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Acute Kidney Injury
Ali Salim, MD
Professor of Surgery
Chief, Division of Trauma, Burns, Surgical Critical Care, and Emergency General Surgery
Disclosures
I have nothing to disclose
Acute Kidney Injury
Incidence
Definition
Causes
Treatment
RRT Controversies
Acute Kidney Injury
Sudden decline in kidney function
Due to:
Loss in small solute clearance
↓ GFR
Acute Kidney Injury
Sudden decline in kidney function
Disturbances in :
Fluid
Electrolytes
Acid base balance
Acute Kidney Injury
Sudden decline in kidney function
Spectrum of disease
Subclinical injury
Complete organ failure
Acute Kidney Injury
Common in ICU
7% of hospitalized patients
36% to 67% of critically ill patients
Acute Kidney Injury
↑ morbidity
↑ cost
↑ length of stay
↑ mortality
Mortality ↑ proportionately with ↑ severity
50% - 70% in severe AKI requiring RRT
Independent risk factor for in-hosp mortality
Acute Kidney Injury
↑ development of chronic kidney disease
Definitions
Definitions
RIFLE
AKIN
KDIGO
RIFLE
R -risk
I - injury
F - failure
L – loss
E – end stage kidney disease
Uses serum creatinine and UOP
RIFLE SCr Criteria UOP Criteria
R ↑ SCr x 1.5 < 0.5 ml/kg/hr x 6
hrs
I ↑ SCr x 2 < 0.5 ml/kg/hr x 12
hrs
F ↑ SCr x 3, or SCr ≥ 4
w/ an acute rise of at
least 0.5
< 0.5 ml/kg/hr x 24
hrs, or anuria x 12 hrs
L Persistent loss of
kidney function > 4
weeks
E Persistent loss of
kidney function > 3
months
AKIN
A - acute
K - kidney
I - injury
N - network
Even very small changes in SCr (≥ 0.3mg/dl)
adversely impact outcome
AKIN Stage SCr Criteria UOP Criteria
1 ↑ SCr ≥ 0.3 or ↑1.5 to
2 fold from baseline
< 0.5 ml/kg/hr > 8
hrs
2 ↑ SCr > 2 to 3 fold
from baseline
< 0.5 ml/kg/hr > 12
hrs
3 ↑ SCr > 3 fold from
baseline, or SCr ≥ 4
w/ an acute rise of at
least 0.5
< 0.5 ml/kg/hr x 24
hrs, or anuria x 12 hrs
KDIGO
K - Kidney
D - disease
I – improving
G - global
O - outcomes
Merging of RIFLE and AKIN
KDIGO
AKI
SCr ↑ ≥ 0.3 in 48 hours; or
SCr ↑ ≥ 1.5 times baseline within 7 days; or
UOP < 0.5 ml/kg/hr for 6 hours
Biomarkers
Replace or complement serum creatinine
Can diagnose AKI earlier
May provide information regarding etiology
Cystatin C is used in some hospitals
Causes of AKI
Top 5 Causes of AKI
Sepsis – up to 50% of cases
Major surgery
Low cardiac output
Hypovolemia
Medications
Medications
NSAIDS
Antimicrobials
Aminoglycosides
Amphotericin
Penecillins
Acyclovir
Chemotherapeutic agents
Other Causes
Hepatorenal syndrome
Trauma
Cardiopulmonary bypass
Abdominal compartment syndrome
Rhabdomyolysis
Obstructive Uropathy
Radiocontrast dye
Management of AKI
Optimizing hemodynamics
Maintain renal perfusion
Avoid hyperglycemia
Avoid nephrotoxins
Diuretics for volume overload
Adequate nutrition
RRT
Management of AKI
Optimizing hemodynamics
Maintain renal perfusion
Avoid hyperglycemia
Avoid nephrotoxins
Diuretics for volume overload
Adequate nutrition
RRT
Only treatment option for AKI
Management of AKI
No other supportive measures available
Best therapy is avoidance of further injury
Early intervention appears to be beneficial
Ideal intervention still under debate
Indications for RRT
No current consensus on indications
“Absolute” indications
Severe hyperkalemia
Clinically apparent signs of uremia
Severe acidemia
Volume overload
Renal Replacement Therapy
Choice of modality??
Timing of intervention??
Dose/Intensity of treatment??
Choice of Modality
Continuous versus intermittent
Continuous
SCUF
CVVH
CVVHD
CVVHDF
Choice of Modality
Continuous more closely approximate
normal physiology
Slow correction of metabolic derangements
Slow removal of fluid
Better tolerated in critically ill and
hemodynamically unstable
Data??
Intensity of Renal Support
Intensive renal support:
No decrease in mortality
Did not improve recovery of kidneys
Did not reduce rate of nonrenal organ failure
Zhang et al Am J Kid Dis 2015;66:322-330
Zhang et al Am J Kid Dis 2015;66:322-330
Zhang et al Am J Kid Dis 2015;66:322-330
Continuous versus Intermittent
No difference in outcome
Choice is influenced by:
Individual site availability
Resources
Cost
Clinician bias
Renal Replacement Therapy
Choice of modality??
Timing of intervention??
Dose/Intensity of treatment??
Timing of RRT
Early intervention seems to be important
When to start when conventional indications
are absent?
How early is early?
2011
2011
Earlier appears to be better
Heterogeneous studies
Definitive recommendation cannot be
made…
2011
2016
KDIGO stage 2
SCr ≥ 2 times baseline or
UOP < 0.5 ml/kg/hr ≥ 12 hrs
Plasma neutrophil gelatinase-associated
lipocalin > 150
2016
Early – within 8 hours of diagnosis
N=112
Delayed – within 12 hours of stage 3 AKI or
upon an absolute indication
N=119
2016
Early initiation
↓ mortality (39.3% vs 54.7%, p=0.03)
↑ renal recovery (53.6% vs. 38.7%, p=0.02)
↓ RRT duration (9 days vs. 25 days, p=0.04)
↓ hospital stay (51 days vs. 82 days, p<0.001)
2016
2016
AKIKI Study
KDIGO stage 3
Mechanical ventilation; or
Catecholamine infusion
AKIKI Study
Early
Immediately after randomization
Late
If at least one criteria met
Severe hyperkalemia
Metabolic acidosis
Pulmonary edema
BUN > 112
Oliguria > 72 hours
AKIKI Study
Early
N=311
Within 2 hours after randomization
Late
N=308
Within 57 hours after randomization
2016
Delayed:
No difference in mortality
Averted need of RRT in many
2016
Timing
Question of timing remains unanswered
Still need definition of “early”
More studies warranted
Renal Replacement Therapy
Choice of modality??
Timing of intervention??
Dose/Intensity of treatment??
Dose/Intensity of Treatment
Intensities range from intensive to less
intensive with respect to CRRT
Can also have variable intensities with
intermittent dialysis
What is best??
No difference in outcome between
intensive renal support and less-intensive
support
2016
Cochrane Review - 2016
Compared less intense (range 20-25
ml/kg/hr) to more intense (35-48 ml/kg/hr)
No difference:
Mortality
Renal recovery
Postsurgical AKI
High intensity appears to reduce risk of death
Acute Kidney Injury
Incidence
Definition
Causes
Treatment
RRT Controversies
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