Contrinuous ultrafiltration with periods of dialysis

INTENSIVE CARE NURSING, Q Longman Group 1986

1986, I, 168-176

TECHNICAL

Continuous ultrafiltration with periods of dialysis. A. D. Milne Acute Renal Failure (ARF)

is a frequent and well

defined clinical entity. As a complication operative

patients

trauma,

in post-

and those who have suffered

it has a high mortality

(Holbach

et al.,

bolic patient using this method, it may be necessary exchange

up to 24 1 of fluid per day. The

transmembrane elevating

pressure (TMP)

the

collection

vessel

is controlled

by

to reduce

the

of manage-

negative pressure created by the water column in

ments in these patients being the removal offluid,

the filtrate tubing. Blood flow through the system

accompanied

is dependent

198 1). Despite one of the cornerstones by standard

precautions

balancing

in the critically

hydration

remains a problem.

may require antibiotic load. The products

and Total

Parenteral

of haemodialysis

balance

in these

however a large number tolerate

fluid

goal of dialysis. The

these methods.

fluid removed currently

Homburg

There

are

who do not

patients

succumb

however, of this anisotropic fibre

membrane,

in use in the Respiratory manufactured Hersteller

The machine Intensive

by Fresenius

M.T.S.

(UF)

impossible.

offers several advantages

to patients:-

several advantages al.,

recent

1984).

development

to these patients.

However,

of conti-

haemofiltration an effective

ultrafilt-

as well as dialysis, with or without referred

The

Bad

(Fig. 1).

with Periods of Dialysis,

arterio-venous

A.G.

Medizintechnische

to complications such as symptomatic hypotension, thus rendering these methods difficult if not nuous

Care

is the ‘Fresenius

This machine offers volume controlled ration

is

the amount of

by this membrane.

Systeme Gmbh.

which

to water, led to the adaptation

Unit at Glasgow Royal Infirmary A2008C’

patients.

hollow

ofa machine capable ofcontrolling

the management

of patients These

polysulfone

and/or haemofilt-

ration has until now facilitated of fluid

Nutri-

of this fluid and the waste

is the therapeutic

on the patient’s own cardiac output.

The development, highly permeable

medications,

all of which carry a necessary removal

application

for fluid

acute over-

Clinical situations

the use of vaso-active

therapy

tion (TPN)

ill patient,

UF. This technique,

Continuous

Ultrafiltration to as CUPID,

offered

(Williams clearance

et

Fluid removal can be achieved

of

out accompanying

gently with-

drop in blood pressure.

uraemic toxins can only be counted on at filtration rates of IO-20 mls/min which is only

As the fluid to be removed in any 24 h period is a continuous process, fluid is balanced

achieved

between

at a trans membrane

pressure of 200-

500 mmHg and a blood flow rate of 200-250 mls/ min. (Amicon, 1983). At average systolic pressure of 100 mmHg the ultrafiltration rate is only about 6-20

mls/min. To treat uraemia

Alex. D. Mike, Glasgow,

168

Drive, Dennistoun,

G31 ZPU.

Manuscript (Reprint

33 lngleby

accepted

requests

17 Nov.

to A. Milne)

in a hypercata-

7986.

the body. The rate

the various fluid compartments of fluid

removal

is easily

of and

accurately controlled therefore TPN and other required fluid intake can be regulated to meet the needs of the patient without risking overhydration. The machine offers dialysis without any further priming of lines which means dialysis can be performed for shorter periods of time

INTENSIVE

CARE

CUPID

CONVENTIONAL DIALYSIS 1000

dialysis

169

NlrRSING

I

II

6

10

I I IlIIIIIIIII

I

900 Creatinine

I

a00-

Jli

6C

Wea

600-

4c

2C 200

t

6

Days

Fig. 1. The Fresenius A2008C

7

Specialised

(a) cardiogenic

levels while avoiding rapid changes in serum

(b) refractory

osmolality.

(c) adult respiratory

Our regime is to dialyse for four 1 in any 24 h.

also resolves the potential

disequilibrium may

result

syndrome. from

removing

urea

blood more rapidly than from resulting in cerebral oedema. Figure dialysis

2 illustrates and

potassium

CUPID

the effects on urea,

problem

This

of

condition from

13 14

15

16

the

pulmonary

oedema,

hypernatraemia, distress syndrome

(d) acute liver failure. Questionable (a)drug

patients with:

or poison intoxication.

the brain,

of conventional creatinine

and

levels in the same patient.

Technical

aspects

The membrane is made ofanisotropic polysulfone hollow fibres. These form a semi-permeable membrane to remove plasma water continuously.

Indications There

for CUPID

are three categories

addition, of patients

who may

benefit from CUPID. 1. General patients: (a) with hypervolaemia

resistant

17

patients with:

more frequently resulting in a gentle decrease in serum Urea, Creatinine and Potassium

This

12

Fig. 2. Graph showing Urea, Creatinine and Potassium levels on a patient initially receiving conventional dialysis then CUPID

Dialysis Machine

h periods at 6 hourly intervals

11

to diuretic

therapy, (b) those who need total parenteral nutrition but are already overloaded with fluid. (c) hyperkalaemic patients.

solutes with a molecular

than 50000 transported

In

weight of less

Daltons, e.g. Urea, Creatinine, are across the membrane. (Figure 3)

There is no protein loss, the molecular Albumin being 60000 Daltons.

weight of

Blood is circulated extracorporeally from the arterial system through a blood pump into an arterial bubble trap, then through the membrane. Within the membrane the pre-set volume ofUF is

170

INTENSIVE

CARE

NURSING

Sieving coefficient DIALYSIS MEMBRANE

0,5-

1

1

I

urea credinine

tye~cl&

10000

1000

100

62

indin

myoljlobin

dbumin

Fig. 3. Sieving Coefficient of Traditional ‘Cellulosic’ membrane, the new polysulphone membrane and the normal Glomerulus

removed

from the blood by a volumetric

which exerts a trans-membrane The

mean

T.M.P. Pbi + Pbo 2

pressure. (Fig. 4)

is defined as: Pdi + Pdo -

pump

EXTRACORPOREAL CIRCUIT

Blood pump

T.M.P.

Arterial pressure /

2 R

Pbi = Blood pressure on the inlet side of dialyser. Pbo

=

Blood

pressure

dialyser. Pdi = Dialysate

on the outlet

side of

Pressure

on the inlet side of

Pressure

on the outlet side of

dialyser. Pdo = Dialysate

asonic air detector

dialyser. The

primary

force which

achieves

the T.M.P.

gradient is the hydrostatic pressure. The hydrostatic pressure has two components:

1. A positive component

in the blood compart-

ment which results from the resistance to blood flow through the coil, 2. A negative component in the ultrafiltrate side of the membrane. The

positive

pressure

in the blood compart-

ment ‘forces’ fluid across the membrane into the ultrafiltrate compartment while simultaneously

Optical detector4

beno”

‘lamp

)

To patient

Fig. 4. Schematic diagram showing blood flow through the extracorporeal circuit

the negative hydrostatic pressure exerted by the machine ‘draws’ fluid from the blood into the ultrafiltrate compartment. Unlike conventional machines, where UP was

INTENSIVE

achieved

by clamping

applying

a negative

until the required ‘Fresenius offers

the

venous

pressure volume Volume

line

lines

had been removed, the Controlled UF wher-

eby one sets the volume

of fluid to be removed

any

the

1 h period,

whatever that

pressure

pre-set

machine

is necessary

volume.

machine

For

allowing

dialysis

which

the

prevents

a bicarbonate

by great

cular

changess

purposes,

the

has

also

shown

haemodynamic

1978),

el al., 1977), intravas-

(Rodrigo

redistribution4

debate.

et al.,

(Graefe

to be

(Paganini

pressure

to be major

contributors

in selected

or internal

for conventional

:\N

dialysis.

;ZRTERIO-VENOUS consists

of two pieces

of silastic

SHUNT, tubing

and

two teflon

vessel tips. The vessel tips are inserted

surgically

into an artery

.joined

is brought together

the artery

out

by a Teflon

is shunted

are at the ankle and

brachial

and

connector,

the wrist,

of a shunt

When

blood from

although

sites

femoral

also be used.

good

(3) longterm Llisadvantages

blood

line is opened

to allow

membrane

to be returned

to the patient.

Advantages

is smaller.

conventional

The

dialysis

is that

However,

personel.

method

5°0

ankle

2. avoids

with blood is conti-

any problem.

shunt

lifeline, 1)) experi-

is the

in the majority

tends

two main

line only

is a patient’s

AV

and in the

of total

only be handled

An

of access

lumen

since CIIPID

for haemodialysis therefore

blood

disadvantage

this does not present

Access

The

line is then clamped

are as for a double

lumen

subcla-

line while the \‘enous line

the venous

preferred

of our patients.

to be the most

common

site for,

reasons: damaging

of a chronic formation

of patient the radial

situation

movement artery

developing

and

in the event requiring

the

of an AV fistula.

Care of an AV Shunt The shunt strict

is inserted

aseptic

usually

use is possible.

oozing

subside

Strict

with

surgeon.

is best left alone for 24-48

the shunt

observation

are:

local anaesthetic

by a vascular

dressing

tely. Some flow,

under

conditions,

h. However,

( 1) infection,

may be used immedia-

is to be expected if left

alone,

but

but will frequent

is important.

aseptic

technique

must

be maintained

when dressing the shunt. A mask, sterile gown and gloves MUST be worn. The shunt is dressed every second day unless there is a

(2) clotting,

: 3) haemorrhage, 14) the shunt limits patient movement. 2. A DOUBLE LUMEN LINE - inserted subclavian

line or an internal

used when

a shunt

term

large lumen

The arterial

the

‘fhc

line with a ‘Y’ hub. Blood

into the arterial

The initial

are:

i 1) it is easily inserted, (2) allows

I!F.

The silastic

the skin.

into the vein. The main

and

sites could

Advantages

a vein.

through

in

line.

NEEDLE

1. it is less restrictive (AV)

increase

is clamped.

enced Vascular access Reliable long-term vascular access is vital. The types of access suitable for CUPID are those

tubing

jugular

3. A SINGLE

and should

patients.

suitable

resulting

nuous,

all shown

move-

are the same as for any subrlavian

flow is recycled.

(Kersh

which

with

complications

et al.. 1974) have

insufliciencys

of patient

ment.

et al., 1979) and

autonomic

171

NURSING

Disadvantage - blood flow is unlikely to reach 200 mls/min without producing a high venous

is drawn

stability.

of much

is no restriction

vian or internaljugular

acid base shifts. The use of

multifactorial

osmolar

to produce

proportionating

basis of this is the subject

Probably

in

apply

use of a bicarbonate

dialysate

acc,ompanied

in order

two

for

will

dialysis

incorporates

pumps,

The

and

(2j there

and/or

to the dialysate

CARE

jugular

is not possible

use is expected.

Advantages are: ( 1) it is easily inserted,

problem as a

line. This is

or if only short

necessitating

removal

at some other time. During dressing procedures be carefully bleeding,

observed the sutures

of the dressing the shunt

must

for signs of infection carefully

the exit sites of the silastic for signs of erosion.

examined, tubing

or and

examined

172

INTENSIVE

CARE

NURSING

4. A swab is taken for bacteriology use of the correct

antibiotic

event of a shunt becoming

to enable the quickly

in the

infected.

5. The shunt is then cleaned with ‘Betadine’ and a dry dressing applied, supported bandage.

Care must be taken not to compress from the dressing.

6. Some swelling and pain are to be expected after insertion therefore elevation of the limb and bed rest for 223 days is advisable effective in conjunction

name

Registrar

event

of an emergency

Clotting lotting

and

with good analgesia.

Information

effective

catheter.

The

shunt

frequently

in conjunction

anticoagulation

therapy

to

in the

or problem

arising overnight.

1. Blood pressure, heart rate: Indication 2. Venous Reflects

central

of patient’s

venous

pressure,

fluid status.

pressure: resistance

to flow through

If suddenly

increased,

the dia-

? kink

in

is the biggest preventable

life-threa-

could

membrane,

be due

to clotting

or in the vascular

in the

access.

A

sudden drop in venous pressure is likely to be due to a disconnected 3. Ultrafiltration Poor

prevent this. Infection

situation

recorded and relevance

crease

can occur and requires careful dec-

must be observed with

of the

venous line or venous spasm. A slow in-

Problems

with a special

number

on call are also recorded

related to CUPID

lyser.

Anticipated

and telephone

Renal

by a crepe

the silastic tubing nor to leave large loops of silastic tubing protruding

sion. The

line.

pressure:

blood

flow or a clotting

membrane

would cause an excessive negative pressure

tening situation in acute renal failure (Thom-

to be exerted by the machine.

son 1973)

positive pressure not related to changes in

aseptic

and is only prevented

technique

being

used

by strict

in all

pro-

cedures. Disconnection

can

be avoided

nursing and patient

education,

by careful with proper

support of blood lines and special care when repositioning Throughout patient

the patient. the

requires

time

constant

on the machine, supervision

toring.

Patient

CUPID

is a series of repeated

observations

monitoring

of the

while

patient’s

the

and monireceiving

and continuous appearance

the venous pressure may be due to a fault in the balancing mechanism within the machine Optimum

blood flow for clearance

or the patient’s

basic condition. The machine itself gives valuable information about patient/machine relationships. Built into the machine

are a series of alarms all of

which should be understood

of urea is

2-300

mls/min. Below this dialysis is ineffi-

cient.

Poor

hypotension 5. Ultrafiltration

flow is usually

the result of

of poor shunt siting. rate:

Amount of fluid the machine is being asked to remove each hour. 6. Ultrafiltrate

(measured):

The actual amount

removed measured

comfortable a procedure for the patient as possible, and early detection of any abnormality that may result from either CUPID

itself.

4. Blood flow:

and

physiological state. As with any procedure, the role of the nurse is to provide as safe and as

An excessive

7. Ultrafiltrate Machine

each

hour

manually

is to

ensure accuracy. cumulative (machine):

running

total also recorded sent to determine chine accuracy.

at prema-

by the nurse if they

are to be of any value in the early detection of problems/complications. A special chart has been devised for the recording of this information. It is a 24 h chart containing all relevant information, e.g. dialyser type, dialysate fluid used, concentration of Heparin infusion and Prostacycline infu-

Other information given by the machine includes that related to the: 8. Temperature of the dialysis fluid: if too hot, haemolysis occurs and the patient’s temperature may rise. If too cold, cooling of the patient’s blood occurs resulting in an

INTENSIVE

increased

metabolic

rate

temperature.

Cool

cause

or arterial

venous

to raise

dialysis

the

fluid

spasm

I73

NURSING

DIALYSATE CIRCUIT

body

may

CARE

also

as well as a

reduction in the clearance of urea. a measurement of the sodium 9. Concentration: content of the dialysate fluid. If too high, sodium will cross the membrane resulting in an

increase

level.

in the

patient’s

If too low, the patient’s

serum

sodium

serum

sodium

level will be lowered. 10. Air

bubble

detector

detector: to

scan

there

is an ultrasonic

blood

returning

patient

in the event of the bubble

There

is also

an

situated

below

provide

further

optical

the

(light)

ultrasonic

security.

to

the

trap failing. detector

detector

They

to

both

operate

fluid

leaving

Fig. 5. Schematic the machine.

independently.

11. Blood

leak

detector:

the machine blood

dialysate

is monitored

in the event

for the presence

of a membrane

N.B. In theory,

a blood

lines

by testing

confirmed

machine even

for

if no

lines, and

presence

blood

was

experience 12. Bypass bypass

the

system

is not

When

whereby

dialysate

temperature through

is not being

brane,

passed

the flow indicator

or concentra-

These dialysate

are

shown

through

in the

flow through

membrane. and dialysate

light

giving

infusion

the mem-

be a serious

diagram

the machine

of the (Fig. 5)

Outside

the normal

blood

quickly. Clotting can occur anywhere extracorporeal circuit, on the membrane dialyser, Platelets

clots in the of the

or within the method of vascular access. are damaged by contact with a foreign

surface

and platelet

factor

platelet

aggregation

resulting

III is released in activation

causing of the

clotting process. Normally blood placed in a plain glass tube will take 8812 min to form a clot. For

by

known.

rate

of

complica-

which

could

who has recently

the

occurring intima

inhibitor

as Flolan

pump

containing

added

to 30 ml of normal is commenced 5 ml/h

vasodilator, It is also

of Heparin.

WC

(Wellcome)

via

a

20 ml of stock solution saline

at lml/h maximum

e.g. flushing,

blood

of platelet

circulation.

the action

syringe

prostag-

of the

It is also a potent

Prostacycline

appear, system

is a naturally

to potentiate

until

is for

or trauma.

so in the pulmonary

lml/h vascular

is bleeding,

It is the most potent

thought

usual main

in a patient

vessels.

infusion

Anticoagulation

The

produced

more

The

iu/h.

landin

aggregatron

pump

in 49 mls water

iu/ml.

infusion

problem

Prostacycline

give

flashes.

500

infusions.

via a syringe

iu Heparin

is 1000-2500

had surgery a

fluid that is

the

up of 25000

to 30 min by the

Prostacycline

infusion

tion of Heparin

no

incorporates

and

Heparin

injection

the

membranes.

this valve is in operation,

fluid

necessitate

had

The made

losses. Although

machine

passed

the

discarding

this must be prolonged

use of Heparin

would,

risk, we have

of ruptured valve:

not of the correct tion

visible,

patient

this is an ever-present

leaving

of blood

the procedure, replacing

CUPID,

leak in the dialysate

the

discontinuing

of

rupturing.

fluid

diagram of the dialysate flow through

(0.9q0i.

The

and increased

by

rate or side effects

hypotension,

nausea.

head-

ache. The infusion must be decreased by 0.5 ml/h in order to discontinue infusion. This prevents a rebound hypertension, again more marked in the pulmonary

circulation.

This

is

important

CUPID has to be discontinued suddenly result of an emergency. It can be continued central

line either

at the same rate if CUPID

be recommenced or decreased CUPID is complete.

by 0.5

if

as the via a is to

ml/h

if

174

INTENSIVE

CARE

NURSING

Nursing Intervention 1. Monitor 2. Avoid

blood needle

3. Observe

clotting

times.

punctures

where

puncture

urine,

5. Alert

aspirate,

for occult

and over-

are being

considered.

allowed

for the discontinuing

Time

pro-

levels.

To ensure

fluid re-

placement

is adequate

To

and

invasive

serum

potassium

pressure

5. Accurate

when

cedures

wedge

4. Temperature

stools

blood.

all staff members

venous

pressure/Pulmonary

for signs of bleeding.

nasogastric

ultrafiltrate

3. Central possible.

sites, incisions,

all skin condition 4. Test

due to abnormal

fluid

replacement

must be

observe

for

tion or heat

loss.

Fluid

regime

fully

calculated

place

of the Prosta-

infec-

is care-

losses

to reand

pro-

vide nutrition.

cycline. 6. Handle

the

enough

patient

assistance

7. Protect

with

to prevent

the respiratory

humidity.

care

Carry

with

with

oral

CAUTION:

Fluid

of volumetric

trauma.

tract

out

and

adequate

hygiene

fre-

quently. the

endo-tracheal

tube

carefully

and frequently. 9. Reposition 10. Be aware

frequently.

of all possible

interactions,

fluid

measurement: trafiltrate,

the patient many

drug

apparently

simple

and drugs

loss

should

drains,

sures

sweating,

bowel

movements.

pumps

substitution.

recording

losses

en-

are within

expected/calculated

exces-

sive

be by use

Peristaltic

Accurate

e.g. Ulnasogastric

aspirate,

reactions

pumps.

are too inaccurate for ultrafiltration (Williams et al., 1984) 6. Accurate

8. Observe

replacement

infusion

losses.

loose

are nephrotoxic.

Potential problems The above ing CUPID drawn The logical

mentioned is over

up to meet nurse

and

in intensive

and emotionally is defenceless this and Relatives sensory

the plan

of patients and defence

of care

needs

of the patient. of the psycho-

the patient

and his relatives.

care is dependent

on those around

do all they

receiv-

also be aware

it is essential

they are subject hospital

above

the other

should

needs of both

A patient

care for patient’s

that

him. Because

enter

hospital

when

he

realise

defences.

ill patient

and acquired

The integrity

the use of endo-tracheal

tubes

with

they may even be attached

intact,

all their however

they come

bypasses

the body’s

e.g. a contaminated

the

antibiotics

to the

the body.

The

swallowed

in

is likely

defects

body

or tracheostomy

defence

systems,

and

to a source of infection

humidifier.

destroy

to have

in normal

of the skin is interrupted,

his anxieties.

to stress as soon as they enter

and particularly

A critically

This is an ever present circuit and anticoagu-

tubes

can to relieve mechanisms

lation. SEPSIS:

both natural

physically

his carers

EXSANGUINATION: risk with an extracorporeal

the normal

Broad

spectrum

bacterial

use of H2 blockers

allows

mouth

or

secretions

flora

of

bacteria

nasogastric

area where their relatives are. They suffer stress because they are bewildered by the machinery, perhaps horrified by the treatments and saddened

feeds to multiply in the stomach, while steroids and uraemia suppress the immune system in

by what they see and don’t 1978; Fielo el al., 1974).

general. The

various

thought.

Skin

PATIENT PARAMETERS MONITORED

understand.

(Haynes,

charge

RATIONALE

1. Blood

Pressure

Early detection povolaemia

2. Heart

rate/rhythm

To detect

of hy-

arrhythmias

to plastic

giving-sets scales tubing,

in

use

adhere

by

presenting

also

require

electrostatic an opportu-

nity for bacteria to enter central lines, arterial lines, shunts, etc. All intravenous delivery lines are changed every 24 h. CUPID lines however are only changed every 4-5 days therefore great care must be taken to prevent contact with the floor; and when

taking

blood

for clotting

times the lines

INTENSIVE

OFF

THEATRE

ON

1

1

Temp. OC

CARE

175

NCRSING

40

39 _ WCC 38-

36 -

I

I

I

I

2

I

I

I

4

1

1

6

I

8

1

I

10

1

I

I

12

Fiq. 6. Patient temperature chart showing temperature of a patient with elevated white cell count, no ansbiotics and on CUPID

must be kept as clean as possible. bacteriostatic Initially were

daily specimens

sent

has now been discon-

BODY

That

lise at 37°C white

when

cell counts

results

were

TEMPERATURE:

as such although

patient’s

on CUPID

tends often

and no antibiotic

to stabi-

despite

high

therapy.

POWER

FAILURE:

circuit

use either

until

power

return ofblood be discontinued

fluid several

CUPID

method wastes

overload

is restored

to the patient as a result.

In summary, established nitrogenous

to maintain

and

advantages

ifthe

have handles patency

the

procedure

is to

new,

yet

for the removal of fluid and in a variety of patients with acute

renal

over

conventional

while only having one major nuous heparinisation.

failure.

while

fluid balancing.

of fluid at the

and

same

electrolyte

time

creating

intra-vascular space for parenteral nutrition, blood or blood products and drugs. It

is a

procedure

workload comfort

of nurses,

that

greatly

but greatly

and haemodynamic

increases

improves

the

patient

stability.

Acknowledgements Dr. Keith Royal

Simpson, Infirmary

Registrar,

Renal

Unit,

Glas-

for his advice

and

assist-

ance.

of the

or to allow

is a relatively

correction

disorders

gow Blood pumps

stability. and accurate

(Fig.

dialysis.

for manual

3. Gentle

Not

heat loss does

temperature

2. Effective

not

6) ELECTROLYTE DISORDERS: Prevented by accurate fluid replacement and removal and also by regular

1. Circulatory

and blood cultures

and this practice

a problem

ADVANTAGES:

24 h.

The

tinued. ALTERED occur.

ofUF

fluid is

every

to bacteriology.

significant

strictly

Dialysate

but this is also changed

It offers methods

disadvantage-conti-

References Amicon Corporation Scientific Systrms Division. 1983 Amicon Operating Instructions Diafiiter 20 Haemofilter Danvers Massachusetts Fielo B S, Edge S C 1974 Technical nursing of thr adult, Collier Macmillan, pp 2 15-2 16 Graefe U, et al. 1978 Less dialysis induced morbidity and vascular instability with bicarbonate in dialysate, Annals of Internal Medicine 88: 332 Haynes G 1978 The Problem of Stress, Intrnsivr Car< Nursing. Times Publication pp 42.-43

176

INTENSIVE

CARE

NURSING

Holbach G, Thies E, Liepe B 1981 The non mechanical arteriovenous haemofiltration to reduce fluid retention in patients with post operative or post traumatic acutr renal failure, Anaesthetic Intensive Therapy 16: 198 Kersh E S et al.1974 Autonomic insufficiency in uraemia as a cause of hacmodialysis induced hypotmtion. New England Journal Medicine. 290: 650-653 Paganini E P et al. 1979 Haemodynamics of isolated ultrafiltration in chronic haemodialysis patients. Transactions of the American Society for Artificial Internal Orqans 2.5: 422

Kodrigo F et al. 1977 Osmolality changes during haemodialysis: natural history, clinical correlations and influence of dialysate glucose and intravenous mannitol. Annals of Internal Medicine 86: 554-56 1 ‘l‘homson P B 1973 Nursing care of a patient with acute renal failure, Medical Examination Publishing Company Iur. pp 30-38 Williams \T, Perkins L 1984 Continuous ultrafiltration, a new I.C.U. procedure for thr treatment of fluid overload Critical Care Nurse July/August 4: 44-49