Trying to Study for Urinary/Bowel test...have a ?

[chinacatSN]

I have a test on disorders of the urinary system and bowels (not GI, just small & large intestine) coming up on Friday.

When I study, it really helps me remember things if I understand how the ENTIRE process works - how physiology, pathophys, and comorbids all come together. That being said, here's my question:

What's the difference between ischemia and reduced blood flow? I'm studying ARF and my med/surg book lists the causes for intra-renal failure as: ischemia, reduced blood flow, toxins (such as contrast media), and nephrolithiasis as the most common causes.

From what I understand, ischemia and reduced blood flow are pretty much the same thing - right? I just want to make sure I understand the difference. I've looked them up in Tabers, Mosby's, and googled it - everything says that ischemia is reduced or decreased blood flow - so, is it just a typo in the book or am I totally missing the mark?

[Emilynn09]

Ischemia is restricted blood flow that results in tissue damage, and reduced blood flow is just what it says it is.

Hope that helps. I know it's rather simplistic. :)

[2bnurseplease]

As you probably know, blood carries oxygen which the tissue needs to function (tissue can be anything from skin to organs, such as the kidney). When there is reduced blood flow, the tissue does not receive oxygen and therefore cannot survive (begins to die). This is referred to as "ischemia".

If you have ischemia in the heart, you have a heart attack (not enough blood/oxygen to heart). If you have ischemia of the brain, you have a stroke (not enough blood/oxygen to brain). If you have ischemia of the skin, you get necrosis (tissue death).

Some causes of ischemia are vasoconstriction (arteries become smaller causing less blood to flow through them and as a result, less blood to get to the organs), a blood clot in the arteries, carbon monoxide poisoning or hemorrhage (outright bleeding where blood and oxygen are not getting to the tissues).

The causes of intra-renal failure is reduced blood flow to the kidneys. This can be caused by hemorrhage (think excessive bleeding - if you're bleeding out, the blood is not getting to the kidneys, right...) or dehydration (if there's not enough blood in your body, then the kidney is not getting enough blood).

Though it is important to understand pathophysiology, for your tests, it is also important that you think about how this relates to what the nurse does. For example, if the kidney is not receiving enough fluid, what kind of urinary changes would the nurse see? If you think about it, the kidney is not receiving enough blood (the body's fluid), so you could probably guess that the body's natural instinct would be to keep as much fluid as possible, hence urine output would decrease.

[semester1kid]

Think of it this way: ischemia is a result of reduced/lack of blood flow (as mentioned above, tissue is starting to die) ...so it's more that one can cause the other...not so much that one is the same as the other.