Respiratory fRiday: Platypnea, platypus, orthodeoxia, orthodontics?

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Platypnea-orthodeoxia:
* What's that you say? 
- dyspnea and deoxygenation when moving to SITTING UPRIGHT from supine
= wait, that's not normal!
= improved with lying FLAT
- due to INTRAPULMONARY shunting when moving UPRIGHT
​
- suspect with:
= hepatopulmonary syndrome
- possible mechanism of vasodilation and thus increased perfusion of capillaries at lung BASES (which are least oxygenated)
- liver cirrhosis- see this in ~40% of cirrhotic patients
- portal HTN
- hepatitis
- look for finger clubbing!
- pulmonary congestion at bases
​
= AV shunting
= ASD or PFO w/ shunting
= ARDS = rare causes
- Pericardial effusion/restrictive pericarditis
- Significant PE load
- Ileus
* Why do I care? 
- Treatment in the ER: 
- Increased mortality in cirrhotic patients especially with PO2 <60mmHg
- LIVER TRANSPLANT: definitive (but lower post-transplant survival)
- TIPS: decrease shunting, improved gas exchange (theoretical)
- Nitric Oxide Synthesis inhibition or TNF inhibition: no evidence yet
 
- MDM:
- not all respiratory distresses = CHF, pneumonia or PE
- consider extra-pulmonary contribution to SOB
- not all treatments will work all the time
- keep an eye out for variation and be suspicious something else is going on
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Toxic Thursday: EKG changes in overdoses!

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To follow-up on the digoxin toxicity POD from aggggggges ago, here's a sampling of some pathognomonic EKG changes in the setting of drug toxicity (this is NOT all-encompassing-- there's a lot more out there!) 1) Older woman with HTN comes in w/ dizziness. 2) Young disheveled guy, somnolent. 3) Old guy on blood thinner w/ HTN, new renal failure and weakness. ​

4) Old Asian man with cardiac and renal problems comes in vomiting (1st EKG from PMD's office, 2nd from MMC)

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5) Old lady with vomiting syncopizes (First EKG progresses to second

​ ------------

Answers:

1) Long PR interval = AV nodal delay

= 1st degree Heart Block (may progress to complete heart block)

- Beta-blockade

- Calcium-channel blockade

- Digoxin

- Opioids, clonidine

​

2) Interventricular slowed conduction w/ long QRS, right axis deviation w/ R/S ration >0.7 in aVR

= Na-channel blockade

- TCA toxicity

- Anticholinergics

- Na-channel blockers like the "ides'

- Propanolol

- Anesthetics like bupivicaine

- Carbamazepine

 

3) Atrial tachycardia w/ AV block and PVCs (can also have PACs)

- digoxin! (classical finding)

​

 

4) Ventricular dysrhythmia w/ beat-to-beat alteration of QRS orientation

= Bidirectional Ventricular Tachycardia  (may also have multiple ectopic beats mixed in)

- digoxin! (pathognomonic finding)***

- also a few herb toxidromes (aconite)

​ 5) Long QT = prolongation of repolarization = risk of Torsades

- Non-toxicological risks: female, >60yo, genetics, structural heart dz/LV dysfunction

- Sympathicomimetics and:

​- Use the QT normogram (based on absolute QT) to predict risk of Torsades! (drugs that cause bradycardia are MORE likely to cause Torsades)

*** Just to summarize, the most common EKG presentations of digoxin toxicity are:

1) PACs/PVCs

2) Atrial tachycardia w/ AV block (classic)

3) Bidirectional VT (answer on tests)

 

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Wellness Wednesday: Where'd the sun go?

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If you have a hankering for something lightly medical, this is your day! You have two options:
1) Check this out. Got to love new media.
2) Or, since this is my last Wednesday POD and something very special is happening next week, here's a Wacky Wellness Wednesday pearl for you all! (small medical connection at the end! links embedded throughout!)
 
THE GREAT AMERICAN ECLIPSE:
* The Thing Itself: 

- Why's this one so special? 
= it really isn't. There have been millions. But this one is the first TOTAL solar eclipse to run over the entire US since 1918. We like our astrologyonomy in 'Murika.
- Why do we care?
= They're beautiful
= Soooooo many scientific discoveries: 
* 2000ya: calculated the distance from the Earth to the Moon
* 17th century: What, solar flares are THOUSANDS of miles tall?!
* 18th century: a glass prism splits light into a rainbow because different elementsreact differently!
* 19th century: the sun's made of HOT HYDROGEN GAS (not sodium) and we discovered a new element (HELIUM!)
* 20th century: the weather is related to the sun ie. the winds changed direction during an eclipse!
* 20th century: light bending around the sun confirms the theory of general relativity (whaaaaaat?!)
* What's to come next??
* BTWs history: 
- This is a busy month for astrological phenomena as well as our exploration of the universe
= 40th anniversary of the Voyager 1 & 2 launches that gave us such wonders as:
* the first man-made object to LEAVE THE SOLAR SYSTEM
* an OCEAN below ice on Europa
* volcanoes x100 the power of earth's erupting on Io
* lightning on Jupiter!
* the discovery of 24 (twenty-four!!) new moons in the solar system
* the rings of Jupiter, Uranus, Neptune

 

* Eclipse in medicine:

- Eye damage: "magnifying glass on a leaf"
= takes ~1.5mins for permanent damage to be done even if not continuous unprotected observation
= cameras and regular glasses won't protect you
= can try the pinhole technique
- Changes in hormones?
- Changes in animals?
- (and if you want more: https://www.nytimes.com/guides/science/how-to-watch-a-solar-eclipse)
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