Renal replacement therapy

Question 1

Name the three functions of the kidney?

Answer 1

Filtration, ultrafiltration and reabsorption

• Removal of waste
• Producing erythropoietin
• Blood pressure management
• Electrolyte balance

1) toxin removal-nitrogenous waste, potassium
2) fluid removal-blood pressure control
3) Hormone production-hydroxylation of vitamin D and production of erythropoeitin

So renal replacement has to offer all 3 of these in order to work well

Question 2

Measuring Kidney function:

Answer 2

• Inulin infusion is gold standard but in practice we use people’s creatinine levels

Question 3

CKD:

Answer 3

• Use eGFR, for monitoring and diagnosing CKD but in acute settings we use raw creatinine values as eGFR lags so not good for acute kidney injury.
• Stage 1 and 2 for eGFR over 60 dont have any detectable kidney abnormalities
• Stage 3a to 3b is common in elderly and most won’t develop kidney failure or need rrt.
• RRT is only required for a few people with GFR under 15

Question 4

For patients instead of saying egfr of 30, can say to patients you have 30% of function.

Couldn’t biopsy which is gold standard for cause, because his kidneys were too small by then so it was not possible.

What should he do for RRT?

Answer 4

Question 5

What should he do for RRT?

Question 6

RRT-4 key choices:

Answer 6

• Most common is kidney transplantation. Can be from a live donor or they may be recently deceased.
• Conservative care-best supportive management and watch and wait. Non-intervential-used in comorbid patients or people neae end of life where this would just make symptoms worse. Can give erythropoietin supplements to keep them going.
• Peritoneal dialysis
• Haemodialysis

Question 7

What’s most common?

Answer 7

Number on RRT has increased greatly. Majorly due to increased transplants

People on transplants tend to live longer than people on other method of dialysis.

Survival on RRT is poor. Diagnosis of kidney cancer has worse prognosis than many cancers. Reason for this is prodominently cardiovascular disease eg Ischaemia and stroke as renal disease is a big cardiovascular risk.

Question 8

Key message

Answer 8

Transplant BEFORE starting dialysis. No benefit of starting dialysis before.

Question 9

Transplantation

Answer 9

Most effective form of RRT. Note-we don’t use transplants for AKI.

We leave people’s own kidneys in as their kidney still has some function which can be beneficial

Put in LIF or RIF

Cheaper than dialysis

Question 10

Who’s eligible for a transplant?

Answer 10

• Both with malignancy and infection we have to use immunosuppression which can make these worse.
• Transplantation is a major op so make sure that they have enough time to make the most of the benefits.

Question 11

Pre-emptive vs transplantation after dialysis

Answer 11

Survival is better too.

BUT… people who are preemptively transplanted often are in a different situation though because people who have to start dialysis often have to start in a hurry so have a different situation.

Question 12

Live donor vs deceased:

Answer 12

• Last longer
• Wait time is less, so less time to acquire problems on dialysis
• Happens in a planned way, whereas deceased transplant is unexpected and is often rushed or at night.
• Live donor-can work donor up and so risk from them is less

Question 13

HLA matching and cross-match

Answer 13

Match HLA at A, B and DRB1 only

Can see in this person has a 3 out of 6 mismatch. Complete mismatch would be less good but between 1 and 6 is fine.

Often quite permissive of poorly matched kidneys as benefit of transplant is so great.

Check whether they have any anti-HLA antigens

Cross-matching is way more important than HLA matching

Question 14

National programme sharing scheme:

Answer 14

Match HLA at A, B and DRB1 only

Can see in this person has a 3 out of 6 mismatch. Complete mismatch would be less good but between 1 and 6 is fine.

Often quite permissive of poorly matched kidneys as benefit of transplant is so great.

Check whether they have any anti-HLA antigens

Cross-matching is way more important than HLA matching

Question 15

Answer 15

80% of transplants are kidneys

Dialysis is important as not everyone can receive a transplant or is well enough for it.

Question 16

Answer 16

Do you want to dialyse in hospital or at home?

Not so good at hormone production and need to give vit d and eyrthopoeitin.

Getting GFR of 15-20

Question 17

Peritoneal dialysis

Answer 17

Drain fluid from tummy and then add new fluid

Question 18

Types of perioneal dialysis

Answer 18

Question 19

Difference

Answer 19

CAPD-exchanges during the day several times. Don’t need to be connected but have to have litre of fluid in tummy

Other one does lost of short exchanges over night so have max free time

Question 20

Peritoneal dialysis

Answer 20

Question 21

Haemodialysis

Note-arrows are the wrong way in this diagram

Answer 21

Blood is removed ideally out of fistula and then is anti-coagulated and filtered to remove air bubbles before being reinfused.

Question 22

What does haemodialysis need?

Answer 22

Blood is removed ideally out of fistula and then is anti-coagulated and filtered to remove air bubbles before being reinfused.

Question 23

Pros and cons of haemodialysis?

Answer 23

Note-comes down to patient choice. One is not more effective than the other

Question 24

Dialysis access:

Answer 24

Operation takes 6-8 weeks to develop and doesn’t always work. Other way is quicker but has greater infection risk

Question 25

PD access:

Answer 25

Question 26

Answer 26

No study suggesting dialysis early helps

Don’t really have a GFR to start it at

Question 27

When to start? Look out for these:

Answer 27

Question 28

AKI-dont use transplant as a lot of people get better. PD is cheap and easy to set up and so is used for AKI most commonly Haemodialysis can also be used

Answer 28

Question 29

Summary:

Answer 29