AKI Flashcards
Acute kidney injury: rapid loss of kidney function
- rise in creatinine or reduction of urine output
2. can develop azotermia (increase in nitrogenous waste)
Acute kidney injury: can change in severity
develop over hours to days
Acute kidney injury: can range in how long it occurs and when it occurs
nephrotoxic takes longer to reach than oliguric phase
Acute kidney injury: most common causes
hypotension, hypovolemia, exposure to nephrotoxic agents
What is the most common cause of AKI in the hospital?
pre-renal and ATN (acute tubular necrosis)
What is AKI define by?
A rise in serum creatinine and/or reduction in urine output
What 3 causes is AKI classified into?
- prerenal
- intrarenal
- postrenal
Pre renal AKI is caused by..
External causes —> decreased perfusion of kidneys —> decreased function
Less blood going to kidneys to be filtered and decreased nutrient
Ex: cardiac issue, dehydration, bleeding and burns
How will the body compensate in prerenal AKI?
increase blood flow by increasing blood volume by:
- Angiotensin II
- Aldosterone
- Norepinephrine
- ADH
Prerenal can lead to..
intrarenal
Intrarenal AKI is caused by
direct damage to the kidney tissue –> impaired nephron functioning —> increased waste and H2O and decreased ability to maintain electrolytes
Direct damage can be caused by
prolonged ischemia, nephrotoxins, hemoglobin release from hemolyzed RBIs, myoglobin released from necrotic muscle cells or acute tubular necrosis
Infection, injury
Post renal AKI is caused by
mechanical obstruction of urinary flow and is below the kidneys —> prevention of draining system —> increase pressure and build up of waste —> decrease kidney function
What causes mechanical obstruction?
BPH, prostate cancer, calculi, trauma, external factors, neurological injury
Hydrpnephrosis
bilateral ureter obstruction
If blockage fixed within 48 hours, can usually make a complete recovery
Is post renal AKI common?
no, only about 10% of AKI
What is acute tubular necrosis caused by?
disruption in the basement membrane and patchy destruction of the tubular epithelium
Nephrotoxic agents blood up and plug tubules of kidneys –> tubular epithelial cells slough off and plug tubules –> alters kidney’s ability to filter appropriately
What happens if the basement membrane is not destroyed in ATN?
the epithelium can regenerate and the condition is more reversible
RIFLE
Classificaiton of the stages of AKI. R- risk I- injury F- failure L- loss E- end-stage kidney disease Monitor I/Os closely, serum creatinine and GFR
AKI phases
- Oliguric
- Diuretic
- Recovery
Oliguria
decreased UO of less than 400ml/day
Can occur within 1-7 days of injury
What if the cause of oliguria is ischemia?
oliguria can happen in as fast as 24 hours
Can you determine the type of AKI by what urine is being produced?
Yes
Type of AKI if Anuria
less than 50ml/day
complete bilateral obstruction along urinary tract
Type of AKI if oliguria
prerenal
Type of AKI if nonoliguric
ATN or intrarenal ATN
Oliguric phase
Common symptom: oliguria: less than 400ml/day
50% won’t be oliguric
Longer in the oliguric phase –> poorer prognosis
Lasts 10-14 dyas
Oliguric vs. Nonoliguric
Nonoliguric patients have a higher GFR and/or they reabsorb less in the tubules
Less severe injury with nonoliguric