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Elevated levels of urea and nitrogenous wastes in the blood (eg: elevated BUN)
Azotemia
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Symptoms associated with accumulation of metabolic by-products and endogenous toxins in the blood
Uremia
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What are common symptoms of uremia?
- N/V
- Loss of appetite
- Weakness
- Mental confusion
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What is the normal 24 hr range of urine output?
1-1.5 L
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What two things affect urine output?
- Blood Volume Status
- Diuretic Use
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Non-oliguria
> 500 mL of urine/day in patients with renal insufficiency
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Oliguria
Less than 400-500 mL of urine/day
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Anuria
< 50-100 mL urine/day
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What is "a complex disorder used to describe abrupt changes or reductions in golmerular function"?
- Acute Kidney Injury
- (formerly known asAcute Renal Failure)
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What two factors are associated with AKI?
- Increased length of hospital staty
- Increased ventilator days
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Define pre-renal disease
Damage caused by hypoperfusion of the renal cells
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Give two examples of intravascular volume depletion that can cause pre-renal disease
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Give two examples of reduced effective circulating volume that can cause pre-renal disease
- Sepsis
- Heart Failute
- Ascites
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How do ACEi and NSAIDs cause pre-renal disease?
Alter the hemodynamic state to the kidney
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Give an example of occlusion of pre-renal vasculature
Bilateral renal artery stenosis
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What type of renal disease is classified by direcct damage to the renal cells?
Intrisinc renal disease
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What causes 85% of intrinsic AKI?
Acute tubular necrosis
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Describe the etiology of intrinsic renal failure.
- Vasculature damage: small vessel emboli or vasculitis
- Glomerular damage: glomerulonephritis
- ATN
- Acute, allergic interstitial nephritis (2nd most common)
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What is a result of extending pre-renal states or exposure to direct toxins (i.e. uric acid, contrast media, aminglycosides)?
Acute tubular necrosis
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What is an inflammatory, immunologic reaction within the renal interstitium that can result from drugs, infections, or autoimmune disorders?
Acute, allergic interstitial nephritis (AIN)
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What is another name for post-renal disease?
Obstructive
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What are the three types of obstruction?
- Bladder outlet (prostate hypertrophy or prostate cancer)
- Urethral
- Tubular (crystal deposition from medications)
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What does RIFLE stand for?
- Risk of renal dysfunction
- Injury to the kidney
- Failure of kidney function
- Loss of kidney function
- End Stage Renal Disease
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What does RIFLE consist of?
- Renal dysfunction (1st 3)
- Clinical outcomes (Last 2)
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What can the diagnosis and classification criteria for RIFLE be based on?
Change in SCr and U/O
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In the RIFLE classification how long must signs be present for the classification of ESRD?
> 3 months
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What is the time constraint of AKIN?
48 hours
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What are the SCr criteria for Stage 1 based on AKIN?
> 0.3 mg/dL or > 1.5-2.0 x baseline
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What is the U/O output criteria for Stage 1 based on AKIN?
< 0.5 ml/kg/hr x 6 hr
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What is the SCr criteria for Stage 2 based on AKIN?
> 2-3 x baseline
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What is the U/O criteria for Stage 2 based on AKIN?
< 0.5 ml/kg/hr x 12 hr
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What is the SCr criteria for Stage 3 based on AKIN?
- > 3 x baseline
- > 4.0 mg/dL with an acute rise > 0.5 mg/dL
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What is the U/O criteria for Stage 3 based on AKIN?
< 0.3 ml/kg/hr x 24 hr or anuria x 12 hr
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AKI is abrupt reduction in kidney function manifested by a ___ increase in SCr, a ___% increase in SCr, or a reduction in urinary output ___________
- 0.3 mg/dL
- 50
- < 0.5 ml/kg/hr x 6 hr
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What are some limitations of RIFLE and AKIN?
- Need baseline SCr levels
- May be 1-2 delay in SCr increase after injury
- U/O Variable based on fluid status and diuretic use
- Primarily studied/validated in the critically ill population
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What are three diagnostic procedures for AKI?
- Renal ultrasound
- Kidney-ureter-bladder (KUB) X-ray
- Cystoscopy with retrograde pyelography
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How does a patient with pre-renal AKI present on the physical exam?
- Hypotension
- Dry mucus membranes
- Decrease CO
- Edema
- Ascites
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What will a patient's urine sediment look like in pre-renal disease?
Normal
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Fill in the following values for a patient with pre-renal AKI: Urine Na, FEna, BUN/SCr ratio
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What does a patient's urine sediment look like in intrinsic renal disease?
- Granular and epithelial casts
- RBCs
- WBCs may be present in AIN
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Fill in the following values for a patient with intrinsic AKI: Urine Na, FEna, BUN/SCr ratio
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Fill in the following values for a patient with post-renal AKI: Urine Na, FEna, BUN/SCr ratio
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How does a patient with post-renal AKI appear on physical exam?
- Prostatic enlargment
- Bladder distension
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What will a patient's urine sediment look like in a patient with post-renal disease?
- Variable
- Cellular debris
- RBCs
- Crystals possible
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What are some non-pharmacologic strategies for preventing AKI?
- Avoidance of nephrotoxic drugs in high risk patients
- Maintain hemodynamic stability to avoid hypotension, hypovolemia (i.e. hydration patients in shock, dehydration, adminstration of contrast dye; maintain CO in patients with CHF)
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What are risk-factors for AKI?
- Pre-existing renal dysfunction
- Age > 75 y/o
- Volume depletion or decreased circulating volume
- Serious infections (i.e. sepsis)
- Comorbidities (i.e. DM)
- Exposure to nephrotoxins (i.e. contrast dye)
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What are two methods to prevent contrast dye induced nephropathy?
- Sodium bicarbonate + hydration
- N-acetylcysteine (NAC) + hydration
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What are some possible medications that can be used to treat AKI?
- Dopamine- Increase renal blood flow and U/O
- Fenoldopam- Increase renal blood flow and U/O--may be useful in critically ill
- Loop diuretics- increased urine flow, decrease renal ischemia
- Calcium Channel blockers- reduce renal vasoconstriction--may have some benefit in renal transplant population
- N-acteylcysteine- antioxidant effect--may be useful in contrast dye induced AKI if given + hydration
- Ascorbic acid- antioxidant effect
- Erythropoietin- may protect against ischemic injury
- Natriuretic peptides- increase renal vasodilation and perfusion--may decrease the need for dialysis
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Is the use of loop diuretics in AKI supported at this time?
No
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What are typical indications for renal replacement therapy?
- Acid-base abnormalities
- Elecrtolyte imbalance
- Intoxications
- Overload of fluid
- Uremia
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What are two types of renal replacement therapy?
- Intermittent hemodialysis (IHD)
- Continuous renal replacement therapy (CRRT)
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What is the most commonly used agent in fluid overload?
Furosemide
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What is a risk of using high dosed loop diuretics?
Increased risk of ototoxicity
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What type of administration should be used to overcome diuretic resistance and avoid adverse reactions associated with high serum concentrations?
Continuous Infusion
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What are three common strategies to reduce diuretic resistance?
- Lower sodium intake
- Increase dose or use continuous infusion
- Combine diuretics with different sites of action
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What is the most common complication of AKI?
Hyperkalemia
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What is the first sign of hyperkalemia?
Peaked T waves
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When should hyperkalemia be treated?
If the patient is symptomatic or ECG changes present
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What is the K+ goal when treating hyperkalemia?
< 5 mmol/L
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What drugs are used to treat hyperkalemia in AKI?
- Calcium gluconate
- Insulin (plus glucose)
- B-adrenergic agonists
- Sodium polystyrene sulfonate (Kayexalate)
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What is the purpose of using calcium gluconate in Hyperkalemia?
Cardioprotection: stabilizes membrane voltage
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What is the onset of calcium gluconate?
1-3 minutes
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Why are insulin (plus glucose) and B-adrenergic agonists used in hyperkalemia?
Redistribution of K+ into the cells
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What is the onset of action for insulin (plus glucose) and beta adrenergic agonists?
10-30 minutes
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What is the purpose of using Kayexalate in hyperkalemia?
Removal: eliminates K+ from the gut in exchange for Na+
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What is the onset of action for Kayexalate?
1-3 hours
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