VASCULAR SURGERY II

Principles of renal accesssurgery and transplantationDavid C Mitchell

William D Neary

AbstractThe treatment of end stage renal failure is renal replacement therapy. This

may be by dialysis (blood or peritoneal) or by kidney transplantation. The

outlook for those who have a successful renal transplant has improved

significantly over the past 20 years: graft survival from non-heart-beating

donation is nowa meanof 14 years, and 18 years for live donor transplants.

Unfortunately the number of renal transplants fails to meet the

demand from patients on the transplant waiting list. The shortfall has

to be managed by dialysis. Life expectancy of a patient on haemodialysis

is one-fifth to one-quarter of that of the age-matched healthy population,

but doubles following successful transplantation.

The predominant type of dialysis is blood dialysis. To provide this,

patients require a portal of access to the circulation. This patient group

requires timely and well-planned renal access surgery. Circulatory access

is their lifeline. Failure of access, coupled with the need for emergency

admission, is a major cause of morbidity and mortality.

Keywords Access; renal; surgery; transplantation

Introduction

Vascular access surgery is used for all patients who need

repeated, frequent access to the circulation. The renal dialysis

patient is an obvious example, but other groups include patients

such as those needing plasmapheresis (multiple sclerosis), life-

long antibiotic treatments (cystic fibrosis) and drug or elemental

infusion (short gut syndrome). For renal patients, continued life

is dependent on functioning access. Access must be placed in

a timely manner and a planned approach should be used. This

ensures that subsequent access procedures in the same patient

are not compromised by lack of suitable vessels.

Guiding principles are to place access in the non-dominant

arm and in upper limbs rather than lower. Native arterio-

venous fistulae are formed by anastomosis of a suitable vein to

an adjacent artery.

All suitable patients coming to access surgery should have

been assessed and entered onto the renal transplant waiting list.

Diagnosis of need for renal access

The ideal form of vascular access is the arterio-venous fistula. It

has the lowest morbidity and failure rate once established.

David C Mitchell MA MBBS MS FRCS is a Consultant Surgeon at Southmead

Hospital, Bristol, UK. Conflicts of interest: none.

William D Neary FRCS is a Consultant Surgeon at Southmead Hospital,

Bristol, UK. Conflicts of interest: none.

SURGERY 28:6 293

Standard-setting documents such as the Kidney Dialysis

Outcomes Quality Initiative and Fistula First, in the USA, have

encouraged much higher rates of fistula placement.

Timing of fistula placement is more difficult. There is no purpose

in placing a functioning fistula years before end stage renal failure

occurs, as resources are wasted maintaining it and it may be lost

without ever benefiting the patient.At the same time, failure to have

a functioning arterio-venous fistula (AVF) when dialysis is required

will necessitate placement of a central venous cannula, associated

with higher risk of infection and central venous stenosis. Use of

central venous lines, as primary access, in patients who ‘crash land’

on haemodialysis, has excess mortality. It is standard practice to

place access some months in advance of anticipated need.

Creatinine alone is a poor predictor of the severity of renal

dysfunction. Variations in muscle mass with age, sex and body

mass index can cause large variations. Glomerular filtration rate is

the gold standard for assessment of renal function, but measuring

it is costly and time consuming. Estimated glomerular filtration

rate (eGFR) converts serum creatinine to eGFR by using a formula

that tries to correct for the race, sex age and measured creatinine.

Trends in this value can point to the need for access. There is

evidence that eGFR does not predict onset of dialysis, but does

predict risk of cardiovascular death. A suggested figure of 15e25

is widely used but the decision is probably best undertaken by

a nephrologist, in conjunction with the above information.

Choice of access surgery

There are three routes used for establishing vascular access.

These are the arterio-venous fistula (AVF), prosthetic access

graft, or central venous catheter (CVC) (Figures 1e3). Each has

advantages and disadvantages (see Table 1).

Choosing the type of access requires experience and an

understanding of the needs of the patient. Principles governing

choice of access include:

Fitness of the patient

Both AVF and grafts require good blood flow both to maintain

patency and to be useable for dialysis. Patients with failing hearts,

or unable to increase cardiac output to maintain flow will not be

suitable for these types of access. In this situation, a decision has to

be made to use a CVC or not to embark upon haemodialysis.

Adequacy of vessels

The state of arteries and veins needs to be considered when

planning vascular access (Figure 4). The most commonly

encountered difficulty is absence of suitable veins due to

previous cannulation. Patients with renal failure are taught to

stop anyone from cannulating veins which might later be used

for access. Venous cannulae should be placed in the back of the

hand. Access should be placed in the non-dominant limb wher-

ever possible. Some patients may need Duplex scanning to

identify useable vein. Heavily calcified (that is rigid) arteries such

as those found in diabetic patients may be unable to allow

increased flow for fistula maturation or to maintain graft patency.

Central vein stenosis or occlusion

Patients with previous CVC placement, pacemakers or portacaths

may have stenosis of central veins. In these patients, imaging of

these veins is advised.

� 2010 Elsevier Ltd. All rights reserved.

Brachiocephalic fistula pre-anastomosis

Figure 1

Graft

Vein

Artery

Thigh loop polytetrafluoroethylene (PTFE)

Figure 3

VASCULAR SURGERY II

Patient preference

Patients may have a strong preference for certain types of access.

Younger patients may be particularly sensitive about the cosmetic

appearance of a fistula and may request brachio-cephalic AVF,

thigh grafts or CVC. It is the role of the medical team to make

Forearm loop polytetrafluoroethylene (PTFE)

Figure 2

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patients aware of the advantages and disadvantages of their

choices and to support them in providing acceptable access.

Operative techniques

Choice of operation is based on the factors above. The ideal

access is usually an AVF in the distal part of the non-dominant

limb. An AVF has the advantage of being robust, and throm-

bosis and infection resistant when compared to the alternatives.

AVF requires the least maintenance of any type of access. The

principle issue with AVF is the difficulty faced in establishing

them. This may take more than one operation.

Local or regional anaesthesia is preferred wherever possible.

Many procedures can be carried out in the day case facility,

minimizing in-hospital time.

Arterio-venous fistula

These should be fashioned as end-of-vein to side-of-artery anas-

tomoses. At the wrist or in the anatomical snuffbox, some surgeons

prefer end-to-end anastomoses. Results from the two approaches

are broadly similar. At the wrist a long anastomosis is preferred.

This reduces narrowing from intimal hyperplasia and maximizes

flow in small vessels. Non-absorbable Prolene sutures are used.

More proximal AVF are fashioned using the end-to-side

configuration, but more care needs to be taken to keep the anas-

tomosis at about 8 mm length. Larger anastomoses are prone to

develop very high flows, which may steal blood from the distal

part of the limb. In some cases, high flows (usually of 2 litres/

minute or more) can precipitate high output cardiac failure.

When the easily accessible superficial veins (cephalic and

forearm basilic) are exhausted, attention may have to focus on

deeper veins (basilic or great saphenous). These veins may form

good-quality AVF, but need transposing towards the skin to make

them accessible to dialysis needles. Basilic vein transposition is

associated with approximately 75% primary patency.

Arterio-venous access grafts

The commonest conduit material used is polytetrafluoroethylene

(PTFE), but many types of access graft material can be used.

� 2010 Elsevier Ltd. All rights reserved.

Advantages and disadvantages of vascular access procedures

AVF Graft CVC

Ease of

placement

Variable depending on state of veins.

Easy LA procedure for primary wrist and

elbow AVF; more complex for

transposition procedures.

Variable, often needs GA

or loco-regional block.

Usually straightforward unless CV stenosis.

Advantages Usually LA day case procedure (75%).

Robust once established.

Resistant to thrombosis and infection.

Revision rate about 15% per year.

Can bridge long distance

between artery and vein.

Usually easy to establish

provided vessels adequate.

Insertion under LA; tunnelled if

required for more than 3 weeks.

Not dependent on good cardiac output.

Can be used immediately for dialysis.

Disadvantages May take months to mature for use.

Difficult to establish; only about 55%

will be useable 1 year after formation.

May need revising to promote maturation.

Needs a couple of weeks to

become incorporated prior

to use (unless designed

for immediate use).

Prone to thrombosis, mostly due

to venous intimal hyperplasia.

More susceptible to infection than AVF.

Revision rates about 85% per year.

Vulnerable to sepsis.

Associated with higher mortality than AVF.

Venous stenosis around catheter may

preclude future access placement in limb.

AVF, arterio-venous fistula; CVC, central venous catheter; GA, general anaesthetic; LA, local anaesthetic.

Table 1

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Some grafts are designed with self-sealing coatings to allow

immediate cannulation after placement. Grafts may be placed in

any configuration between suitable artery and vein.

A graft of 6 mm diameter is usually adequate for dialysis.

Smaller grafts may prove difficult to puncture accurately with

dialysis needles.

Grafts may need subsequent removal for sepsis. This can be

a very difficult operation, particularly around the artery in an

infected groin. Complete removal of all graft material is required

to eliminate infection. A vein interposition cuff between artery

and graft, placed at initial surgery, may facilitate subsequent

removal.

Central venous catheters

The main advantage of CVC is that they can be used immedi-

ately. They are the mainstay for providing dialysis in acute

kidney injury and in patients with chronic renal disease who

present acutely, before placement of permanent access.

Figure 4 Clinical assessment. This forearm has vein suitable for radioce-

phalic or snuffbox fistula.

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Catheters should be placed in large central veins (for example

jugular veins) using a Seldinger technique under ultrasound

guidance. CVC is prone to infection, so if it is anticipated that the

catheter will remain in place for more than a week or two, the

catheter should be tunnelled beneath the skin to a point remote

from the vein. Eradication of methicillin-resistant Staphylococcus

aureus (MRSA) carriage is an important part of reducing sepsis

related to CVC use.

Surveillance of access

Vascular access requires surveillance to detect abnormalities

which may give rise to failure.

Failure occurs most commonly with grafts, due to stenosis at

the venous anastomosis. When thrombectomy is performed with

catheters or at open operation, it is vitally important to treat any

stenosis or the graft will probably clot again. Failure may also

occur due to over-dialysis of patients, or volume depletion

secondary to fluid loss (diarrhoea and/or vomiting). In this

situation the thrombosis is consequent on low flow states.

AVF is less likely to fail, but degrade rapidly after thrombosis.

AVF needs to be declotted rapidly, within 48e72 hours if they are

to be salvaged after failure. CVCs also tend to clot but can often

be resuscitated with endovascular techniques. There is no formal

surveillance programme for CVC and this may in part reflect the

fact that many of the CVC are placed temporarily as a bridge to

more permanent access.

Techniques for surveillance of grafts and AVF include:

� clinical assessment

� flow estimation

� assessment of dialysis efficacy.

Intra-dialytic measurements of flow or recirculation within the

access and external duplex scanning to detect abnormalities are

useful surveillance techniques. Most clinicians will be concerned

with a fall in flow rate of 20% or more, or an absolute flow of less

� 2010 Elsevier Ltd. All rights reserved.

VASCULAR SURGERY II

than 600 ml/minute. Treatment modalities to deal with threat-

ened access are best determined by a multidisciplinary team.

Managing failing access

The failing AVF fistula

Treatment options may include angioplasty or surgery. Angio-

plasty may be useful for stenosis. Some fistulae exhibit rapid

aneurysmal enlargement and ligation may be the preferred option.

AV grafts

Grafts usually work well initially unless there is some technical

problem with their placement. Subsequent reduction in flow is

most commonly due to stenosis at the venous anastomosis.

Angioplasty is effective at prolonging graft survival and Amer-

ican studies have shown that with repeated interventions,

longevity of grafts can approach that of AVF.

When angioplasty is unsuccessful, or if the graft has been

clotted for a few days and cannot be lysed successfully, surgical

revision may be effective.

Graft infection can be very difficult to eradicate. The simplest

approach is graft removal, but this often needs to be followed by

temporary CVC placement risking catheter infection. Localized

infection at needling sites and small abscesses can be managed

by antibiotics and local graft excision with adjacent skip grafting.

Central venous catheters

The commonest cause of failure is clotting or obstruction to flow by

the development of a sheath of fibrin around the catheter tip. Clotted

catheters can be re-opened by passage of guide wires and small wire

brushes. Fibrin sheaths can be difficult to remove. An alternative is

to change the CVC over a wire, which sometimes improves flow.

CVC is the form of access most susceptible to infection. Best

management is to remove the CVC and treat the patient with

Fibrous cuffs lyingsubcutaeous and periperitoneal

Catheter tiplying in pelvis

Continuous ambulatory peritoneal dialysis (CAPD) catheter p

Figure 5

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antibiotics for a few days until better. A new catheter can then be

placed, ideally in a new location or at the same site if there is no

overt inflammation. Patients can develop severe complications

from catheter sepsis including infective endocarditis, arthritis,

and discitis. Early aggressive antibiotic treatment of infection is

important to minimize the risk of complications.

Vascular steal syndrome

This is a problem peculiar to fistula and grafts. In the limb,

a proportion of blood flow is directed through the access. It is not

uncommon to see reversed flow in the artery beyond the anas-

tomosis. This is not usually a problem at the wrist as the ulnar or

interosseous arteries provide adequate flow to the hand. At the

elbow, reversed flow in the brachial artery may be asymptom-

atic, providing collateral vessels at the elbow maintain adequate

flow to the hand.

If the collateral flow is inadequate, the patient may complain of

coolness, numbness and tingling, or overt pain. If this occurs

rapidly after access placement (that is on waking or the anaes-

thetic block wearing off) this is a clinical emergency. Once

neurological deficit is present, it is difficult to reverse it even with

access ligation. This aggressive version of steal is called ‘ischaemic

monomelic neuropathy’ and usually leaves a permanent deficit.

True vascular steal usually presents within a few days, but

can present later in AVF if they enlarge or there is progressive

arterial narrowing. Symptoms are not always present at rest and

may sometimes only be present after a period of dialysis.

Peritoneal dialysis

Peritoneal dialysis, whilst not a vascular access procedure,

provides an alternative, durable method of dialysis. It can be

placed with a simple operation and can be used rapidly if the

peritoneum is secured about it (Figure 5).

Patient left with smallmidline scar anduncuffed catheter

lacement

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VASCULAR SURGERY II

This method of dialysis should be considered in all patients

before stage 5 renal failureandshouldbe reconsidered furtherdown

the line when repeated vascular access procedures start to fail.

Desperate access

When all standard access has been used consideration of more

esoteric routes of access may be considered. This situation is likely

to become more common with existence of increasing numbers of

stage 5 renal failure patients and without a commensurate increase

in transplantation. Examples include necklace grafts between

contralateral axillae and even use of the inferior vena cava. Risks of

these grafts are far higher and complications can be fatal. The point

at which one makes the decision to withdraw renal support from

such patients can be very difficult. Another complex decision can

be to use arteries and veins for access that preclude subsequent

transplantation.

Renal transplantation

Preoperative workup of the renal transplant patient

A renal transplant may be a life-changing procedure but is a major

operation involving general anaesthesia, in a patient group who

are, by the nature of their renal failure, at high risk of complica-

tions, especially cardiac. In order to benefit from transplantation

they must have the cardiorespiratory reserve to survive a major

vascular procedure. Iliac arteries must have sufficient blood flow

to perfuse the transplanted kidney as well as the lower limb. If

patients and their transplants survive the excess mortality of the

first 3 months they will be then required to spend many years on

immunosuppression having been more likely to have been

exposed to hepatitis B and C during their time on dialysis.

Clinical assessment of the potential recipient involves a thor-

ough history and examination. Patients older than 50 years, all

patients with diabetes or any history of ischaemic heart disease,

congestive cardiac failure, cerebrovascular disease or peripheral

vascular disease will need either an exercise electrocardiography

(ECG) or myocardial perfusion scan if they are unable to reach

their predicted maximal heart rate. Positive tests need referral to

a cardiologist prior to activation on a transplant waiting list.

Any history or clinical finding consistent with peripheral

vascular disease necessitates ankle brachial pressure index

measurement and duplex scanning of lower limb arteries to

ensure they will be able to perfuse both transplant and lower

limb. Obesity with a body mass index of greater than 35 is

a contraindication to surgery, both from the increased recipient

cardiovascular risk but also from the increased complexity of the

surgery performed onto vessels made more difficult to access.

Liver disease requires referral to a hepatologist. Patient compli-

ance with medical treatment is also important to assess, as failure

to comply with immunosuppressive medication will result in

poor outcome, depriving a recipient likely to benefit, from

receiving a functioning transplant.

Once activated onto the transplant waiting list all recipients

should be re-assessed at 3-yearly intervals to exclude progression

of cardiorespiratory disease.

Potential sources of transplant organs

The kidneys may be donated from the healthy population (live-

related donation, paired donation, altruistic donation) or from

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the dead or dying donors who have expressed a wish to donate

their organs and whose relatives agree to organ donation.

Elective transplantation

When a patient is judged fit enough physiologically to be

accepted onto the transplant waiting list, consideration should be

made as to potential live-related donation from fit and well

members of the family, who are immunologically similar enough

to reduce risk of rejection of the donor organ by the recipient.

This is a contentious area and care has to be taken to avoid

causing harm to potential live-related donors as a result of

nephrectomy. It must be established that they are not under

coercion to provide a kidney.

Renal function declines with age, so any donor must have

sufficient renal function that they will not subsequently require

renal support themselves. Risk of death from renal donation is

approximately 1 in 3000. Some donations such as parent to child

or spouse-to-spouse are morally easier to justify than child to

parent or altruistic donation. Clear procedures need to be in place

to allow potential donors and recipients to discuss their wishes

with psychologists and all members of the transplant team.

Donor nephrectomy

Laparoscopic donor nephrectomy is increasingly used to harvest

kidneys. There is little strong evidence that it provides reduction in

perioperative morbidity and mortality, but it does provide an

improved aesthetic result for the donor and has comparable

mortality results worldwide (0.03%). Both laparoscopic retrieval

and hand-assisted retrieval have similar results in terms of organ

function.

The recipient must tolerate the presence of the donor kidney.

ABO incompatibility or positive T cell crossmatch used to

preclude donation of that organ to that recipient. Pairing donors

unable to donate to their spouses, but able to donate to another

couple, may allow this issue to be resolved. Practical issues exist

in ensuring that such an arrangement cannot be abused for

instance by one donor withdrawing consent after the other has

donated a kidney, as well as keeping anonymity between the

couples to avoid conflict if only one transplant is successful.

Longer chains of donating pairs compound such issues.

Desensitization has provided an alternative way to get around

ABO incompatibility. Plasmapheresis removed anti-ABO anti-

bodies and stronger immunosuppression, augmented by splenec-

tomy, or anti-CD 20 antibody, can allow improved graft tolerance.

Urgent transplantation

Kidneys harvested from people who have had a major, non-

survivable injury or illness and who expressed a wish to

donate organs, of which their next of kin are aware, form the

majority of renal transplant operations. The donors may be heart

beating or non-heart beating.

A heart-beating donor is one who has suffered an unrecov-

erable brain insult and who is brainstem dead. Such a patient

may donate their organs in a relatively controlled surgical

procedure. Non-heart-beating donors are those who are dying

from unrecoverable illness and in whom further supportive care

is judged futile. Death is expected to occur soon after withdrawal

of cardiorespiratory support. In these cases it is much less certain

that renal donation will be possible, as rapid death may not

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VASCULAR SURGERY II

happen following the withdrawal of support. After support has

been withdrawn, hypoxia and reduced organ perfusion occur as

well as bacterial translocation from the gut. If this continues for

more than 1 or 2 hours, the kidneys will be too damaged to be of

use for donation. If asystole occurs within this 2-hour period then

the patient is left undisturbed with the family present for

a further 5 minutes to give them time together, guaranteeing

irrecoverable brain death and is then rapidly transferred to

theatre for organ harvest.

Renal harvest surgical technique

A midline laparotomy incision is made and the infrarenal aorta

rapidly exposed. A catheter with a proximal and distal balloon is

passed up the aorta. The distal balloon is inflated and the cath-

eter pulled back and the proximal balloon then inflated after

which cold perfusion fluid is passed rapidly between the balloons

(Figure 6). This passes into the kidneys and visceral circulation,

rapidly cooling the abdominal contents. The inferior vena cava is

opened and drained to remove warm blood and allow cool

perfusion fluid to circulate through the kidneys. The right and left

colons are rapidly mobilised and ice placed over each kidney.

Now that the organs are chilled the remainder of the operation

can proceed at a gentler pace. Both kidneys are removed with an

aortic patch. The right kidney is removed with a section of vena

cava, which can be useful for lengthening the shorter right renal

vein. Variations in anatomy such as multiple renal arteries need

to be recognized. Lymph nodes from the small bowel are taken

for histological examination, as is a sample of splenic tissue, for

cross matching.

Preparation

The kidneys are prepared by removing the surrounding protec-

tive perinephric fat, leaving the hilum undisturbed. The

Placement of renal perfusion catheter

Proximal occlusion

balloonDistal occlusion

balloon

Triple lumen perfusion catheter

Figure 6

SURGERY 28:6 298

suprarenal glands are removed. It is important to preserve the

tissue between the hilum, ureter and lower pole of the kidney, as

excessive dissection here may devascularize the ureter. The renal

artery and vein are dissected to ensure the suprarenal artery is

tied and the gonadal vein is removed. Artery and vein are flushed

to ensure there are no leaks e any found are repaired. The

prepared kidney is placed on ice.

Tranplantating the donor kidney

Once an appropriate recipient has been found and tissue typing

confirms satisfactory immunological match, consent is taken for

the operation. The patient will receive oral prednisolone prior to

arriving in theatre. Interleukin 2 receptor antibodies will be given

to the majority of patients in the perioperative period.

The recipient is draped and prepared on the operating table. A

urinary catheter is placed so that the bladder may be inflated

subsequently. It is easier but not essential to place a right donor

kidney in the right iliac fossa and a left in the left. A Rutherford

Morris incision is made and external iliac vessels identified and

controlled. The vein is opened and stay sutures prepare the

vessel to accept the transplant kidney. When all is ready the

kidney is removed from ice and the time is noted. For the rest of

the procedure the kidney is frequently cooled and handling is

kept to a minimum. After completion of the venous anastomosis

a bulldog clamp is used to test this, preventing early restoration

of iliac vein blood flow with retrograde flow of warm blood flow

into the cool kidney. The external iliac artery is then controlled

and opened and the aortic patch inlaid. The arterial anastomosis

is tested in similar manner to the vein before both clamps are

removed and the kidney inspected to ensure global reperfusion.

Haemostasis may be necessary prior to inflation of the bladder

and anastomosis of the ureter to it, which may be done in

a number of ways, with or without a stent.

The abdominal wall is closed in two layers over a redivac

drain. It is critical that the patient remains paralysed until the

abdominal wall is closed, as coughing can expel the transplant

kidney, disrupting the anastomoses with rapid exsanguination

and likely loss of a functioning kidney.

Postoperative period

The full scope of perioperative care with immunosuppression and

variations in treatment dependent on rapid or delayed graft

function are beyond the scope of this article. All transplants are

assessed clinically and by duplex imaging in the first 24 hours

post-transplantation, to ensure global perfusion is maintained and

that no hydronephrosis or perigraft collection exists. If the kidney

is structurally sound then patience is exercised in waiting return

of renal function. Depending on the health of the donor and cold

ischaemic time, it may be some time before urine output and renal

function occur. Transplant nephrectomy should be reserved for

the patient with increasing surgical site pain, worsening inflam-

matory markers and precipitously falling platelet count.

The excess mortality of renal transplantation exists for the

first 3 months following surgery. If successful however, patients’

life expectancy should double and the need for dwindling

vascular access is halted.

Acute rejection

In well-matched patients and with modern immunosuppression

this is becoming less of an issue and affects about 20% of

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VASCULAR SURGERY II

transplantations. Modification of the immunosuppression regime

with pulsed methylprednisolone is used to treat acute rejection.

Results

Results have improved greatly over the past 20 years. Overall

graft function in the long term depends on the underlying

SURGERY 28:6 299

problem that led to renal failure in the first place, the age of the

recipient and the age and co-morbidity of the donor.

In selected patients who are fit enough for the procedure,

renal transplantation offers large survival benefits over and

above the improved quality of life that results from not needing

haemodialysis. A

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