AKI Flashcards
(41 cards)
The kidney’s inability to excrete nitrogenous waste, maintain fluid balance, AND maintain electrolyte balance over a period of hours to days is the definition for which condition?
acute kidney injury
In global south nations, what is the primary cause of AKI?
hypovolemic shock from diarrhea
In global north countries, what is a primary cause of AKI?
bypass cardiac surgery
If you have CKD, what is your risk of developing AKI in a hospital?
2 to 40x higher
Per KDIGO, what changes in serum creatinine define AKI?
o Increase in serum creatinine by ≥0.3 mg/dL within 48 hours; or
o Increase in serum creatinine by ≥1.5 times baseline, which is known or presumed to have occurred within the prior seven days;
per KDIGO, what urine volume changes define AKI?
urine volume < 0. 5 mL/kg/h (oliguria) for 6 hours
Define oliguria
Oliguria is defined as 24 hour urine output <500 ml.
Define anuria
Anuria is defined as 24 hour urine output of <50 ml.
What term is interchangeable with AKI?
acute renal failure (ARF)
• Extracellular volume expansion manifesting as hypertension, congestive heart failure, pulmonary or peripheral edema
• Hyperkalemia
• Metabolic acidosis
• Hyperphosphatemia
• Anemia due to a decrease in the production of erythropoietin
• Uremia (a toxic metabolic state due to a variety of accumulated toxins)
These are all systemic manifestations of what syndrome?
acute kidney injury
How is pre renal AKI defined?
a reduction in the glomerular filtration rate (GFR) as a result of decreased renal perfusion that is reversed with restoration of perfusion and not associated with structural damage of the kidney.
What parameter defines pre renal AKI?
effective arterial pressure, as interpreted by the arterial baroreceptors
Name 4 possible causes of pre renal AKI
- Decreased CO: CHF, MI
- Hypovolemia: Dehydration, GI losses, Blood loss
- Peripheral vasodilation: Sepsis, Shock
- Selective renal ischemia: Renal autoregulation disruption (ACE inhibitors, AII receptor antagonists (ARBs), NSAIDs), Renal vascular occlusion
CHF and MI’s could cause pre renal AKI through what mechanism?
decreased CO
Dehydration, GI losses and blood loss would cause pre renal AKI through what mechanism?
hypovolemia
Sepsis and shock would cause pre renal AKI through what mechanism?
peripheral vasodilation
Renal autoregulation disruption (ACE inhibitors, AII receptor antagonists (ARBs), NSAIDs) and renal vascular occlusion would cause pre renal AKI through what mechanism?
selective renal ischemia
In general, what FeNa suggests prerenal disease?
< 1 % but NOT diagnostic
How do you calculate FeNA?
(UNa X SCr)/ (SNa X UCr) x 100
What is the numerator for the FeNa calculation?
UNa X SCr
What is an appropriate response by the kidney to decreased renal perfusion?
reabsorption of almost all Na (i.e. very low FeNa)
What FeNa result would suggest that acute tubular necrosis should be considered?
1 -2%
>2% is usually ATN
What are the 4 limitations for using FeNa in establishing the cause of AKI?
- The FENa criterion of < 1% to diagnose prerenal disease applies only to patients with a marked reduction in GFR.
- Single measurements of serum creatinine may not provide an accurate estimate of the GFR.
- There are a number of causes of AKI other than prerenal disease in which the FENa can be <1%.
- The FENa may be > 1% when prerenal disease occurs in patients with CKD or any cause of sodium wasting, such as diuretic therapy while the diuretic is still acting.
How do you manage pre renal AKI?
rapid diagnosis, reversal of underlying process (i.e. volume resuscitation or BP support)
