Title: Kidney Problems in the Surgical Patient
1Kidney Problems in the Surgical Patient
- Dr. Bob Richardson
- TGH Nephrology
- 2007
2Agenda
- Assessment of kidney function
- Acute renal failure
- Case studies of acute renal failure
- Chronic renal failure
- Causes and stages of chronic kidney disease
- Surgery in patients with chronic kidney disease
- Surgery in dialysis patients
- Routine IV therapy in healthy patients
3Assessment of Kidney Function
- A normal GFR and a normal urinalysis rules out
significant renal disease - How to estimate GFR?
- Serum creatinine
Serum creatinine
creatinine
GFR urine
muscle
serum
4Determinants 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
5How to Correct for Differences in Muscle Mass
- Measure GFR directly
- Creatinine clearance with 24 h urine
- Radionucleide GFR (nuclear medicine)
- Estimate GFR Using Formulas
- Cockcroft-Gault
- MDRD (used by Ontario outpatient labs to give
eGFR)
6Cockcroft-Gault Equation
- Serum creatinine, age, weight, gender
- (140-age) Weight1.2/serum creatinine
creatinine clearance in ml/min (X 0.85 for women) - Can be done using calculator
- Avialable on Clinical desktop in Misys at UHN
7MDRD equation
- Serum creatinine, age, gender, race (black or
white) - Only useful for patients with known kidney
disease - Ontario out-patient labs now report eGFR using
this formula
8Examples of Calculated Ccr
- Two patients same serum creatinine
- 20 yr old male, 80 kg, creatinine 100 umol/L
calculated GFR 1.92 mL/s or 115 ml/min
(Normal gt 1.5) - 65 year old woman, 40 kg, creatinine 100 uM
calculated GFR 0.5 mL/s or 30 ml/min - Moral you need to look at more than the serum
creatinine
9Acute Renal Failure
- Renal response to reduced effective circulating
volume - Prerenal ARF
- Ischemic and toxic acute tubular necrosis
- Obstruction
- Abdominal compartment syndrome
- Case studies
- Dialysis for ARF
10Renal Response to Reduced Effective Circulating
Volume
- What is effective circulating volume
- cardiac output vs peripheral vascular resistance
- how cardiovascular receptors see arterial
filling - Effective circulating volume is reduced in
- volume depletion (hemorrhage, diarrhea etc)
- systemic vasodilatation (sepsis, liver failure)
- congestive heart failure
11Consequences 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 lt 20 mM
- Water retention Uosm gt500
12Angiotensin II and Regulation of GFR
13Causes of Acute Renal Failure
- 1. Prerenal
- 2. Vascular
- 3. Glomerular
- 4. Tubulo-interstitial
- 5. Obstruction
1
2
3
4
5
14Prerenal 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
- NSAIDs, Cyclosporine
- Renal arteriolarsclerosis (age, hypertension)
15Prerenal Failure-Clinical
- Hypovolemia
- hemorrhage
- diarrhea, vomiting, burns
- pancreatitis, ascites
- SIRS/capillary leak
- Septic shock
- Cardiogenic shock
- Drugs cyclosporine, NSAIDs, etc
16The Kidney In Prerenal Failure
- Normal renal response to reduced effective
circulating volume - oliguria (lt 0.5 ml/kg/h)
- normal urinalysis (no protein or casts)
- high urine osmolality (ADH acting)
- low urine Na or chloride
- increasing serum creatinine
- Rapid improvement in urine flow and serum
creatinine if prerenal state corrected
17Ischemic Acute Tubular Necrosis
- Causes same as prerenal ARF - more severe or
more prolonged - Ischemia is synergistic with
- sepsis (especially gram -)
- biliary obstruction with jaundice
- angiographic dye
- myoglobin (rhabdomyolysis)
- cardiopulmonary bypass
18Tubular proteins (markers of injury) in patients
on bypass for lt 70 minutes or gt 90 minutes Ann
Thoracic Surg 200375906
19Pathophysiology of Ischemic ATN
- 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
20Urine in Ischemic ATN
- Oliguria (if severe injury) or non-oliguric
- Urine flow may increase with furosemide
- Isotonic urine (300 mosmol/kg)
- High urine sodium ( gt 30 mmol/L)
- hematuria, heme granular casts, debris on
urinalysis
21Urine in ATN note blood cells, tubular (white )
cells, debris and characteristic heme granular
casts (muddy brown casts)
22Toxic Acute Tubular Necrosis
- Aminoglycosides, amphotericin, cisplatin etc
- Aminoglycosides
- 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
- gentamicin more toxic than tobramycin
- prevent by limiting course to lt 10 days
23Obstruction and Acute Renal Failure
- Males prostate
- Females pelvic malignancy
- Either
- single kidney and stone, clot
- retroperitoneal malignancy
- lymphoma
- bladder, rectum
- Retroperitoneal fibrosis
24Obstruction (2)
- Urine flow anuric to polyuric
- Isotonic, high urine sodium
- Diagnosis by ultrasound
- Treatment
- bladder catheter!
- Unilateral or bilateral percutaneous nephrostomy
- Ureteral stent (retrograde or antegrade)
- Good prognosis if caught in lt 1-2 months
25Abdo U/S in Obstruction
Normal
26Other Causes of Acute Renal Failure
27Abdominal Compartment Syndrome
- Normal IP pressure 0-10 mmHg
- ACS when IP pressure gt 25 mmHg
- Increased renal vein resistance
- Reduced RBF and GFR
- Low urine Na
- Causes trauma, pancreatitis, liver transplant,
bowel obstruction often with massive amounts of
fluid resuscitation
28Atheroembolic disease
- 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
29Contrast-induced ARF
- Oliguric ARF within 24 h of procedure
- Cause unknown (vascular vs toxic)
- Risk factors
- renal failure (GFR lt 30 ml/min)
- diabetic nephropathy with GFR lt 40 ml/min)
- Congestive heart failure
- Prevention
- IV saline or IV sodium bicarbonate
- N-acetylcysteine (controversial)
- Prognosis usually good except DM CKD 4-5
30Less Common Causes of ARF
- Allergic interstitial nephritis drug
reaction penicillins, cipro, NSAIDs, Septra etc - Thrombotic Microangiopathy (hemolytic uremic
syndrome) - Toxemia of pregnancy
- Bone marrow transplant
- Cyclosporine
- Toxigenic E.Coli (Walkerton)
- Malignant hypertension etc.
31Assessment of Patient with ARF
- History prior renal function BP, ECFV, weight
change - Drugs diuretics, antibiotics, NSAIDs, ACE
inhibitors, angio dye, cyclosporine - Physical Exam BP, JVP, edema, ascites,
peripheral pulses, bruits, urine flow - Lab lytes, creatinine, urea, CBC, film
urinalysis, urine lytes, osmolality - Renal U/S if dx unclear
32Consequences of Acute Renal Failure
- ? ECF volume pulmonary edema, edema
- Hyperkalemia if oliguria
- Uremia anorexia, nausea, vomiting,
encephalopthy, etc - Metabolic acidosis, hypocalcemia,
hyperphopsphatemia, anemia - Prognosis
- with multiorgan failure in ICU mortality 60-70
- with no other organ failure, prognosis is good
33Dialysis for Acute Renal Failure
- Indications
- Pulmonary edema
- Hyperkalemia
- Serum creatinine gt 500 umol/L
- Serum creatinine gt 300 with oliguria
- Methods
- Conventional, intermittent HD (3-5 h daily)
- CVVHD - using Prisma - heparin vs citrate
- CVVHDF - addition of hemofiltration
- SLED (sustained low efficiency HD) 8 hours 6
days/wk
34Case History 1
- 65 yr old admitted 2 months post CABGAVR
- 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?
35Case 1
- Differential
- Post-infectious GN
- Ischemic ATN
- Athero-embolic disease
- GENTAMICIN-INDUCED
36Case 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
37Case 2
- Differential
- Ischemic ATN
- Renal artery thrombosis
- ATHERO-EMBOLIC DISEASE
38Case History 3
- 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?
39CASE 3
- Ischemic ATN
- Obstructive jaundice
- Gram-negative bacteremia
- Hypotension
40Case 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
41Case 4
- Thrombotic Microangiopathy
- HELLP syndrome
- Post-partum acute renal failure
42Case 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?
43Case 5
- Differential
- Ischemic ATN
- Abdominal compartment syndrome
44Summary Risk Factors for ARF in Surgical Patients
- Obstructive jaundice
- Sepsis syndrome - especially with MOF
- Angiography
- dye renal failure/diabetes
- atheroembolic disease - vasculopaths
- Prolonged use of aminoglycosides (gt 7 d)
- Hypotension with pre-existing renal disease
especially in the elderly - Cyclosporine for transplantation
45Chronic Kidney Disease
- GFR ml/min
- Stage 1 gt90
- Stage 2 (mild) 60-90
- Stage 3 (moderate) 30-60
- Stage 4 (advanced) 15-30
- Stage 5 End stage KD lt 15
- GFR measured or calculated using Cockcroft-Gault
or MDRD equation
46Causes/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
47Patients with Chronic Kidney Disease
- 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
patients kidney function and why?
48What Happens Post Donor Nephrectomy?
- Serum creatinine rises by 40 (not 100)
- Increase in single nephron GFR of 40
- Afferent and efferent arterioles dilate,
increased glomerular blood flow and pressure - Mild increase in proteinuria chronically
- Normal life expectancy, no increased risk of
renal failure with loss of 50 of nephrons
49What if More Nephrons are Lost?
- Increased single nephron GFR by afferent and
efferent arteriolar dilatation - If lose gt 65 of nephrons, get structural changes
in glomeruli and arterioles due to
hyperfiltration and hypertension - Proteinuria and progressive renal failure
- Predictors of progessive disease?
- Higher serum creatinine
- Hypertension
- Amount of proteinuria gt 1 g/d is bad, gt3 g worse
50Impact 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 - Limited ability to excrete extra sodium, water
and potassium - Limited ability to retain sodium and water
51Impact 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
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53Impact of Renal Dysfunction on Outcomes of CABG
Circulation 20061131063 485,000 US patients
2002-3
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56Why 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
- Vascular calcification
- Chronic inflammation
- Increased SNS, increased vascular stiffness
- Increased homocysteine
57Case History 6
- 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?
58Case 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
- request nephrology cardiac assessment
- will renal disease progress anyway? -operate when
on dialysis?
59Case History 6
- Surgery is planned after cardiac assessment
- Maintain as stable a BP as possible and avoid
hypotension ( lt 130 systolic in this patient) - Accurate fluid replacement to avoid volume
depletion or overload - Monitor serum potassium (daily lytes)
60Case History 7
- 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
61Management of HD Patient
- 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)
62Peri-Operative Intravenous Fluid
- What is normal intake of water, Na and K?
- Water 1.5-2 L/d
- Sodium 150 mmol/day
- Potassium 50 mmol/day
- What is main risk of IV fluid post-op?
- Hyponatremia from large volume hypotonic fluid
63Prevention of Postoperative Hyponatremia
- Avoid large volumes of hypotonic fluid unless the
patient is hypernatremic - Limit volume of I.V. fluid given to meet
patients needs - Adjust volume to patients body weight
64Peri-operative IV Fluid
- Annals Surgery 2003238641
- 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
65Peri-operative IV Fluid -Standard
- 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
66Peri-operative IV Fluid Restricted
- Intra-op
- No preloading
- No replacement of third space loss
- Blood loss volume/volume with HAES
- Post-op
- 1000 ml 5 D/W for remaining OR day
- Then oral fluid or IV if needed
- Furosemide if weight increased by 1 kg
67Results
68Complication frequency related to IV fluid and wt
gain on operative day
69A Comparison of Albumin and Saline for Fluid
Resuscitation in the Intensive Care Unit
- NEJM 20043502247
- Previous meta-analysis suggested albumin
resuscitation increased mortality - RCT in 7,000 ICU patients
- 4 albumin vs crystalloid for fluid
- No difference in mortality
70Summary
- 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