Renal Replacement Therapy

Question 1

Who should RRT be offered to?

Answer 1

Patients with ESRD (eGFR<15)

Question 2

What are the two types of dialysis available?

Answer 2

Haemodialysis and peritoneal dialysis

Question 3

Describe how haemodialysis works

Answer 3

Dialysis fluid and the patients blood run in opposite directions and are separated by a semi-permeable membrane. Certain molecules are able to pass across the membrane but others are not, for example ions will pass across but proteins do not leave the patients blood as they are too large. The concentration of ions in the dialysis fluid can then be used to alter the patients serum concentrations. Ultrafiltration (increased pressure of the patients blood relative to the dialysis fluid) allows for removal of excess circulating volume

Question 4

What properties of the kidney can dialysis not replace?

Answer 4

Synthetic capabilities including:
Vitamin D activation
EPO production

Question 5

What needs to be surgically created before haemodialysis can be carried out?

Answer 5

An AV fistula provides the venous access

Sometimes a central venous catheter (central line) is used for dialysis but this is less common

Question 6

Roughly how long does a haemodialysis session take? How many times a week does it need to be done?

Answer 6

Around 3 hours

Should be done around 4 times per week

Question 7

When should dialysis be considered in patients with an AKI?

Answer 7

Creatinine >500
Oligo or anuric
Uraemia- causing pericarditis (rub) or encephalopathy (flap), N+V, abnormal mental function
Hyperkalaemia (not responding to standard treatment and high risk of cardiac arrest)
Severe pulmonary oedema
Metabolic acidosis

Question 8

What must patients be vaccinated for before starting haemodialysis?

Answer 8

Hepatitis B (As it is a blood borne virus)

Question 9

What kind of eGFRs does haemodialysis produce?

Answer 9

Not very high ones, still less than 15

Question 10

Patients with renal disease are prone to metabolic acidosis, what is added to dialysis fluid to manage this complication?

Answer 10

Bicarbonate- which draws out hydrogen ions from the blood.

Alternatively lactate or acetate may be added, these are metabolised to bicarbonate

Question 11

When should dialysis be started in CKD?

Answer 11

When the eGFR drops below 10, or if the patient is highly symptomatic or very fluid overloaded

Patients with Stage 5 CKD should be counselled about RRT

Question 12

Describe how peritoneal dialysis works

Answer 12

Dialysis fluid is placed into the patients peritoneal space. The peritoneal membrane acts as the semi-permeable membrane across which there is exchange of molecules. This requires a peritoneal catheter that is normally at the anterior abdominal wall.

Question 13

Where is peritoneal dialysis done?

Answer 13

Peritoneal dialysis can be done at home unlike haemodialysis which is done at hospitals or dialysis centres

Question 14

What is used in dialysis fluid to generate an osmotic gradient?

Answer 14

Dextrose is used

Question 15

How might peritoneal dialysis be done?

Answer 15

A machine can be used for continuous ambulatory peritoneal dialysis, this can be connected overnight and automatically does the exchanges, cycling throughout the night.

Alternatively the person can carry out the exchanges themselves and swab the bags over after 3-4 hours.

Question 16

What is essential for patients to do for peritoneal dialysis?

Answer 16

Patients attend an education course, they learn how to carry out peritoneal dialysis and the importance of good hand hygiene and keeping the catheter clean. They should report any signs of infection early on or any contamination of the catheter.

Question 17

What are some complications of peritoneal dialysis?

Answer 17

Peritonitis

Encapsulating peritoneal sclerosis

Question 18

What can encapsulating peritoneal sclerosis cause?

Answer 18

Recurrent bowel obstruction

Fibrosis of the peritoneum

Question 19

What might be an early sign of peritonitis?

Answer 19

If the draining fluid is slightly cloudy- it should be clear

Question 20

Who is peritoneal dialysis good for?

Answer 20

As it can be done at home and overnight it is good for young people and they can keep up with normal schedules. It maintains more independence and doesn’t require large times to be spent in dialysis centres. It is also better than haemodialysis for patients with severe cardiac disease

Question 21

What are some negatives of peritoneal dialysis?

Answer 21

It does not last forever, the peritoneal membrane can wear out and so patients may have to transfer to haemodialysis
It is not suitable for people with previous major abdominal surgery due to adhesions that can form
There is a risk of peritonitis and encapsulating peritoneal sclerosis
It is not suitable for patients who cannot do it themselves as it requires a lot of education and patient control

Question 22

How should the type of dialysis be selected?

Answer 22

It is the patient’s choice. The pro’s and cons of each should be explained to patients and they can make an informed decision. There is a lot of information so written information should be given. Also could visit dialysis centre to learn more from staff and other patients.

Question 23

What are some complications of haemodialysis?

Answer 23

Risk of BBV (Problem if going abroad for haemodialysis)
Risk of hypotension due to rapid fluid removal
Can cause vascular damage so patients are at risk of central vein occlusion, haemodialysis induced digital ischaemia, ischaemic neuropathy (decreased perfusion distal to AVF)
Failure of AVF eventually
Risk of infection due to repeated vascular access