Essay on Renal Dialysis | Medical Science

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Essay on Renal Dialysis

Essay # 1. History of Renal Dialysis:

As early as 1913 Abel, Rowntres and Turaer performed haemodialysis in dogs with an artificial kidney made of several celloidin tubes. Later, Haas used reed tubes, paper membranes, peritoneal membranes etc. as semipermeable membranes for haemodialysis. With the availability of heparin in 1918, continuous-flow-haemodialysis was attempted.

By 1930 most of the basic requirements of modern haemodialysis were available. However, it was not until the mid-1940’s that the first successful experiments in human haemodialysis were reported. In 1947 Alwall of Sweden first reported the use of ultrafiltration. Till this period dialysis therapy was limited to acute renal failure.

Maintenance haemodialysis for chronic renal failure was made possible only after the problem of vascular access was solved by Quinton and Scribns in 1960 by introduction of arteriovenous shunt. This was further improved by Brescia in 1966 with the development of arteriovenous fistula and the modern era of chronic haemodialysis really started.

The first reported use of peritoneal dialysis comes from Putnam in 1922. However, the first human survivor of the application of peritoneal dialysis for renal failure was reported in 1946 by Irank et al. Automatic cycling device for peritoneal dialysis was introduced in 1965 and further improved in 1969; this reduced the risks of peritonitis.

It was Tenckhoff in 1968 who gave a boost to chronic peritoneal dialysis by developing the in-dewelling peritoneal catheter. Continuous ambulatory peritoneal dialysis (CAPD) is a significant achievement by such workers as Popovich, Oreopoules and others in the period 1976-1978.

Dialysis is a process by which toxic materials which accumulate in the body due to renal failure may be removed by diffusion across a semipermeable membrane. Dialysis may also be used in some acute poisonings, without any renal failure. On the other hand, patients of acute renal failure with obvious correctable factors like gross fluid electrolyte depletion, obstructive uropathy or due to hepatotoxic drugs can often be managed conservatively.

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Essay # 2. Indications of Renal Dialysis:

Dialysis may be required temporarily in acute reversible renal failure. This method maintains life while the kidneys may recover their function or it may be needed life-long at periodic intervals in chronic irreversible renal failure and in so-called end stage renal disease (ESRD).

The indications for dialysis are both clinical and biochemical as follows:

Biochemical:

Blood urea level of 200 mg and creatinine of 10 mg and above are often taken as levels for which dialysis indicated. These usually correspond to creatinine clearances of less than 5 ml/min.

However in general, patients with diabetic nephropathy are started earlier on dialysis. Hyperkalaemia (serum potassium above 6.5 -7mEq/L is one of the most urgent indications for dialysis.

Clinical:

(1) Intractable pulmonary oedema

(2) Pericarditis

(3) Peripheral neuritis

(4) Gastrointestinal haemorrhage

(5) Refractory hypertension

(6) Uraemic coma

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Essay # 3. Types of Renal Dialysis:

There are two types of dialysis:

(1) Haemodialysis:

Where the semipermeable membrane is an artificial membrane e.g. cellulose acetate, amprophan etc.

(2) Peritoneal Dialysis:

Where the patient’s peritoneum is utilised as the membrane across which diffusion occurs.

1. Haemodialysis: 

Haemodialysis involves pumping out blood from the patient at a sufficient rate (about 200ml/min), passing it through the dialyser membrane, across the other surface of which is seen the dialysis fluid (at a rate of about 500ml/min), so that diffusion of waste products can occur and then returning the ‘purified’ blood returns to the body.

The dialyser or artificial kidney may be of different types. The average duration of each haemodialysis is five hours and may have to be repeated two to three times per week. The patient needs to be heparinised (5000-10,000 units of heparin dialysis) during haemodialysis to prevent clotting of blood in the extracorporeal circulation.

The most important requirement for haemodialysis is adequate vascular access. In patients likely to require repeated haemodialysis one good forearm vein of at least one side should be spared for intravenous infusions and repeated venepunctures.

The various means of vascular access are as follows:

(1) Arteriovenous Fistula:

This is the most important access for long-term use and is most commonly created between the radial artery and the cephalic vein at the wrist. If an artery and adequate vein are not long enough, these may be connected by autologous or homologous vein graft, dacron graft, teflon graft etc.

The advantage is that it can be used for several years and frequency of infection and thrombosis is low. Its disadvantage is that it requires a maturing time which may vary from one week to a few months, thus precluding its use for emergency haemodialysis.

(2) Arteriovenous Shunt:

An A-V shunt consists of a silastic tubing with teflon tips inserted between neighbouring artery and vein usually done in lower half of the left forearm. Its advantage is that it is immediately ready for use. For dialysis vessels need not be punctured, only the silastic tubing need to be opened in the middle and the two open ends connected to the tubings of the blood delivery system.

Its major disadvantage is its short life because of high incidence of infection, thrombosis and stenosis. It also carries with it risks of serious haemorrhage due to disconnection or snapping of the silastic tubing between arterial and venous tubings.

Both the above access-procedures may be complicated by certain circulatory disorders e.g.:

(i) Distal ischaemia rarely leading even to gangrene through A.V. connection or ligation of the artery.

(ii) Swelling, pain and redness of the extremity due to venous hypertension.

(iii) High output cardiac failure, particularly in elderly individuals with a large promixal A.V. fistula.

(3) Femoral Vein or Subclavian Vein Catheterisation:

Seldinger technique is another means of vascular access for emergency use.

Risks of infection and thrombosis are significant; there has even been fatal pulmonary embolism following thrombosis around the catheter tip. So one catheter should preferably not be kept for more than a few days.

Patients kept on maintenance haemodialysis may have almost a normal diet (especially protein intake needs no restriction); however, restriction of food rich in potassium'(mainly fruits, including the dry fruits rich in potassium) should be enforced, except during dialysis itself.

Of course, hypertensive patients need some salt restriction. If fluid restriction is needed, depending upon the patient’s urine output an average weight gain of 0.5 kg of body weight per day in between dialysis is usually acceptable.

Extra fluid in the body can be removed during haemodialysis by the process of ultrafiltration. Many patients have fluid overload when first put on dialysis. One of the most important jobs of the nephrologist is to determine the ideal or dry weight of each patient.

The drugs that chronic dialysis patients need to take routinely are:

(1) Vitamin B complex including folic acid and iron; these should be taken at least after each dialysis.

(2) Phosphate binders — most commonly aluminium hydroxide gel to be taken with meals.

(3) Some patients also need calcium supplement and active forms of Vitamin D e.g. 1.25 dihydroxycholecalciferol (Rocaltrol).

Many patients on dialysis are also hypertensive and hence will require antihypertensive drugs but the requirements may be reduced once the patient is put on regular dialysis.

Chronic haemodialysis may be done in the following settings:

(1) As ‘out patient’ treatment in hospital dialysis centres.

(2) Home haemodialysis.

(3) Limited-care haemodialysis.

In our country most dialysis patients have to depend on hospital haemodialysis service but only a few such units are really available in big cities only. Private facilities of haemodialysis are also limited to big cities and very few patients can utilise the facilities due to high cost involved.

Problems Related to Haemodialysis:

1. Requirement of adequate vascular access and its complications.

2. Need for heparinisation, with risks of intracranial, gastrointestinal, pericardial and pleural haemorrhage.

3. Cardiovascular instability, particularly hypotension during haemodialysis.

4. Dialysis disequilibrium syndrome manifested by headache, vomiting, confusion and coma most likely due to rapid change in osmolarity owing to haemodialysis.

5. Pyrogenic reaction and other allergic reactions.

6. Abnormal losses of vitamins, aminoacids and blood. During each haemodialysis up to 50 ml of blood may be lost due to deposition of RBC, platelets and fibrin on the dialysis membrane and blood tubings, in spite of use of heparin. Further acute blood loss may infrequently occur from accidental rupture of dialysis membrane.

7. Complement leucocyte induced pulmonary dysfunction.

8. Haemolysis.

9. Dialysis dementia or encephalopathy, which is a long-term problem, is most likely form of aluminium toxicity due to inappropriate high level of aluminium in the water used for preparing the dialysis fluid.

10. Hard water syndrome, manifested by headache, nausea, vomiting and hypertension during dialysis — it is due to acute hypercalcaemia owing to excess calcium in the dialysate. The last two complications call for proper deionisation of the water used for preparing dialysis fluid.

2. Peritoneal Dialysis:

Peritoneal dialysis, like haemodialysis, may be performed temporarily in acute renal failure or on a long-term basis as chronic peritoneal dialysis.

i. Acute Peritoneal Dialysis:

In an acute setting pertioneal dialysis is done by inserting a plastic catheter in the peritoneal cavity under local anaesthesia. Commercially available peritoneal dialysis fluid is run into the peritoneal cavity through the cathether, usually 1.5 to 2 litres at a time and this is retained for about half an hour to allow diffusion across the peritoneal membrane and then allowed to run out.

Where excess fluid needs to be removed, hypertonic peritoneal dialysis fluid containing extra glucose is used. Peritoneal dialysis being a slow process, such cycles have to be continued for 24-72 hours in one go, usually the plastic catheter has to be removed after each dialysis. This is a simple procedure requiring sophisticated machine and can be carried out in any general hospital provided the dialysis fluid and the catheter are available.

ii. Chronic Peritoneal Dialysis:

This requires permanent peritoneal access by surgical implantation of a soft silastic peritoneal catheter, developed by Palmer and modified by Tenckhoff.

Chronic peritoneal dialysis may be of 3 types:

(1) Chronic Intermittent Peritoneal Dialysis (CIPD):

This involves 2 litres exchange each hour for 10-14 hours at a time. The process is simplified by the availability of automatic cycler which introduces and drains the peritoneal fluid for patients with some residual renal function.

Three such dialyses may be required per week and with the automatic cycler this may be done in the night during sleep. However, with residual GFR falling below 3 ml/min, longer periods are required. This method can be quite useful for short periods in patients waiting for a renal transplant or during maturation of an AV fistula for haemodialysis.

(2) Chronic Ambulatory Peritoneal Dialysis (CAPD):

This is a very significant development introduced by Popovich et al in 1976, and promoted by Oreopoules et al in 1978. In this method two litres of a commercial peritoneal dialysis fluid contained in soft plastic bag are run into the peritoneal cavity. The empty bag attached to the catheter is rolled up and held under the belt or waist band.

The fluid is retained for 4-6 hours during daytime and allowed to remain 10-12 hrs during night and then the fluid is drained back into the empty bag, which is then discarded. A new bag is then connected and fresh dialysate run into the peritoneal cavity.

The longer the dwelling time during night, the better is the removal of creatinine; moreover “middle molecule” clearance is better with CAPD. For most patients four exchanges of two litres/day provide adequate dialysis. The special attraction of CAPD for the patient is the minimum interruption of work or recreation as the patients can remain ambulatory throughout.

(3) Chronic Cyclic Peritoneal Dialysis (CCPD):

This is a variant of CAPD where dialysis is performed during the night and two litres of fluid are retained in the peritoneal cavity during daytime. The single connection and disconnection in a day is said to reduce the incidence of peritonitis; however the requirement of an automatic cycler device limits the mobility of the patient.

Advantages of Peritoneal Dialysis:

1. No need for vascular surgery.

2. No need for systemic heparinisation, hence safe for use in presence of bleeding disorders, in a patient with suspected intracranial or pericardial haemorrhage.

3. The slower correction of fluid and electrolyte abnormalities is advantageous for patients with cardiovascular instability and better tolerated by children and the elderly.

4. No need for machines except when automatic cycler is used.

5. Little interference with work or recreation for patients on CAPD.

6. Better biochemical control on CAPD as compared to haemodialysis.

7. Less anaemia on CAPD, possibly because of better removal of middle molecules which are believed to suppress erythropoiesis.

8. Higher levels of high density lipoprotein cholesterol (HDLC) in patients on CAPD, then on haemodialysis — so incidence of vascular disease may be reduced.

Disadvantages/Problems of Peritoneal Dialysis:

1. Risk of peritonitis is most important. Recurrent peritonitis not only causes impairment of health, and even death from septicaemia but also leads to obliteration of the peritoneal cavity, thus making further peritoneal dialysis impossible.

2. Longer treatment time as it is a slow process; this means that the patient has to be on dialysis for longer periods intermittently, or there has to be continuous involvement.

3. Catheter malfunction.

4. Moderate protein loss (about 5-10 g/day on CAPD).

5. Should not be used in cases of recent abdominal surgery.

6. Should better be avoided in patients with chronic lung diseases or respiratory insufficiency as the large amount of fluid in the peritoneal cavity pushes up the diaphragm causing basal atelectasis and increasing the chance of infection.

7. In presence of certain diseases like systemic sclerosis, vasculitis and malignant hypertension clearance is inadequate.

8. In severe hypercatabolic states clearance with peritoneal dialysis may not be adequate to control hyper potassaemia.