Acute Kidney Injury Flashcards
What is the definition of acute kidney injury?
An abrupt (within 48 hours) reduction in kidney function, defined as:
• Increase in serum creatinine of > 0.3mg/dL OR
• % increase in serum creatinine of 50% OR
• Oliguria of 6 hours
What is the relationship between acute kidney injury and critical illness?
AKI is often found in critically ill patients
What are the 3 groups of AKI causes?
- Prerenal Azotemia
- Intrinsic Renal Disease
- Postrenal Obstruction
What are the causes of prerenal azotemia?
i. True hypovolemia
ii. Decreased effective circulating volume
iii. Renal artery stenosis/occlusion
iv. NSAID/ACE-I/ARB mechanism
What are the causes of intrinsic renal disease?
i. Vascular causes
ii. Glomerular disease
iii. ATN
iv. AIN
What are the causes of postrenal obstruction?
i. Bladder outlet obstruction
ii. Bilateral ureteral obstruction
iii. Unilateral ureteral obstruction in a solitary kidney
What are the 2 most common causes of AKI?
- Prerenal Azotemia
- Ischemic ATN
What can prerenal azotemia progress to if it is not corrected?
Ischemic ATN
What is prerenal azotemia?
It is an appropriate response to renal hypo perfusion that leads to a build up of nitrogen compounds in the blood
What are some of the causes of prerenal azotemia?
- Decreased ECV
- Renal artery stenosis
- Drug-induced impaired renal autoregulation
What is the normal renal response to drop in BP?
- Afferent vasodilation
- Efferent vasoconstriction
What is the effect of NSAIDs on the GFR?
NSAIDs decrease the GFR by causing afferent arterial vasoconstriction
What is the effect of ACE-I/ARBs on the GFR?
They do not affect the GFR that much. They dilate the efferent arterioles which has a protective effect.
What are some of the risk factors for postern disease?
- Older men with prostate disease
- Solitary kidney
- Intra-abdominal (pelvic) cancer
What are the 4 categories of intrinsic renal disease?
- vascular causes
- glomerular diseases
- acute interstitial nephritis
- acute tubular necrosis