Acute Kidney Injury Flashcards
acute kidney injury/ acute renal failure definition
sudden impairment of kidney function resulting in the retention of nitrogenous and other waste products normally cleared by the kidneys
BUN and SCr increased
oliguria/anuria
BUN
blood urea nitrogen
LIVER= protein metabolism
So the substances that increase protein will also increase BUN
classification of AKI
• Prerenal= assoc with decreased amt of blood that is flowing to the kidney
○ When there is prob outside kidneys which affects blood flow
• Renal= acute injury inside kidneys
• Postrenal= blockage of urine outflow
prerenal
- increased BUN= increased reabsorption and decreased filtration
- increased SCr= ONLY due to decreased filtration
renal
- increased BUN= ONLY due to decreased filtration
* SCr mostly stays the same
things that cause prerenal
anything that causes hypoperfusion
○ Hypovolemia= burns, severe diarrhea, elderly if they are dehydrated
○ Liver failure= reduced effective amt of circulating blood
§ Blood has been moved to certain areas and is not accessible to kidneys (if blood is trapped)
○ Congestive heart failure
○ Impaired renal autoregulation (NSAIDS, ACE-I/ARB, cyclosporine)
things that cause renal/ instrinsic
○ Important one= sepsis= presence of bact in the blood → leads to destruction of tubules and interstitium
○ Ischemia= occurs when you have hypoperfusion ○ Nephrotoxins= a lot of meds and/or contrast agents that are nephrotoxic but you also have endogenous nephrotoxins (hemolysis)
○ Vascular diseases
things that cause postrenal
bladder outlet obstruction
what is the most common form of AKI?
prerenal azotemia
prerenal azotemia
inadequate renal plasma flow and intraglomerular hydrostatic pressure (no parenchymal damage to kidney except if it goes on for long enough)
drop in BP with NSAIDS
○ Meds affect prostagladin prod
○ Vessel cannot dilate since meds are inhibiting prostaglandins
○ Hydrostatic pressure drops and increases angiotensin
drop in BP w/ ACE-I/ARB
○ Vessel cannot be narrowed
○ Increased perfusion which decrease ANG II
hepatorenal syndrome (prerenal azotemia)
caused by advanced liver cirrhosis (liver failure)
• Blood is trapped in splanchnic circulation
○ So don’t have loss of blood but blood is moved in circulation → kidney doesn’t have enough blood → activation of vasoconstrictor responses
○ Fragmentation of renal parenchyma → blood cannot go through the liver
ex of endogenous toxins that affect kidneys
myoglobin, hemoglobin, uric acid, myeloma ligh chains
postrenal
anything that causes obstruction in the urinary tract
• Common causes= kidney stones, prostatic enlargement (in older men), cancer/ tumors
• Hydronephrosis= kidney will be replaced with urine to where it is just a big sac of urine
