SM 195: AKI

Question 1

Definition of AKI

Markers of AKI

Answer 1

AKI: deterioration of renal function over hours to days
Markers: Falling GFR, SCr = slow to rise until AFTER GFR falls

Question 2

three different consensus definitions of AKI

Answer 2

1. RIFLE Criteria: Risk - Injury - Failure - Loss of fx - ESRD
   Observes GFR + Urine output over 7 days
2. AKIN: 3 stages based on SCr or Urine output over 48 hours, detects less severe AKI, avoids unreliable GFR
3. KDIGO: combination of AKIN + RIFLE
   SCr high/rising (>0.3mg/dL) in 48hrs OR SCr elevated 1.5x baseline in 7 days OR Urine Output <0.5mL/kg/hr over 6 hours

Question 3

Epidemiology of AKI (effect on mortality, natural hx, survival outcomes, cost)

Answer 3

Dx increases hospital mortality and 30-day mortality in cardiac surgery patients
Natural Hx: 4 outcomes:
1. Full Recovery
2. AKI to CKD: new reduced baseline, no full recovery
3. Acute-on-Chronic KD: new reduced baseline that then deteriorates
4. AKI to ESRD: no recovery at all
Survival Outcomes: worse outcomes as you progress through RIFLE criteria
cost: healthcare cost, resource utilization, cost increases with staging severity, ESRD ~ 7% of all Medicare expenditures

Question 4

Clinical Manifestations of AKI

Answer 4

Most are asymptomatic!
Vague symptoms: malaise, hematuria, flank pain, dyspnea, HTN, edema, confusion, lethargy
Oliguria/Anuria
Hyperkalemia + Metabolic Acidosis

Question 5

Cause of Pre-renal AKI

Answer 5

Low blood volume, hypotension, or perceived low EABV

May present with Edema or Volume Depletion

Question 6

Lab Tests of Prerenal AKI

Answer 6

Low Urine Na, Low FeNa

Highly Concentrated Urine

Question 7

Cause of Post-renal AKI and why it lowers GFR

Answer 7

bilateral obstruction in urinary tract

GFR drops due to obstruction increasing hydrostatic pressure in bowman’s space

Question 8

Hallmark of Interstitial Intrinsic AKI

Answer 8

HIGH EOSINOPHILS