Acute Kidney Injury Flashcards
Technical Definition of AKI
Within 48 hours, abrupt decline in kidney function including one of the following…
Serum creatinine increases >0.3mg/dL
Serum creatinine increases 50%
Oliguria of less than 0.5 mL/kg/hr for over 6 hours
3 general categories for AKI Causes
Prerenal
Intrinsic Renal
Postrenal
What are the 2 most common causes of AKI?
Prerenal azotemia
Ischemic ATN
List some causes of Prerenal Azotemia
Absolute or relative decrease in ECV
Vascular stenosis or occlusion
Impaired renal autoregulation (with low ECV state)
Describe the two primary mechanisms of renal autoregulation. Which drugs could interrupt each process?
Afferent arteriole vasodilation (inhibited by NSAIDs)
Efferent arteriole vasoconstriction (inhibited by ACEIs or ARBs)
What is the biggest cause of postrenal failure?
Obstruction
What are some risk factors for postrenal failure?
Old men with prostate disease
Solitary kidney
Intraabdominal cancer
How to diagnose postrenal failure?
Physical exam
Renal ultrasound
Measurement of post void residual volume
What are some causes of Intrinsic Renal Failure?
Vascular (malignant HTN)
Acute glomerular diseases
AIN (drug associated or not)
ATN (Ischemic or nephrotoxic)
What are the most common causes of ATN?
Sepsis
Surgery
Nephrotoxic exposure (ABX, recreational drugs, hemoglobinuria, myoglobinuria, tubular proteins or crystals)
Describe the pathogenesis of ATN.
First, see dirty or muddy brown urine.
Enter an oliguric phase, then a polyuric phase during recovery
What is malignant HTN?
BP > 180/120 with impending/progressive end organ damage
HTN encephalopathy Intracerebral hemorrhage ACS LV dysfuntion Aortic dissection Eclampsia
What are the two general categories of acute glomerular disease?
Nephrotic syndrome
Nephritic syndrome
Describe some basic characteristics of nephritic syndrome
Hematuria, maybe a little proteinuria
Tends to have inflammation
Active urinary sediment (cells and casts present)
Describe some basic characteristics of nephrotic syndrome
Proteinuria
No inflammatory component
Acute Interstitial Nephritis (AIN) is most commonly caused by what?
Drugs (PPIs, ABX, NSAIDs)
Infections
What is the classic triad of AIN symptoms?
Fever
Rash
Peripheral eosinophilia
Signs that a patient is in volume overload (too wet)
Abdominojugular reflux
S3 gallop
Ascites
Peripheral edema and rales heard
Signs that a patient is in volume depletion (too dry)
Dry mucous membranes
Skin tenting
Neck veins flat at 0 degrees
Signs of shock
BUN Creatinine Ratio >10:1 may indicate…
Prerenal azotemia Increased urea load Obstructive uropathy Ureteroenterostomy Decreased muscle mass
BUN Creatinine Ratio =10:1 may indicate…
Normal
ATN
CKD
BUN Creatinine Ratio
Decreased urea load
Inhibition of creatinine secretion
Increased creatinine load
Increased muscle mass
What are the situations when you might consider putting a patient on dialysis?
AEIOU
Acidosis (severe or refractory) Electrolyte derangement (severe hyperkalemia) Intoxication syndrome Overload (significant pulm edema) Uremia
What drugs should you be careful about using in patients at risk for AKI?
NSAIDs
ACEIs
ARBs
What is the general prognosis of AKI?
Most people recover, but 5-16% of cases are irreversible
