AKI Flashcards
Definition of azotemia
Elevation in nitrogenous waste products and creatinine
Uremia definition
Symptoms associated with accumulation of metabolic by-products and endogenous toxins in the blood caused by azotemia
Uremia symptoms
Fatigue Anorexia N/V Pruritus Mental status changes
Normal urine output
1 - 1.5L per 24 hours
Urine output in non-oliguria
> 500 mL/day in patients with renal insufficiency
Urine output in oliguria
< 400-500 mL/day
Urine output in anuria
< 50-100 mL/day
What is pre-renal AKI?
Hypoperfusion of the renal cells
What are pre-renal causes of AKI?
Intravascular volume depletion
Reduced effective circulating volume
Occlusion of pre-renal vasculature
Drug induced
What is intrinsic AKI?
Direct damage to the renal cells
What are vasculature causes of intrinsic AKI?
Thrombotic thrombocytopenia purpura
Hemolytic uremic syndrome
Renal artery thrombosis
What are causes of intrinsic AKI due to the glomerulus?
SLE
Glomerulonephritis
Post-infection
What is AIN?
Acute, allergic interstitial nephritis
Inflammatory, immunologic reaction within the renal interstitium
What are the causes of AIN?
Drugs
Infections
Autoimmune disorders
What is ATN?
Acute tubular necrosis
What are the 3 phases of ATN?
Initiation
Maintenance
Recovery
What is the initiation of ATN?
Damage and decrease in GFR
What is the maintenance of ATN?
Toxin or ischemia has been removed but the kidney stays in the state
What is the recovery of ATN?
Building new epithelial
What can cause ATN?
Extending pre-renal states or exposure to toxins
What causes post-renal AKI?
Caused by an obstruction in the urinary collection system
What are causes bladder outlet obstruction?
Prostatic hypertrophy
Cancer
Improperly placed bladder catheter
What are causes of ureteral obstruction?
Cervical cancers
Retroperitoneal fibrosis
Nephrolithiasis
What are causes of renal pelvis/tubules obstruction?
Nepholithiasis (crystal deposition from medications)
What are RF for AKI?
Age (> 65 yo) Pre-existing renal dysfunction Volume depletion Serious infections Comorbidities Exposure to nephrotoxins
What are comorbidities associated with AKI?
HF
CV issues
DM
Liver disease
What is AKIN stage 1 SCr criteria?
Increased SCr >/= 0.3
OR
Increased >/= 1.5- to 2-fold from baseline
What is AKIN stage 1 UO criteria?
< 0.5 ml/kg/hr x > 6 hours
What is AKIN stage 2 SCr criteria?
Increased SCr to > 2- to 3-fold from baseline
What is AKIN stage 2 UO criteria?
< 0.5 ml/kg/hr x > 12 hours
What is AKIN stage 3 SCr criteria?
Increase SCr to > 3-fold from baseline or SCr >/= 4.0 with an acute increase of at least 0.5
What is AKIN stage 3 UO criteria?
< 0.3 ml/kg/hr x 24 hours
OR
Anuria x 12 hours
What is KDIGO stage 1 SCr criteria?
1.5-1.9 times baseline
OR
>/= 0.3 increase
What is KDIGO stage 1 UO?
< 0.5 ml/kg/h for 6-12 hours
What is KDIGO stage 2 SCr criteria?
2.0-2.9 times baseline
What is KDIGO stage 2 UO criteria?
< 0.5 ml/kg/h >/= 12 hours
What is KDIGO stage 3 SCr criteria?
3.0 times baseline OR Increase in SCr >/= 4.0 OR Initiation of renal replacement therapy OR In patients < 18 years, decrease in eGFR < 35 ml/min/m2
What is KDIGO stage 3 UO criteria?
< 0.3 ml/kg/h x >/= 24 hours
OR
Anuria for >/= 12 hours
What are the limitations of diagnosis and staging AKI?
Need a baseline SCr level
May be 1-2 day delay to SCr increase after injury
UP can be variable
Primarily studied/validated in critically ill population
What are some diagnostic procedures for AKI?
Renal ultrasound Catheter Kidney-ureter-bladder (KUB) x-ray Cystoscopy with retrograde pyelography Renal biopsy
What are types of Intrinsic AKI?
AIN
ATN
How to differentiate causes of AKI: Pre-renal Physical Exam Urine Sediment Urine RBC Urine Na FEna BUN:SCr ratio
PE: Hypotension, dry mucous membranes, decreased CO, edema, ascites Urine sediment: Normal Urine RBC: None Urine WBC: None Urine Na: < 20 FEna: < 1 BUN:SCr ratio: >/=20:1
How to differentiate causes of AKI: Intrinsic Physical Exam Urine Sediment Urine RBC Urine WBC Urine Na FEna BUN:SCr ratio
PE: Variable Urine Sediment: GRanular and epithelial casts Urine RBC: 2-4+ Urine WBC: 2-4+ Urine Na: > 40 FEna: > 2 BUN:SCr ratio: <20:1
How to differentiate causes of AKI: Post-renal Physical Exam Urine Sediment Urine RBC Urine WBC Urine Na FEna BUN:SCr ratio
PE: Prostatic enlargement, bladder distension
Urine sedment: Variable, cellular debris, RBCs, crystals possible
Urine RBC: variable
Urine WBC: 1+
Urine Na: > 40
FEna: Variable
BUN:SCr ratio: 15:1
What are non-pharmacologic strategies for prevention of AKI?
Avoidance of nephrotoxins
Maintain hemodynamic stability to avoid hypotension, hypovolemia
What are pharmacologic strategies for prevention of AKI?
Prevention of contrast media-induced nephrotoxicity (CIN)
Sodium bicarbonate + hydration
Loops
What is the dose of sodium bicarbonate in AKI?
Alkalinizing agent
Dose - 154 mEq sodium bicarbonate in 1L D5W infuse at 3 mL/kg/h x 1 hr before procedure, then 1 mL/kg/h during procedure and 6 hours after procedure
What are the desired goals of AKI treatment?
Rapid identification of cause Removal or reduction of causative agents Prevent further kidney injury Prevent complications Regain renal function
What is the mainstay of AKI treatment?
Supportive care
What is supportive care for AKI treatment?
Stop nephrotoxic drugs
Maintain adequate hemodynamic status
Maintain glucose control
Manage complications
What are indications for renal replacement therapy in AKI?
A - acid-base abnormalities E - Electrolyte imbalances (hyperkalemia usually) I - Intoxications O - Overload of fluids U - Uremia
What are the types of renal replacement therapy?
Intermittent HD (IHD)
Continuous renal replacement therapy (CRRT)
Hybrid
What are the causes of diuretic resistance?
Excessive sodium intake Inadequate diuretic dose or inappropriate regimen Reduce bioavailability Reduced renal blood flow Increased sodium reabsorption
What are the complications of AKI?
Fluid overload Hyperkalemia Hypernatremia Infection CV GI Neurologic
What are the treatments for fluid overload?
Minimize fluid intake
Loop diuretics
Reduction of diuretic resistance
What is the most commonly used loop for fluid overload?
Furosemide
What is the IV bolus dosing of furosemide in fluid overload?
40-80 mg x 1 (caution - high doses are associated with ototoxicity)
Strategies to reduce diuretic resistance
Identify and eliminate/reduce potential cause
Increase dose or use continuous infusion
Add an additional diuretic with a different mechanism
Drugs to reduce diuretic resistance
Thiazide diuretics (Chlorothiazide 250-500 mg IV q12h) Thiazide-like diuretics (Metolazone 5-10 mg PO q24h))
Hyperkalemiain AKI
Most common complication
Clinical symptoms of hyperkalemia
Usually asymptomatic
May have palpitations or skipped heartbeats
EKG changes: peaked T waves, prolongation of PR and QRS intervals, disappearance of P wave/merger with QRS and T waves
Drugs to treat hyperkalemia
Calcium gluconate (give every pt this)
Insulin (plus glucose)
Albuterol
Sodium polystyrene sulfonate (Kayexalate)
Calcium gluconate MOA
Cardioprotection: stabilizes membrane voltage (not a true treatment, does not contribute to K levels at all)
Calcium gluconate onset
1-3 minutes
Calcium gluconate duration
30 minutes
Calcium gluconate comments
May potentiate digoxin toxicity
Give over slow 20-30 minute infusion if patient is on dig
Calcium and bicarb are incompatible
Insulin (plus glucose) and Albuterol MOA
Redistribution: increases cellular K uptake to decrease plasma K level
Insulin (plus glucose) and Albuterol onset
10-30 min
Insulin (plus glucose) Duration
2-6 hours
Albuterol duration
2-4 hours
Insulin (plus glucose) comments
Glucose given to avoid hypoglycemia
Glucose is unnecessary if BS > 250
Monitor glucose levels closely
Albuterol comments
Works better when combined with insulin and glucose
25% of patients do not respond
Tachycardia is common
Sodium polystyrene sulfonate MOA
Removal: eliminates K from the gut in exchange for Na
Sodium polystyrene sulfonate Onset
1-3 hours
Sodium polystyrene sulfonate duration
4-6 hours
Sodium polystyrene sulfonate comments
Sorbitol used to minimize constipation
Quicker onset with rectal route
Sorbitol associated with bowel necrosis
May lead to Na retention
Hypernatremia treatment
Sodium restriction
What is the most common cause of death in AKI?
Infection
How can infections cause AKI?
Sepsis can lead to AKI
What are CV complications of AKI?
HTN with intermittent hypotension
CHF, arrhythmias, and pulmonary edema
What are the GI complications of AKI?
Increased risk of bleeding
Stress ulceration
N/V
What are neurologic complications in AKI?
Altered mental status
Seizures
Somnolence
