Renal Failure Flashcards
Functions of the kidneys
Fluid and electrolyte balance
Excretion of waste
Regulation of BP (RAAS)
RBC production (erythropoietin: stimulates RBC prod)
Vitamin D production
Acid-base balance
3 ways the kidneys control bicarbonate:
- Monitor reabsorption
- Production of new bicarb
- Control acid / bugger (excretion of small amts of hydrogen ions - buffered by phosphates/ammonia)
Term for accumulation of nitrogenous wastes:
Azotemia
What is normal GFR?
80-125 mL/min (180L/day)
How much urine do the kidneys produce every minute?
1 mL/min
What is a normal UOP?
mL/hr and mL/kg of weight
*30-60 mL/hr
Aka *0.5-1 mL/kg
Characteristics of acute kidney injury
Oliguria: scant urine output
Azotemia: accumulation of nitrogenous wastes (BUN/creatinine)
Acid-base disturbances
*What is the best measure of renal function?
BUN
What can cause creatinine to increase?
Reduced renal function
Protein break down (can be skewed by diet)
With chronic kidney disease, how long does it take to start showing symptoms?
Takes 3-6 months for BUN & creatinine to increase
*Slow and insidious onset
Prerenal causes of an AKI
Hypovolemia
Hemodynamic instability
Volume depletion
Hypoperfusion
Vasodilation
Decreased cardiac output
Intrarenal causes of an AKI
Acute Tubular Necrosis (most common):
- Sepsis
- Medications (nephrotoxic agents)
- Prolonged ischemia
- Rhabdomyolysis
Medications that can cause intra-renal AKI
Antibiotics - aminoglycosides
NSAIDs
Contrast Media
Why is contrast media nephrotoxic?
Attaches to RBCs temporarily and needs to be filtered by the kidneys
Need to force fluids before and after
How does rhabdomyolysis cause intra-renal AKI
Massive amts of protein breakdown
Gets filtered out by the kidneys and they can’t tolerate all the little strands of protein
Causes of post-renal AKI
Obstruction of flow:
Stones
BPH
Ligation of ureter (by fibrous band)
Foley obstruction
3 phases of AKI
Initiation/onset
Maintenance/oliguric/anuric
Recovery/diuretic
When does phase 1 of AKI occur?
From the time of the event to signs of decreased renal perfusion
How long does phase 1 of AKI last?
A few hours to 2 days
How do we know a patient is having signs of decreased renal perfusion?
Client will be unable to compensate:
- Body is not able to produce enough urine <30mL/hr
- Will also have risking BUN/creatinine
What is the treatment strategy for a patient in phase 1 of AKI?
Figure out what is causing the problem and treat it (want to try to get them out of phase 1)
- Potentially reversible
- No intrinsic renal damage in this stage
Characteristics of AKI phase 2
BUN and creatinine increase daily
Pt is oliguric - output <400 mL/day
Fluid overload
Electrolyte imbalances
*Acidosis
Treatment strategy for a pt in phase 2 AKI
Dialysis required as immediate as possible
8-14 day duration (GFR = 5-10mL/min)
Complications of phase 2
Uremia (build up of uremic acid)
Hyperkalemia (caused by sodium and water being trapped in vascular space, which leaves potassium trapped in the cells)
Infection
What occurs in phase 3 of DKI?
Return of tubular function
BUN&Creatinine begin returning to normal (takes 4-6 months)
Residual impairment of GFR (regain 70-80%)
Treatment strategy of phase 3 of DKI
Support pt and let nature take its course
What is the most specific diagnostic for renal disease?
24 hour creatinine clearance test
What is the most direct reflection of GFR?
Calculated GFR based off of creatinine clearance test
Is an estimated value
Serum tests that determine if pt has renal disease
Elevated Creatinine
Elevated BUN
BUN:creatinine ratio >20:1
Serum osmolality
Normal range for creatinine
0.5-1.2 mg/dL
What is BUN affected by?
Catabolism
Bleeding
Dehydration
What does the BUN:creatinine ratio indicate?
Shows the probability or renal vs. nonrenal issues
Ex: if ratio is 45:2, something going on, but prob not kidney issue
Gold standard to diagnose kidney failure
CT
What does a CT scan show?
Structures
Accumulation of fluid
Why isn’t a KUB the best diagnostic option?
Shows structures
No contrast, lights not on
Why isn’t IVP the best diagnostic option?
Shows structures, has contrast
But watched on x-ray, doesn’t show us what’s going on
Why isn’t a renal scan the best option for diagnosis?
Good for diagnosing, shows renal uptake of isotopes
But pt has to go to neural medicine and ICU pts can’t leave
What is the 2nd best option for diagnosing? why?
Renal angiography
Shows abnormalities in blood flow, infarction, masses
Allows obstruction to be seen
Why isn’t a renal ultrasounds best for diagnosing?
Can see obstruction and size
But these are done later, after pt is out of ICU
Neurological symptoms of a patient with renal failure
Confusion
Lethargy
Decreased LOC
Stupor