rk dialysis

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Renal replacement therapy

RK


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Dialysis

Definition

Artificial process that partially replaces renal

function

Removes waste products from blood by

diffusion (toxin and solute clearance)

Removes excess water by ultrafiltration viaosmosis (maintenance of fluid balance)

Wastes and water pass into a special liquid

called dialysis fluid or dialysate


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Selection for HD/PD

Clinical condition

Age(PD prefer in young pt)

Lean body mass

Vascular access availability

Lifestyle

Patient competence/hygiene (PD - high risk of

infection) Affordability / Availability

Patient preferrence


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Indication for dialysis

Complication of uremia(uremic pericarditis,progressive neuropathy, uremic encephalopathy,cramps)

Volume overload unresponsive to diuretics

Hyperkalemia unresponsive to potassiumrestriction

Metabolic disturbances: severe progressive

metabolic acidosis, hyperkalemia,hyperphosphatemia, hyper/hypocalcemia

Removal of drugs causing acute renalfailure(gentamicin, lithium, aspirin overdose)


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Haemodialysis

Dialysis process occurs outside the body in amachine

The dialysis membrane is an artificial oneknown as dialyser

The dialyser removes the excess fluid andwastes from the blood and returns the filteredblood to the body

Haemodialysis needs to be performed threetimes a week

Each session lasts 3-6 hrs


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Requirements for HD

Good access to patients circulation

Good cardiovascular status (dramatic changes

in BP may occur)


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Hemodialysis Apparatus

Dialyzer (cellulose, substituted cellulose,synthetic noncellulose membranes)

Dialysis solution (dialysate water must remain

free of Al, Cu, chloramine, bacteria, andendotoxin)

Tubing for transport of blood and dialysis solution

Machine to power and mechanically monitor theprocedure (includes air monitor, proportioningsystem, temperature sensor, urea sensor tocalculate clearance)


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HD Unit in hospital

Specially designed Renal Unit within a hospital

Patients must travel to the Unit 3 times a week

Patients are unable to move around while on

dialysis; may chat, read, watch TV or eat

Nursing staff prepare equipment, insert the

needles and supervise the sessions


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HD Access

2 criteria for HD access:

Must provide good flow

Reliable access

A fistula: arterio-venous (AV)

Vascular Access Catheter: Internal jugular or

femoral vein


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AV Fistula Access

Matures in about 6 weeks

Ensure good working order

Avoid tight clothing or wrist watch on fistula arm

Assess fistula daily; notify immediately if not working

Avoid BP cuff on fistula arm

Avoid blood sampling on fistula arm

Avoid sleeping on fistula arm

Grafts (synthetic) may be used to create an AV fistula


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AV Fistula

Preferred form of dialysis access

Typically end-to-side vein-to-arteryanastamosis

Types Radiocephalic (first choice)

Brachiocephalic (second choice)

Brachiobasilic (third choice, requiressuperficialization of basilic vein, i.e. transposition)

Lower extremity fistulae are rare


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Dialysis - the Present


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AV Fistula


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Vascular Access Catheter

Double lumen plastic tube

May be placed in Jugular, Subclavian or Femoral

vein

May be temporary or permanent

Temporary awaiting fistula or maturation

Permanent poor vessels for fistula creation e.g.

children and diabetics Catheters must be kept clean, dry and dressed to

prevent infection


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Vascular Access Catheter


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Adv vs Disadv

Adv: max solute clearance, best treatment of

severe hyperkalemia, ready availability, limited

anticoagulation time, bedside vascular access

Disadv:hemodynamic instability, hypoxemia,

rapid fluid and solute shift, complex

equipment, need specialized staff, AV fistula

takes time to form

Eff t f HD Lif t l


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Effects of HD on Lifestyle Travel:

Cannot travel to long distance places/vacation because notavalaibility of dialysis centre or to book in advance with HD unitof places of travel

Responsibility & Independence:

Young patients may defaulted their dialysis leads to uremia

Family relationship Anxiety of living with renal failure affects relationship with

partner

Sport & Exercise:

Can exercise and participate in most sports Body Image:

Esp with fistula; patient can be very self conscious about it

C li ti f HD


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Complication of HD Rapid changes in BP

fainting, vomiting, cramps, chest pain, irritability, fatigue, temporary loss ofvision

Fluid overload esp in between sessions

Fluid restrictions

more stringent with HD than PD

Hyperkalaemia

esp in between sessions

Loss of independence

Problems with vascular access poor quality, blockage etc. Infection (vascular access catheters)

Pain with needles Bleeding and thrombosis

from the fistula during or after dialysis

Infections

during sessions; exit site infections; blood-borne viruses e.g. Hepatitis, HIV


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Peritoneal Dialysis (PD)

Fluid and solute exchange between the peritonealmembrane capillaries and dialysate in theperitoneal cavity

Access is by PD catheter, a soft plastic tube

Catheter and dialysis fluid may be hidden underclothing

Suitability

Cannot done in patients with prior peritoneal scarringe.g. peritonitis, laparotomy

And patients who unable to care for self


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PD principle

Fluid across the membrane faster than solutes;

therefore longer times are needed for solutetransfer

Protein loss in PD fluid is significant ~ 8-9g/day

Protein loss s during peritonitis PD patients require adequate daily protein

averaging 1.2 1.5g/kg/day

Other substances lost in the dialysate

Amino acids, water soluble vitamins, somemedications and hormones

Calcium and dextrose are absorbed from the

dialysate fluid into the circulation


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Dialysate content

Standard dialysis solution contains:

Na+

132 mEq/l Cl- 96 -102 mEq/l

Ca2+ 2.5 3.5 mEq/l

Mg2+ 0.5 -1.5 mEq/l

Dialysis solution buffer:

Sodium lactate

Pure HCo3-

HCo3- /Lactate combinations


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Types

Continuous Ambulatory Peritoneal Dialysis

(CAPD)

Automated peritoneal Dialysis (APD)


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CAPD

Dialysis takes place 24hrs a day, 7 days a week

Patient is not attached to a machine for treatment

Exchanges are usually carried out by patient after

training by a CAPD nurse

Most patients need 3-5 exchanges a day i.e.

4-6 hour intervals with 30 mins per exchange

May use 2-3 litres of fluid in abdomen No needles are used

Less dietary and fluid restriction


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CAPD Exchange


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APD

Uses a home based machine to perform exchanges

Overnight treatment while patient sleeps

The APD machine controls the timing of

exchanges, drains the used solution and fills theperitoneal cavity with new solution

Simple procedure for the patient to perform

Requires about 8-10 hrs

Machines are portable, with in-built safety

features and requires electricity to operate

PD A


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PD Access

Done under

LA or GA


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DIET

Managing the diet

a) can slow renal disease

b) need for dialysis can be delayed


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Foods to control are those containing: Protein

Potassium

Sodium

Phosphorous

Fluid


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Adv vs Disadv

Adv: simple to set/form, easy to use,

hemodynamically stable, no anticoagulation,

bedside peritoneal access,

Disadv: unreliable ultrafiltration, slow fluid

and solute clearance, drainage failure/leakage,

catheter obstruction, peritonitis,

hypoglycemia


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Lifestyle Changes with PD

Flexibility

Can be performed almost anywhere

Least impact on work / school life (esp APD)

Travel

Dialysis supplies can be delivered to most parts of the

world; travel more flexible. APD machines are portable;

will fit into a car boot, can be carried by train/air

Responsibility

Requires more responsibility from patient but more

independence


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Lifestyle Changes with PD

Sports/Exercise

Most are possible

Advice on swimming, lifting, contact sports

Family relationship

May affect relations based on patient anxiety

Delivery & Storage of Supplies

Home delivery and storage

A months supplies 40 boxes; space to store

Specially recruited and trained delivery staff


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Complication

Body Image Problems

Esp with a permanent catheter Abdominal stretching

Fluid Overload

Much less a problem than with HD

Dehydration

Less common than fluid overload

Abdominal Discomfort Bloated feeling

C li ti


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Complication Poor drainage

Catheter displacement/malposition/occlusion

Leakage

Fluid may leak around catheter exit site. (May leakinto scrotum)

Infections Exit site infections

Tunnel infection

peritonitis


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Complication

Hernia

Aggravation of pre-existing herniae after repair

development of new herniae

Declining effectiveness of the peritoneum

e.g. repeated infection

Effect of glucose in the dialysis fluid

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