Renal Therapeutics III: Renal Replacement Flashcards by Sama Safaa

What is the aim of renal dialysis?

For patients with GFR

How well did you know this?

Not at all

Perfectly

What are the 2 general techniques of renal dialysis?

Haemodialysis

Peritoneal dialysis

How well did you know this?

Not at all

Perfectly

Which 2 processes does dialysis try to mimic?

Ultra-filtration followed by reabsorption

How well did you know this?

Not at all

Perfectly

How is ultra-filtration carried out in haemodialysis?

Artificial membrane

Fast cycles of fresh dialysis fluid = more effective than peritoneal dialysis

How well did you know this?

Not at all

Perfectly

How is ultra-filtration carried out in peritoneal dialysis?

Patient’s own peritoneal membrane

Dialysis reaches equilibrium before fluid change

How well did you know this?

Not at all

Perfectly

When is dialysis used?

ARF (in oliguric phase)
CRF
Drug overdose
Poisoning

How well did you know this?

Not at all

Perfectly

What is required in order to mimic ultra-filtration?

Membrane similar to glomerular basement membrane

Differs in pore size

How well did you know this?

Not at all

Perfectly

How is water removed in haemodialysis?

By hydrostatic force

How well did you know this?

Not at all

Perfectly

How is water removed in peritoneal dialysis?

By osmotic pressure (between blood and dialysis fluid)

How well did you know this?

Not at all

Perfectly

How is waste removed during dialysis?

Blood is exposed (through a membrane) to a solution with a low concentration of substances to be removed

How well did you know this?

Not at all

Perfectly

How is conservation of useful substances mimicked?

Tubular reabsorption does not exist

Replacement dietary supplementation oradding substances to dialysis fluid = transfer to patient

How well did you know this?

Not at all

Perfectly

Why is heparin added to the blood during dialysis?

Anticoagulant
To prevent thrombosis in the blood circuit of the dialysis machine
Prevents air bubbles in blood getting into body

How well did you know this?

Not at all

Perfectly

What does the dialysis fluid remove from the blood?

Urea
Creatinine
Potassium
Calcium (also in)
Sodium (also in)
Plasma water

How well did you know this?

Not at all

Perfectly

What does the blood take up from the dialysis fluid?

Calcium (also out)
HCO3-
Sodium (also in)

How well did you know this?

Not at all

Perfectly

Name the 4 haemodialysis techniques

Conventional haemodialysis
Haemofiltration
High-flux haemodialysis
Haemodiafiltration

How well did you know this?

Not at all

Perfectly

What is conventional haemodialysis?

Low-flux membranes allow diffusive, but little convective solute removal
Middle molecule clearing is poor

How well did you know this?

Not at all

Perfectly

What is haemofiltration?

Purely convective treatment
Poor small molecule clearance
Middle molecule clearance excellent
Not a long term treatment for ESRF

What is high-flux haemodialysis??

Highly permeable membranes used

= Good diffusive removal of middle molecules and small solutes

What is haemodiafiltration?

Haemofiltration (convective) but high flux haemodialysis (=highly permeable membranes)

List 5 side effects of haemodialysis

Fatigue
Low blood pressure - due to fluid loss
Muscle cramps - during dialysis due to fluid loss
Itchy skin - due to potassium build up, can be managed by a low potassium diet
Staphylococcal infections

What is peritoneal dialysis?

Home-based renal replacement therapy for patients with ESRF
2L of sterile dialysis fluid (dialysate) runs directly into the peritoneal cavity using a cathetar
Dialysis takes place between the blood in peritoneal capillaries and the dialysate, across the peritoneal membrane
Dialysate drained out

How is water removed from the blood in peritoneal dialysis?

The dialysate contains lots of glucose = osmotic gradient
Therefore water can be removed via osmosis
Amount of water removal can be adjusted by altering glucose concentration

How is the pH of the blood buffered?

By absorption of lactate and bicarbonate from the dialysate

What are the 3 techniques of peritoneal dialysis?

Intermitted peritoneal dialysis (IPD)
Continuous ambulatory peritoneal dialysis (CAPD)
Automated peritoneal dialysis (APD)

What is intermitted peritoneal dialysis (IPD)?

Hospitalised patients Carried out over 24-48 times over 1-2 days 30 mins each Repeated 2-3 times weakly

What is continuous ambulatory peritoneal dialysis (CAPD)?

Patient carries fluid in abdomen continuously Changed 2-5 times daily Closest method to normal kidney function

What is automated peritoneal dialysis (APD)?

Machine to switch between bags used at home More rapid cycle Night-time exchanges might be enough

How can drugs be given in peritoneal dialysis?

Can be given in the CAPD fluid (abdomen) | e.g. antibiotics and insulin

List 2 common problems with peritoneal dialysis

Infection - peritonitis or exit site | Hyperglycaemia - glucose in dialysate causes this and obesity, especially in CAPD

List 2 advantages of PD over HD

``` Patient autonomy and independence Lifestyle advantages (e.g. easier work and travel) ```

List 2 disadvantages of PD vs HD

Peritonitis and exit site infection | Patient or carer needs to be able to perform technique

List 3 things that would make a deceased person's kidney less attractive to donate

If the deceased donor has suffered from: Diabetes Insipidus Hypothermia Problems with hormone levels

What is histocompatibility?

Tissue compatibility

What are the 2 important immunological criteria for histocompatibility?

Blood group Human leucocyte locus-A (antigen compatibility) Better matching kidney = reduced immunosuppressant doses

Describe the process of the surgical procedure of a kidney transplant

Organ placed extraperitoneally (peritoneum preserved for eventual dialysis) Connected to blood circulation and and ureter implanted to bladder Original kidneys usually left in except if problems e.g. hypertension, stones, tumours etc

Name the 3 types of rejection which could occur after a transplant

Hyperacute or immediate rejection Acute rejection Chronic rejection

Explain what a hyperacute/immediate rejection is

Caused by pre-existing antibodies Happens within hours Untreatable and rare Results in renal vascular thrombosis

Explain what an acute rejection is

Most common form T cell-mediated response to antigens Results in vascular and tubular damage Unspecific symptoms

Explain what a chronic rejection is

After the first few months Immune-complex deposition within glomeruli and renal vessels Leads to glomerulonephritis = irreversible

What are the 3 areas of medical management for renal transplants?

1. Initial choice and subsequent modulation of immunosuppressant regimen to prevent early & acute rejection 2. Management of complications and side effects of immunosuppressant therapy 3. Management of poorly function renal transplant

What are main problems that patients experience from immunosuppressant therapy?

Hypertension Malignancy (caused by the cytotoxic agents) Vascular diseases Infections