Download Renal Problems in the Surgical Patient

Renal Problems in the Surgical
Patient
Dr. Bob Richardson
TGH Nephrology
2009
Agenda
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Assessment of kidney function
Acute renal failure
Case studies of acute renal failure
Chronic kidney disease
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Causes and stages of chronic kidney disease
Surgery in patients with chronic kidney
disease
Surgery in dialysis patients
Routine IV therapy in healthy patients
Assessment of Kidney
Function
A normal GFR and a normal urinalysis
rules out significant renal disease
 How to estimate GFR?
Serum creatinine

creatinine
Serum
creatinine
GFR
muscle
serum
kidney
urine
Serum creatinine is an
imperfect method of
estimating GFR; there is no
perfect method.
Determinants of Serum
Creatinine
Muscle mass
 age (muscle mass falls with age)
 gender (women less muscle than men)
 Weight, fitness (muscle vs fat)
 Nutritional state (muscle loss)
GFR
How to Correct for Differences in
Muscle Mass
Measure GFR directly:
 Creatinine clearance with 24 h urine
 Radionucleide GFR (nuclear medicine –
functional renal imaging)
Estimate GFR Using Formulas
 Cockcroft-Gault
 MDRD (used by Ontario Labs to give
eGFR)
MDRD equation
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Serum creatinine, age, gender, race
(black or caucasian)
Only useful for patients with known
kidney disease
Ontario labs now report eGFR using this
formula
GFR determines stage of CKD
Chronic Kidney Disease
Stage
Stage
Stage
Stage
Stage
1
2
3
4
5
GFR ml/min
>90
(mild)
60-90
(moderate)
30-60
(advanced)
15-30
End stage KD < 15
GFR measured or calculated using MDRD equation
Limitations of eGFR (MDRD)
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Cannot be used to determine if kidney
function is normal
Not validated in acutely ill hospitalized
patients
Not well validated in Asians
Most useful for stable patients with
known CKD
Examples of Calculated Ccr
Two patients: same serum creatinine 100
umol/L:
 20 yr old male, 80 kg, creatinine 100
umol/L Creatinine clearance: 115 ml/min
 65 year old woman, 40 kg, creatinine 100
uM Creatinine clearance 30 ml/min
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Moral: you need to look at more than the
serum creatinine
Case 1:
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67 year old man with large abdominal
mass
Biopsy = sarcoma
Encases right kidney, left kidney
atrophic
Serum creatinine 140 umol/L
What would the effect of surgery be on
residual GFR?
Case 1
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Creatinine 140 uM
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Functional renal imaging
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eGFR = 48 ml/min (stage 3 CKD)
Blood side GFR = 38 ml/min
75% function to right, 25% to left
Estimated residual GFR if right nephrectomy
is 10-12 ml/min (stage 5 CKD)
Conclusion: patient will likely need dialysis
post-op
Acute Renal Failure
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Renal response to reduced effective
circulating volume
Prerenal ARF
Ischemic and toxic acute tubular necrosis
Obstruction
Abdominal compartment syndrome
Case studies
Dialysis for ARF
Renal Response to Reduced Effective
Circulating Volume
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What is “effective circulating volume”?
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cardiac output vs peripheral vascular resistance
how cardiovascular receptors “see” arterial filling
Effective circulating volume is reduced in:
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volume depletion (hemorrhage, diarrhea etc)
systemic vasodilatation (sepsis, liver failure)
congestive heart failure
Consequences of Reduced Effective
Circulating Volume on the Kidney
Arterial baroreceptors:
 SNS
 circ. catecholamines
 ADH
JG apparatus
 renin, angiotensin II,
aldosterone
Effects on Kidney
 renal blood flow (BP +
renal vasc. resistance)
 GFR/RBF (efferent
constriction by AII,
preserves GFR)
Sodium, chloride retention
urine [sodium] < 20 mM
Water retention Uosm >500
Angiotensin II and Regulation of GFR
Causes of Acute Renal
Failure
1. Prerenal
2. Vascular
1
2
3
3. Glomerular
4. Tubulo-interstitial
4
5. Obstruction
5
Prerenal Acute Renal Failure
GFR =
arterial BP
renal vascular resistance
BP depends on venous return, heart rate,
contractility, systemic vascular resistance
RVR may be increased by:
 catecholamines, angiotensin II
 sepsis, hepatic failure
 NSAID’s, Cyclosporine
 Renal arteriolarsclerosis (age, hypertension)
Prerenal Failure-Clinical
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Hypovolemia
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hemorrhage
diarrhea, vomiting, burns
pancreatitis, ascites
SIRS/capillary leak
Septic shock
Cardiogenic shock
Drugs: cyclosporine, NSAID’s, etc
The Kidney In Prerenal Failure
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Normal renal response to reduced effective
circulating volume:
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oliguria (< 0.5 ml/kg/h)
normal urinalysis (no protein or casts)
high urine osmolality (ADH acting)
low urine [Na] or [Cl-]
increasing serum creatinine
Rapid improvement in urine flow and serum
creatinine if prerenal state corrected
Ischemic Acute Tubular Necrosis
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Causes: same as prerenal ARF - more severe
or more prolonged
Factors that increase risk for ATN:
 sepsis (especially gram -)
 biliary obstruction with jaundice
 angiographic dye
 myoglobin (rhabdomyolysis)
 cardiopulmonary bypass
 CKD
Tubular proteins (markers
of injury) in patients on
bypass for < 70 minutes or
> 90 minutes
Ann Thoracic Surg
2003;75:906
Pathophysiology of Ischemic ATN
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Necrosis of cells of thick ascending limb
and proximal tubule in outer medulla
Cells and cell debris enter lumen and
cause obstruction and backleak of
filtrate
Glomeruli are normal
Continued hypotension causes
prolonged severe vascoconstriction
Dilated
tubules
Focal loss of
tubule cells lining
tubular basement
membrane
Debris in
tubule
lumens
Interstitial
edema
Urine in Ischemic ATN
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Oliguria (if severe injury) or non-oliguric
Urine flow may increase with
furosemide
Isotonic urine (300 mosmol/kg)
High urine sodium ( > 30 mmol/L)
hematuria, heme granular casts, debris
on urinalysis
Urine in ATN: note blood cells, tubular (white ) cells, debris and
characteristic heme granular casts (muddy brown casts)
Toxic Acute Tubular Necrosis
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Aminoglycosides, amphotericin, cisplatin
etc
Aminoglycosides:
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accumulate in proximal tubule, cause cell
necrosis
tubular obstruction and backleak
non-oliguric,  creatinine at 7-10 days
toxicity most related to duration of
therapy
prevent by limiting course to < 10 days
Obstruction and Acute Renal Failure
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Males: prostate
Females: pelvic malignancy
Either:
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single kidney and stone, clot
retroperitoneal malignancy
 lymphoma
 bladder, rectum
Retroperitoneal fibrosis
Obstruction (2)
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Urine flow: anuric to polyuric
Isotonic, high urine sodium
Diagnosis by ultrasound
Treatment:
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bladder catheter!
Unilateral or bilateral percutaneous nephrostomy
Ureteral stent (retrograde or antegrade)
Good prognosis if caught in < 1-2 months
Abdo U/S in
Obstruction
Normal
Other Causes of Acute Renal
Failure
Abdominal Compartment
Syndrome
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Normal IP pressure 0-10 mmHg
ACS when IP pressure > 25 mmHg
Increased renal vein resistance
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Reduced RBF and GFR
Low urine [Na]
Causes: trauma, pancreatitis, liver
transplant, bowel obstruction often with
massive amounts of fluid resuscitation
Atheroembolic disease
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obstruction and inflammation of small renal
vessels due to cholesterol emboli
follows aortography, CABG, aortic OR
usually elderly vasculopaths - aortic AS
ischemic toes, livido reticularis, abdo pain
slowly progressive renal failure over weeks
bland urinalysis, eospinophilia
Contrast-induced ARF
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Non-oliguric ARF within 24 h of procedure
Cause unknown (vascular vs toxic)
Risk factors:
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Prevention:
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Stage 4-5 (GFR < 30 ml/min)
diabetic nephropathy with GFR < 40 ml/min)
Congestive heart failure
IV saline or IV sodium bicarbonate
N-acetylcysteine (controversial)
Prognosis: usually good except DM + CKD 4-5
Less Common Causes of ARF
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Allergic interstitial nephritis – drug reaction
penicillins, cipro, NSAID’s, Septra etc
Thrombotic Microangiopathy (hemolytic
uremic syndrome)
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Toxemia of pregnancy
Bone marrow transplant
Cyclosporine
Toxigenic E.Coli (Walkerton)
Malignant hypertension etc.
Assessment of Patient with ARF
History: prior renal function; BP, ECFV
 Drugs: diuretics, antibiotics, NSAID’s,
ACE inhibitors, angio dye, cyclosporine
 Physical Exam: BP, JVP, edema, ascites,
peripheral pulses, bruits, urine flow
 Lab: lytes, creatinine, urea, CBC, blood
film, urinalysis, urine lytes, osmolality
Renal U/S, renal biopsy if dg unclear
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Consequences of Acute Renal Failure
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 ECF volume: pulmonary edema, edema
Hyperkalemia if oliguria
Uremia: anorexia, nausea, vomiting,
encephalopthy, etc
Metabolic acidosis, hypocalcemia,
hyperphosphatemia, anemia
Prognosis:
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with multiorgan failure in ICU mortality 60-70%
with no other organ failure, prognosis is good
Dialysis for Acute Renal Failure
Indications:
 Pulmonary edema
 Hyperkalemia
 Serum creatinine > 500 umol/L
 Serum creatinine > 300 with oliguria
Methods:
 Conventional HD (3-5 h, 3-6 days/wk)
 CRRT - using Prisma machine heparin vs citrate
 SLED (sustained low efficiency HD) 8 hours 3-6
days/wk
Case History 1
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65 yr old admitted 2 months post CABG+AVR
fever, weight loss, dyspnea
Febrile,  JVP, aortic systolic and diastolic m
blood cultures + for strep. Sp.
Dg: bacterial endocarditis: gentamicin+ Pen
Serum creatinine: Day 1
5
8
10
130 125
165
265
What is differential diagnosis?
Case 1
Differential:
 Post-infectious GN
 Ischemic ATN
 Athero-embolic disease
 GENTAMICIN-INDUCED
Case History 2
75 yr old with claudication; smoker, hypertension
 Aorto-bifemoral graft for AAA + iliac disease
 2 days post-op has 2 painful blue toes; good
distal pulses; abdominal pain
 Creatinine:
preop day 1
7
14
28
135
145
165 225
450
Urinalysis: trace blood, no protein, no casts
?Cause of acute renal failure
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Case 2
Differential
 Ischemic ATN
 Renal artery thrombosis
 ATHERO-EMBOLIC DISEASE
Case History 3
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45 yr old woman with cholelithiasis
1 wk RUQ pain, pale stools, dark urine,
jaundice
2 days spiking fever, chills, vomiting
BP 90/60, HR 110; temp 39; jaundice
U/S: dilated bile ducts, distal duct stone
Blood cultures: Klebsiella
Creatinine 175  260 umol/L; urine= blood,
heme granular casts
Diagnosis?
CASE 3
Ischemic ATN
 Obstructive jaundice
 Gram-negative bacteremia
 Hypotension
Case History 4
42 year old primigravida
 At 34 wks mild increase in BP (140/80)
 35 wks: unwell, edema, proteinuria (3+)
 C-section
Creat
HGB
Plat
AST
Preop
98
125
125
200
24 h
175
80
25
1500
48 h
370
60
10
3500
 ?Diagnosis
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Case 4
Thrombotic Microangiopathy
 HELLP syndrome
 Post-partum acute renal failure
Case 5
50 year old man with known alcoholic cirrhosis
 Presents with 5 days of nausea, vomiting, severe
epigastric pain, distended abdomen
 Serum amylase 1,500 = necrotizing pancreatitis
 Given 3 L crystalloid and colloid for hypotension
 Requires intubation for acute respiratory failure
 In ICU: BP 95/65, CVP 25, oliguric
Differential?
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Case 5
Differential
 Ischemic ATN
 Abdominal compartment syndrome
Summary: Risk Factors for ARF in Surgical
Patients
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Obstructive jaundice
Sepsis syndrome - especially with MOF
Angiography
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dye: renal failure/diabetes
atheroembolic disease - vasculopaths
Prolonged use of aminoglycosides (> 7 d)
Hypotension with pre-existing renal
disease especially in the elderly
Cyclosporine for transplantation
Chronic Kidney Disease
Stage
Stage
Stage
Stage
Stage
1
2
3
4
5
GFR ml/min
>90
(mild)
60-90
(moderate)
30-60
(advanced)
15-30
End stage KD < 15
GFR measured or calculated using MDRD equation
Causes/Risk Factors for CKD
Risk Factors
Diabetes
Hypertension
Age
Smoking
High Cholesterol
Organ transplantation
Causes
Diabetic nephropathy
Hypertension/vascular
Glomerulonephritis
Polycystic Kidneys
Obstruction
Multiple myeloma
Calcineurin-inhibitors
Patients with Chronic Kidney Disease
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You are helping Dr. Robinette do a
nephrectomy on a healthy living
kidney transplant donor
You ask yourself: what is going to
happen to this patient’s kidney
function and why?
What Happens Post Donor
Nephrectomy?
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Serum creatinine rises by 50% (not
100%)
Increase in single nephron GFR of 50%
Afferent and efferent arterioles dilate,
increased glomerular blood flow and
pressure
Normal life expectancy, no increased risk
of renal failure with loss of 50% of
nephrons
What if More Nephrons are Lost?
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Increased single nephron GFR by afferent and
efferent arteriolar dilatation
If lose > 65% of nephrons, get structural
changes in glomeruli and arterioles due to
hyperfiltration and hypertension
Proteinuria and progressive renal failure
Predictors of progessive disease?
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Higher serum creatinine
Hypertension
Amount of proteinuria: > 1 g/d is bad, >3 g worse
Impact of Chronic Kidney Disease on
Surgical Outcomes (1)
Patients with stage 3-5 CKD are at risk:
 Already maximally vasodilated
 Cannot further autoregulate in response
to hypotension: ATN
 Limited ability to excrete extra sodium,
water and potassium
 Limited ability to retain sodium and
water
Impact of Chronic Kidney Disease on
Surgical Outcomes (2)
Patients with stages 3-5 CKD have
increased risk of mortality with surgery
 Higher death rates after CABG
 Higher death rates after aortic surgery
 Higher death rates after MI
O.R. of Death at 30 d. Post CABG
6
5
4
3
2
1
0
>100
80-99 60-79 40-59
0-39
Creatinine Clearance ml/min
Lok et al:Am Heart J 2004
Impact of Renal Dysfunction
on Outcomes of CABG
18
16
14
12
10
8
6
4
2
0
Deaths
Stroke
> 14 days
1
2
Circulation 2006;113:1063
485,000 US patients 2002-3
3
4
CKD Stage
5
Mortality Following Arterial Surgery
40
Renal Failure
Normal
%
30
20
10
0
Elective
Urgent
Type of Surgery
Gerrard et al:Br J Surg 2002;89:70
All
Why Increased Mortality in CKD?
Increased incidence of vascular disease
(atherosclerosis)
 Risk factors for kidney disease are risk factors
for atherosclerosis
 Reduced GFR promotes vascular disease:
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Vascular calcification
Chronic inflammation
Increased SNS, increased vascular stiffness
Increased homocysteine
Case History 6
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65 yr old woman assessed in vascular
surgery clinic for 5.5 cm AAA
Hypertension (160/90), type 2 DM
Urine: negative blood, 1 g/L proteinuria
Creatinine 275 umol/L (eGFR 20
ml/min)
What are concerns regarding her low
GFR- what should you do?
Case History 6
Risks:
 If aortogram: contrast-induced ATN or
atheroembolic disease
 If OR: hypotension, aortic cross-clamp
inducing ischemic ATN
 If surgery: markedly increased mortality risk
Plan: (Nothing evidence-based!)
 request nephrology; cardiac assessment
 will renal disease progress anyway? -operate
when on dialysis?
Case History 6
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Surgery is planned after cardiac
assessment
Maintain as stable a BP as possible and
avoid hypotension ( < 130 systolic in
this patient)
Accurate fluid replacement to avoid
volume depletion or overload
Monitor serum potassium (daily lytes)
Case History 7
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A 79 year old man with a solitary kidney
develops gross hematuria
CT = 2 cm mass in mid-zone of kidney
consistent with renal cell Ca
Operate or not?
Q: What is mortality rate annually in 80
year old on dialysis?
A: 20-30%
Management of HD Patient
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Preserve HD access: lower or upper arm
AV fistula or PTFE graft
No BP, IV or venesection in that arm
Call nephrology to arrange dialysis
No IV fluids unless patient is
hypovolemic (ask nephrology)
No IV potassium unless hypokalemic
(ask nephrology)
Peri-Operative Intravenous Fluid
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What is normal intake of water, Na+ and
K+ ?
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Water: 1.5-2 L/d
Sodium: 150 mmol/day
Potassium: 50 mmol/day
What is main risk of IV fluid post-op?
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Hyponatremia from large volume hypotonic
fluid
Prevention of Postoperative
Hyponatremia
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Avoid hypotonic fluid unless
the patient is hypernatremic
Limit volume of I.V. fluid given to
meet patient’s needs
Adjust volume to patient’s body
weight
Peri-operative IV Fluid
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Annals Surgery 2003;238:641
RCT of standard vs restricted IV fluid in
patients undergoing colorectal resection
Multicenter study from Denmark
Powered to detect a 20% difference in
complications with 80% power
86 patients per group
Peri-operative IV Fluid Standard
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Intra-op
 500 ml HAES 6% in NS
 Third space loss: NS 7 ml/kg/h X1 h,
then 5 ml/kg/h X 2, then .3 ml/kg/h
 Blood loss: up to 500 ml: 1-1.5 L NS
then HAES
Post-op
 1-2 L crystalloid/day
Peri-operative IV Fluid:
Restricted
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Intra-op:
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No preloading
No replacement of third space loss
Blood loss: volume/volume with HAES
Post-op
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1000 ml 5% D/W for remaining OR day
Then oral fluid or IV if needed
Furosemide if weight increased by 1 kg
Results
Standard Restricted
IV fluid OR day
5.4 L
2.7 L*
IV fluid POD 1
1.5 L
0.5 L*
Max increase
wt
0.9 kg
3.5 kg*
Complications
40
21*
Compl -major
18
8*
Complication frequency related to IV
fluid and wt gain on operative day
A Comparison of Albumin and Saline
for Fluid Resuscitation in the
Intensive Care Unit
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NEJM 2004;350:2247
Previous meta-analysis suggested
albumin resuscitation increased
mortality
RCT in 7,000 ICU patients
4% albumin vs crystalloid for fluid
No difference in mortality
Summary
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Be familiar with stages of CKD
Interpretation of serum creatinine
Risks factors for ARF in surgical patients
Differentiation of prerenal failure from
ATN
Impact of CKD stage 3-5 on surgical
outcomes