2. Acute Kidney Injury in ICU
Dr. Firouzeh Moeinzadeh Nephrologist
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3. Purposes Definition of AKI Etiology of AKI in ICU setting
Renal replace therapy in ICU
Fluid or diuretics?
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4. AKI is not a single disease but rather a syndrome comprising multiple clinical conditions
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5. Depending on the definition, acute renal failure was said to affect anywhere from 1 to 25% of intensive care unit (ICU) patients and to carry a mortality rate from 15 to 60%.
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6. Patients, especially patients in the ICU, are dying of AKI and not just simply with AKI.
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8. RIFLE classification was useful for predicting
Recovery of renal function: P≤0.001
Requirement for renal replacement therapy: P≤0.001
Length of hospital stay for survivors: P≤0.001
In-hospital mortality: P=0.035
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9. Survival appears to be affected for at least 1 year and maybe longer.
It is the interaction between susceptibility (i.e., features intrinsic to the patient) and exposure (i.e., the causative factor or factors).
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10. Urinary tract obstruction
Exposures:
Myonecrosis
Heart failure
Sepsis
Nephrotoxins
Ischemia
Urinary tract obstruction
Major surgery
Liver disease
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11. SEPSIS induced AKI
Several studies have reported that sepsis induced AKI is associated with short- and long-term risk of death.
The development of sepsis appears to be common in patients with AKI and is associated with high mortality and increased hospital duration.
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12. Multiple common settings: sepsis, cardiac surgery, radio contrast…… is common!!
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13. Recovery of renal function is also a problem, with many patients failing to recover renal function: patients with AKI who required renal replacement therapy that 33% of the survivors were still on renal replacement therapy after 12 months.
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14. less severe AKI may be associated with important long-term outcomes including progression of CKD and cardiovascular disease
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16. AKI and the (innate) immune system
Increased myocardial transcription of tumor necrosis factor-a and interleukin (IL)-1.
Blockade of tumor necrosis factor-a inhibited apoptosis.
Patients with septic AKI have impaired leukocyte rolling when compared with septic patients without AKI.
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17. Treatment of AKI Intermittent hemodialysis (IHD),
Treatment of acute kidney injury (AKI) is principally supportive -- renal replacement therapy (RRT) indicated in patients with severe kidney injury.
Goal: optimization of fluid & electrolyte balance
Multiple modalities of RRT :
Intermittent hemodialysis (IHD),
continuous renal replacement therapies (CRRTs)
hybrid therapies, ie sustained low-efficiency dialysis (SLED)
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18. Timing of initiation of RRT
Earlier initiation of RRT in critically ill patients with AKI may have a beneficial impact on survival and outcomes but data is insufficient
Many recommend initiation of RRT prior to the development of advanced uremic symptoms, or when the BUN reaches mg/dL
No known threshold of fluid overload for initiating RRT
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19. Discontinuation of RRT
Until “evidence of recovery of kidney function”
Improved urine output in oliguria
Decreasing creatinine
Creatinine clearance minimum 12 mL/min, some say 20 mL/min
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20. RRT in sepsis/MODS
RRT has been proposed as a “Extracorporeal blood purification therapy (EBPT)” as adjuvant therapy for sepsis/MODS for removal of harmful inflammatory mediators or endotoxemia
Some support from animal models and small clinical studies
Eg cytokines can be demonstrated in dialysis effluent
Miller's Anesthesia, 7th ed. 2009
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Foot. Current Anaesthesia and Critical Care 2005; 16:

21. RRT in sepsis/MODS Overall, no good data showing improved outcomes
Insufficient evidence to support a role for RRT as adjuvant therapy for septic shock unless severe acute renal failure is present.
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22. Conclusions
AKI in the ICU is common and associated with high mortality
The best time to initiate and stop RRT is controversial
No good data that CRRT is better than IRRT in the ICU, except for a few specific situations
Consider CRRT if severely unstable pts, severe volume overload, combined renal/hepatic failure
IRRT best if bleeding risk or acute hyperkalemia/poisoning
SLED is the most flexible
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23. Conclusions
More intense RRT dosing in the ICU does not improve outcome
Insufficient evidence to support a role for RRT as adjuvant therapy for septic shock unless severe acute renal failure is present
Ultrafiltration is effective for fluid removal in CHF
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24. Specific considerations in ICU patients with AKI
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25. Oliguria and AKI in ICU Very common.
Oliguria is short-lived, the typical response is observation (but not always).
Is sustained, two responses are typically applied
Fill (fluid administration) hoping that urine will “spill”
Squeeze (increase BP with vasoactive drugs) and diurese (start and sustain diuresis with loop diuretic)
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26. Fill and Spill is dangerous and futile
In the vast majority of ICU patients there is no “fluid depletion”
More fluid= No difference to renal blood flow
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27. More fluid =Minor short-lived changes in urine output
More fluid =Increased risk of dangerous fluid overload
Yet “fill & spill” is very common
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28. After fill and spill (into the lungs!)
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29. Why we need to squeeze Almost all ICU patients are fluid replete
Almost all are relatively hypotensive
The typical MAP in a 60 year old man is >100 mmHg !!
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30. Renal blood flow is pressure dependent at low MAP
Restoring blood pressure closer to normal may improve renal blood flow and diuresis
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32. Why we also need to diurese
Sustained oliguria leads to fluid overload due to obligatory fluid intake in ICU
Fluid, acid-base, potassium management is much easier if urine output is maintained
Loop diuretics have useful effects on renal hemodynamics
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33. Possible beneficial effects of loop diuretics
Renal Vasodilatation (Direct vasodilatation, Inhibition of renal prostaglandin dehydrogenase; Blockade of TGF-induced vasoconstriction; Blockade of obstruction effect.
Increased tubular flow (Decreased tubular obstruction by casts; Less back-leak; Decreased back pressure with effect on GFR)
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34. Oliguria/AKI: A Real ICU doctor’s approach
Restore MAP with noradrenaline (norepinephrine)
Make sure CO is adequate
All simultaneous and rapid (minutes)
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35. Approach….. Administer furosemide infusion
Maintain diuresis at between 1-2 ml/kg/hr
Administer potassium and magnesium as needed
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36. The Physiological Folly of (excessive) Fluid Filling
Fluids are bad after surgery
Fluids are bad in ARDS
They are physiologically futile in oliguria
After the first couple of hours, they are physiologically irrational in most ICU patients
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37. In critically ill patients and in patients with AKI, fluid accumulation has been shown to worsen prognosis.
A 10% fluid accumulation was associated with adverse outcomes in clinical settings.
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38. Mortality was lower when fluid overload was corrected by dialysis.
The duration of fluid overload while remaining on dialysis was similarly associated with increased mortality, suggesting a cumulative effect of fluid overload on mortality.
Mortality was lower when fluid overload was corrected by dialysis.
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39. Cumulative fluid overload may also be associated with a decreased likelihood of renal recovery.
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40. Conclusions Fluids can have a high physiological price
Fluids do not correct vasodilatation
Fluids do not increase renal O2 delivery
They do not increase perfusion pressure
You can get rid of vasopressor effects in minutes but getting fluid out is not that easy
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41. Are you agree:
fluids kill !!
Squeeze and diurese !!
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42. Thanks for your attention
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