Crrt in aki

DR Samir Sally, MD
Consultant Internal Medicine & Nephrology,
MUNC, Mansoura University, Egypt

ARF: History
• Ischuria Renalis: 1st description of ARF, by William
Heberden in 1802.
• Acute Bright’s disease: in William Osler’s
Textbook for Medicine (1909).
• War Nephritis: During the 1st World War.
• Crush Syndrome: During 2nd World War.
• Acute Renal Failure: First use of the term ARF
by Homer W. Smith in his textbook “The kidney-
structure and function in health and disease (1951).

ARF
• ARF: is defined as an abrupt or rapid decline in renal
filtration function (over hours to weeks) and usually
reversible.
• This is one of 35 definitions in the literature.
• No precise biochemical deﬁnition of ARF was
proposed.
• No consensus on the diagnostic criteria or
clinical deﬁnition of ARF.

AKI and RIFLE Criteria
• In 2004 the ADQI (Acute Dialysis Quality
Initiative) group published their consensus
definition for AKI, the Risk–Injury–Failure–
Loss–Endstage renal disease (RIFLE)
classification

KDIGO 2012
• VOLUME 2 | ISSUE 1 | MARCH 2012
• http://www.kidney-international.org
• The first precise
biochemical,
clinical definition of
AKI with diagnostic
criteria

• AKI is deﬁned as any of the following:
– Increase in SCr by ≥ 0.3mg/dl (≥ 26.5 umol/l)
within 48 hours; or
– Increase in SCr to ≥ 1.5 times baseline, which is
known or presumed to have occurred within the
prior 7 days; or
– Urine volume < 0.5ml/kg/h for 6 hours.
KDIGO 2012: AKI Definition

• 5–20% of critically ill patients experience an episode of AKI
during the course of their illness
• AKI requiring RRT: 4·9% of all admissions to intensive-care
units (ICU)
• Mortality in hospitalised patients ranging from 10%-80%:
– Patients who present with uncomplicated AKI, have a mortality rate of
up to 10%.
– Patients presenting with AKI and multiorgan failure have been
reported to have mortality rates of over 50%.
– If renal replacement therapy is required the mortality rate rises
further to as high as 80%.
AKI: Incidence

AKI: Management
High Risk Patients

AKI: Management
• Evaluate for causes: Evaluate patients with AKI promptly to
determine the cause, with special attention to reversible causes.
• Stage the severity: Monitor patients with AKI with measurements
of SCr and urine output to stage the severity,
• Manage according to stage and cause: Manage patients
with AKI according to the stage and cause.
• Evaluate after 3 months: Evaluate patients 3 months after AKI
for resolution, new onset, or worsening of pre-existing CKD.
– If patients have CKD, manage these patients as detailed in the KDOQI CKD
Guideline
– If patients do not have CKD, consider them to be at increased risk for CKD and
care for them as detailed in the KDOQI CKD Guideline 3 for patients at
increased risk for CKD.

Stage 1 Stage 2 Stage 3
AKI: Management according to stages

1. OLIGOANURIA: Non obstructive oliguria or anuria
2. METABOLIC ACIDOSIS: Severe metabolic acidosis
3. AZOTAEMIA: (blood urea >30mmol/l)
4. HYPERKALAEMIA (K>6.5)
5. UREMIC MANIFESTATIONS: pericarditis, encephalopathy
6. DYSNATRAEMIA: (Na>160 or <115)
7. HYPERTHERMIA
8. CEREBRAL OR PULMONARY OEDEMA: Clinically significant
9. COAGULOPATHY: requiring large amounts of blood products
in patients with pulmonary oedema
10. INTOXICATIONS: Dialysable drug overdose and toxins
AKI: Renal Replacement Therapy (RRT)
Indications

Advantages
• Hemodynamic stability
• Easy to use in ICU
• Continuous removal of toxins
• Easy control of fluid balance
• No treatment-induced
increase of intracranial
pressure
• Early use of TPN
• User-friendly machines
Disadvantages
• Slower clearance of
toxins
• Need for prolonged
anticoagulation
• Patient immobilization
• Hypothermia
• Increased costs
Continuous RRT

Advantages over IHD in critically ill pts.
• Allows adequate volume of nutrition without compromising
fluid balance
• Decreased vasopressor requirements during fluid removal
• Increased hemodynamic stability
• Optimizes fluid balance in lung injury
• Continuous control of fluid balance
Continuous RRT

AKI:RRT Modalities
KDIGO 2012 Recommendations
1. Use continuous and intermittent RRT as
complementary therapies in AKI patients.
2. We suggest using CRRT, rather than standard
intermittent RRT, for hemodynamically unstable
patients.
3. We suggest using CRRT, rather than intermittent
RRT, for AKI patients with acute brain injury or other
causes of increased intracranial pressure or
generalized brain edema.

It is Now
For
In
CRRT
Nature Reviews Nephrology 6, 521-529 (September 2010)

• CRRT is indicated in
any patient who
meets criteria for
hemodialysis therapy
but cannot tolerate
intermittent dialysis
due to hemodynamic
instability
CRRT Indications

CRRT Modalities
• SCUF- Slow Continuous Ultrafiltration
– Ultrafiltration
• CVVH- Continuous Veno-Venous Hemofiltration
– Convection
• CVVHD- Continuous Veno-Venous Hemodialysis
– Diffusion
• CVVHDF- Continuous Veno-Venous Hemodiafiltration
– Diffusion and Convection

SCUF

• Pros
– Filters blood effectively
– Control fluid balance by
regulating
transmembrane
pressures
– No replacement fluid
therefore less pharmacy
cost
• Cons
– No replacement fluid
given so electrolyte
abnormalities can occur
– Low ultrafiltration rates
that keep electrolytes
balanced do not remove
urea effectively
SCUF

Predilution
Replacement Fluid
Postdilution
CVVH

CVVHD

Predilution
Replacement Fluid
Postdilution
CVVHDF

• CVVHDF is probably the most common type of
CRRT used.
• It combines aspects of both CVVHD and CVVH.
• CVVHDF removes small and middle molecules.
CVVHDF

Modality Selection

Size of molecules cleared by CRRT Hemofilter
28
Molecular weights
Small Molecules
Diffusion is better than
convection
Middle Molecules
Convection better than
diffusion
Nothing above 50.000 is cleared
Mode of removal
Large Molecules
Convection or adsorbtion

CRRT: Prescription

Internal Jugular Vein
– Primary site of choice due to lower associated risk of
complication and simplicity of catheter insertion.
Femoral Vein
– Patient immobilized, the femoral vein is optimal and
constitutes the easiest site for insertion.
Subclavin Vein
– The least preferred site given its higher risk of
pneumo/hemothorax and its association with central
venous stenosis.
CRRT: Vascular Access

The length of the catheter chosen will
depend upon the site used
– Size of the catheter is important in the pediatric
population.
The following are suggested guidelines for
the different sites:
–RIJ= 15 cm French
–LIJ= 20 cm French
–Femoral= 25 cm French
CRRT: Vascular Access

CRRT: Time of Initiation

• Clinicians tend to delay RRT when they
o Suspicion that patients may recover on their own.
o Concern for the well-known risks associated with
the RRT procedure:
oHypotension
oArrhythmia
oMembrane bioincompatibility
oComplications of vascular access
oAnticoagulant administration.
CRRT: Time of Initiation

Timing of CRRT initiation:
Conclusion
Renal Indications
• Fluid overload unresponsive to
diuretic treatment
• Hyperkalaemia (>6.5 mmol/L or
rapidly rising level)
• Azotaemia (urea >36 mmol/L)
• Severe acidaemia (pH <7.1)
• Oliguria (urine output <200
mL/12 hours) or anuria (urine
output <50 mL/12 hours)
• Uraemic complication like
bleeding, pericarditis, or
encephalopathy
In critically ill and hemodynamically unstable pts. CRRT should be
initiated if one of the following
Non Renal Indications
• Drug overdose with dialysable toxin
• Patients requiring large amount of
fluids, parentral nutrition or blood
product but at risk of developing
pulmonary oedema or acute
respiratory distress syndrome
• Sepsis and systemic inflammation
• Cardiac failure
• Hyper or hypo-thermia with core
temperature >39.5ºC or <30ºC

• It is recommended that an improvement in the patient‟s
clinical condition and urine output would justify temporary
discontinuation of ongoing renal support to see if AKI is
recovering. UK Renal Association 5th Edition, 2011
• Bouman et al : Urine output returned to and was stable at >
60 ml/h.
• Uchino et al :
– Urine output of ≥ 450 ml/day without diuretic
– Urine output of ≥ 2400 ml/day with diuretic
CRRT: Discontinuation
Bouman et al. Crit Care Med 2002;30:2205–2211.
Uchino et al. Crit Care Med 2008

0%
10%
20%
30%
40%
50%
60%
20 ml/kg/h 35 ml/kg/h 45 ml/kg/h
41%
57% 58%
%Survival
CRRT Dose
Ronco et al: Survival by CRRT Dose
Ronco et al, Lancet 2000, 356:26-30 2000

Patients: 1124
Intensive Therapy (563): 35 ml/kg/hour
Less Intensive Therapy (561): 21 ml/kg/hour
Mortality at 60 days: 302/563 vs 298/561
P value: Non Significant
The VA/NIH Acute Renal Failure Trial Network:. N Engl J Med 2008, 359:7-20. 2008

 Randomized to
CVVHDF with effluent 25ml/kg/h
CVVHDF with effluent 40ml/kg/h
• Primary endpoint = mortality at d 90
Multicenter (n=35) PRCT in Australia and New Zealand
n=1508
The RENAL Replacement Study Investigators. N Engl J Med 2009; 361: 1627-38 2009

CRRT: Dose
0
10
20
30
40
50
60
70
80
Ronco et al
2000
Bouman et al
2002
Saudan et al
2006
ATN Trial
2008
Tolwani et al
2008
RENAL 2009
PercentSurvival
Studies
% Survival by CRRT Dose
High Dose
Low Dose
P Value: NS

CRRT: Dose

Exercise on Dosing
Mr. Smith, 60 kg, ARF
Required dose: 35ml/kg BW/hr CVVHDF
– Pre: 30%
– Post:70%
– Pt., fluid removal: 100 ml/hr
– Dialysate: ?????
42
Calculation: 60kg x 35 ml/kg/h = 2100 ml/h
Flow rates
1000 ml Dialysate
1000 ml Replacement
700 ml Post-Replacement
300 ml Pre-Dilution (PBP)

Exercise on Dosing
Mrs. Jones, 100 kg, Polytrauma with Rhabdo
Required dose: 35ml/kg BW/hr
Mode: CVVHDF
– Pre-Replacement : 50% Post 50%
– Pt. fluid removal: 200 ml/hr
43
Calculation: 100kg x 35 ml/kg/h = 3500 ml/h
Flow rates:
1650ml Dialysate
1600ml Replacement
800 ml Post-Replacement
800 ml Pre-Replacemnt

Therapy Table (Example)
44
Acute Renal Failure Sepsis Rhabdomyolyse
Dose (ml/kg/BW/hr) 35 50 35
Blood flow (ml/min) 150-350 250-450 > 150
Patient 60 kg
Dialysate
Replacement Post
Replacement Pre = PBP
60 x 35 = 2100 ml
900 ml
400 ml
800 ml
60 x 50 = 3000 ml
1200 ml
600 ml
1200 ml
60 x 35 = 2100 ml
500 ml
550 ml
1050 ml
Patient 70 kg
Dialysate
Replacement Post
70 x 35 = 2450 ml
1000 ml
450 ml
1000 ml
70 x 50 = 3500 ml
1300 ml
700 ml
1400 ml
70 x 35 = 2450 ml
500 ml
650 ml
1300 ml
Patient 80 kg
Dialysate
Replacement Post
80 x 35 = 2800 ml
1000 ml
600 ml
1200 ml
80 x 50 = 4000 ml
1400 ml
900 ml
1800 ml
80 x 35 = 2800
500 ml
750 ml
1550 ml
Patient 90 kg
Dialysate
Replacement Post
90 x 35 = 3150 ml
1050 ml
700 ml
1400 ml
90 x 50 = 4500 ml
1500 ml
1000 ml
2000 ml
90 x 35 = 3150
500 ml
900 ml
1750 ml

• No anticoagulation
• Unfractionated heparin
• LMW Heparin
• Citrate
• Prostaglandins - PGI2, PGE1
• Danaparoid
• r-Hirudin
• Argatroban
CRRT: Anticoagulation

• No anticoagulation is indicated in:
– Prolonged bleeding times
– Thrombocytopenia
– Liver failure
• The filter needs to be changed after about 8 h.
• When using CRRT without anticoagulation:
– Use a pre-dilution technique
– Increase the dialysate flow to 3 l/h
– Periodic saline flushes.

TYPICAL REGIMEN IN CRRT :
o Priming of the circuit ( 5000 IU / L )
o Initial Heparin Bolus : 5 - 8 IU / kg
o Infuse Heparin at : 5 to 12 IU / kg / hr
ACT on post filter : Adjust heparin rate to keep
ACT between 1.5 & 2.0 times
STANDARD HEPARIN

Advantages
• Easy to use
• Effective
• inexpensive
Disadvantages
• Occasional
Thrombocytopenia
• Hemorrhagic Risk
with Bleeding
patient
STANDARD HEPARIN

• Vascular access
– Vascular spasm(initial BFR too high)
– Movement of catheter against vessel wall
– Improper length of hemodialysis catheter inserted
• Fluid volume deficit
– Excessive fluid removal without appropriate fluid
replenishment
CRRT: Complications

• Hypotension
– Intravascular volume depletion
– Underlying cardiac dysfunction
• Electrolyte imbalances
– High ultrafiltration rates (high clearance)
– Inadequate replenishment of electrolytes by
intravenous infusion,
– Inadequate replenishment of bicarbonate loss
during CRRT
CRRT: Complications

• Acid/base imbalance
– Renal dysfunction
– Respiratory compromise
• Blood loss
– Ineffective anticoagulation therapy
– Clotting of hemofilter
– Inadvertent disconnection in the CRRT system
– Hemorrhage due to over-anticoagulation
– Blood filter leaks
CRRT: Complications

• Air embolus
– Leaks or faulty connections in tubing
– Line separation.
• Cardiac arrest
– Hypotension/hypertension
– Hemolysis
– Air embolism
– Circulatory overload
– Arrhythmias
CRRT: Complications

CRRT: Conclusion
• The first precise, biochemical and clinical
definition of AKI: presented by KDIGO on March
2012 which allows clear diagnostic criteria and
management according stages.
• Incidence of AKI: is increasing particularly hospital
acquired AKI with mortality ranging from 10 – 80 %.

CRRT: Conclusion
• KDIGO Plan of management of AKI
– Evaluate for cause
– Stage severity
– Mange according to cause and stage
– Evaluate after 3months for development of CKD or high
risk
• Dialyzable toxins and drugs should be familiar for
nephrologist
– Lithium, Methanol, Ethylene glycol, Salicylate,
Barbiturates, Metformin, Aminoglycosides, Metronidazole,
Carbapenems, Cephalosporins and most

CRRT: Conclusion
• CRRT is the leading form of RRT: for AKI in intensive
care units wordwide.
• CRRT is suggested: for AKI patients with acute brain
injury or other causes of increased intracranial
pressure or generalized brain edema.
• CVVHDF: is probably the most common type of CRRT
used. It combines aspects of both CVVHD and CVVH,
and removes small and middle molecules

CRRT: Conclusion
• Subclavian vascular access should be avoided.
• The length of the catheter chosen will depend upon
the site used.
• No significant benefit of initiating CRRT early vs late,
so it is recommende to initiate if renal or non renal
insications are present

CRRT: Conclusion
• ATN trial, 2008 (1124 patients) and RENAL trial,
2009 (1508 patients): showed no significant
difference between intensive CRRT dose (35 ml/kg/h)
and less intensive CRRT dose (20 ml/kg/h).
• In hypercatabolic and multi-organ failure: the higher
CRRT dose is recommended.

Crrt in aki

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