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Acute Renal Failure Syed Rizwan, MD Acute Renal Failur

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Acute Renal Failure Syed Rizwan, MD Acute Renal Failure Comprises a family of syndromes Abrupt decrease in GFR(over hours to days) MANIFFESTATIONS of ARF Increase in ... – PowerPoint PPT presentation

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Title: Acute Renal Failure Syed Rizwan, MD Acute Renal Failur


1
Acute Renal Failure
  • Syed Rizwan, MD

2
Acute Renal Failure
  • Comprises a family of syndromes
  • Abrupt decrease in GFR(over hours to days)

3
MANIFFESTATIONS of ARF
  • Increase in BUN
  • Increase in creatinine
  • Oligouria(lt 400 500 cc)

4
DEFINITION
  • No consensus
  • Multiple
  • Relative rise in Serum Creatinine
  • gt 0.5mg/dl if baseline creatinine is normal
  • gt 1 mg/dl if baseline serum creatinine is high

5
Creatinine and GFR
  • Creatinine produced in muscles
  • Creatinine excretion depends on,
  • Glomerular filtration
  • Proximal tubular excretion
  • Change in Serum Creatinine with no change in GFR
  • Muscle wasting or amputation lowers creatinine
  • Medications(Trimethoprim, Cimetidine) increase
    creatinine by deceasing tubular excretion

6
Blood Urea and GFR
  • Increase BUN with no change in GFR
  • GI Bleed
  • Hyper catabolic states
  • Protein loading
  • Glucocorticoids
  • Tetracycline
  • Decrease BUN with no change in GFR
  • Protein Malnutrition
  • Severe Liver disease

7
ARF and Biomarker
  • Lack of sensitivity of BUN and creatinine
  • Need for Biomarkers
  • Kidney Injury Molecules-1(KIM-1) increased in
    Patients with Acute Tubular Necrosis
  • None available for cliniical utility yet

8
Epidemiology of ARF
  • Incidence, etiology and outcome varied depending
    on Population studied and Definition used
  • Mostly in-Patient than out Patient
  • 5-7 of hospital admissions
  • Mortality varies between 20-85 depending on
    cause

9
ARF Classification
  • Prerenal
  • Renal
  • Postrenal

10
Prerenal ARF
  • Hemodynamically mediated reduction in GFR in
    absence on Renal Parenchymal injury.
  • ARF resolves if hemodynamic insult is reversed
  • If hemodynamic insult is sustained, can result in
    overt renal injury

11
Renal ARF
  • Renal Parenchymal injury

12
Postrenal ARF
  • Acute obstruction to the Urinary Tract

13
Prerenal Azotemia
  • Decreased Glomerular perfusion(no renal injury)
  • True Volume Depletion e.g. Diarrhea
  • Effective Volume Depletion, cirrhosis
  • Altered Intrarenal Hemodynamics e.g. ACEI
  • Affenet dilatation
  • Efferent vasoconstriction

14
Prerenal Azotemia
  • True or Effective Volume depletion,
  • Neurohumoral vasoconstrictor
  • Increased catecholamine
  • Renin-angiotensin system activation
  • Increased vasopressin release

15
Renal Autoregulation
  • Maintains Glomerular Blood Flow and thus GFR
  • Afferent Vasodialtaion,
  • Prostaglandins
  • Kallikrein-kinin
  • Myogenic influence
  • Nitiric oxide
  • Efferent vasoconstriction
  • Angiotension 11

16
Prerenal Azotemia
  • Prerenal ARF presents with
  • Oligouria
  • Low Urine Na from Na retention
  • Increased BUN creatinine ratio gt201
  • FENa lt 1
  • Existing Renal Insufficiency or Diuretic can
    alter this picture

17
ARF and ACEI ARB
  • ACEI ARB have greatest benefits in Patients
    with high risk of ARF
  • Old age
  • Diabetics
  • Cardiomyopathy
  • CHF with higher dose oh Diuretic
  • Renal Vascular disease
  • Chronic Kidney disease

18
Prerenal ARF with ACEI ARB
  • Efferent Vasodilatation deceases GFRmedications
  • Lower GFR raises serum creatinie but usually less
    than 30
  • Must monitor serum creatinine and electrolytes
    before and after starting or changing dose of
    these medications
  • Stop if ARF
  • Correct volume status
  • W/u for renal Artery Stenosios
  • Can reintroduce cautiously if reversible factors
    corrected

19
Prerenal ARF NSAIDs
  • Both COX1/Cox!! Inhibitors cause lower
    Prostaglandins synthesis
  • Impairs Afferent vasodilatation decrease
    Glomerular perfusion
  • Effect greatest in high risk population
  • CHF
  • Cirrhosis
  • CKD
  • Vascular disease
  • elderly

20
Abdominal Compartment Syndrome
  • Unusual cause of ARF
  • Associated with increased intra-abdominal
    pressure
  • Manifestations,
  • Respiratory compromise
  • Decreased cardiac output
  • Intestinal ischemia
  • Hepatic Dysfunction
  • Oliguric ARF
  • Increased renal venous pressure
  • Recovery with decreased intraabdominal pressure

21
Post-Renal ARF
  • Obstruction complete or Partial
  • Anuria or variable urine output
  • Recovery depends on duration of obstruction
  • Conditions Sonogram may not show obstruction,
  • Retroperitoneal fibrosis
  • Tumors
  • Adenopathy
  • Encasing ureter prevent dilatation

22
ARF- Renal
  • Useful to categorize according to Anatomical
    injury.
  • Primary sites,
  • Glomerulus- Acute Glomerulonephritis
  • Tubules- Acute Tubular Necrosis
  • Interstitium- Acute Interstial Nephritis
  • Vascular- Atheroembolism
  • ATN- most common
  • U/A-Protein, RBC,Casts,pigments

23
Acute Tubular Necrosis
  • Ischemic vs Nephrotoxic
  • Most frequently multi-factorial
  • Medical vs Surgical
  • Ischemic- Hypotension,shock
  • Nephrotoxic- Dye induced, Rhabdomyolysis

24
Acute Tubular Necrosis
  • Initiation, maintenance, recovery Phases
  • Mortality from very low to very high
  • Potentially Preventable
  • Long term outcome in survivors very good

25
ATN- Specific Syndromes
  • Radiocontrast Nephropathy
  • Rhabdomyolysis
  • Aminoglycoside Related
  • Amphotericin B associated

26
Radiocontrast Nephropathy
  • 10 of Hospital acquired ATN
  • Mild and Transient in Majority
  • Risk factors,
  • Amount of Dye(gt 100cc)
  • Volume Depletion
  • Renal Insufficiency
  • DM
  • Old Age
  • CHF
  • ACEI or NSAIDs

27
Radiocontrast Nephropathy
  • Risks higher with higher creatinine
  • Normal- negligible risks
  • Mild- Moderate RI(Creatininelt 2) 5-10 risks
  • Mild- Moderate RI with DM- 10-40 risks
  • Advanced Renal Disease- gt50

28
Radiocontrast Nephropathy
  • Pathogenesis incompletely understood
  • Severe Renal vasoconstriction within seconds of
    contrast administration
  • Direct Renal Tubular injury
  • FENa lt 1

29
Radiocontrast Nephropathy
  • Independent risk factor of death
  • Prevention in high risk Patients
  • Consider Alternate imaging.g. MRI
  • Volume repletion with Saline
  • Minimize amount of Dye
  • Low Osmolality contrast media?
  • N-Acetylcysteine(Mucomyst)?
  • Fenoldopam-Selective Dopamine agonist?
  • Lasix, Mannitol, Dopamine not helpful, may be
    risky
  • Prophylactic Hemodialysis- not helpful

30
Radiocontrast Nephropathy
  • N-Acetylcysteine reducing agent, scavenge
    reactive oxygen species(ROS)
  • No good large randomized trial to prove its
    efficacy
  • Impact on morbidity and mortality unknown
  • Used commonly in practice b/o potential benefits
    and lack of Toxicity

31
Aminoglycoside Nephrotoxicity
  • Usually after 7-10 days
  • Depends on dose and frequency
  • Direct Proximal Tubular injury
  • Once a day dosing may be less Nephrotoxic
  • K. Ca. MG wasting
  • Risk factors- age, Renal insufficiency,
    Dose,Volume depletion

32
ARF from Rhabdomyolysis
  • Muscle injury leading to ARF
  • Most cases subclinical
  • Myoglobinuria cause,
  • Renal vasoconstriction
  • Proximal tubular damage
  • Intratubular cast (Obstruction)
  • Hypovolemia(Third Spacing)
  • Metabolic Acidosis,
  • Electrolyte Imbalance(K,Ca,P)

33
ARF from Rhabdomyolysis
  • Subclinical causes more common
  • Drugs
  • PVD
  • Seizure
  • FENa lt 1
  • U/A- Heme/vie but no RBC
  • Aggressive Volume replacement
  • Urinary Alkalization?, Mannitol?

34
Amphotericin B Nephrotoxiciy
  • Very high incidence of ARF
  • Binds to sterol in cell membrane
  • Multiple sites in Nephrons
  • Distal Tubular Acidosis
  • Mg and K wasting
  • Dose dependent
  • Liposomal Amphotercin formulation less toxic
  • Saline loading helpful

35
Postoperative ARF
  • ARF after vascular,cardiac and major abdominal
    surgery.
  • Very high mortality
  • Multifactorial
  • 1-5 after CABG.
  • Risk factors,
  • Renal disease, cardiogenic shock,emergent
    surgery, Left main disease etc,

36
Acute Interstitial Nephritis
  • Classical triad(fever rash eosinophilia) not
    usually seen
  • Mostly Drug related e.g. Cipro
  • Infection Strept., Staph, CMV, EB virus,
    Hantaan virus etc
  • Systemic Diseases SLE, Sarcoidosis.
  • Eosinophiluria may be absent
  • Dx by renal Biopsy.
  • Rx supportive, Hold Drug, Steroids ?

37
Atheroembolic ARF
  • Require high degree of suspicion
  • Cholesterol emboli
  • Renal failure acute or subacute
  • Multisystem disorder
  • Lived reticularis
  • Digital Ischemia(Blue Toe Syndrome)
  • GI bleed, TIA, Rahbdomyolysis

38
Atheroembolic ARF
  • ARF after vascular procedure
  • ARF can be abrupt needing dialysis within few
    days.
  • Can be subacute occurring in staggered steps
    separated by stable renal function.
  • Patients on Anticoagulants are at high risk
  • Eosinphilia, eosinphiluria, low complement.
  • High mortality

39
Hepatorenal Syndrome
  • Profound renal vasoconstriction
  • Resemble Pre-renal Azotemia
  • Volume Expansion fail to improve renal function.
  • Pathogenesis incompletely understood
  • Oligiuric ARF, FENa low
  • Diagnosis of exclusion

40
Hepatorenal Syndrome
  • Two Types
  • Type 1 HRS rapid ARF, hospitalized Pt.,gt90
    mortality
  • Type 11 HRS insidious onset, slow progression
    of RI, refractory ascites, better prognosis.
  • ATN vs HRS
  • Low FENa I n ATN
  • casts in Bilirubinemia with HRS

41
Hepatorenal Syndrome
  • Rx difficult
  • Volume expansion with Albumin
  • Terlipressin(vasopressin analogue)
  • Midodrine (selective alpha 1 adrenergic agonist)
    octreotide(a somstoastatin analogue)
  • TIPS, Liver Transplantation
  • Dialysis in selective Patients

42
ARF in HIV/AIDS
  • Prerenal Azotemia
  • Renal salt wasting from Adrenal Insufficiency.
  • HIV Nephropathy
  • High risk for ATN
  • Drug side effects e.g. Pentamidine.Crystal
    nephropathy(indinavir)
  • TTP(prognosis worse )
  • Rhabomyolysis

43
ARF from RPGN
  • Less common
  • Rapidly Progressive Glomerulonephritis include
    vasculitis, SLE, Wagner's
  • Active Urinary sediments(RBC cast diagnostic)
  • Higher degree of Proteinuria
  • Serology helpful(ANCA, ANA,IgMantibodyetc0
  • Renal Biopsy usually required.
  • Early diagnosis essential to prevent ESRD
  • Rx with Steroids and Cytoxan

44
Rx of ARF
  • No proven Drugs
  • Many cause preventable
  • Volume expansion
  • Withdrawal of Drugs
  • Diuretics help in management but not curative
  • Dopamine potentially harmful

45
RRT in ARF
  • Renal Replacement Therapy usually the only option
    in severe ARF.
  • Indication of RRT
  • HYPERKALEMIA
  • METABOLIC Acidosis
  • Uremic Symptoms
  • Fluid Load
  • Prophylactic
  • RRT
  • Intermittent Hemodialysis
  • CVVHD
  • Extended Daily Dialysis(6-12h)
  • Peritoneal Dialysis- not favored

46
CVVHD vs Hemodialysis
  • HD
  • more stable Pt, SBP gt90, no heparin, allows
    larger amount of fluid removal in3-4 hours
  • CVVHD
  • Unstable Pt., low BP with high dose Pressers,
    allows gradual removal of fluids 24h
  • EDD
  • Allows no heparin dialysis, gradual removal of
    fluids, but expensive b/o Nursing Support

47
RRT- how to improve outcome?
  • Lot of Questions to answer
  • Frequency of Dialysis
  • Quantification of Dialysis
  • Type of Membrane of Dialysis
  • Synthetic vs. Cellulose
  • Does Erythropoietin improves outcome?
  • Faster fluid removal vs. slow fluid removal?
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