Acute Kidney InjuryProf.Dr.Gülçin KantarcıYeditepe University Nephrology Department

Aims & objectives

• State the definition, pathophysiology, clinical findings and prevention methods of acute kidney injury

Reference1. Current Medical Diagnosis and Treatment, Maxine A. Papadakis, Stephen J. McPhee, Eds. Michael W. Rabow, Associate Ed. http://accessmedicine.com/resourceTOC.aspx?resourceID=1Chapter 22. Kidney Disease (ACUTE RENAL FAILURE: GENERAL)2. Bates' Guide to Physical Examination & History Taking 11th edition, Bickleys LS, Szilagyi PG; Lippincott Williams and Wilkins¸ 3. Kumar and Clark's Clinical Medicine, 8th edition; Kumar & Clark, Elsevier4. Andreoli and Carpenter's Cecil Essentials of Medicine 8th edition, Andreoli and Carpenter, ElsevierPART 11: RENAL AND GENITOURINARY DISEASES 122: Acute Kidney Injury , Bruce Molitoris Editor: Goldman, Lee5. CURRENT Diagnosis & Treatment: Nephrology & Hypertension Edgar V. Lerma, Jeffrey S. Berns, Allen R. Nissenson (ACUTE RENAL FAILURE Chapter 9-11-14)

PRESENTATION TOPICS

• Essentials of Diagnosis• General Considerations• Clinical Findings• Classification & Etiology

ACUTE KIDNEY INJURY ( Acute renal failure) • also known as acute renal failure, is defined as a

sudden decrease in kidney function, resulting in an inability to maintain acid-base, fluid and electrolyte balance and to excrete nitrogenous wastes

• It often results from major trauma, illness, or surgery but is sometimes caused by a rapidly progressive, intrinsic renal disease.

Kidney Disease: Improving Global Outcomes. Clinical practice guideline on acute kidney injury. 2011. www.kdigo.org

• Serum creatinine rises ≥ 1.5 fold from the reference value, which is known or presumed to have occurred within one week or

• urine output is < 0.5ml/kg/hr for >6 consecutive hours

• If a reference serum creatinine value is not available within 3 months (acceptable up to one year) and AKI is suspected

• repeat serum creatinine within 24 hours • a reference serum creatinine value can be estimated from the nadir

serum creatinine value if patient recovers from AKI

Symptoms of Acute Kidney Injury

• anorexia, nausea, vomiting. • Seizures and coma may occur if the condition is untreated. • Fluid, electrolyte, and acid-base disorders develop quickly. • Hypovolemia can cause states of low blood flow to the

kidneys, sometimes termed prerenal states, whereas hypervolemia can result from intrinsic or postrenal disease.

• Pericardial effusions can occur with uremia, and a pericardial friction rub can be present

Fluid overload in ARF

Diagnosis

• based on laboratory tests of renal function, including serum creatinine.

• urinary sediment, and imaging are needed to determine the cause.

CLINICAL CRITERIA

RIFLE criteria(ADQI workgroup Crit Care 2004)

AKIN (Acute Kidney Injury Network) (Mehta et al.Acute Kidney Injury Network Crit Care 2007)

RIFLE kriterleri (ADQI workgroup Crit Care 2004)

Serum creatinine criteria Urine output criteria

1

Increase in serum creatinine of more than or equal to 0.3 mg/dl

(≥ 26.4 μmol/l) or increase to more than or equal to 150% to 200%

(1.5- to 2-fold) from baseline

Less than 0.5 ml/kg/hr for more than 6 hours

2bb

Increase in serum creatinine to more than 200% to 300%

(> 2- to 3 fold) from baseline

Less than 0.5 ml/kg/hr for more than 12 hours

3

Increase in serum creatinine to more than 300% (> 3-fold)

from baseline (or serum creatinine of more than or equal to 4.0

mg/dl [≥ 354 μmol/l] with an acute increase of at least 0.5 mg/dl

[44 μmol/l])

Less than 0.3 ml/kg/hr for

24 hours or anuria for 12 hours

AKIN (Acute Kidney Injury Network)Mehta et al. Critical Care 2007

Prerenal azotemia

• inadequate renal perfusion. causes ECF volume depletion cardiovascular disease.

Main cause of AKI

PRE-RENAL (%55-60) • Intravascular volume depletion -Hemorrhage -GI losses -Renal losses -Skin and mucous membrane losses -Third space losses

• Renal vasodilation• Systemic vasodilaton• Decreased cardiac output• Pharmocologic agent that acutely impair autoregulation & GFR

symptoms of prerenal AKI (ARF)symptoms related to hypovolemia, including thirst, decreased

urine output, dizziness, and orthostatic hypotension. How can we distinguish Prerenal AKI? • Ask about volume loss from vomiting, diarrhea, sweating,

polyuria, or hemorrhage. • Patients with advanced cardiac failure leading to depressed

renal perfusion may present with orthopnea and paroxysmal nocturnal dyspnea.

• Insensible fluid losses can result in severe hypovolemia in patients with restricted fluid access and should be suspected in elderly patients and in comatose or sedated patients.

Renal causes of AKI ( 35-40 %)intrinsic renal disease or damage • most common causes: - prolonged renal ischemia (post ischemic ATN) -nephrotoxins.• RPGNWegener / PAN/ Goodpasture • Nephrotoc. Vanco. /aminogli. /NSAID/ Amphoterisin-B, Radiocontrast• Acute pyelonephritis• Acute tubulointertisisel nephrithis (ATIN)• Cholesterol crystal embolism• Contrast nephropathy

Renal ARFGlomerular diseases: Nephritic syndrome of hematuria, edema, and

HTN indicates a glomerular etiology of AKI. Query about prior throat or skin infections.

Tubular diseases: ATN should be suspected in any patient presenting after a period of hypotension secondary to cardiac arrest, hemorrhage, sepsis, drug overdose, or surgery.

• A careful search for exposure to nephrotoxins (Vanco. /aminogli. /NSAID/ Amphoterisin-B, Radiocontrast) should include a detailed list of all current medications and any recent radiologic and angiographic examinations

• Pigment-induced AKI should be suspected in patients with possible rhabdomyolysis (muscular pain, recent coma, seizure, intoxication, excessive exercise, limb ischemia) or hemolysis (recent blood transfusion).

• Allergic interstitial nephritis should be suspected with fevers, rash, arthralgias, and exposure to certain medications including NSAIDs and antibiotics.

Postischemic acute tubular necrosis (ATN) • Postischemic acute tubular necrosis (ATN) can

result from prolonged hypotension due most commonly to:

•Major surgery (particularly cardiac surgery, abdominal aortic aneurysm surgery, and surgery to correct obstructive jaundice)

•Sepsis•Marked hypovolemia•Severe pancreatitis

Pathophysiology of Postischemic acute tubular necrosis (ATN) Endothelial injury from vascular perturbations

• Ischemia/hypoxemia (including re-perfusion injury) • Tubular cell necrosis/apoptosis

• Shed into lumen, tubular obstruction • Decreased tubular flow • Tubulo-glomerular back-leak leads to decreased GFR

Formation of inflammatory mediators • Oxidative stress, cytokine release

Abolishment of renal autoregulation • Intrarenal vasocontriction > vasodilatation

Pathophysiology 2

AKI involves both vascular and tubular effects

AKI that secondary to sepsis;sympathetic system and renin-angiotensin-aldosterone system are stimulated and cause renal vasoconstriction

Diagnostic Work-Up for AKI

History and physical examination Urinalysis, urine microscopy Urine chemistry Response to treatments (volume) Imaging (U/S) Serologies +/- Kidney biopsy

Nephrotoxicity

Acute tubuler injury•Aminoglycosides•Acyclovir•Indinavir•Cysplatin•Cyclosporin•cephalosporines•Amphotericin

Acute int. nephritisAll drugs

Hemodynamic disregulation•ACEI•ATII RB•Cyclosporin•NSAID•Radiocontrast Nephrotoxicity

RADIOCONTRAST NEPHRO.

Risk FactorsRisk Factors• Preexisting renal failure• DM• >2ml/kg Radio contrast• volume depletion• Age>60• Hyperuricemia• hepatic failure

What can we do?What can we do?•Cr controls before the exposure•Non-Nephrotoc. Contrast media•Lower the contrast dose•Hydration (Before 12 hour)%0.45 NaCl 100ml/hour or sodyum bicarbonate•Oral theophylline (200mg; 2x1)

•Onehour before-48 hours •N-acetylcystein (600mg; 2x1)

•24 hour before-48 hours

Sodium bicarbonate solution for prevention of contrast-induced nephropathy

• I.V. infusion: 154 mEq/L sodium bicarbonate in D5W solution: 3 mL/kg/hour for 1 hour immediately before contrast injection, then 1mL/kg/hour during contrast exposure and for 6 hours after procedure

• To prepare solution, remove 154 mL from 1000 mL bag of D5W; replace with 154 mL of 8.4% sodium bicarbonate; resultant concentration is 154 mEq/L

CRUSH SYNDROME

Crush trauma of the muscles

• MYOGLOBIN Glomerular filtrate• Dehidratation• Tubular obstruction is depens upon the death cell and gelous

Myoglobin

Crush Syndrome• Hypovolaemic shock (due to sequestration of water in the injured

muscle cells) • Dark urine (Due to high concentration of myoglobin in the

gloemerular filtrate which comes from the swollen muscles)• Hyperkalemia (release of cellular potassium by the injured muscle

cells) This can also lead to:• Metabolic acidosis (release of cellular phosphate and sulphate by

the injured muscle cells) • Acute Kidney Injury • Disseminated intravascular coagulation (DIC)

CRUSH SYN. PREVENTION from AKI• The general goals for preventive therapy in all cases of heme pigment-induced AKI are the correction of volume depletion, if present, and prevention of intratubular cast formation. In the case of disaster crush victims preventive measures should be applied at the disaster field, in the field hospitals, and after admission to regular hospitals.•The most important preventive measure at the disaster field is the correction of volume depletion. •The approach to prevention of AKI in the patient with rhabdomyolysis due to crush syndrome varies based upon the location of the patient and ability to closely monitor the victim.

Kantarci G, Vanholder R, Tuglular S, et al.Am J Kidney Dis. 2002 Oct;40(4):682-9.Acute renal failure due to crush syndrome during Marmara earthquake.

Fluid Replacement

• Normotension %0.45 NaCl• Hypotension Cause ?

• Bleeding ? E.S• Dehidratation? %0.9 NaCl• Compartment Syn? MannitolTo prevent ARF:

• i.v. fluid 1L/hr ( During first hours 1-1.5 lt ) • Fluid %0.45 NaCl

Postrenal azotemia

• obstructive nephropathy is due to various types of obstruction in the voiding and collecting parts of the urinary system

POST-RENAL (<%5) Early diagnosis is important Urinary obstr.

• Bilateral obstruction of the ureter, pelvis • BPH, Prostate Ca• Cervix, ovarian Ca• uretral masses, Stones• Ureteral obstrustion (stone, mass)• DM papillary nec.

AKI

In 748 AKI patients ATN —% 45 Prerenal —% 21 Acute on Chronic — %13 Urinary tract — %10 GN or vasculitis— %4 AIN — %2 Atheroembolism — %1

Liano, F, Pascual, J, and the Madrid Acute Renal Failure Study Group. Epidemiology of acute renal failure: A prospective, multicenter, community-based study. Kidney Int 1996.

‘Acute on Chronic Renal FailureCauses:–Hypovolemi–Nephrotox.– Infection–Obstruction–KKY–Accelerated HT

27%

73%

ARFMOF+ARF

Kidney Int 1998;53: S16-S24

ARF ın ICU is the part of MOF

ARF IN ICU

AKI in ICU

•AKI requiring dialysis reduced survival %50,

•Hospital mortality %69•After 6-12 months %70 still survived

30

53

8091

100

0

20

40

60

80

100

MODS+ABY

İzole aby2 OSY3 OSY4 OSY5 OSY

Kidney Int 1998;53: S16-S24

MORTALTY IS CORRELATED WITH NUMBER OF ORGANS

Diagnosis of AKI

• Diagnosis relies on functional parameters (Cr, UOP) • AKI is more readily reversible in early stages • Need a more sensitive biomarker to detect early injury • Permit early targeted interventions to reverse or ameliorate

AKI• Cystatin C, urinary NGAL(Neutrophil gelatinase associated

lipocalin), IL-18, KIM-1(Kidney injury molecule)• Even very small incremental increases (>0.3 mg/dL) in SCr

cause significant loss of function and increased morbidity and mortality

• Early diagnosis is essential

Diagnostic Work-Up for AKI

THERAPHY

• Prerenal Management of hypovolemia and hypoperfusion.

• Renal Theraphy of causes, plasmaferesis, immunsup.

• Post renal obstruction

Maintaining Renal Perfusion Pressure

vasoconstrictors, vasopressor medications (eg, norepinephrine) should be used only to treat arterial hypotension (dopamine ,norepinephrine)

target mean arterial pressure 60 to 65 mm Hg (patients with long-standing hypertension and/or renal vascular disease may require substantially higher pressures to maintain renal perfusion)

intra-abdominal hypertension is associated with decreased renal perfusion and may result in AKI.

Mortality/Morbidity

• AKI is not a benign disease. In a recent study, a 31% mortality rate was noted in patients with AKI not requiring dialysis, ICU mortality 50-69 %

• Mortality rates are generally lower for nonoliguric AKI (>400 mL/d) than for oliguric (<400 mL/d) AKI, reflecting the fact that nonoliguric AKI is usually caused by drug-induced nephrotoxicity and interstitial nephritis

SUGGESTED READING

Goldman's Cecile Medicine 24th edition Elsevier

Goldman L, Schafer AI

The Cleveland Clinic Intensive Review of Internal Medicine 5th edition

Lippincott Williams and Wilkins

Stoller JK, Michota FA, Mandell BF

CURRENT Diagnosis & Treatment: Nephrology & Hypertension Edgar V. Lerma, Jeffrey S. Berns, Allen R. Nissenson (ACUTE RENAL FAILURE Chapter 9-11-14)