Effect of Squatting on Preload??? - 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 01-01-2011
USMLE Forums Scout
 
Steps History: ---
Posts: 15
Threads: 12
Thanked 1 Time in 1 Post
Reputation: 11
Send a message via Skype™ to steps275
Heart

Effect of Squatting on venous return????

At some places it is written that it increases preload while at some places it shows that it decreases preload...
Really confused...
MTB fischer says preload increases:here is link
http://books.google.com/books?id=07P...return&f=false

While this site says it decreases ... http://www.scribd.com/doc/37239626/C...-Heart-Disease

There was a ques in UWORLD about TOF n squatting but it is poorly explained about preload...
Well in TET spell treatment squatting relives symps by;;;
1-Constricting arteries n thus increasing afterload
2- And it can help in tet spell only if it decreases preload ..

Any good explanation plzz... or we have to just skip venous role of squating in tet spell treatment and remember its increasing preload effect while ansering murmur ques..:-((

Here is another link supporting decrease venous return..
http://books.google.com/books?id=s6C...return&f=false
Reply With Quote Quick reply to this message
The above post was thanked by:
pkul85 (07-27-2013)



  #2  
Old 01-01-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 742
Threads: 137
Thanked 2,462 Times in 441 Posts
Reputation: 2565
Smile Physiologic Sequence of Squatting and it's effect on TOF Spell, Afterload, and Preload

Squatting --> Obstruction of Femoral Arteries --> Increased Peripheral vascular resistance --> Increased LV Afterload --> Increased LV Pressure --> Decreased Right ventricular over Left Ventricular pressure gradient --> Decreased shunting of blood from right ventricle to left ventricle (R to L shunt) through the VSD --> Improved flow to the pulmonary artery --> Better alveolar perfusion --> Better oxygenation --> Decreased symptoms of TOF spell.

But also,

Squatting --> Obstruction of Femoral Veins --> Increased pooling of blood in the venous reservoir (high capacity veins) --> Decreased preload --> Decreased Venous Return --> Decreased blood coming back to the right ventricle --> again decreasing the flow across the VSD (RV to LV shunt)

I also suggest you read this
Knee Chest Position in children
Reply With Quote Quick reply to this message
The above post was thanked by:
Ace3 (08-02-2011), adedotun (07-07-2011), Arhtur liu (01-29-2015), armor (08-14-2014), carla (06-20-2013), dr 2A (08-02-2011), dr z (01-24-2011), dr_ram (01-01-2011), drjones (08-26-2016), drkanthiomc (10-31-2013), hedihav_x (01-01-2011), hepevirus (06-11-2014), jeniaz (03-21-2014), mayankkaushal (09-29-2014), mle guy (06-02-2011), ms.med (01-11-2011), pkul85 (07-27-2013), star123 (08-03-2011), Taiwan_Guy (07-24-2011), yarasara77 (08-03-2012)
  #3  
Old 01-01-2011
USMLE Forums Guru
 
Steps History: 1 + CS
Posts: 438
Threads: 111
Thanked 233 Times in 133 Posts
Reputation: 243
Default

Thank you Rasheed for your explanation, I was always confused about that.
Reply With Quote Quick reply to this message
 
  #4  
Old 01-01-2011
USMLE Forums Scout
 
Steps History: ---
Posts: 15
Threads: 12
Thanked 1 Time in 1 Post
Reputation: 11
Send a message via Skype™ to steps275
Default

Ya i know that ..and it shud be the mechanism to get relief from tet spells..but the prob is that for valvular prob n to ans wether murmur inc or dec w squating we need to know that fact properly coz in MTB ficher said opposite..I have also pasted the link to that and there are lot of site saying that squating increase preload...
Reply With Quote Quick reply to this message
  #5  
Old 01-01-2011
USMLE Forums Addict
 
Steps History: 1+CK+CS
Posts: 167
Threads: 8
Thanked 134 Times in 47 Posts
Reputation: 144
Default hey thanks

Quote:
Originally Posted by rasheed View Post
Squatting --> Obstruction of Femoral Arteries ........
hey rasheed thank you very much for such a nice explanation nd now my doubt about squatting in rx of tof is clear........u doing such a nice job man keep it up man thanks once again
Reply With Quote Quick reply to this message
  #6  
Old 01-01-2011
USMLE Forums Addict
 
Steps History: 1+CK+CS
Posts: 167
Threads: 8
Thanked 134 Times in 47 Posts
Reputation: 144
Default

Quote:
Originally Posted by steps275 View Post
Well in TET spell treatment squatting relives symps by;
TET spell mean????full name??????????
Reply With Quote Quick reply to this message
  #7  
Old 01-02-2011
USMLE Forums Scout
 
Steps History: Not yet
Posts: 55
Threads: 2
Thanked 93 Times in 27 Posts
Reputation: 103
Default hemodynamic effects of squatting.

I was searching on the internet last month, coz i had the same doubt.
i accumulated some info, i would like to share it.

Squatting shows its effect on hemodynamics in two phases:

1. Immediate- due to compression on peripheral veins.
2. Sustained- due to two reasons (A and B) explained below.

-First phase lasts for 20-30seconds, in which, there is sudden fall in venous return form lower extremities (decreased pre-load). This is the reason for DECREASED VENOUS RETURN IN FIRST PHASE. This phase helps by trapping highly de-oxygenated blood in legs and feet, therefore the child is relieved of the symptoms as soon as the child assumes this position.

-During next 15seconds, there is increased peripheral vascular resistance (mostly arterioles), in-turn increasing the left ventricular after-load.

-In about a minute's time the second phase sets in. This phase is due to increased left ventricular after-load (REASON A), which increases the left ventricular pressure ''relative'' to the right ventricular pressure. This leads to reduction of right to left shunt (as the pressure in left is higher than in the right ventricle), which in-turn increases pulmonary blood flow and allows better oxygenation of blood.
-It is assumed that due to INCREASED SKELETAL MUSCLE TENSION in squatting position, venous blood is pumped back to the heart. This leads to INCREASED VENOUS RETURN IN SECOND PHASE (REASON B), leading to INCREASED CARDIAC OUTPUT, which relives the child of cyanotic spell.
-please note that the increased cardiac output in second phase is only during the time when the child is in squatting position. Once the child resumes to standing position, the cardiac output and vascular resistance return to the baseline level

Therefore, there is,
Decrease in venous return during EARLY PHASE OF SQUATTING.
Increase in venous return during LATE PHASE.

Any corrections or suggestions are welcome.
Reply With Quote Quick reply to this message
The above post was thanked by:
Ace3 (08-02-2011), Amenah (01-02-2011), armor (08-14-2014), dr 2A (08-02-2011), dr z (01-24-2011), drkanthiomc (10-31-2013), fido256 (11-04-2014), lee-usmle (01-02-2011), mayankkaushal (09-29-2014), mle guy (06-02-2011), pkul85 (07-27-2013), rasheed (01-02-2011), Taiwan_Guy (07-24-2011), yarasara77 (06-14-2015)
  #8  
Old 01-11-2011
USMLE Forums Newbie
 
Steps History: ---
Posts: 5
Threads: 0
Thanked 21 Times in 5 Posts
Reputation: 31
Idea!

Quote:
Originally Posted by steps275 View Post
Effect of Squatting on venous return????

Any good explanation plzz... or we have to just skip venous role of squating in tet spell treatment and remember its increasing preload effect while ansering murmur ques..:-((

[/URL]
dear steps275..

i see that ur confused bcos of not knowing when to answer "squatting increases preload", n when to answer "squatting increases afterload" as the mechanism for a given scenario...so let me try to help u out here..

there r 2 places where questions on Squatting comes up in USMLE (usually in step 2)

1) Squatting is part of a physical exam maneuver in patients with a murmur (or asxtic pts in whom u suspect mitral valve prolapse)...here the usmle wants to determine whether u r able to correlate the effect of various hemodynamic changes on the murmur (or does it elicit a murmur if none existed earlier)....
(Note: in old pts/or pts who cant squat...an equivalent test is to do a knee-chest flexion while supine..causes same hemodynamic change as a squat!!)

2) Children with TOF instinctively/from previous experience know they have to Squat to get immediate relief from tet/hypoxic spell.. n the usmle wants to determine whether u know the mech of how this relief is attained.

Now, what u shud understand is that...

in the first scenario... while we(physicians) ask the pt to squat during the physical exam...we r actually continuously auscultating this patient(while he was standing and immediately on squatting and then on standing again)[remember, how we were taught to "be seated" when asking the pt to squat so that we could continue auscultation uninterruptedly during this activity!!].

What we r trying to achieve from this continuous ausc....is to determine what happens to the existing murmur when the squat squeezed blood through the veins into the heart..ie..what is the effect on the murmur because of the INCREASED PRELOAD brought about by this SUDDEN squat.

however , in the 2nd scenario...as u must have read correctly from many of the posts above...while the child REMAINS Squatted, (ie over time)..this squat actually INCREASES AFTERLOAD...decreases R to L shunts etc..

Now, we never wait for this long (ie till the squat increases the afterload) during a P/E maneuver to determine whether murmur has undergone any change due to the increased afterload...
if we wanted to check the effect of afterload on a murmur [n we do in some cases....eg to differentiate b/w systolic murmur of mitral valve prolapse(inc with inc afterload) n Hypertrophic cardiomyopathy(dec with inc aftrload), b/c BOTH of them have a softer/decreased murmur with increased preload n viceversa]...so, if we wanted to check effect of afterload on a murmur...we wud ask pt to do a Handgrip(ask pt to squeeze ur fingers with both his palms), n NOT a PROLONGED squat (althou theoretically it can also give u the same result)

In short... if u dont want to read all the crap said upto now , n still want to get ur doubt cleared....let me summarize...

"When squatting is done as a P/E maneuver..we r looking for its ability to INCREASE PRELOAD n bring about a change in murmur" (a high yield point...ALL murmurs-AS/AR/MR/MS n their Pulm n Tricusp equivalents have INCREASED INTENSITY of murmur when preload increases, EXCEPT MVP and HCM).

"When children with TOF Squat..they do so b/c they r looking for the ability of the Squat to increase Systemic vascular Resistance (increase afterload)"

"If we wanted to check the effect of increased afterload on a murmur through a P/E maneuver...we wud ask the patient to do a handgrip exercise"

Cheers!!

Last edited by Rich; 01-11-2011 at 02:44 PM. Reason: typing error!!
Reply With Quote Quick reply to this message
The above post was thanked by:
Ace3 (08-02-2011), bassatom (06-28-2011), Desmin (02-04-2017), docoftheworld (06-02-2011), dr z (01-24-2011), jeniaz (04-14-2014), lookingup (05-18-2011), mayankkaushal (09-29-2014), mle guy (06-02-2011), pkul85 (07-27-2013), Taiwan_Guy (07-24-2011), vienna4u (06-03-2011)
  #9  
Old 08-02-2011
USMLE Forums Addict
 
Steps History: 1+CK+CS
Posts: 158
Threads: 33
Thanked 10 Times in 9 Posts
Reputation: 20
Help

Quote:
Originally Posted by rasheed View Post

But also,

Squatting --> Obstruction of Femoral Veins --> Increased pooling of blood in the venous reservoir (high capacity veins) --> Decreased preload --> Decreased Venous Return --> Decreased blood coming back to the right ventricle --> again decreasing the flow across the VSD (RV to LV shunt)

I also suggest you read this
Knee Chest Position in children
So does squatting increase or decrease PRE-load ? Isn't squatting supposed to increase preload ????
Reply With Quote Quick reply to this message
  #10  
Old 08-03-2011
USMLE Forums Addict
 
Steps History: 1+CK+CS
Posts: 158
Threads: 33
Thanked 10 Times in 9 Posts
Reputation: 20
Help

Quote:
Originally Posted by dr_ram View Post

Squatting shows its effect on hemodynamics in two phases:

1. Immediate- due to compression on peripheral veins.
2. Sustained- due to two reasons (A and B) explained below.

-First phase lasts for 20-30seconds, in which, there is sudden fall in venous return form lower extremities (decreased pre-load). This is the reason for DECREASED VENOUS RETURN IN FIRST PHASE. This phase helps by trapping highly de-oxygenated blood in legs and feet, therefore the child is relieved of the symptoms as soon as the child assumes this position.
Can you please further clarify the above mentioned statement (Immediate stage) !
Reply With Quote Quick reply to this message
  #11  
Old 01-03-2017
USMLE Forums Newbie
 
Steps History: Not yet
Posts: 1
Threads: 0
Thanked 0 Times in 0 Posts
Reputation: 10
Default

Dude. Thank you SO MUCH. My brain doesn't hurt any more, and the anger sharks are back in their pen.
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
The effect of MRCP (UK) on US residency? Dr. N Elham IMG Residency Match Forum 12 11-02-2013 02:15 PM
Effect of Starvation Diet sam01 USMLE Step 1 Forum 10 08-15-2011 09:26 PM
Leukopenia Side Effect sam01 USMLE Step 1 Forum 4 06-29-2010 05:38 AM
The Effect of your Specialty Score! RRMadukha IMG Residency Match Forum 5 05-30-2010 06:58 AM
PAO2 effect on PACO2! flex USMLE Step 1 Forum 2 08-15-2009 12:22 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)