1. (AKI) Acute Kidney Injury
Dr. Waleed Khairy, MD
Ain Shams University

2. Definition of AKI
There are more than 35 definitions of AKI (formerly acute renal failure) in literature!

3. Definition of Acute Kidney Injury (AKI) based on “Acute Kidney Injury Network”
Stage
Increase in Serum Creatinine
Urine Output 1
1.5-2 times baseline OR
0.3 mg/dl increase from baseline
<0.5 ml/kg/h for >6 h 2
2-3 times baseline
<0.5 ml/kg/h for >12 h 3
3 times baseline OR
0.5 mg/dl increase if baseline>4mg/dl
Any RRT given
<0.3 ml/kg/h for >24 h
Anuria for >12 h

4. RIFLE criteria for diagnosis of AKI based on The “Acute Dialysis Quality Initiative”
Increase in SCr
Urine output
Risk of renal injury
Injury to the kidney
Failure of kidney function
0.3 mg/dl increase
2 X baseline
3 X baseline OR
> 0.5 mg/dl increase if SCr >=4 mg/dl
< 0.5 ml/kg/hr for > 6 h
< 0.5 ml/kg/hr for >12h
Anuria for >12 h
Loss of kidney function
End-stage disease
Persistent renal failure for > 4 weeks
Persistent renal failure for > 3 months
Am J Kidney Dis Dec;46(6):

5. Epidemiology AKI occurs in ≈ 7% of hospitalized patients.
36 – 67% of critically ill patients (depending on the definition).
5-6% of ICU patients with AKI require RRT.
Nash K, Hafeez A, Hou S: Hospital-acquired renal insufficiency. American Journal of Kidney Diseases 2002; 39:
Hoste E, Clermont G, Kersten A, et al.: RIFLE criteria for acute kidney injury are associated with hospital mortality in critically ill patients: A cohort analysis. Critical Care 2006; 10:R73.
Osterman M, Chang R: Acute Kidney Injury in the Intensive Care Unit according to RIFLE. Critical Care Medicine 2007; 35:

6. Mortality according to RIFLE
Mortality increases proportionately with increasing severity of AKI (using RIFLE).
AKI requiring RRT is an independent risk factor for in-hospital mortality.
Mortality in pts with AKI requiring RRT 50-70%.
Even small changes in serum creatinine are associated with increased mortality.
Hoste E, Clermont G, Kersten A, et al.: RIFLE criteria for acute kidney injury are associated with hospital mortality in critically ill patients: A cohort analysis. Critical Care 2006; 10:R73.
Chertow G, Levy E, Hammermeister K, et al.: Independent association between acute renal failure and mortality following cardiac surgery. American Journal of Medicine 1998; 104:
Uchino S, Kellum J, Bellomo R, et al.: Acute renal failure in critically ill patients: A multinational, multicenter study. JAMA 2005; 294:
Coca S, Peixoto A, Garg A, et al.: The prognostic importance of a small acute decrement in kidney function in hospitalized patients: a systematic review and meta-analysis. American Journal of Kidney Diseases 2007; 50: .

7. Increase in Creatinine without AKI
Inhibition of tubular creatinine secretion
Trimethoprim, Cimetidine, Probenecid
Interference with creatinine assays in the lab (false elevation)
acetoacetate, ascorbic acid, cefoxitin
flucytosine

8. Increase in BUN without AKI
Increased production
GI Bleeding
Catabolic states (Prolonged ICU stay)
Corticosteroids
Protein loads (TPN-Albumin infusion)

9. New Biomarkers in AKI Alternatives to Serum Creatinine
Urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL)
Ann Intern Med 2008;148:
Urinary Interleukin 18
Am J Kidney Dis 2004;43:
Urinary Kidney Injury Molecule 1 (KIM-1)
J Am Soc Nephrol 2007;18:

10. NGAL: IL-18: KIM-1: Expressed in proximal and distal nephron
Binds and transports iron-carrying molecules
Role in injury and repair
Rises very early (hours) after injury in animals, confirmed in children having CPB
IL-18:
Role in inflammation, activating macrophages and mediates ischemic renal injury
IL-18 antiserum to animals protects against ischemic AKI
Studied in several human models
KIM-1:
Epithelial transmembrane protein, ?cell-cell interaction.
Appears to have strong relationship with severity of renal injury

11. Urine analysis Unremarkable in pre and post renal causes
Differentiates ATN vs. AIN. vs. AGN
Muddy brown casts in ATN
WBC casts in AIN
RBC casts in AGN

13. Major Disease Categories Causing AKI
Disease Category
Incidence
Prerenal azotemia caused by acute renal hypoperfusion
55-60%
Intrinsic renal azotemia caused by acute diseases of renal parenchyma:
-Large renal vessels dis.
-Small renal vessels and glomerular dis.
-ATN (ischemic and toxic)
-Tubulo-interestitial dis.
-Intratubular obstruccttion
35-40%
*>90%*
Postrenal azotemia caused by acute obstruction of the urinary tract
<5%

14. Prerenal Azotemia Intravascular volume depletion
bleeding, GI loss, Renal loss, Skin loss, Third space loss
Decreased cardiac output
CHF
Renal vasoconstriction
Liver Disease, Sepsis, Hypercalcemia
Pharmacologic impairment of autoregulation and GFR in specific settings
ACEi in bilateral RAS, NSAIDS in any renal hypoperfusion setting

15. Intrinsic Renal Azotemia
Large Renal Vessel Disease
Thrombo-embolic disease
Renal Microvasculature and Glomerular Disease
Inflammatory: glomerulonephritis, allograft rejection
Vasospastic: malignant hypertension, scleroderma crisis, pre- eclampsia, contrast
Hematologic: HUS-TTP, DIC
Acute Tubular Necrosis (ATN)
Ischemic
Toxic
Tubulo-interestitial Disease
Acute Interestitial Nephritis (AIN), Acute cellular allograft rejection, viral (HIV, BK virus), infiltration (sarcoid)
Intratubular Obstruction
myoglobin, hemoglobin, myeloma light chains, uric acid, tumor lysis, drugs (indinavir, acyclovir, foscarnet, oxalate in ethylene glycol toxicity)

16. Postrenal azotemia Stones Blood clots Papillary necrotic tissue
Urethral disease
anatomic: posterior valve
functional: anticholinergics, L-DOPA
Prostate disease
Bladder disease
anatomic: cancer, schistosomiasis
functional: neurogenic bladder

17. Initial diagnostic tools in AKI
History and Physical exam
Detailed review of the chart, drugs administered, procedures done, hemodynamics during the procedures.
Urinalysis
SG, PH, protein, blood, crystals, infection
Urine microscopy
casts, cells (eosinophils)
Urine lytes
Renal imaging
US, Mag-3 scan, Retrograde Pyelogram
Markers of CKD
iPTH, size<9cm, anemia, high phosphate, low bicarb
Renal biopsy

18. 5 Key Steps in Evaluating Acute Kidney Injury
Obtain a thorough history and physical; review the chart in detail
Do everything you can to accurately assess volume status
Always order a renal ultrasound
Look at the urine
Review urinary indices

19. Prevention of AKI in ICU
Recognition of underlying risk factors
Diabetes
CKD
Age
HTN
Cardiac/liver dysfunction
Maintenance of renal perfusion
Avoidance of hyperglycemia
Avoidance of nephrotoxins
Dennen P, Douglas I, Anderson R,: Acute Kidney Injury in the Intensive Care Unit: An update and primer for the Intensivist. Critical Care Medicine 2010; 38:

20. Antibiotics
AntiHyperlipidemics
Aminoglycosides (10-15% Incidence of Acute Tubular Necrosis)
Statins
Vasculitis reaction
Gemfibrozil
Occurs in 10-20% patients on 7 day course
Associated with Acute Renal Failure due to Rhabdomyolysis
Nephrotic Syndrome type reaction
Results in non-oligurics; increased Creatinine
Fenofibrate (Tricor)
Diuretics (Thiazides and furosemide)
Increases Serum Creatinine without significant decrease in GFR
A single dose early in septic course is usually safe
Allopurinol
Cimetidine
Serum Creatinine rise is reversible on stopping Fenofibrate
Sulfonamides
Amphotericin B (Incidence 80-90%)
Chemotherapy
Dilantin
Levofloxacin
Ciprofloxacin
Ifosphamide
Rifampin
Causes Fanconi's Syndrome
Tetracycline
Miscellaneous Drugs
Acyclovir (only nephrotoxic in intravenous form)
Chronic Stimulant Laxative use
Resulting chronic volume depletion and Hypokalemia causes nephropathy
Pentamidine
Chemotherapy and Immunosuppressants
Radiographic contrast
Cisplatin
ACE Inhibitors
Methotrexate
Expect an increase of Serum Creatinine in Chronic kidney disease
Mitomycin
Cyclosporine
NSAIDs
Heavy Metals
Aspirin
Mercury Poisoning
Low dose Aspirin reduces Renal function in elderly
Lead Poisoning
Arsenic Poisoning
Decreased Creatinine Clearance after 2 weeks of use
Bismuth
Changes persisted for at least 3 weeks off Aspirin
Lithium related kidney disorders
Polydipsia and Nephrogenic Diabetes Insipidus
Mesalamine (Asacol, Pentasa)
Mesalamine is an NSAID analog and has systemic absorption from the bowel
Acute Renal Failure
Dialysis indications: Creatinine >2.5 or Seizures, ALOC, Rhabdomyolysis
Penicillins and Cephalosporins
Chronic kidney disease with fibrosis
Hypersensitivity (fever, rash, arthralgia)

21. Prevention of Contrast-Induced Nephropathy
Avoid use of intravenous contrast in high risk patients if at all possible.
Use pre-procedure volume expansion using isotonic saline (?bicarbonate).
NAC
Avoid concomitant use of nephrotoxic medications if possible.
Use low volume low- or iso-osmolar contrast
Dennen P, Douglas I, Anderson R,: Acute Kidney Injury in the Intensive Care Unit: An update and primer for the Intensivist. Critical Care Medicine 2010; 38:

22. Prevention of AKI in hepatic dysfunction
Intravenous albumin significantly reduces the incidence of AKI and mortality in patients with cirrhosis.
Albumin decreases the incidence of AKI after large volume paracentesis.
Albumin and terlipressin decrease mortality in HRS.
Sort P, Navasa M, Arroyo V, et al.: Effect of intravenous albumin on renal impairment and mortality in patients with cirrhosis and spontaneous bacterial peritonitis. New England Journal of Medicine 1999; 341:
Gines P, Tito L, Arroyo V, et al.: Randomised comparative study of therapeutic paracentesis with and without intravenous albumin in cirrhosis. Gastroenterology 1988; 94:
Gluud L, Kjaer M, Christensen E: Terlipressin for hepatorenal syndrome. Cochrane Database Systematic Reviews 2006; CD

23. Management of AKI in ICU
Treatment is largely supportive in nature Maintain renal perfusion
Correct metabolic derangements
Provide adequate nutrition
? Role of diuretics
Renal Replacement therapy remains the cornerstone of management of minority of patients with severe AKI

24. Maintaining renal perfusion
Human kidney has a compromised ability to autoregulate in AKI.
Maintaining haemodynamic stability and avoiding volume depletion are a priority in AKI.
Kelleher S, Robinette J, Conger J: Sympathetic nervous system in the loss of autoregulation in acute renal failure. American Journal of Physiology 1984; 246: F

25. Maintaining renal perfusion
The individual BP target depends on age, co- morbidities (HTN) and the current acute illness.
A generally accepted target remains MAP ≥ 65.
Bourgoin A, Leone M, Delmas A, et al.: Increasing mean arterial pressure in patients with septic shock: Effects on oxygen variables and renal function. Critical Care Medicine 2005; 33:

26. Volume resuscitation – which fluid?
no statistical difference between volume resuscitation with saline or albumin in survival rates or need for RRT.
Finfer S, Bellomo R, Boyce N, et al.: A comparison of albumin and saline for fluid resuscitation in the intensive care unit. New England Journal of Medicine 2004; 350:

27. Volume resuscitation – how much fluid?
Fluid conservative therapy decreased ventilator days and didn’t increase the need for RRT in ARDS patients.
Association between positive fluid balance and increased mortality in AKI patients.
Wiedeman H, Wheeler A, Bernard G, et al.: Comparison of two fluid management strategies in acute lung injury. New England Journal of Medicine 2006; 354:
Payen D, de Pont A, Sakr Y, et al.; A positive fluid balance is associated with worse outcome in patients with acute renal failure. Critical Care 2008; 12: R74

28. Which inotrope/vasopressor?
There is no evidence that from a renal protection standpoint, there is a vasopressor agent of choice to improve kidney outcome.
Dennen P, Douglas I, Anderson R,: Acute Kidney Injury in the Intensive Care Unit: An update and primer for the Intensivist. Critical Care Medicine 2010; 38:

29. Renal vasodilators?
renal dose dopamine (<5 μg/kg of body weight/min) increases RBF and, to a lesser extent, GFR. Dopamine is unable to prevent or alter the course of ischaemic or nephrotoxic AKI]. Furthermore, dopamine, even at low doses, can induce tachy- arrhythmia’s, myocardial ischaemia, and extravasation out of the vein can cause severe necrosis .Thus, the routine administration of dopamine to patients for the prevention of AKI or incipient AKI is no longer justified.
Lauschke A, Teichgraber U, Frei U, et al.: “Low-dose” dopamine worsens renal perfusion in patients with acute renal failure. Kidney 2006; 69:
Argalious M, Motta P, Khandwala F, et al.: “Renal dose” dopamine is associated with the risk of new onset atrial fibrillation after cardiac surgery. Critical Care Medicine 2005; 33:

30. Role of ANP analogues in AKI?
61 patients in 2 cardiothoracic ICU with post-op AKI assigned to receive recombinent ANP (50ng/kg/min) or placebo
The need for RRT before day 21 after development of AKI was significantly lower in ANP group (21% vs 47%)
The need for RRT or death after day 21 was significantly lower in ANP group (28% vs 57%)
Crit Care Med Jun;32(6):1310-5

31. Is there a role for Fenoldopam in prevention or treatment of AKI in ICU setting?
Dopamine-1 receptor agonist, lack of Dopamine-2, and alpha-1 receptor effect, make it a potentially safer drug than Dopamine!
Reduces in hospital mortality and the need for RRT in AKI
Reverses renal hypoperfusion more effectively than renal dose Dopamine
So far so good specially in cardiothoracic ICU patients, awaiting more powered trials in other groups!
J Cardiothorac Vasc Anesth Feb;22(1):23-6.
J Cardiothorac Vasc Anesth Dec;21(6):847-50
Am J Kidney Dis Jan;40(1):56-68
Crit Care Med Mar;34(3):707-14

32. Is there a role for diuretics in the treatment of AKI in ICU setting?
Loop diuretics may convert an oliguric into a non- oliguric form of AKI that may allow easier fluid and/or nutritional support of the patient. Volume overload in AKI patients is common and diuretics may provide symptomatic benefit in that situation. However, loop diuretics are neither associated with improved survival, nor with better recovery of renal function in AKI.
JAMA Nov 27;288(20):
Crit Care Resusc Mar;9(1):60-8

33. NAC
The most recent trials seem to confirm a potential positive preventive effect of N- acetylcysteine (NAC), particularly in contrast- induced nephropathy (CIN), NAC alone should never take the place of IV hydration in patients at risk for CIN; fluids likely have a more substantiated benefit. (150 mg/kg in 500 mL saline (0.9%)] over 30 min immediately before contrast exposure and followed by 50 mg/kg in 500 mL saline (0.9%) over the subsequent 4 h )

34. EPO
Erythropoietin (EPO) has tissue-protective effects and prevents tissue damage during ischaemia and inflammation, and currently trials are performed with EPO in the prevention of AKI post-cardiac surgery, CIN and post-kidney transplantation.

35. Case 1
26 yo F is involved in a MVA, with multiple fractures, blunt chest and abdominal trauma. She was briefly hypotensive on arrival to ED, received 6L NS and normalized BP. Non contrast CT showed small retroperitoneal hematoma. On day#2 her SCr is 0.9 mg/dl, lipase is elevated and tense abdominal distension is noted. US showed massive ascites. UOP drops to <20 cc/hr despite of 10 L total IV intake. On day#3, SCr is 2.1mg/dl, CVP is 17, UNa is 10 meq/L, with a bland sediment.
What is the cause of her AKI?
What bedside diagnostic test and therapeutic intervention is indicated?

36. Bladder pressure was 29 mmHg
UOP and SCr improved with emergent paracenthesis.
Dx: Abdominal Compartment Syndrome causing decreased renal perfusion from increased renal vein pressure.

37. Case 2
59 yo M, s/p liver transplant in 2001 and acute on chronic rejection, now decompensated ESLD, is admitted with worsening ascites, hepatic encephalopathy and GI bleed (which is now controlled). The only medications he has been receiving are Lactulose and omeprazole. He has been hemodynamically stable with average BP~100/70 mmHg.He had a 3.5 L paracenthesis on day 2. His SCr has been slowly rising from 1.2 to 4.7 mg/dl within the 2nd to 4th day of admission and his UOP has dropped to 150 cc/day. His daily FeNa is <1% despite of 2 L fluid challenge. His Urine sediment is blend. His renal US is normal.
What is the cause of his AKI?

38. Patient required HD.
He had a second liver transplant and came off HD after the surgery with stable SCr of 1.4 mg/dl.
Dx: Hepatorenal Syndrome (HRS)

39. Hepatorenal Syndrome
Major diagnostic criteria:
No improvement with at least 1.5 L fluid challenge
SCr >1.5 mg/dl or GFR< 40 cc/min
Absence of proteinuria (<500 mg/d)
Other causes are rouled out (obstruction, ATN, etc.)
Minor diagnostic criteria:
Urine volume < 400 cc/day
UNa < 10 meq/L
SNa < 130 meq/L
Urine RBC < 50/hpf

40. Case 3
45 yo M with CHF and Bipolar Disorder on Lithium for 10 years, admitted for abdominal pain after a heavy meal, which turned out to be due to acute cholecyctitis. He was kept NPO on D5 1/2NS 50 cc/hr. Next morning he felt well but thirsty and hungry, BP=120/80, I/O=1200/4500. His SCr rose from 1.2 to 1.9 mg/dl. SNa 149 meq/L. UNa 10 meq/L. UOsm 190 mOsm/Kg.
What is the cause of his AKI?

41. Patients IVF was changed to ½ NS, replacing 80% of UOP per hour
Patients IVF was changed to ½ NS, replacing 80% of UOP per hour. SCr and SNa improved to baseline in 2 days.
Dx: Prerenal azotemia secondary to renal free water loss in DI.

42. Case 4
54 yo F with CAD, on statin, started a new exercise program with intense weight training. She was brought to ED with neck pain, and LE weakness. VS stable, normal UOP, with dry mucosa. LE muscle strength 2/5 bilaterally. BUN 40 mg/dl, creatinine=8 mg/dl. FeNa 1.5%. Renal US normal. UA: , 3+ blood, few RBCs, few granular casts.
What would be the next test to order?
What may be the cause of her AKI?

43. Her CPK=57,700
She was treated with IV NaHCO3 to alkalinize urine to PH>6.5 .
Her UOP remained normal but she required HD for uremia.
Dx: ATN due to Rhabdomyolysis

44. Case 5
72 yo M with DM, and prostate cancer metastatic to the bone, s/p radiotherapy, on hormonal therapy. He is admitted with weakness, progressive weight loss, and persistent nausea. His med list also includes Diclofenac sodium daily for hip pain. BP=150/90, 350cc of urine collection immediately after foley placement, and normal exam. BUN=107 mg/dl, creatinine=9.8 mg/dl (2.0 almost for 6 months), which remained unchanged with hydration. Uric acid=8.2 mg/dl. UA: 1.010, 1+ protein, 1+ blood, few RBCs, no cast, no WBC. US showed cm kidneys, no hydronephrosis.
What seems to be the cause for his AKI?

45. Patient was initiated on HD for uremia and remained HD dependent for his symptomatic uremia.
Patient and his family were concerned about his renal recovery (outcome), so a renal Bx was done showing severe chronic interstitial nephritis, with fibrosis and glomerulosclerosis.
Dx: ESRD due to chronic tubulo-interstitial disease secondary to NSAIDs

46. Case 6
38 yo M with post ERCP pancreatitis, is admitted to ICU, intubated for hypoxic respiratory distress, is anuric, febrile, and hypotensive, requiring massive volume resuscitation, on two vasopressors. He has received 11 L of NS and other IV meds within the last 8 hours and currently his CVP~12, has coarse crackles, and 2+ edema. His Creatinine rose from 1.2 to 3.5 the morning after the above event, FeNa > 1%, UNa 45 meq/L, UA: , no protein, no blood, moderate epithelial cells, many muddy brown granular cell casts, moderate epithelial cell casts. US showed normal sized kidneys with no hydronephrosis.
What is the cause of his AKI?

47. He was started on CVVH (continuous veno- venous hemofiltration )for volume control. Has had a long hospital stay complicated with polymicrobial bacteremia and VAP (Ventilator-associated pneumonia).
Dx: ATN secondary to renal ischemia and sepsis

48. Natural Clinical Course of ATN
Initiation Phase (hours to days)
Continuous ischemic or toxic insult
Evolving renal injury
ATN is potentially preventable at this time
Maintenance Phase (typically 1-2 wks)
Maybe prolonged to 1-12 months
Established renal injury
GFR < 10 cc/min, The lowest UOP
Recovery Phase
Gradual increase in UOP toward post-ATN diuresis
Gradual fall in SCr (may lag behind the onset of diuresis by several days)

49. Thank you!