Approach to Acute Kidney Injury

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Approach to Acute Kidney Injury

• Dr. Mohammed Al-Ghonaim MBBS,FRCP(C)

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Objective

• At the end of this tutorial you will be able to
• Define AKI
• Know the epidemiology of AKI
• Know the etiology of AKI
• Manage AKI
• Diagnose AKI
• Treat AKI

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Normal Kidney Function

• Fluid Balance
• Electrolyte Control
• Acid-base balance
• Metabolism and Excretion
• Hormone production (Erythropoietin production,
  Renine )

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Acute Kidney Injury (AKI)

• Deterioration of renal function over a period of
  hours to days, resulting in
• the failure of the kidney to excrete nitrogenous
  waste products and
• to maintain fluid and electrolyte homeostasis

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Acute Kidney Injury (AKI)

• An abrupt (within 48 hours) absolute increase in
  increase in creatinine by 0.3 mg/dl (26.4
  µmol/l)or percentage increase of gt50 from base
  line or urine output lt0.5 ml/hour for 6 hours
• azotemia (accumulation of nitrogenous wastes)
• decreased urine output (usually but not always)
• Oliguria lt400 ml urine output in 24 hours
• Anuria lt100 ml urine output in 24 hours

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Epidemiology

• It occurs in
• 5of all hospitalized patients and
• 35 of those in intensive care units
• Mortality is high
• up to 7590 in patients with sepsis
• 3545 in those without

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Median hospital length of stay (LOS) stratified
by single acute organ system dysfunction (AOSD),
including acute renal failure (ARF).
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Etiology of ARF
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Etiology of ARF
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Causes of AKI
Hilton, R. BMJ 2006333786-790
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Pre-renal AKI

• Volume depletion
• Renal losses (diuretics, polyuria)
• GI losses (vomiting, diarrhea)
• Cutaneous losses (burns, Stevens-Johnson
  syndrome)
• Hemorrhage
• Pancreatitis
• Decreased cardiac output  
• Heart failure
• Pulmonary embolus
• Acute myocardial infarction
• Severe valvular heart disease
• Abdominal compartment syndrome (tense ascites)

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Case -1

• 75 years old female, known to have
• DM II
• HTN
• Presented with nausea, vomiting and diarrhea for
  3 days
• Medication Insulin, lisinopril,
• Serum Creatinine 150

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Case-1

• What other information do you want to know?
• History
• Physical examination
• Investigations
• What is your diagnosis?
• Acute Kidney Injury.
• What is the etiology of AKI?
• Pre renal (dehydration)

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Case -1

• What do you expect to fined in urine analysis?
• Normal
• What do you expect urinary Na, osmolality?
• Urinary Nalt10
• Osmolality gt 300
• Fractional excretion of Na lt1

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Post-renal AKI

• Ureteric obstruction
• Stone disease,
• Tumor,
• Fibrosis,
• Ligation during pelvic surgery
• Bladder neck obstruction
• Benign prostatic hypertrophy BPH
• Cancer of the prostate
• Neurogenic bladder
• Drugs(Tricyclic antidepressants, ganglion
  blockers,
• Bladder tumor,
• Stone disease, hemorrhage/clot)
• Urethral obstruction (strictures, tumor)

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Post-renal AKI
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Renal

• Glomerular  
• Antiglomerular basement membrane (GBM) disease
  (Goodpasture syndrome)
• Antineutrophil cytoplasmic antibody-associated
  glomerulonephritis (ANCA-associated GN) (Wegener
  granulomatosis, Churg-Strauss syndrome,
  microscopic polyangiitis)
• Immune complex GN (lupus, postinfectious,
  cryoglobulinemia, primary membranoproliferative
  glomerulonephritis)
• Tubular
• Ischemi
• Totoxic
• Heme pigment (rhabdomyolysis, intravascular
  hemolysis)
• Crystals (tumor lysis syndrome, seizures,
  ethylene glycol poisoning, megadose vitamin C,
  acyclovir, indinavir, methotrexate)
• Drugs (aminoglycosides, lithium, amphotericin B,
  pentamidine, cisplatin, ifosfamide, radiocontrast
  agents)

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Renal

• Interstitial
• Drugs (penicillins, cephalosporins, NSAIDs,
  proton-pump inhibitors, allopurinol, rifampin,
  indinavir, mesalamine, sulfonamides)
• Infection (pyelonephritis, viral nephritides)
• Systemic disease (Sjogren syndrome, sarcoid,
  lupus, lymphoma, leukemia, tubulonephritis,
  uveitis

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Clinical feature-1

• Signs and symptoms resulting of primary disease
• Signs and symptoms resulting from loss of kidney
  function
• decreased or no urine output, flank pain, edema,
  hypertension, or discolored urine
• weakness and
• easy fatiguability (from anemia),
• anorexia,
• vomiting, mental status changes or
• Seizures
• edema

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Clinical feature-2

• Asymptomatic
• elevations in the plasma creatinine
• abnormalities on urinalysis
• Systemic symptoms and findings
• fever
• arthralgias,
• pulmonary lesions

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AKI Diagnosis

• Blood urea nitrogen and serum creatinine
• CBC, peripheral smear, and serology
• Urinalysis
• Urine electrolytes
• U/S kidneys
• Serology ANA,ANCA, Anti DNA, HBV, HCV, Anti GBM,
  cryoglobulin, CK, urinary Myoglobulin

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AKI Diagnosis

• Urinalysis
• 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
• Hansel stain for Eosinophils

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AKI - Diagnosis

•   Urinary Indices
•                           UNa   x   PCr
           FENa          x  100
                                   PNa   x   UCr
  FENa lt 1 (Pre-renal state)
• May be low in selected intrinsic cause
• Contrast nephropathy
• Acute GN
• Myoglobin induced ATN
• FENa gt 1 (intrinsic cause of AKI)

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Case -1 revisited

• What do you expect to fined in urine analysis?
• Normal
• What do you expect urinary Na, osmolality?
• Urinary Nalt10
• Osmolality gt 300
• Fractional excretion of Na lt1

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AKI
Causes of acute kidney injury
Differentiation between Pre-renal, renal and
post-renal causes
Prerenal Renal postrenal
Hypovolaemia Decreased active blood volume Decreased cardiac output Renovascular obstruction Acute tubular necrosis Interstinal nephritis Glomerular disease (acute glomerulonephritis) Small vessel diease Intrarenal vasoconstriction (in sepsis) Tubular obstruction Bilateral ureteric obstruction Unilateral ureteric obstruction Bladder outflow obstruction
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Case -2

• 75 years old Saudi male,
• DM II, HTN and Osteo arthritis knees
• you have been called to see because of
• high serum creatinine is 2000 µmol/l
• urea 100
• K 5.5
• What is next?

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Case -2

• History
• No history of vomiting or diarrhea
• History of increase urinary frequency and weak
  urinary stream
• On examination
• BP 140/94 mmHg pulse 78 /min
• FiO2 saturation is 93 on room air
• Diagnosis
• acute vs chronic
• Serum creatinine 2 months ago 89

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Case-2

• First step
• Investigations
• Urine analysis, Urine Na
• Ultra sound kidney

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Renal failure
Differentiation between acute and chronic renal
failure
Acute Chronic
History Short (days-week) Long (month-years)
Haemoglobin concentration Normal Low
Renal size Normal Reduced
Serum Creatinine concentration Acute reversible increase Chronic irreversible
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Case-3

• You are working as nephrology resident and it is
  Monday, 0230 P.M and general surgery resident
  calls you for a consult
• 68 years old Saudi male underwent colectomy this
  morning pre operative creatinine was 88 µmol/l
  and now it is 249 µmol/l?
• How to approach this pateint?

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Case-3

• What other information you need to know?
• known to have DM II on diet, found to have anemia
  subsequent work up showed that he has colon
  cancer underwent colectomy this morning pre
  operative creatinine was 88 µmol/l and now it is
  249 µmol/l
• And urine output for the last 3 hours is lt10 cc
  and dark colour
• Intra operative course was complicated by major
  bleeding requiring blood transfusion, and his
  blood pressure was low

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Case-3

• Physical examination
• Asses volume status
• Blood pressure
• Pulse
• JVP
• Urine out put
• Laboratory investigation
• K 4.7, Bicarbonate 21, Cl 99, Na 137
• Urinary Nagt 10, Urine osmolality lt 350

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Case -3

• What is your diagnosis?
• Acute Kidney Injury
• Where is the etiology?
• Renal?
• ATN (acute tubular necrosis)
• AIN (acute interstitial nephritis)
• GN (glomerulonephritis)

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Case-3

• Diagnosis
• Acute Kidney Injury secondary to Acute tubular
  necrosis due to shock

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Treatment of AKI

• Optimization of hemodynamic and volume status
• Avoidance of further renal insults
• Optimization of nutrition
• If necessary, institution of renal replacement
  therapy

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Case-3

• After assessment your staff advise the following
• IVF bolus 1 litter then 100 cc/hour
• Next day when you came to assess the patient you
  found him incubated and they told you he went
  into respiratory distress
• BP 120/78mmHg
• Urine output none for the last 3 hours

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Case-3

• Lab result as follow
• K 6.3
• Creatinine 350µmol/l
• Bicarbonate 17
• What next

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AKI
Causes of acute kidney injury
Changes during acute renal failure Hyperkalaemia
(? ECG abnormalities) decreased
bicarbonate elevated urea elevated
creatinine elevated uric acid Hypocalcaemia Hyp
erphoshataemia
In many chases kidney can recover from acute
renal failure The function has to be temporarily
replaced by dialysis disturbed fluid or
electrolyte homeostasis must be
balanced primary causes like necrosis,
intoxication or obstruction must be treated
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Indication for renal replacement therapy

• Symptoms of uremia ( encephalopathy,)
• Uremic pericarditis
• Refractory volume over load
• Refractory hyperkalemia
• Refractory metabolic acidosis

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Acute Tubular Necrosis

• Most common cause of intrinsic cause of ARF
• Often multifactorial
• Ischemic ATN
• Hypotension, sepsis, prolonged pre-renal state
• Nephrotoxic ATN
• Contrast, Antibiotics, Heme proteins

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Acute Tubular Necrosis

• Diagnose by history, ? FENa (gt2)
• sediment with coarse granular casts, RTE cells
• Treatment is supportive care.
• Maintenance of euvolemia (with judicious use of
  diuretics, IVF, as necessary)
• Avoidance of hypotension
• Avoidance of nephrotoxic medications (including
  NSAIDs and ACE-I) when possible
• Dialysis, if necessary
• 80 will recover, if initial insult can be
  reversed

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Contrast nephropathy

• 12-24 hours post exposure, peaks in 3-5 days
• Non-oliguric, FE Na lt1 !!
• RX/Prevention 1/2 NS 1 cc/kg/hr 12 hours
  pre/post
• Mucomyst 600 BID pre/post (4 doses)
• Risk Factors CKD, Hypovolemia ,DM,CHF

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Rhabdomyolysis

• Diagnose with ? serum CK (usu. gt 10,000), urine
  dipstick () for blood, without RBCs on
  microscopy, pigmented granular casts
• Common after trauma (crush injuries), seizures,
  burns, limb ischemia occasionally after IABP or
  cardiopulmonary bypass
• Treatment is largely supportive care. With IVF

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Acute Glomerulonephritis

• Rare in the hospitalized patient
• Diagnose by history, hematuria, RBC casts,
  proteinuria (usually non-nephrotic range), low
  serum complement in post-infectious GN), RPGN
  often associated with anti-GBM or ANCA
• Usually will need to perform renal biopsy

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Atheroembolic ARF

• Associated with emboli of fragments of
  atherosclerotic plaque from aorta and other large
  arteries
• Diagnose by history, physical findings (evidence
  of other embolic phenomena--CVA, ischemic digits,
  blue toe syndrome, etc), low serum C3 and C4,
  peripheral eosinophilia, eosinophiluria, rarely
  WBC casts
• Commonly occur after intravascular procedures or
  cannulation (cardiac cath, CABG, AAA repair,
  etc.)

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Acute Interstitial Nephritis

• Usually drug induced
• methicillin, rifampin, NSAIDS
• Develops 3-7 days after exposure
• Fever, Rash , and eosinophilia common
• U/A reveals WBC, WBC casts, Hansel stain
• Often resolves spontaneously
• Steroids may be beneficial ( if Scrgt2.5 mg/dl)

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Case-4

• 63 yrs. old women with Hx of long standing
• DM II and HTN (20 years)
• C/O muscle aches and pain for 2 weeks
• No Hx of nausea, vomiting and diarrhea
• Seen 3 days before at private clinic
• SCr 139
• ALT 160 AST 83
• U/A 3 glucose, 1 protein, Hb

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Case-4

• Medications list
• Bisoprolol, Irbesartan, Simvasatin, and
  Gemfiborzil
• On Ex
• ill looking, Bp 140/90, P 105/min, O2 sat 95
  on room air, JVP 3-4 cm ASA
• No L.L oedema
• Muscle tenderness with normal power
• Chest normal
• CVS normal S1 and S2 no murmurs

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Differential diagnosis of acute renal failure
Hilton, R. BMJ 2006333786-790
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Case-4

• SCr 350
• CK very high
• K 5.2
• U/A 3 protein,3 Hb
• U/S kidney normal

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Case-4

• Acute kidney injury secondary to rhabdomyolysis
  (drug related )

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Case -5

• 70 years old male
• C/O Vomiting blood for 1 day
• On Ex
• Bp 120/80 mmHg ,P100/min JVP 4cm
• Lab
• SCr 80, urea 11
• Diagnosis?

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AKI

• Laboratory Evaluation
• Scr, More reliable marker of GFR
• Falsely elevated with Septra, Cimetidine
• small change reflects large change in GFR
• BUN, generally follows Scr increase
• Elevation may be independent of GFR
• Steroids, GIB, Catabolic state, hypovolemia
• BUN/Cr helpful in classifying cause of AKI
• ratiogt 201 suggests prerenal cause

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Pre-renal AKI

• History
• Physical examination
• Volume status
• Blood pressure, Pulse, JVP
• Urine out put
• Investigation
• SCr, urea
• Urine analysis
• Urine electrolytes

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Differential diagnosis of acute renal failure
Hilton, R. BMJ 2006333786-790