SARS-CoV-2 than Influenza, but d/t greater variability, in SOME cases VL much higher (below arrow).

DROPLET PHYSICS: 

As the 3rd COVID-19 wave hits our country, I wonder whether we will see a big rise in fatality rates in the fall/winter weather.  

Although number of reasons exist for this, relative humidity (RH) mediates a number of potential mechanisms.

1/ The night before last here in Boston, the temp dropped to 28 deg F (-2.2 C).  The outside RH was ~ 40%.  

Meanwhile, the indoor temp is ~ 70 deg F (21 C), this translates to an indoor RH of 10%

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If you haven't seen @EM_RESUS recent thread on a scary asthma case, pls read it and see how such a situation should be handled.

https://twitter.com/EM_RESUS/status/1193554173310226432?s=20

Here, my aim is to delve a bit more into the physiology of BiPAP/CPAP for asthma.

@tony_breu @AdamRodmanMD @rbganatra During severe asthma, the rate of lung emptying is markedly slowed, and thus expiration is interrupted by the initiation of inspiration. This retained volume gets "stacked" over the already accumulated, retained air - leading to Dynamic Hyperinflation (DH) or Auto-PEEP.

My goal for these #Tweetorials is to empower you to apply engineering/physics concepts to clinical care. To do this, we will do "deep-dives", going deeper than typical physiology courses and applying to real clinical cases. In this thread, we go deeper into Laplace's Law.
1/20 Last week, I had a patient with hydronephrosis. Looking at CT scans, have you noticed that the renal pelvis usually dilates out of proportion to the ureter? To me, the ureter is often tough to trace 2/2 smaller diameters. Can Laplace explain this?

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In this inaugural Physics in Medicine #tweetorial we will see how Laplace's Law applies to medicine: From compressive stockings to diverticulosis.

1/18 Pierre Simon Laplace = quite the stud. In mathematics, known for the Laplace transform (diff calc), Laplacian (Vector calc), and Laplace distribution (prob theory).

But easily mixed up with Lagrange and Legendre. Why all the French "L" mathematicians in 1700s? @AdamRodman