Pulse Pressure and Vessel Compliance - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-21-2011
bronchiole's Avatar
USMLE Forums Addict
 
Steps History: Step 1 Only
Posts: 121
Threads: 18
Thanked 66 Times in 37 Posts
Reputation: 76
Question Pulse Pressure and Vessel Compliance

In my understanding, if vessel compliance is increased, diastolic BP should decrease.
but in Kaplan notes, both 2008 and 10 version, they say, in case of pulse pressure, decreased vessel compliance = decreased diastolic BP.

kinda confused here. what am I missing?

plus, if anyone of you have Kaplan 2008 errata....please help me here with that.

thank you.
Reply With Quote Quick reply to this message
The above post was thanked by:
Sam imkeyim (08-12-2016)



  #2  
Old 02-21-2011
USMLE Forums Guru
 
Steps History: 1+CK+CS+3
Posts: 335
Threads: 24
Thanked 295 Times in 152 Posts
Reputation: 305
Default

ok I'll try to break it down for you.

If a vessel is compliant, it means that volume changes cause less changes in pressure. If a vessel is less compliant, volume changes would cause a greater change in pressure. So in a less compliant vessel, during diastole when the volume decreases, the pressure drop is also greater and we get a lower diastolic pressure.

In mathematical terms, compliance= change in volume/change in pressure

If change in volume is constant, compliance is inversely proportional to change in pressure. So if a vessel is less compliant, the change in pressure (or drop in pressure in case of diastole) is larger.
Reply With Quote Quick reply to this message
The above post was thanked by:
bronchiole (02-21-2011), maksemous (11-05-2012), Mondoshawan (02-21-2011), Sam imkeyim (08-12-2016), tarsuc (01-30-2016), wimzie (02-21-2011)
  #3  
Old 02-21-2011
bronchiole's Avatar
USMLE Forums Addict
 
Steps History: Step 1 Only
Posts: 121
Threads: 18
Thanked 66 Times in 37 Posts
Reputation: 76
Default

First of all, thanks for your time.

I don't have any problem understanding that. I mentioned that in my post. I am just confused when they are mentioning pulse pressure ,they are saying the exact opposite of what you/I said and that is in both editions. Hence, my confusion.


but according to your explanation, if I consider pulse pressure,
pressure change (systole has to increase and diastole has to decrease) increased and volume change is constant, only then i can think that decreased vessel compliance comes with decreased diastolic.

Please give a response on it.

btw,u made a good explanation.
Reply With Quote Quick reply to this message
  #4  
Old 02-21-2011
USMLE Forums Guru
 
Steps History: 1+CK+CS+3
Posts: 335
Threads: 24
Thanked 295 Times in 152 Posts
Reputation: 305
Default

OK I am not sure I understood your question but if I did, you got it right.

Pulse pressure= systolic pressure-diastolic pressure

So decreased compliance will lead to high systolic and low diastolic, means large difference and large pulse pressure.
Reply With Quote Quick reply to this message
The above post was thanked by:
maksemous (11-05-2012), Mondoshawan (02-21-2011), steps (02-21-2011)
  #5  
Old 02-21-2011
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 590
Threads: 31
Thanked 1,227 Times in 410 Posts
Reputation: 1251
Default

Quote:
Originally Posted by bronchiole View Post
In my understanding, if vessel compliance is increased, diastolic BP should decrease.
I think this is where you're backwards.

What doctorsmonters wrote is correct: a fixed stroke volume going into a vessel with decreased compliance results in a greater pulse pressure - that is to say, a greater gap between systolic and diastolic pressures. Systolic pressure goes up with decreased compliance and diastolic goes down.

hope that helps?
Reply With Quote Quick reply to this message
The above post was thanked by:
bronchiole (02-22-2011), conspicous (02-21-2011), doctorsmonsters (02-21-2011), tarsuc (01-30-2016)
  #6  
Old 02-22-2011
bronchiole's Avatar
USMLE Forums Addict
 
Steps History: Step 1 Only
Posts: 121
Threads: 18
Thanked 66 Times in 37 Posts
Reputation: 76
Default

Quote:
Originally Posted by Mondoshawan View Post
I think this is where you're backwards.

What doctorsmonters wrote is correct: a fixed stroke volume going into a vessel with decreased compliance results in a greater pulse pressure - that is to say, a greater gap between systolic and diastolic pressures. Systolic pressure goes up with decreased compliance and diastolic goes down.

hope that helps?
yeah,that is exactly what I said in my 2nd post.thanks for your input.
Reply With Quote Quick reply to this message
  #7  
Old 02-22-2011
bronchiole's Avatar
USMLE Forums Addict
 
Steps History: Step 1 Only
Posts: 121
Threads: 18
Thanked 66 Times in 37 Posts
Reputation: 76
Default

Quote:
Originally Posted by doctorsmonsters View Post
OK I am not sure I understood your question but if I did, you got it right.

Pulse pressure= systolic pressure-diastolic pressure

So decreased compliance will lead to high systolic and low diastolic, means large difference and large pulse pressure.
thanks a lot.I am glad that it is now clear to me.thank you sooo much.
Reply With Quote Quick reply to this message
The above post was thanked by:
doctorsmonsters (02-22-2011)
  #8  
Old 02-22-2011
USMLE Forums Guru
 
Steps History: 1+CK+CS+3
Posts: 335
Threads: 24
Thanked 295 Times in 152 Posts
Reputation: 305
Default

I'm glad too!
Reply With Quote Quick reply to this message
The above post was thanked by:
bronchiole (02-22-2011)
  #9  
Old 07-30-2011
USMLE Forums Addict
 
Steps History: Step 1 Only
Posts: 157
Threads: 33
Thanked 10 Times in 9 Posts
Reputation: 20
Help

Thanks for your explanations mentioned above, it really helped. But can someone help me apply those rules into valvular disease !

What is the mechanism behind wide pulse pressure in Aortic Regurgitation and narrow pulse pressure in Aortic stenosis ?

Aren't Both supposed to have wide (high) pulse pressure because in case of Aortic stenosis systolic pressure increases and diastolic pressure decreases, while in case of regurgitation diastolic pressure decreases due to less blood volume.
Reply With Quote Quick reply to this message



Reply

Tags
Cardiovascular-, Physiology-

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pressure Volume Loops Sabio USMLE Step 1 Bits & Pieces 3 08-06-2011 01:57 PM
blood flow in vessel? kemoo USMLE Step 1 Forum 2 01-27-2011 11:37 AM
mechanism for elevated pulse rate khushboo USMLE Step 1 Forum 14 09-16-2010 09:30 AM
Peripheral Circulation and the Pressure between two points? Kabutar111 USMLE Step 1 Forum 2 07-31-2010 03:18 PM
Which vessel is involved! sam01 USMLE Step 1 Forum 4 07-06-2010 10:53 PM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)