acute renal failure - wmh

8/7/2019 Acute Renal Failure - WMH

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Acute Renal Failure

Dr Wong Mun Hoe

MBBS (IMU) M.Med (UM)Internal Medicine


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So True, So False?


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Outline

Definitions Acute Renal Failure (ARF) and

Acute Kidney Injury (AKI)

Etiology Pathogenesis

Investigations

Management


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Acute Renal Failure (ARF)

What does it mean?

A clinical syndrome characterized by

an abrupt decline in GFR and

accumulation of nitrogenous waste

products


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Lack of urine = ARF?

Urine volume can be normal (non-

oliguric)

Decreased (oliguric less than 400mls/24hours)

Absent (less than 100mls/ 24 hours)


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ARF to AKI

There is lack of standard definition for acute renal failure.

Therefore a group of experts have gathered around to formthe ACUTE DIALYSIS QUALITY INITIATIVE group (ADQI)

Measuring creatinine and urine output

The group has developed and published a set of consensus

criteria for classifying acute renal failure in 2002. Newterminology ACUTE KIDNEY INJURY (AKI) was introduced.

ACUTE KIDNEY INJURY NETWORK (AKIN)


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RIFLE Criteria


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RIFLE vs AKIN


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Incidence of AKI

Hospital admission : 2-7%

ICU admission : 5-25%

ICU admission with AKI requiring dialysis : 4%

Commonest cause for AKI - SEPSIS


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Acute Kidney

Injury

Pre-Renal

Glomerular

Intrinsic

Tubulo-interstitial

Post-Renal

AcuteTubularNecrosis


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Pre-Renal

Lack of blood supply to the kidneys: Inadequate blood volume

- massive blood loss eg trauma/ post

surgery- massive loss of fluidseg diarrhea, excessive use of diuretics

severe burns Adequate blood volume but poor cardiac

output- cardiogenic shock, large pericardial effusion


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Pre-Renal

Decreased effective blood volume:

Nephrotic Syndrome

Cirrhosis of the liver

Afferent arteriolar vasoconstriction

Drugs (NSAIDs, cyclosporine, amphotericin B,noradrenaline)

Hepatorenal Syndrome Radiocontrast agents,


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Pre-Renal

Efferent arteriolar vasodilatation

ACE-I, ARB

Systemic vasodilatation

Sepsis

Anaphylaxis

Anesthetics

Drug overdose


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Renal

Blood supply to the Kidney is adequate

No outflow tract obstruction

Cause of ARF lies within the kidneyInterstium

Glomeruli

Tubules


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Renal

Interstium InterstitialNephritis

Glomeruli AcuteGlomerulonephritis

Tubules TubularNecrosis


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Acute Interstitial Nephritis

Drug induced Infection related

Penicillins

Cephalosporins

SulfonamidesRifampin

Phenytoin

Bacterial

Viral

RickettsialTuberculosis

Frusemide

NSAIDs Malignancy

Idiopathic

Systemic diseases

SLE

Sarcoidosis

Sjogrens syndrome


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Drug induced acute interstitial nephritis

Fever

Eosinophilia

Rash

Renal biopsy

Inflammatory cells

including

Eosinophils in the

interstitium


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Urine examination

shows

Eosinophils


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Glomerular

Usually RPGN

- pauci immune eg wegeners

granulomatosis- Linear immune complex deposition eg

Good pastures syndrome

- Granular immune complex deposition eglupus nephritis, post infectious


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CRESCENTIC GN

Pathologic diagnosisextracapillary cell

proliferation within

Bowman space

The clinical manifestation

is the Rapidly Progressive

Glomerulonephritis (RPGN):

- active urine sediments- rapid rise in s.creatinine

- poor response to treatment

Many different aetiologies


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Urinary abnormalities in Acute

Glomerulonephritis

Urinary casts

RBC casts

Dysmorphic rbcs


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Acute Tubular Necrosis

Acute tubular necrosis

- common cause of Acute renal

failure in surgical / ICU setting- due to Ischaemic or toxins

Massive losses of blood

volume Any prolonged and severe

cause of renal hypoperfusion

Drugs eg Aminoglycosides

Toxins such as heavyMetals

Myoglobinuria


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The term acute tubular necrosis refers to the

histology seen in this condition following

severe ischaemia or exposure to nephrotoxins

Acute tubular epithelial necrosis during the

acute phase of the illness

Evidence of tubular cell regeneration during

recovery


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Damage mainly occurs in the outer medullary

segment (S3 segment of proximal tubule and

thick ascending limb of loop of Henle)

- lower basal blood flow

- higher oxygen requirement


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Post Renal

The blood supply to the kidneys is normaland the kidneys are normal

The cause is obstruction of the urinary

outflow tractsObstruction of both ureters rare occurrence

Obstruction of ureteric orifices Ca bladder, Ca

Cervix

Obstruction of urethra Prostatomegaly,Uretheral stricture


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Renal calculi


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Post Renal

NORMAL HYDRONEPHROSIS


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Approach to Renal Failure

Determine that there is renal failure

Detailed history

Blood tests

Urine output

What is the cause?

Acute vs chronic

Pre-renal, renal, post renal

When cause is established, instituteappropriate treatment


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Is it renal failure?

Elevated serum urea and creatinine

Oliguria/ anuria


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What is the cause?

Post renal obstructive; exclude with u/s

KUB

Pre-renal hypotension (from sepsis,

dehydration ,cardiac failure, blood loss)

Renal ATN, DRUGS, glomerulonephritis


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Investigations

Urine

Blood

X-rays (KUB)Ultrasound Kidney Ureter bladder (KUB)

Intravenous urography

CT urethrogram (CTU)Renal Biopsy


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Urine

Microscopy

Casts

RED - suggest glomerulonephritis/vasculitis

WHITE - a tubulointerstitial disease or acutepyelonephritis

Red and white cells

crystals

UrinalysisSpecific gravity, Protein, Glucose, Ketones, Nitrite,

pH


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Blood

Urea (BUN), Creatinine (Ratio of Urea:

creatinine 10-15:1)

Blood gasses Calcium/Phosphate


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X-rays


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Ultrasound KUB

Exclude obstructive uropathy

Polycystic kidneys


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Complications


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What does this ECG show?

Tall, Symmetrical, Tented T Waves

HYPERKALEMIA


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Metabolic acidosis

Severe acidosis may impair cardiac

contractility reduce cardiac output more

tissue hypoxia worsen lactic acidosis

NaHCO3 infusion NOT indicated in all cases

may cause more problems eg

Pulmonary edema (esp in anuric patients)

Hypernatremia

Metabolic alkalosis


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Metabolic acidosis

Primary aim of therapy reversal of

underlying disease

NaHCO3 only used in severe metabolic

acidosis eg pH


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Acute pulmonary edema

Breathless

Raised JVP

Bibasal crepitations


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Renal Replacement Therapy (RRT)

Volume overload not responding todiuretic

Hyperkalemia (K+ >6.5 or rising)

Severe metabolic acidosis

Symptomatic uremia (pericarditis,encephalopathy, bleeding dyscrasia,

nausea, vomiting, pruritus)

Uremia (BUN >100)

Method : intermittent HD or continuous RRT (CRRT)


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Summary

Definitions Acute Renal Failure (ARF) and

Acute Kidney Injury (AKI)

Etiology

Pathogenesis

Investigations

Management


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So True, So False?


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Thank You


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New dialysis patients, Malaysia 1980

to 2003.


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Patients dialyzing in Malaysia on

December 31, 1980 to 2003

acute renal failure - wmh

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