HEMODIALYSIS ANDARTIFICIAL KIDNEY

INTRODUCTION

Dialysis is the artificial replacement of lost

kidney functions.

Used in Chronic Kidney Disease(CKD) stage 5

or End Stage Renal Disease(ESRD).

Typically needed when 90% or more kidney

function is lost.

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DAILY WASTE PRODUCTION IN A NORMAL AND URIMIC PERSON

Component Normal man(g/day)

Uremic patient(g/day)

Water 1500 300

Urea 30 12

Creatinine 0.6 0.2

Uric acid 0.9 0.4

Na+ 5 0.4

Cl- 10 1.2

Ca2+ 0.2 0.1

PO4 3- 3.7 1.8

K+ 2.2 0.5

HSO4+ 8.2 -

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KIDNEY FAILURE :CAUSES

Diabetes mellitus

Hypertension

Glomerulonephritis(GN)

Polycystic kidney

Overuse of common drugs such as aspirin,

ibuprofen, codeine

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TREATMENT: ARTIFICIAL WASTE REMOVAL

A body fluid is contacted with a “dialysate” solution

across a semipermiable membrane.

Dialysate contains no waste material.

Body fluid will loose those materials to dialysate via

diffusion through SPM.

Clean body fluid is returned back to the body.

Component g/liter Component Meq/liter

NaCl 5.8 Na+ 132

NaHCO3 4.5 K+ 2.0

KCl 0.15 Cl- 105

CaCl2 0.18 HCO3- 33

MgCl2 0.15 Ca2+ 2.5

Glucose 2.0 Mg2+ 1.5

DIFFERENT METHODS OF WASTE DISPOSAL

A. Internal method

1. Peritoneal dialysis.

2. Gastro dialysis.

3. Intestinal dialysis.

4. Pleural dialysis.

B. External Method

1. Filter Bed absorption column

2. Ultrafiltration method

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ADVANTAGES AND DISADVANTAGES OF INTERNAL DEVICES

Advantages: Avoidance of handling blood Simplicity of equipment

Disadvantages:Poor efficiency in most casesUncomfortablenessLoss of proteinMembrane infectionThe necessity that the dialysate must be extremely sterile

HEMODIALYSIS

It is the most commonly used process

Purpose - removal of wastes from the body

Water retention / removal

Salt retention / removal

Protein retention

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HEMODIALYSIS MACHINE

DESIGN CRIETERIONS

1. Efficient to remove nitrogenous & toxic waste and

excess ionic species.

2. Efficient in removing excess water.

3. Small internal blood-side volume(~500ml or less).

4. low blood-side flow resistance.

5. Constructed of blood-compatible material.

6. Reliable, repeatable and easy to operate.

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DIALYZER

It is called an artificial kidney

It is designed to provide controllable transfer of solutes and water across a semi permeable membrane separating flowing blood and dialysate streams.

The transfer processes are diffusion (dialysis) and convection (ultrafiltration).

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Types of hemodialyzer:

i. Flat plate

ii. Coil type

iii. Tubular

iv. Hollow fiber

FLAT PATE TYPE OF HEMODIALYSER

The assembled unit consists of parallel epoxy boards having lengthwise channels and grooves.

Two cellophane sheets are inserted between each board-to-board joint.

Headers direct blood to the channels between two cellophane sheets and dialysate to the gap between cellophane and board.

Flow is normal counter-current.

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COIL TYPE OF HEMODIALYSER Most popular type is called

Kolff Twin Coil.

The membrane consists of two cellophane tubes flattened and placed on a support screen and tightly wound around a plastic core.

Flow is “cross-flow”.

Limitation:Coil design don’t produceuniform dialysate flow.

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HOLLOW FIBRE DEVICES This is the most effective

type of dialysis unit consisting up to 11000 capillaries made of regenerated cellulose.

No blood pump in needed.

It provides low blood flow resistance and high efficiency.

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RECIRCULATION OF DIALYSATE SYSTEM (ReDy)

A recirculating dialysate system is used with artificial kidney to eliminate toxic substance from the dialysate solution.

It is used to maintain continuously a normal dialysate solution.

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Recirculating dialysis system consist of several layers:

1. Urease: it converts urea

into ammonium carbonate

2. Zirconium phosphate:

absorbs ammonium ion.

3. Hydrated zirconium oxide:

absorbs phosphate ion.

4. Activated carbon: absorbs

uric acid, creatinine and

other organic waste

MASS TRANSFER EQUATION OF THE DIALYZER

BBDD

DBo

dCQdCQdW

dACCKdW

and

WALL

MEMBRANE

Mass transfer in a differential length of a dialyzer

D

B

DBB

DBBDBBD

B

DBBBD

B

DBDDD

B

D

B

QQCCd

QdW

CCdQdCdCQQ

QdW

dCQdCQdWQ

QdW

dCQdCQQ

QdW

Q

Q

1

1

&

dA

QQK

CC

CCd

dACCK

QQCCd

Q

DBo

DB

DB

DBo

D

B

DBB

11

1

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Equating the dW’s,

Integrate assuming constant Ko

meano

DiBo

DoBi

DiBoDoBio

DiDoBoBi

DB

DBo

DiBo

DoiB

CAKW

CC

CC

CCCCAKW

W

CC

W

CC

QQSince

AQQ

KCC

CC

log

ln

11

11ln

REFERENCES

Lysaght MJ. Maintenance dialysis population dynamics: current trends and long-term implications. J Am Soc Nephrol 2002; 13: 37–40

Moeller S, Gioberge S, Brown G. ESRD patients in 2001: global overview of patients, treatment modalities and development trends. Nephrol Dial Transplant 2002; 17: 2071–2976

PRESENTED BY

Debarati Saha4th year,7th semRoll No.071090131013

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