AKI

Question 1

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?

Answer 1

acute kidney injury

Question 2

In global south nations, what is the primary cause of AKI?

Answer 2

hypovolemic shock from diarrhea

Question 3

In global north countries, what is a primary cause of AKI?

Answer 3

bypass cardiac surgery

Question 4

If you have CKD, what is your risk of developing AKI in a hospital?

Answer 4

2 to 40x higher

Question 5

Per KDIGO, what changes in serum creatinine define AKI?

Answer 5

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;

Question 6

per KDIGO, what urine volume changes define AKI?

Answer 6

urine volume < 0. 5 mL/kg/h (oliguria) for 6 hours

Question 7

Define oliguria

Answer 7

Oliguria is defined as 24 hour urine output <500 ml.

Question 8

Define anuria

Answer 8

Anuria is defined as 24 hour urine output of <50 ml.

Question 9

What term is interchangeable with AKI?

Answer 9

acute renal failure (ARF)

Question 10

• 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?

Answer 10

acute kidney injury

Question 11

How is pre renal AKI defined?

Answer 11

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.

Question 12

What parameter defines pre renal AKI?

Answer 12

effective arterial pressure, as interpreted by the arterial baroreceptors

Question 13

Name 4 possible causes of pre renal AKI

Answer 13

• 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

Question 14

CHF and MI’s could cause pre renal AKI through what mechanism?

Answer 14

decreased CO

Question 15

Dehydration, GI losses and blood loss would cause pre renal AKI through what mechanism?

Answer 15

hypovolemia

Question 16

Sepsis and shock would cause pre renal AKI through what mechanism?

Answer 16

peripheral vasodilation

Question 17

Renal autoregulation disruption (ACE inhibitors, AII receptor antagonists (ARBs), NSAIDs) and renal vascular occlusion would cause pre renal AKI through what mechanism?

Answer 17

selective renal ischemia

Question 18

In general, what FeNa suggests prerenal disease?

Answer 18

< 1 % but NOT diagnostic

Question 19

How do you calculate FeNA?

Answer 19

(UNa X SCr)/ (SNa X UCr) x 100

Question 20

What is the numerator for the FeNa calculation?

Answer 20

UNa X SCr

Question 21

What is an appropriate response by the kidney to decreased renal perfusion?

Answer 21

reabsorption of almost all Na (i.e. very low FeNa)

Question 22

What FeNa result would suggest that acute tubular necrosis should be considered?

Answer 22

1 -2%

>2% is usually ATN

Question 23

What are the 4 limitations for using FeNa in establishing the cause of AKI?

Answer 23

• 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.

Question 24

How do you manage pre renal AKI?

Answer 24

rapid diagnosis, reversal of underlying process (i.e. volume resuscitation or BP support)

Question 25

How is post renal AKI defined?

Answer 25

obstruction anywhere in the urinary tract causing renal failure

Question 26

How does obstruction cause AKI?

Answer 26

Severe or complete obstruction causes a marked increase in hydrostatic pressure in the renal pelvis causing a marked decrease in glomerular filtration rate. Obstruction may also cause tubular derangements in urinary concentrating ability, sodium reabsorption causing sodium wasting, defects in potassium secretion and impaired hydrogen secretion.

Question 27

These are all causes of what condition? 
	Ureteral obstruction
(bilateral to cause AKI)
•	Nephrolithiasis
•	Blood clots
•	Papillary necrosis
•	Retroperitoneal fibrosis
•	External compression, i.e., malignancy
•	Unintentional ligation intraoperatively
	Bladder obstruction
•	Prostatic hypertrophy
•	Prostate or other malignancy
•	Neurogenic bladder
	Urethral obstruction

Answer 27

postrenal AKI

Question 28

What lab study should be ordered to confirm post renal AKI?

Answer 28

BUN/Cr ratio

Question 29

What are two procedures that can be done to confirm and treat post renal AKI?

Answer 29

renal US and foley catheterization

Question 30

Following relief of obstruction, what is the next step in a post renal AKI?

Answer 30

post obstructive diuresis - resolved when electrolyte hemostasis and euvolemia reached

Question 31

These are all causes of what type of AKI? 
o	Vascular
o	Glomerular 
o	Interstitial
o	Tubular
	ATN

Answer 31

intrinsic

Question 32

Proteinuria and hematuria in a UA in the setting of possible AKI should indicated what process?

Answer 32

intrinsic AKI

Question 33

What lab studies should be ordered in evaluating a possible intrinsic AKI?

Answer 33

UA
urine sediment
Renal US

Question 34

What is indicated by urine eosinophils?

Answer 34

allergy

Question 35

What should be closely monitored when managing an AKI?

Answer 35

• Review electrolytes (Na, K, HCO3, calcium, phosphorous, magnesium), BUN, creatinine, urine output closely.

Question 36

When should kidney replacement therapy (i.e. dialysis) be considered in the management of AKI?

Answer 36

If these problems persist despite aggressive conservative therapy or in the presence of uremia (pericardial rub, mental status changes, bleeding) or volume overload compromising pulmonary status, consider kidney replacement therapy, dialysis.

Question 37

When managing an AKI in the setting of acidosis, what is the therapy?

Answer 37

bicarbonate

Question 38

When managing an AKI in the setting of a hyperkalemia, what is the therapy?

Answer 38

	Modify diet
	Insulin and glucose
	IV calcium
	Bicarbonate (if acidotic)
	Kayexalate (sodium/potassium exchange resin in gut)
	Loop diuretic
	Beta-agonists
	Dialysis

** just for exposure right now**

Question 39

What is kayexalate? when is it given?

Answer 39

sodium potassium exchange resin in the gut, used in hyperkalemic aKI

Question 40

When managing AKI in the setting of hyperphosphatemia, what is the therapy?

Answer 40

 Modify diet
 Calcium containing binders
 Non-calcium containing binders: sevelamer, lanthanum, aluminum hydroxide

Question 41

When managing AKI in the setting of drug intoxication, what is the therapy?

Answer 41

 Gastric lavage, depending on time of ingestion and ingested drug
 Hemodialysis (if indicated)