Dialysis (renal replacement therapy 1)

Question 1

name 6 functions of the kidney

Answer 1

1. Excretion of nitrogenous waste products
2. Maintenance of acid and electrolyte balance
3. Control of blood pressure
4. Drug metabolism and disposal
5. Activation of vitamin D
6. Production of erythropoietin

Question 2

what is the definition of end stage renal disease (ESRD)

Answer 2

“…irreversible damage to a person’s kidneys so severely affecting their ability to remove or adjust blood wastes that, to maintain life, he or she must have either dialysis, or a kidney transplant…”

Question 3

what are some of the clinical features of advanced CKD

Answer 3

1. patient may be asymptomatic until stages 4 or 5 CKD
2. present with uraemia syndromes - can involve almost every organs system but earliest and cardinal symptoms are malaise and fatigue

Question 4

what value is indicative of renal replacement therapy

Answer 4

eGFR <10 ml/min

Question 5

what re the 4 types of renal replacement therapy

Answer 5

1. renal transplant
2. haemodialysis
3. peritoneal dialysis
4. conservative kidney management

Question 6

what is dialysis

Answer 6

a process whereby the solute composition of a solution, A, is altered by exposing solution A to s second solution, B, through a semipermeable membrane

Question 7

what are the two principles used in dialysis

Answer 7

1. diffusion

2. ultrafiltration

Question 8

define diffusion

Answer 8

the net movement of molecules from a region of high concentration to a region of low concentration until there is an equal concentration - driven by chemical gradient

Question 9

define ultrafiltration

Answer 9

a variety of membrane filtration in which forces like pressure or concentration gradients lead to a separation through a semipermeable membrane

Question 10

what are the 4 prerequisites for dialysis

Answer 10

1. semipermeable membrane
2. adequate blood exposure to the membrane
3. dialysis access
4. anticoagulation

Question 11

what are the 2 types of haemodialysis access

Answer 11

1. permanent - AV fistula, AV prosthetic graft

2. temporary - tunnelled venous catheter, temporary venous catheters

Question 12

what are the main things removed from the blood during dialysis

Answer 12

creatinine and urea

Question 13

what are the two types of restrictions for dialysis patients

Answer 13

Fluid restriction

• Dictated by residual urine output
• Interdialytic weight gain

Dietary restriction

• Potassium
• Sodium
• Phosphate

Question 14

briefly summarise the process of haemodialysis

Answer 14

blood is removed for cleaning - an arterial pressure monitor keeps track of BP - a heparin pump is attached to prevent clotting - a blood pump pumps the blood through one end of the dialyser - fresh dialysate is pumped through the other end - used dialysate is removed from the dialysed - clean blood leaves the dialyser - a venous pressure monitors keeps track of BP - blood passes through air trap and air detector - clean blood flows back into the patient

Question 15

briefly summarise peritoneal dialysis

Answer 15

A balanced dialysis solution is instilled into the peritoneal cavity via a tunnelled, cuffed catheter, using the peritoneal mesothelium as a dialysis membrane

After a dwell time the fluid is drained out and fresh dialysate is instilled

Question 16

what are the three kinds of peritoneal dialysis

Answer 16

1. Continuous Ambulatory Peritoneal Dialysis (CAPD),
2. Automated Peritoneal Dialysis (APD)
3. Hybrid

Question 17

what does the dialysate in peritoneal dialysis contain

Answer 17

contains a balanced concentration of electrolytes

Glucose is the most common osmotic agent for ultrafiltration of fluid

Question 18

what are complications of peritoneal dialysis

Answer 18

Exit site infection

PD peritonitis

• Gram positive – skin contaminant
• Gram negative – bowel origin
• Mixed – suspect complicated peritonitis eg perforation

Ultrafiltration failure

Encapsulating peritoneal sclerosis

Question 19

what are the indications for dialysis in end stage renal disease (ESRD)

Answer 19

Advanced uraemia, (GFR 5-10 ml/min)

Severe acidosis (bicarbonate <10 mmol/l)

Treatment resistant hyperkalaemia (K >6.5 mmol/l)

Treatment resistant fluid overload

**Nephrologist’s clinical judgment is important

Question 20

what is the fluid balance restriction in haemodialysis patients

Answer 20

Usually restricted to 500-800 ml/24 hours

intake allowed = urine output +insensible loss

Question 21

what is the fluid balance restriction in peritoneal dialysis patients

Answer 21

Usually more liberal intake as continuous ultrafiltration is often achieved

Question 22

what drugs are regularly used along with dialysis and what are they for

Answer 22

Anaemia

• Erythropoietin injections
• IV iron supplements

Renal Bone Disease

• Activated Vitamin D (eg calcitriol)
• Phosphate binders with meals (CaCo3)

Coagulation
- Heparin

Water soluble vitamins

? antihypertensives

Question 23

what are complications of haemodialysis

Answer 23

CVS problems

• Intra-dialytic hypotension and cramps
• Arrythmias

Coagulation

• Clotting of vascular access
• Heparin related problems

Other

• Allergic reactions to dialysers and tubing
• Catastrophic dialysis accidents (rare)

Question 24

what are the complications of peritoneal dialysis

Answer 24

Infection

• Exit site infection
• Tunnel infection
• Peritonitis

Mechanical

• Tube malfunction
• Abdominal wall herniae

Ultrafiltration problems

Question 25

how is it chosen what dialysis is ultimately used

Answer 25

Patient choice – most important

• Education
• Shared decision making

Patient related
Perceptions of effectiveness
(Cost and remuneration)

Question 26

what is conservative kidney management

Answer 26

supportive care

• Priority for symptomatic management
• Holistic multi-professional approach
• Anticipatory care planning

Question 27

summary: what is the ultimate indication for dialysis

Answer 27

when eGFR less than 10 ml/m or patient symptomatic of uraemia