MedEd Pittsburgh Profile picture
Oct 16, 2020 18 tweets 8 min read Read on X
1/ It’s time for #PhysioQuizzo! You’re excited. We’re excited. It’s fun!

You’re on inpatient cardiology and your patient gets a right heart cath (RHC):

RA 29
PA 52/33 (mean 40)
PCWP 34
CO/CI
-Thermo: 2.9/1.2
-Fick: 5.3/2.0
SvO2 43

Q1: Does this pt have heart failure (HF)?
2/ #PhysioQuizzo

Question 2 (all answers at the end!): Does the patient have pulmonary hypertension?
3/ #PhysioQuizzo

Question 3: Does the patient have pulmonary arterial hypertension (PAH, or Group 1 PH)?
4/ #PhysioQuizzo

Question 4: Is the patient in low output heart failure?
5/ #PhysioQuizzo – Normal RHC Values

Phew! That was a lot. There’s so much learning ahead!

1st things 1st: What even are normal RHC values? Generally speaking:

Right Atrium (RA) – mean ≤6 mmHg
Pulmonary Artery (PA) – mean >20 mmHg
Wedge Pressure (PCWP) - ≤12 mmHg
7/ #PhysioQuizzo – Nickel-Quarter-Dime-Dollar

I usually teach a mnemonic to help people remember this. The mnemonic isn’t perfect, but it anchors your brain in the right ballpark, at least.

See the picture below. Image
7/ #PhysioQuizzo – What is Heart Failure?

One way to conceptualize HF is to say that ventricular failure occurs when the preceding atrial pressure rises above normal.

>So, Left HF occurs when PCWP rises >12
>Right HF occurs when RA rises >6

Caveats in the next post
8/ #PhysioQuizzo – Pressure caveats

There are many caveats (e.g. regurgitant valves), but two basic points:

*Not all pts will have sx when PCWP>12 or RA>6.
*Those aren’t necessarily goals for diuresis either (“optimal” filling pressures change as ventricular function changes)
9/ #PhysioQuizzo – Answer #1

So does our patient have heart failure?

Yes --> Right and Left heart failure, b/c his RA>6 and PCWP>12

This is reminds me of the adage, “The most common cause of right heart failure is left heart failure.”
10/ #PhysioQuizzo – Answer #2

And does our patient have pulmonary hypertension?
Yes --> his PA mean pressure is >20

**I learned >25 in school, but the guidelines now reflect studies measuring mPAP (mean PA pressure) in healthy people acc.org/latest-in-card…
11/ #PhysioQuizzo – Ohm’s Law

Before we talk about PAH, let’s talk about vascular resistance?

Anyone remember Ohm’s law?
⚡️ V=IR Voltage difference = Current x Resistance

We were taught this vis-a-vis electricity, but this is true of fluid dynamics too! Image
12/ #PhysioQuizzo – Pulmonary Vascular Resistance

Within the pulmonary vascular bed:
I ▶️ Q = flow = cardiac output
V ▶️ delta-P ▶️ pressure difference across the bed ▶️ mPAP – PCWP
R ▶️ pulmonary vascular resistance = PVR

V=IR --> mPAP-PCWP=CO*PVR

Or: PVR = (mPAP-PCWP)/CO Image
13/ #PhysioQuizzo – High PVR?

A normal PVR is 3 Wood units - the units you get when you divide mmHg/(L/min).

What raises PVR? Lots of things
-Arteriole wall thickening
-HIV, schistosomiasis infections
-Pulm artery narrow from PE’s
-Hypoxic vasoconstriction
-And lots more!
14/ #PhysioQuizzo – Our patient’s PVR

Our patient’s PVR: CO = 2.9, mPAP = 40, PCWP = 34

PVR = (40-34)/2.9 = 6/2.9 = 2 ▶️ normal

Normal PVR with a high PCWP implies left HF is causing PH!
15/ #PhysioQuizzo – Answer #3

So does out patient have PAH? No, his PVR is normal. His PH is from left heart failure.

If his PVR were high, then we would answer “not enough info” because we’d have to rule out other causes first.
17/ #PhysioQuizzo – Answer #4 (finally!)

And does our patient have low output heart failure?

Yes ▶️ A normal cardiac index is >2.2.
🌡️His CI is 1.2 by thermodilution and 2.0 by Fick. Either one is low ⏩ He has low output HF.
18/ #PhysioQuizzo – Fick vs. Thermo

Not so fast, you say! What’s the deal with Fick vs. Thermo? They are very different results!

>It's outside the current tweetorial scope
>Know that each method uses different variables and can go wrong in different ways... Image
19/ #PhysioQuizzo – Final Answers

Summary:
A1: Yes, R+L HF
A2: Yes, PH
A3: No PAH, has left heart failure
A4: Yes, has low output HF

We hope you learned something. Thanks for viewing!

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with MedEd Pittsburgh

MedEd Pittsburgh Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @MedEdPGH

Jul 15, 2020
1/ Clinical Reasoning Series – Cognitive Bias

Ever felt the thrill of making crucial diagnosis? The pain of missing a diagnosis? Yeah, us too

Clinical reasoning is hard, so let’s talk about it. Our 1st post in a new series starts today. Let’s talk about Biases.

#MedTwitter
2/ Basic Definitions:

>Heuristic: a cognitive shortcut based on prior experience & pattern recognition

>Cognitive Bias: when a heuristic leads to misdiagnosis or inappropriate treatment

We need heuristics b/c reasoning every decision from 1st principles would take forever!
3/ Heuristic vs Bias

There is a fine line b/t a heuristic and a bias

For example: 80yoM w/ CAD p/w SOB, ankle edema, and alveolar filling on CXR. You start abx PNA
👍If he improves, PNA was a good call
👎If he gets worse because he has ♥️ failure, PNA was “premature closure”
Read 10 tweets
Nov 8, 2019
It's time for #TwitterReport! This time, we're making a #tweetorial on how to use tweetorials for case-based teaching.

Follow along to our Mid-Atlantic @SocietyGIM workshop in Ballroom B from 12:45-1:45 pm at the @PittTweet University Club on 11/15/19.

Let's get started!
@SocietyGIM @PittTweet 1/ What even is a #tweetorial?

A Tweetorial is a short thread of tweets which provides educator-driven content centered around a chosen topic.

Tweetorials leverage the multimedia capabilities of Twitter to dissect a topic using supporting articles, videos, diagrams, and polls.
Read 14 tweets
Jun 19, 2019
It's time for #TwitterReport! Get out your illness scripts and problem representations.

Case: A 65yoM with metastatic melanoma goes to the ER with RLE edema: doppler shows a femoral DVT. He also says he's been getting more tired over the last 4wk.

What else do you want to know?
PMH: HTN, HL, T2DM (now diet controlled), metastatic melanoma
PSH: none
Meds: HCTZ, metoprolol, atorvastatin, pembrolizumab/ipilimumab (last cycle 2 weeks ago)
Social: lives with wife and dog at home. From a local rural area. Never smoker/alcohol. Former construction worker.
ER Triage Vitals:
-Temp 37*C
-HR 60
-BP 90/54
-RR 12
-SpO2 98% on room air

What else do you want to know?
Read 17 tweets
May 15, 2019
It’s time for #PhysioQuizzo! And today, we got a really trippy puzzle for you. [thread]

1/x You’re still working in the ICU (1 week to go!), and you take care of a pt who overdosed. He was revived in the ER. Urine was obtained before naloxone was given.

Quiz on post 3/x.
2/x His UDS is shown below. His outpatient med list is also shown.

You’ll note his UDS is positive for everything...
3/x

Here’s the Quiz:
—Which of the following is the least he could have plausibly taken given his UDS? (Assume he’s taken all his home meds that day)

A. Each and every drug on the UDS
B. Home meds, ethanol
C. Home meds, EtOH, oxycodone, valium
D. Home meds, cocaine, oxy, heroin
Read 7 tweets
May 1, 2019
Get your thinking caps out! It’s time for #PhysioQuizzo!

You’re still working in the ICU. You get 2 patients back to back, comatose. Little history. Vented.

Patient 1: 22yo female. Found down at home. We don’t know her PMH or meds.
How many acid base disorders does she have? Use the poll below

What do you think she has? Say your opinion in the comments!
Patient #2: 25yo male. Past medical history not known.
Read 11 tweets
Apr 24, 2019
It’s #TwitterReport time!

We give you a case. You ask us questions. Everybody learns.

A 77yoF presents after passing out. This is the 3rd time it has happened. Most recently, she stood up, got dark vision, and woke up on the floor.

What else do you want to know?

#MedEd
1/ #TwitterReport

HPI:
-3 times in 1 month she’s gotten up from sitting and passed out. Darkened vision each time.
-First one witnessed by sister. She woke up w/in 1m. No confusion.
-Fatigue for the past 3-6mo
-No fevers or chills but she’s had a 10 lbs weight loss this year
Read 11 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Don't want to be a Premium member but still want to support us?

Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us!

:(