Acute Kidney Injury Flashcards
Prostaglandin vasodilation
Prostaglandin causes renal vasodilation it is also a pain mediatiator be careful with NSAIDs because they prevent prostaglandin
Glomerulus
Non selective filtration dumps everything except the big molecules red blood cells and protein
Re absorption and secretion
Potassium chloride and sodium are re absorbed into tubular capillaries from the proximal tubules loop of he le and distal tubule
Geriatric considerations
Structural kidney changes loss if renal mass and nephrons=greater risk of kidney injury but are not automatically functional loss
Prerenal
External factors that reduce kidney blood flow ex-hypovolemia fluid shifts sepsis heart failure liver failure anaphylaxis blood clots stiffening of renal artery
Intrarenal
Direct damage to kidney tissue causing impaired function of the nephron ex glomerulonephritis interstitial nephritis acute tubular nephritis contrast induced nephropathy
Post renal
Mechanical obstruction of urine outflow ex bph bilateral ureter obstruction foley blockage
Acute tubular necrosis
Most common intrarenal aki
Damage to basment membrane of tubular epithelium, necrotic tissue sloughs off , tubules become blocked
Causes- prolonged pre or post renal failure, hemolyzed red blood cells, increase in myoglobin
Contrast induced nephropathy
Risk factors- dehydration, hypotension, sepsis, use of nephrotic ix meds, greater than 100 ml of contrast, GED less than 60, or older than 75
Aki oliguric phase
Inability to produce urine
Output less than 0.5 ml/kg/hr
Fluid volume overload
Electrolyte imbalances hyperkalemia
Aki diuretic phase
Starting to heal Inability to concentrate urine Output 3-5 L/ day Fluid volume deficit Electrolyte imbalances: hypo atria and hypokalemia (dumping )
Aki recovery phase
May take up to 12 months to fully recover from aki
BUN/ creatinine normalize
Creatinine clearance
Required 24hr urine collection
Approximates Gfr
70-135mL/min/m2
Blood urea nitrogen
6-20mg/dL
Measures urea excretion
Can be influenced by non renal factors infection fever trauma steroid therapy diet
Serum creatinine
0.6-1.3 mg/dL
End product of muscle/ protein metabolism
More reliable than BUN
Requires vein puncture
Calculated glomerular filtration rate
115mL/min
Based on mdrd equation
Adjusted for gender, African Americans, and age
Pre renal diagnostic study
BUN/CR ratio elevated in pre renal
Fraction of excreted sodium normal in pre renal
Intrarenal diagnostic study
Intrarenal normal bun/ cr ratio
FEna elevated
Urinalysis
Casts= intrarenal failure indicate damage to various parts of tubules
Protein, hematuria, Pyuria, alterations in urine specific gravity
Pre renal prevention and early intervention
The #1 cause is priceless
Prevent infection and heavy fluid resuscitation
Intrarenal prevention and early intervention
Screen for risk factors in CAM
Treat strep infections
Contrast associated nephropathy
Avoid in patients at high risk
Hydrate 12 hrs before and after
Give 3 doses of mycomyst po
Evaluate function for 72 hrs after
Nephrotoxic drugs
Aminoglycosides NSAIDs Cephalosporins Tobramycin Vancomycin Chemotherapy Norepinephrine (Monitor trough levels) 75% of meds are metabolized through the kidneys
Uremia
Hold on to nitrogenous waste products bun and creatinine
Itchy, drowsy, confused, irritable, decreased mentation, GI disturbances, uremic frost
