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Thursday, March 19, 2015

Renal Failure: Are You Kidneying me?!

Renal Failure, Kidney Failure, acute, chronic, electrolytes, obesity, nurse, nursing school, NCLEX, clinical, liver failure

Renal Failure: Are You Kidneying Me?!

Renal/Kidney failure is a pretty common condition in our patients at the hospital. They can have an acute episode, or it can be a chronic condition. 25% of patient admitted to the ICU develop Acute Renal Failure. 

I'm currently on a liver transplant ICU-- so nearly everyone has also developed renal failure.

This post I'll discuss acute and chronic renal failure's patho, labs to watch, causes, signs and symptoms, and how to treat these disorders.

P.S. I make terrible puns. Earlier today had a visitor on the unit that broke her humerous bone. I asked if it was funny... No body laughed... #thisiswhyimsingle.


Ok, so we all pretty much know that our kidneys are important to filter the blood in our bodies. 

Here are some terms to learn:
  • Nonoliguria: Between 400-1000 mL/day
  • Oliguria: Less than 400 mL/day
  • Anuria: Less than 50 mL/day
  • Total Anuria: No urine at all

You can have Acute Renal Failure (ARF) or Chronic Renal Failure (CRF).

Acute Renal Failure: can also be called Acute Kidney Failure (AKF) and is a decrease in kidney function that can last from hours to days.

Chronic Renal Failure: is more gradual and occurs slowly over months/years. 

Acute Renal Failure

Your patients in shock, sepsis, trauma, or received cardiac surgery are probably the ones at greatest risk for developing ARF. ARF can be further broken down into: Prerenal, Intrarenal, and Postrenal.

So pay attention to the prefix! Prerenal means something is happening before the renal tubules, usually hypoperfusion. Intrarenal is when tissue has actually been damaged in the tubules, glomerulus, or vessels to the kidneys. Postrenal means that a problem is occurring towards the end of the renal system such as a stone in the bladder blocking the neck and preventing urination. 

You don't want the patient with prerenal problems to advance to intrarenal issues, so this is why it's important to monitor your patients kidney functions. You'll want to be aware of:
  • Hemorrhaging (hypovolemia)
  • Excessive Diuretics (hypovolemia)
  • Excessive Vomiting (hypovolemia)
  • NSAIDs
  • Amphotericin B 
  • Contrast Dyes
  • Rhabdomyolisis (breakdown of muscle tissue)

You'll also want to check the patient's renal labs: Creatinine, BUN, BUN:Creatinine Ratio, Glomerular Filtration Rate, Osmolality

Be aware the BUN can be influenced by overhydration or underhydration. Overhydration will cause the BUN to be decreased. Dehydration will cause the BUN to rise. This is why it is important to compare the BUN to the Creatinine levels. If both levels rise then you know you have a problem. If BUN rises only, then possibly the patient just needs a bolus of fluids. Easy Peasy.

So the takeaway is this: if you have a high Creatinine, you have some sort of kidney disease.

Glomerular Filtration Rate

To determine the MALE patient's GFR use this equation:

GFR = [140 - age] x [weight in kg]
                    72 x Creatinine

To determine the FEMALE patient's GFR use this equation:

GFR = [140 - age] x [weight in kg]  x 0.85
                    72 x Creatinine

Ok. Remember in math "Please Excuse My Dead Aunt Sally" as in Parenthesis, Exponent, Multiplication, Division, Addition, Subtraction. That's what order you go in.

I can't tell you how darn annoyed I get when someone doesn't follow that rule and gets their math all screwed up. Just follow that rule. Don't know which one to do first; subtraction or division? Just think "Please Excuse My Dead Aunt Sally". For the love of God, someone graffiti that all over bathroom stalls across America.

(Can you tell that makes me mad?)

Anywho, GFR is the filtration rate of how many mL the kidneys are filtering per minute. Normal is greater than 90 mL per minute. So when you start to see that number dip below 90 you need to be concerned.

  • 60-89 GFR = Mild kidney damage
  • 30-59 GFR= Moderate
  • 15-29 GFR= Severe
  • Less than 15 GFR= your patient needs dialysis

Here's the takeaway: GFR is specific in evaluating kidney function when compared to creatinine alone. So use that handy dandy equation. And graffiti some bathroom stalls. Shh. I didn't say that. ;)

Phases of Acute Renal Failure

Oliguric Phase: lasts about 1-2 weeks. This might be called the maintenance phase.

Diuretic Phase: may also be called the recovery phase. The kidneys will start to excrete hypotonic urine. The amount depends on how much fluid the patient had taken on before hand. 

Electrolytes to Watch in Acute Renal Failure

  • Hyperkalemia
    • Potassium gets retained because kidney function is impaired. Could also be cause by certain meds.
  • Hypermagnesemia
    • Usually only mild to moderate, occurs because of the decreased GFR
  • Hyperphosphatemia
  • Hypocalcemia
    • Occurs during the oliguric phase
  • Hyponatremia
    • Very common because of the excess fluid volume that the patient's body is unable to excrete.
  • Metabolic Acidosis
    • A high anion gap (high phosphate levels) will occur and the body compensates by lowering bicarb and pH.

Chronic Renal Failure

Switching to Chronic Renal Failure-- it's usually brought on by high blood pressure, or diabetes. You'll stage CRF based off of the GFR that I pointed out earlier. 

This patient will look like: dry, itchy skin. May have pale or yellow skin. Patient can be anorexic, nauseous, vomiting, or have a GI bleed. (Have you smelled a GI bleed yet? Gag. One the other day smelled like buttered popcorn. I have NO idea why? But I think I'm off my popcorn kick.) 

Anyways, these patients will probably have pulmonary edema- so you'll hear crackles when auscultating their breath sounds. They might develop pneumonia. If they are in Metabolic Acidosis they'll start to breathe deeper and faster to compensate. The patient could easily have congestive heart failure. Their peripherals will probably be cool, numb, or possibly burn. The patient might be anemic because of a possible GI bleed, or due to the kidneys not being able to produce erythropoietin. 

Electrolytes to Watch in Chronic Renal Failure

  • Hyperkalemia
  • Hypermagnesemia
  • Hyperphosphatemia
  • Hypocalcemia
  • Metabolic Acidosis
So this looks a lot like Acute Renal Failure, right. You'll be able to differentiate between the two based off of the onset; was it quick or gradual? and based off of labs; what's the BUN:Creatinine ratio? What's the GFR? Remember if creatinine is high, then we have damage. BUN alone doesn't tell the full story.

Treating Kidney Failure

    • this is a little "duh" but seriously, it gets overlooked. Make sure medicines are given in the smallest amount (fluid wise). 
  • Decrease sodium intake
  • Decrease protein intake
  • Avoid foods with magnesium and phosphate (anions-- then we go into Metabolic Acidosis)
  • Don't let CRF patients get constipated. Pooping is how they rid their bodies of potassium. We want them to poop!!
  • Calcium can be given if the patient is hypocalcemic
  • Bicarb infusion
  • Dialysis

Alright. This was torture. I hate the kidneys. I hope you enjoyed and that this was helpful! :)

In case you missed it, here's my post on Congestive Heart Failure. You might find that also helpful in relation to the kidneys and their functioning. 

What would you like to see on my next post? I have ideas but I love to know what you guys are struggling with, because chances are YOU ARE NOT ALONE. Let me know in a comment below! Thanks.



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