Decision making in acute dialysis

Geoffrey Bihl

MB.BCh M.MED FCP(SA)

Nephrologist and Director

Winelands Kidney and Dialysis Centre

Somerset West

South Africa

Important questions in AKI

What is the cause?

– Pre-renal

– Primary renal

– Obstructive

– Combination/Acute on chronic

SONAR EVERY PATIENT WITH ARF

URINALYSIS IN EVERY PATIENT

– P:CR ratio; Microscopy

Important questions in AKI

Can I manage the AKI without dialysis?

•Fluids

•Remove or treat primary cause

•Avoid further nephrotoxins in ICU

•Anti-biotics/analgesics/Contrast

•Blood pressure management

•Sodium bicarbonate in acidosis

Differences Between Renal Support in

AKI and ESRD

Time-frame

Days to weeks versus years

Burden of concomitant illness

Hemodynamic instability

Recoverability of kidney function

Renal Replacement Therapy

in Acute Kidney Injury

When should renal replacement therapy

be initiated in AKI?

Which modality is most appropriate?

What is the appropriate dose of

therapy?

Renal Replacement Therapy

in Acute Kidney Injury

When should renal replacement

therapy be initiated in AKI?

Which modality is most appropriate?

What is the appropriate dose of

therapy?

Timing of RRT

“While there is increasing recognition of

the value of earlier dialysis, the

published consensus, and the practice

in many centers at present, is still to

apply dialysis to relatively ill rather than

to relatively healthy patients”

Teschan PE, et al: Ann Intern Med 1960; 53:992-1016

KDIGO Acute Kidney Injury Clinical

Practice Guidelines

5.1.1: Initiate RRT emergently when life-

threatening changes in fluid, electrolyte, and

acid-base balance exist (Not Graded)

5.1.2: Consider the broad clinical context, the

presence of conditions that can be modified

with RRT, and trends of laboratory tests –

rather than single U&E thresholds alone –

when making the decision to start RRT (Not

Graded)

Classic indications for Acute renal support

Volume overload unresponsive to medical therapy

Metabolic acidosis unresponsive to medical therapy

Hyperkalemia unresponsive to medical therapy

Uremic state

Encephalopathy

Pericarditis

Azotemia without uremic manifestations

Oliguria unresponsive to medical therapy

Dialysis Prescription in acutely ill patient

requires assessment of the:

Fluid Balance Status

Acid-Base Status

Respiratory Status / Ventilation parameters

Cardiac Status

Coagulation Status

Central Nervous System Status

Haemodynamic Status

Inflammation Status

Dialysis Prescription in acutely ill patient

requires assessment of the:

Fluid Balance Status

Acid-Base Status

Respiratory Status / Ventilation parameters

Cardiac Status

Coagulation Status

Central Nervous System Status

Haemodynamic Status

Inflammation Status

PICARD Study: Impact of Fluid Overload at

Initiation of RRT

Bouchard J, et al. Kidney Int 2009; 76: 422-427

Dialysis Prescription in acutely ill patient

Choice of Dialysis Mode

Duration of procedure

Dialyser (Filter) Parameters

Dialysate (Fluid) Parameters including

i. Sodium concentration / modeling

ii. Potassium concentration

iii. Calcium concentration

iv. Bicarbonate / Acetate concentration

v. Temperature

vi. Pumps speed

vii. Anticoagulation regimen

viii. Ultrafiltration volume / modeling

ix. Management of Haemodynamic instability

x. Transfusion instructions

xi. Intradialytic Parenteral Nutrition (if required)

Renal Replacement Therapy

in Acute Kidney Injury

When should renal replacement therapy

be initiated in AKI?

Which modality is most appropriate?

What is the appropriate dose of

therapy?

Modalities of treatment

Intermittent hemodialysis

Continuous therapies

Continuous hemofiltration

Continuous hemodialysis

Continuous hemodiafiltration

Prolonged intermittent RRT

Peritoneal dialysis

Continuous vs. Intermittent Therapy in

Acute Kidney Injury

CRRT IHD p

N 84 82

Apache II 23.7 25.5 NS

Apache III 96.4 87.5 0.045

ICU Mortality 59.5% 41.5 0.02

Hospital mortality 65.5 47.5 0.02

ICU stay 15.1 16.7 NS

Renal recovery 34% 33% NS

Mehta R, et al: Kidney Int 2001; 60:1154-1163

Continuous vs. Intermittent Therapy in

Acute Kidney Injury

CRRT IHD p

N 40 40

CCF score 11.6 12.0 NS

Mortality 67.5 70.0 NS

ICU Mortality 59.5% 41.5% NS

Mean LOS

Survivors 35.8 41.9 NS

Non-survivors 14.3 10.4 NS

Renal recovery 12.5% 10% NS

Augustine JJ, et al. Am J Kidney Dis 2004; 44:1000-1007

Continuous vs. Intermittent Therapy in

Acute Kidney Injury

CRRT IHD p

N 70 55

ICU Mortality 34% 38% NS

Hospital Mortality 47% 51% NS

Uehlinger DE, et al. Nephrol Dial Transplant 2005 20: 1630-1637

CRRT vs. IHD in Acute Kidney Injury:

Hemodiafe Study

Vinsonneau C,, et al: Lancet 2006; 368:379-385

CRRT vs. IHD in Acute Kidney Injury: SHARF Study

Lins RL, et al. Nephrol Dial Transplant 2009; 24:512-518

Meta-analysis of Studies Comparing IHD to CRRT

Bagshaw SM, et al. Crit Care Med 2008; 36: 610-617

Issues in Specific Clinical Settings

CRRT may better

– To protect cerebral perfusion in patients

with:

– Fulmanent hepatic failure

– Acute brain injury

– Cerebral edema

Prolonged Intermittent Renal

Replacement Therapies

Extended Daily Dialysis (EDD)

Sustained low-efficiency dialysis (SLED)

SLEDD

Apparent less effect on haemodynamic profile

Affords judicious fluid removal

Excellent for pH correction

Good solute removal

Can be performed overnight

Requires prolonged anti-coagulation

SLEDD versus CVVHDF

Renal Replacement Therapy

in Acute Kidney Injury

When should renal replacement therapy

be initiated in AKI?

Which modality is most appropriate?

What is the appropriate dose of

therapy?

Dose of CVVHDF in ARF

0

10

20

30

40

50

60

20 35 40

% Survival

Ronco C, et al: Lancet 2000; 356:26-30

41% 57% 58%

ml/kg/h ml/kg/h ml/kg/h

Renal Replacement Therapy in

AKI: Dose of CRRT

24±6 ml/kg/h

25±5 ml/kg/h

Saudan P, et al. Kidney Int 2006; 70:1312-1317

p = 0.005

ANZICS RENAL Study: 90-Day

Survival

Bellomo R, et al. N Engl J Med 2009; 361: 1627-1638

40ml/kg/h

25ml/kg/h

RRT Dose and Survival

Survival

RRT dose

Dose

Dependent

Dose

Independent

So what do we do?

?

There are insufficient data to determine the optimal

timing of RRT in AKI

Clinical trials to evaluate timing need to include

patients who meet criteria for early initiation but

recover or die without receiving RRT.

Although severity of fluid overload is strongly

associated with adverse outcomes, there are

insufficient data to conclude that initiation of therapy

based on severity of fluid overload decreases

mortality

So...

Studies comparing modalities of RRT in AKI

have not demonstrated superiority of any

individual modality

Selection of modality should be guided by

expertise and resources available at the

individual institution

KDIGO Acute Kidney Injury Clinical

Practice Guidelines

5.6.1: Use continuous and intermittent RRT as

complementary therapies in AKI patients. (Not

Graded)

5.6.2: We suggest using CRRT, rather than standard

intermittent RRT, for hemodynamically unstable

patients. (2B)

5.6.3: 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. (2B)

Therefore...

Consider NOT dialysing

Individualise patients

Assess haemodynamic stability and fluid

status

Manage precipitating cause

Consider de-escalating frequency and

changing modality when stabilised