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Old 08-11-2012
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Blood Why hematocrit goes down after bleeding!

A 54-year-old woman is involved in an automobile accident and sustains serious injuries causing hemorrhaging. Which of the following is the cause for the decrease in hematocrit that develops gradually after a hemorrhage?

a) Decrease in blood volume and venous return
b) Decrease in plasma protein concentration
c) Decrease in production of red blood cells (RBCs) in the bone marrow
d) Increase in plasma Na+ concentration
e) Shift of interstitial fluid into the blood vessels

I would appreciate if you could briefly explain your choice I'm having doubts whether the official correct answer is correct indeed so I wanted to leave this question open for discussion Thank you
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Old 08-11-2012
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E. Shift of fluid to the intravascular compartment.
Hemorrhage--> decreased capillary hydrostatic pressure--> fluid enters the blood from the interstitium.
Note that I said interstitium, not from the cells.
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Old 08-11-2012
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Quote:
Originally Posted by smanthrav View Post
E. Shift of fluid to the intravascular compartment.
Hemorrhage--> decreased capillary hydrostatic pressure--> fluid enters the blood from the interstitium.
Note that I said interstitium, not from the cells.
Thanks
I understand that the drop of hematocrit is from the dilution but I was just wondering about other mechanisms that can cause this dilution (like activating RAA -> accumulating more Na+ hence more water in the body)
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Old 08-11-2012
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Quote:
Originally Posted by Casandra View Post
Thanks
I understand that the drop of hematocrit is from the dilution but I was just wondering about other mechanisms that can cause this dilution (like activating RAA -> accumulating more Na+ hence more water in the body)
but aldosterone wdnt cause an inc in Na "concentratn" rit? cz wt Na water too wl b reabsrbd..
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Quote:
Originally Posted by Casandra View Post
Thanks
I understand that the drop of hematocrit is from the dilution but I was just wondering about other mechanisms that can cause this dilution (like activating RAA -> accumulating more Na+ hence more water in the body)
that will also be responsible also,according to me ,but e is more simply the straight choice
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E should be the best option as explained by smanthrav.....
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Old 08-14-2012
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Default correct answer :)

The answer is e) Shift of interstitial fluid into the blood vessels

When hemorrhaging occurs, the loss of whole blood does not alter the hemoglobin, hematocrit, or RBC count because both plasma and RBCs are lost. However, after a few hours, the decreased capillary hydrostatic pressure caused by arteriolar constriction and decreased arterial pressure results in a shift of interstitial fluid into the blood, which uncovers the deficit in the hemoglobin, hematocrit, and RBC count. If the patient was given an infusion of normal (0.9%) saline immediately after a hemorrhage, the above blood parameters would be decreased.
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Old 08-15-2012
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Default What I learned

I learned from a very prominent general surgeon that it takes 6 hours for Hct to lower due to interstitial fluid shift after hemorrhage.
Chris
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