Acute Kidney Injury Flashcards
Criteria of AKI
Serum Creatinine Rises by 26umol/L within 48 hours
or
Serum Creatinine Rises 1.5 fold from reference value within 7 days
or
Urine Output is less than 0.5ml/kg/hr for 6 consecutive hours
Calculating Urine Output
Take total urine volume divide by hours then divide by weight
mL/kg/hours
AKI
- Risk Factors
CKD
Volume Depletion
Nephrotoxic Drugs
Obstruction of Urinary Tract
Renal Disease-Related Chronic Conditions
Hypertension and Diabetes
AKI
- Signs
- Edema
- Foamy or Coloured Urine
- Orthostatic Hypotension (Dizziness when standing)
- Hypertension
AKI
- Assessment
Serum Creatinine and BUN/Urea
- Both are elevated in acute changes to kidney function
What are the different types of AKI
Prerenal
Intrarenal (Intrinsic)
Postrenal
What is the most common kind of AKI
Prerenal (60%)
Intrarenal (35%)
Postrenal (5%)
Prerenal AKI
- What is it?
Renal Hypoperfusion
- Reduction in blood flow reaching the renal arterioles
Prerenal AKI
- Causes (Volemia)
Hypovolemia from:
- Hemorrhage
- Gastrointestinal Fluid Loss
- Renal Fluid Loss
- Extravascular (Blood moves into the tissues, less blood sent into kidneys)
Prerenal Causes
- Causes (Hemodynamics)
Altered Renal Hemodynamics:
- Low cardiac output state
- Systemic Vasodilation (Sepsis AKA Distributive Shock)
–> Blood moves from the plasma to tissues
- Renal Vasoconstriction
- Impaired Renal Autoregulatory Response
- Hepatorenal Syndrome
Prerenal AKI
- Symptoms
Orthostatic Hypotension
Dehydration
- Tachycardia
- Reduced Jugular Venous Pressure
- Decreased Skin Turgor
- Dry Mucous Membranes
Prerenal AKI
- Lab Values
Made up of High Urea, High Creatinine (Sodium and Water have all been absorbed)
- Concentrated Urine
Water and Sodium is reabsorbed
- Low Sodium and Water in Urine
Postrenal AKI
- What is it
Obstruction at any level of the urinary tract that prevents urine flow
- Has to occur in both kidneys at the same time
Postrenal AKI
- Causes
Physical Barrier
- Kidney Stones
- Prostate Hypertrophy
- Cancer
Drugs that Crystallize
- Sulfonamide
- Methotrexate
- Acyclovir
Postrenal AKI
- Symptoms
Pain
Anuria (Lack of pee)
Pyuria
Postrenal AKI
- Lab Values
Urinalysis
- Cellular Debris
- Hematuria (Variable)
- Some WBC in urine
- High Sodium (Sodium is not reabsorbed)
- Either increase or no change in Urea
- Less Concentrated (Water is not reabsorbed)
Intrarenal AKI
- What is it
Acute injury to the kidney itself
- Either acute or chronic cases
2nd most common kind of AKI
Intrarenal AKI
- Causes
- Drugs
- Toxins
- Ischemia
- Infection
- Autoimmune Disease
Intrarenal AKI
- Damaged Sites
Glomerulus
Vascular/Microvascular (Renal Arterioles/Blood Capillaries)
Tubular (ATN = Acute Tubular Necrosis)
Interstitium (AIN = Acute Interstitium Necrosis)
Intrarenal AKI
- Glomerular
- Acute Glomerulonephritis
- Vasculitis
- Thrombotic Microangiopathy (Hemolytic Uremic Syndrome) = Damage to small blood vessels
Intrarenal AKI
- Vascular/Microvascular
- Renal Infarction
- Renal Artery Stenosis
- Renal Vein Thrombosis
- Malignant Hypertension
- Scleroderma
- Atheroembolic
Intrarenal AKI
- Tubular Causes
Ischemic
- Prolonged Prerenal State
- Sepsis
- Systemic Hypotension
Nephrotoxic
- Aminoglycosides
- Methotrexate
- Cisplatin
- Myoglobin
- Hemoglobin
Intrarenal AKI
- Interstitium
Medications:
- Penicillins
- Cephalosporins
- Ciprofloxacin
- NSAIDS
- Phenytoin
- Tumour Infiltration (Lymphoma, Leukemia)
Intrarenal AKI
- Lab Values
Urine Sediment: Casts, Cellular Debris, Protein
RBC + WBC in Urine
High Sodium
Fe(Na) is greater than 2%
Either increase or neutral change in urea
Prerenal vs Intrarenal vs Postrenal
Prerenal
- Very concentrated urine
= Low blood flow to kidneys, water and sodium are still being reabsorbed
Intrarenal
- Presence of RBC, WBC, Cast, Cellular Debris in urine
- High Sodium
= Sign of damage and cell death
Postrenal
- Presence of Cellular Debris in urine
- High sodium
Treatment of AKI
- Hydrate (IV fluids like 0.9% NaCl)
- Diuretics (Furosemide)
–> Only if volume over loaded - Dialysis
- Stop nephrotoxic agent
- Treat underlying disease
- Adjust dosage of medications
AKI and Diuretics
Only to be used in patient that have some urine output
- Meant to reduce pulmonary edema and heart failure
Furosemide and Metolazone
AKI and Dialysis
0.9% NaCl (Normal Saline)
Advantage
- Can correct electrolytes
- Remove uremic toxins
- Treats fluid overloaded patients
Disadvantages
- Causes hypotension which can exacerbate AKI
- Poor venous access makes dialysis difficult
- Infection at site of IV
- Kidneys may not recover
When do we Dialyze
When one of the following occurs
A: Acid- base abnormalities
E: Electrolyte Imbalance
I: Intoxications
O: Fluid Overload
U: Uremia
