Tuesday, August 20, 2013

Darrow-Yannet Diagrams simplified

What are Darrow Yannet diagrams?
They are graphs that tell you the osmolarity and volume changes of body fluids.

X axis represents volume.
Y axis represents solute concentration.

Total body water = 2/3 ICF (Intracellular fluid) + 1/3 ECF  (Extracellular fluid)

Remember:
All volume disturbances originate in the ECF compartment.
Changes in ICF are in response to changes in ECF.

How to make the graph in your head -
Step 1. Figure out what happens to the osmolarity and volume in the ECF compartment (ECF is the smaller compartment)
Step 2. Think how is ICF affected?

Let's review some examples to make sure we understand the concept!

Loss of whole blood, adult diarrhea.

What will happen to volume in ECF compartment?
Will decrease.

What will happen to osmolarity in ECF compartment?
Will not change. (Why? Isotonic fluid is lost.)

What will happen to ICF volume and osmolarity?
No osmotic gradient, therefore, will not change :)

That was easy!
Let's look at a similar example.

Infusion of excessive isotonic saline.

What will happen to volume in ECF compartment?
Will increase.

What will happen to osmolarity in ECF compartment?
Will not change. (Why? Isotonic fluid is infused.)

What will happen to ICF volume and osmolarity?
No osmotic gradient, therefore, will not change.

See? It's very simple!


Loop diuretics, Addison's disease.

(Loops make you lose sodium and water, but more of sodium than water.
Addison's disease is adrenal insufficiency. Aldosterone makes you retain sodium so in the absence of aldosterone, you will lose sodium.)

What will happen to osmolarity in ECF compartment?
Will decrease. (Why? You are losing sodium.)

What will happen to volume in ECF compartment?
Will decrease. (Why? Fluid moves from ECF to ICF)

What will happen to ICF volume?
Will increase. (Decrease in osmolarity shifts the fluid into ICF)

SIADH, compulsive water drinker.

(SIADH: You are conserving too much water due to ADH.
Water drinker: You are having too much water =P )

What will happen to osmolarity in ECF compartment?
Will decrease. (Why? You are diluting by adding water.)

What will happen to volume in ECF compartment?
Will  increase. (Why? You are adding fluid.)

What will happen to ICF volume?
Will increase. (Decrease in osmolarity shifts the fluid into ICF)

So.. You're getting this, right? Let's make it tougher then!

Right heart failure, Cirrhosis, Nephrotic syndrome.

What will happen to osmolarity in ECF compartment?
Will decrease.

What will happen to volume in ECF compartment?
Will  increase.

What will happen to ICF volume?
Will increase.

Can't figure why? Well.. Here's why!



In all three conditions, there is a decreased effective circulatory volume (Effective arterial blood volume)
[See diagram]

This leads to decreased renal blood flow and pressure and increased ADH secretion and activates the renin angiotensin aldosterone system, increasing sodium and water reabsorption.

Note: Total body sodium is increased, however, serum sodium is decreased.
Why?
The alteration in Starling forces redirects the sodium containing fluid in the interstitial space (leading to edema)

*phew* That was work! Let's see what happens during sweating ;)
Sweating.

What will happen to volume in ECF compartment?
Will decrease.

What will happen to osmolarity in ECF compartment?
Will increase. (Why? Hypotonic fluid is lost.)

What will happen to ICF volume?
Will decrease.

Your sweat doesn't taste salty.. That's how I remember it's hypotonic, not hypertonic like tears T_T
Insensible water loss in fever, diabetes insipidus, alcohol.

What will happen to volume in ECF compartment?
Will decrease. (Water is lost. Why? ADH action is lost in Diabetes insipidus, alcohol inhibits pitutary secretion of ADH, water evaporates from the warm skin surface in fever)

What will happen to osmolarity in ECF compartment?
Will increase.

What will happen to ICF volume?
Will decrease.

Note: The ECF contraction is mild because there has been no loss of sodium.

Next one is easy too.. Keep going! < 3


Infusion of sodium bicarbonate, sodium containing antibiotics.

What will happen to osmolarity in ECF compartment?
Will increase.

What will happen to volume in ECF compartment?
Will increase. (Why? Fluid moves from the ICF to ECF)

What will happen to ICF volume?
Will decrease.

..And the last one!!! :D
Hyperosmolar nonketotic coma, diabetic ketoacidosis.


What will happen to osmolarity in ECF compartment?
Will increase. (Why? Glucose is an osmotically active particle)

What will happen to ICF volume?
Will decrease. (Why? Fluid moves from the ICF to ECF)

This gets a little tricky.. ^__^"

What will happen to volume in ECF compartment?
Will decrease.
Why?
Glucose in urine acts as an osmotic diuretic and the water from ECF is lost.

That's all!

This blog post took me forever to write.. I feel the color coding makes it easier to see the changes in the diagrams :)
Hope you had fun learning and revising with me and see you in the next post <3

-IkaN


Updated on 27th August, 2013:

What will happen to the Darrow Yannet diagram if a person running a marathon replaces all the volume lost in sweat by drinking water?

What will happen to total body volume?
Will remain the same. (Why? He replaced all the volume lost by drinking water!)

What will happen to osmolarity in ECF compartment?
Will decrease. (Why? Losing only salt, water loss has been replaced.)

What will happen to volume in ECF compartment?
Will decrease. (Why? Water will shift from ECF to ICF.)

What will happen to ICF volume?
Will increase.

What will happen to osmolarity in ICF compartment?
Will decrease. (Why? You are diluting by adding water.)

Hey, don't be discouraged if you got one question wrong.. We don't understand everything at first but we live, we learn and that's what it is all about :)

Updated on 7th January, 2014: Diagram on isoosmotic volume contraction and  isoosmotic volume expansion.
Updated on 11th September, 2014: Notes typo in infusion of excessive isotonic saline section.

34 comments:

  1. IkaN......Your explanation of the Darrow Yannet Diagram is amazing....The progression from the beginning till the end....it just gets absorbed into your head (unconsciously)....dats how good it is.....hats off to you !!!! You are BRILLIANT !!!!

    ReplyDelete
    Replies
    1. Thank you soo much ^__^ I'm glad it helped :D

      Delete
    2. thank you IkaN the explanation is amazing ; but i dont understand the last one. why do you call the last one as hypoosmotic volume contraction? because you said that the volume in ECF will remain the same.(Why? He replaced all the volume lost by drinking water!). i dont understand why you said volume contraction rather than remaining volume the same.

      Delete
    3. Hey there! Thanks :)

      We say volume contraction because we always talk in reference to ECF.
      He did replace the water but it got shifted to the ICF.
      So though the total body water is the same, the ECF volume has contracted.

      More precisely we should be saying, "Hypoosmotic contraction of ECF volume" =P

      Hope you understand ^__^

      Delete
    4. thank you IkaN for your quick response. I think my problem is that the answer of the question stated that "Will remain the same" . What will happen to volume in ECF compartment?
      Will remain the same. (Why? He replaced all the volume lost by drinking water!)
      What will happen to volume in ECF compartment?
      Will remain the same. (Why? He replaced all the volume lost by drinking water!) but you just answer in your response that "ECF volume has contracted". Am I missing anything here?

      Delete
    5. Oh I'm so sorry for confusing you. I was going sequentially to explain what happens and did a typo there.. I'll update it! =)

      Delete
  2. on the other hand I would like to ask about (i)isoosmotic volume contraction and (ii) isoosmotic volume expansion. why the total body Na doesn't change in given two situations (i,ii) ?

    ReplyDelete
    Replies
    1. The total body Na+ does change. I typed it wrong over there.
      Updated the diagrams though.. Hope I got it right this time :|

      Thank you for the correction!
      You are a keen observer.. Lemme know if there are any more mistakes ^__^

      Delete
  3. Thank you IkaN for all the explanations. I did learn this subject with your notes and with your comments. It is always possible to make a typo that does not discourage you. Thank you again

    ReplyDelete
    Replies
    1. You're most welcome! =)

      Haha yes, why be discouraged? What's the point in being in medicine if you can not admit your mistakes and change accordingly?

      Delete
  4. Perfect explanation... Thanks a lot !!

    ReplyDelete
  5. Read it once and I'm already like "Bring on the test !!! " xDDDDDDD
    Great, simple and clear explanations.
    Thanks @ w @ b

    ReplyDelete
    Replies
    1. Haha you're welcome!
      That's the spirit of learning! All the best for the test =D

      Delete
  6. Thanks for the great step by step explanation it makes everything much more clear!! I just dont quite understand though why diarrhea is isotonic?

    ReplyDelete
    Replies
    1. It depends on the type of diarrhea.. I should've been more specific. I was talking about Secretory diarrhea in this post =)

      Delete
  7. If person A drinks 1 liter of pure water vs person B who drinks 1 liter of Gatorade, who will pee out the most volume in a given period of time? Will it be the same? Different? Also, everything is the same for both (GFR, health, ect.....)

    ReplyDelete
    Replies
    1. Gatorade is isotonic to plasma.

      Darrow Yannet diagram for a person on Gatorade will similar to isoosmotic volume expansion & for a person on pure water will be similar to that of hypoosmotic volume expansion.

      Pure water lowers the osmotic pressure of the plasma and inhibits ADH release. Person on pure water will pee more.

      Delete
  8. Hii there i just wanted to say thanks so much for sharing this!!! I love how u color coded what the lines symbolize on the diagram, because it was confusing the heck out of me as to which line means what!! So thanks a lot i finally get it now hehe :)
    I jst wanted to point out a mistake:
    It should say "isotonic fluid is ADDED" and not "LOST":

    Infusion of excessive isotonic saline.

    What will happen to osmolarity in ECF compartment?
    Will not change. (Why? Isotonic fluid is lost.)

    ReplyDelete
    Replies
    1. Heyy you are most welcome!

      It took me days to create this.. Especially the color variations. I was new at Photoshop =(
      But I am glad I did and it's helping you :D

      Oh blimey! Updated the typo.. Thanks for the correction! <3

      Delete
  9. :DD Thanks :)
    So i have a question......can albumin cross the capillary membrane? I tried searching this up but i can't figure it out!! If you know and could cite a source plz do lemme know! I know that a small amount of plasma proteins can leak out of the capillaries and into the interstitium. BUT does this include albumin?
    Also, there is oncotic pressure in the interstitium, so can oncotic pressure be exerted by plasma proteins OTHER than albumin too?

    ReplyDelete
    Replies
    1. Umm complicated concept.

      Whether albumin can or can not cross the capillary membrane depends on which organ you are talking about.

      If it's the capillaries in the kidneys - it absolutely does not cross the membrane. Only in diseases like minimal change disease does albumin cross glomerular basement membrane.

      In pulmonary microcirculation, the interstitial oncotic pressure is high indicating significant leak of protein (mostly albumin) across the thin capillary walls under normal circumstances.
      Source: http://www.anaesthesiamcq.com/FluidBook/fl4_4.php

      So as a generalization, I would like to say albumin does not cross the capillary membranes. However, this is not absolute.
      You can read more about oncotic pressure and albumin here: http://www.nursingcenter.com/lnc/static?pageid=720126

      Oncotic pressure is definitely exerted by other plasma proteins. Another protein that exerts oncotic pressure is α-Fetoprotein.
      Source: Ganongs textbook of medical physiology.

      Lemme know if you have any other questions! :D

      Delete
  10. I'm glad I discovered this page! I loved the explanation and understood very good, and I had fun because everything is so friendful.
    Keep up the awesome work! You're awesome too

    ReplyDelete
    Replies
    1. Thank you, thank you, friend! :)

      Delete
  11. Thank you. I was having so much trouble understanding these plots while preparing for my entrance exams. This was a very helpful post to say the least and yes, the colours and dotted lines with explanation on the side makes it very easy to read and understand. After the first two, I was quizzing myself and happened to get the answers right! :):)

    ReplyDelete
    Replies
    1. Thank you. I'm SO glad it helped. Testing yourself is a brilliant way to study - Rock that entrance! :)

      Delete
  12. This looks amazing i understand how it works however I have a question, if you add mannitol 20% how would the diagram change since it a diuretic? and what if you add glucose 5% would that be considered as a diuretic too?

    ReplyDelete
    Replies
    1. I think it would look similar to hyperosmotic volume contraction since water is lost. I'm not sure though.

      Delete
  13. Thank you so much !!
    I had studied from this in the begining, and now again just few days before my exams I am here again to revise. Searched a lot to find this article again - now you are going in permanent bookmarks :D

    ReplyDelete
    Replies
    1. Yaay! :D
      You receive permanent love and hugs from us in return <3

      Delete
  14. Ok my teachers are awesome nephrologists and you explained this way better than them. Thanks!

    ReplyDelete
    Replies
    1. Omg that's like the best compliment ever. Thank you!

      Delete
  15. Hi, IkaN, regarding the last diagram, hypoosmotic volume contraction, as you mentioned
    What will happen to osmolarity in ECF compartment?
    Will decrease. (Why? Losing only salt, water loss has been replaced.)

    But, as you mentioned before sweating only cause lose of hypotonic fluid, is this means loss of water only? Or including salt? Because i was wondering sweating only cause loss of hypotonic fluid, how does it leads to losing in salts. Thanks So much!

    ReplyDelete
    Replies
    1. So in hypotonic fluid loss - salt and water, both, are lost.

      But water is lost more compared to salt (only a lil salt is lost)

      Does that answer your question?

      Delete

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