Term
| What are two important markers of kidney function? |
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Definition
- BUN - normal 6-20, measures amount of urea
- SCr - normal 0.6 - 1.2, a measure of kidney function |
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Term
| What are other measurements of kidney function? |
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Definition
- GFR - normal 120 ml/min filtered, cannot be directly measured
- CrCl - inverse to SCr. A high SCr gives a low CrCl |
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Term
| How do you calculate CrCl? |
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Definition
- (140 - age) * IBW / (72*SCr) * 0.85 if female
- IBW = 50 + 2.3(inches over 5 feet) if male, 45.5 + 2.3(inches over 5 feet) if female
- If actual BW > 120% IBW - use AdjBW = IBW + 0.4(actual - IBW) |
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Term
| What is the definition of ARF? |
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Definition
- Retention of Urea, Cr, other waste, bad regulation of electrolytes
- may be anuric, oliguric, or non-oliguric. Diagnosis based on SCr change and urine output |
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Term
| What are the RIFLE classifications? |
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Definition
- Risk - SCr increases 1.5x baseline
- Injury - SCR increases 2x baseline
- Failure - SCr increases 3x baseline, anuric, or SCr > 4
- Loss - Persistant failure, needs RRT for > 4 weeks
- ESRD - needs dialysis for > 3 months |
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Term
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Definition
An increase in BUN or SCr, but an normal GFR
Caused by assay measuring BUN/SCr, or prevention of Cr secretion by cimetidine and trimethoprim |
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Term
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Definition
- A decline in GFR caused by constriction of the afferent and dilation of the efferent
- Caused by lack of compensation in arteriole tone: decreased BV, HF, or cirrhosis, RAS, ACE-I/ARBs, NSAIDs |
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Term
| What is pre-renal failure? |
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Definition
occurs before the kidney, hypoperfusion with or without hypotension
- Compensatory mechanisms activate such as RAAS, ADH, SNS, but eventually fail
- Caused by dehydration, excess hypertensives, HF/sepsis/pulmonary hypertension (hypoperfusion), BRAS
- Meds:cyclosporine, Ace-I/ARBs, NSAIDs, contrast media |
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Term
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Definition
Direct damage occurs to the kidney to vasculature, glomeruli, tubules, or interstitial (AIN)
- Most common cause - acute tubular necrosis due to ischemia or toxin
- Obstruction leads to decr in GFR and urine output, must be removed.
- Penicillins, NSAIDs, hypotension, constriction, contrast media and metals, aminoglycosides, myoglobin |
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Term
| What is post-renal failure? |
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Definition
Obstruction within the urinary collecting system, pressure increases due to accumulating urine
- Causes: BPH, anticholinergic meds, clots, nephrolithiasis, uric acid crystals |
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Term
| Why is SCr an insensitive marker? |
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Definition
| GFR changes rapidly, leading to a delay in diagnosis. Half life prolonged with ARF, the lower the CrCl, the longer the lag |
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Term
| What measurements are used to diagnose ARF instead of CrCl? |
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Definition
- A trend in SCr
- BUN and urine output
- Urine CrCl
- Presence of substances in the urine
- FENa - FENa less than 1% = pre-renal, over 2% = intrinsic |
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Term
| What laboratory values are significant for Pre-renal Failure? |
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Definition
Urine Na < 20
FENa < 1%
Urine osmolality > 1.5
UrineCr/SCr ratio > 40:1
BUN/SCr ratio >20 |
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Term
| What laboratory values are significant for Intrinsic or post-renal Failure? |
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Definition
Debris seen in urine
Urine Na > 40
Fena > 2%
Osmolality < 1.3
UrineCr/SCr < 20:1
BUN/SCr ~15 |
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Term
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Definition
Fluid restricted to 2L/day
watch nephrotoxic meds
Maintain BP
Foley catheter maintenance
Glucose control
- Do not use Loop diuretics, dopamine, Fenoldopam. |
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Term
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Definition
Treat underlying cause - obstruction, meds
Rehydrate if volume depleted - 250 to 500 mL 0.9% saline over 15-30 min, once hypotension resolves 100 to 150 mL/hr until dehydration resolves
- Use diuretics in fluid overloaded patients - Furosemide 40 - 80 mg IV |
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Term
| How is diuretic resistance treated in fluid overloaded patients? |
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Definition
- Lower salt intake
- Use IV continuous therapy or combo. Increase dose.
- D/C Ace-I, NSAIDs
- Combo w/ thiazides, spironolactone, or metolazone |
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Term
| What electrolyte management is necessary in ARF? |
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Definition
- Restrict sodium intake from all sources
- hyperkalemia most common as K is renally eliminated, restrict intake
- Restrict intake of calcium and Mg
- Monitor daily |
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Term
| What are the indications for RRT? |
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Definition
A - acidosis
E - electrolyte imbalance - K/Mg
I - Drug intoxication
O - Fluid overload
U - Uremia |
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Term
| What is the difference between intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT)? |
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Definition
- IHD - most common, must be hemodynamically stable, must be able to tolerate fluid shift, can't be hypotensive
- CRRT - can use in unstable patients for the critically ill, occurs over 24 hours. Need an anticoagulant unlike IHD. |
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Term
| What should be monitored in ARF? |
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Definition
I/O Qshift
Weight daily
Hemodynamics qshift
Metabolic panel/blood glucose daily
medications and levels daily |
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Term
| What is contrast induced nephropathy? |
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Definition
A type of ATN (Intrinsic) caused by contrast dye
RF: diabetes, kidney disease.
Recovery in ~1 week. Give 0.9% infusion to prevent dehydration and sodium bicard infusion
- Prevention: N-acetylcysteine - antioxidant, patients hate it |
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Term
| What kind of ARF do aminoglycosides cause? |
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Definition
| ATN (Intrinsic) - progressive rise in SCr and BUN, hydrate and d/c antibiotic |
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Term
| What is the normal reaction to a kidney insult, and how do drugs affect this? |
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Definition
- Dilation of the afferent (prostaglandins) and constriction of the efferent(angII) to increase blood flow.
- Ace-I decr AngII, body cannot constrict efferent arteriole
- NSAIDS decr prostaglandin formation, Afferent arteriole cannot dilate |
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Term
What are:
- Intratubular obstructions
- Acute allergic interstitial nephritis? |
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Definition
- Obstruction - precipitation of a substance causes an obstruction - uric acid or Rhabdomyolysis
- AAIN - to beta-lactam antibiotics or long term NSAID use. Take prednisone to counteract |
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