Renal Replacement Therapy Dialysis 1

Question 1

What is the definition of end stage renal disease? (ESRD)

Answer 1

“…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 2

What are the clinical features of advanced CKD?

Answer 2

Until CKD stage 4 or 5 - may be asymptomatic

Syndrome of advanced CKD is called uraemia

Uraemic syndrom can involve every organ system but the earliest and cardinal symptom is malaise and fatigue

Question 3

When is RRT usually commenced?

Answer 3

When eGFR is less than 10 ml/min

or patient is symptomatic of uraemia

Question 4

What are the types of renal replacement therapy?

Answer 4

Renal transplant

Haemodialysis (home or hospital)

Peritoneal dialysis (CAPD - continuous ambulatory peritoneal dialysis vs intermittent peritoneal dialysis)

Conservative kidney management

Question 5

What are the two mechanisms of solute movement in dialysis?

Answer 5

Diffusion

Ultrafiltration - pressure filtration

Question 6

What are the pre-requisites for dialysis?

Answer 6

Semipermeable membrane (artifical kidney in haemodialysis or peritoneal membrane)

Adequate blood exposure to the membrane (extracorporeal blood in haemodialysis, mesenteric circulation in PD)

Dialysis Access vascular in haemodialysis, peritoneal in PD

Anticoagulation in hemodialysis

Question 7

What are the different access points for haemodialysis?

Answer 7

•Permanent

–Arteriovenous fistula

–AV prosthetic graft

•Temporary

–Tunnelled venous catheter

–Temporary venous catheter

Question 8

Look at the movement of solutes

Answer 8

Note that creatinine and urea are both completely removed

Question 9

What are the restrictions for dialysis patients?

Answer 9

Fluid - dictated by residual urine output

Dietary restriction - potassium, phosphate, sodium

Question 10

What is the mechanism of peritoneal dialysis?

Answer 10

Balanced solution is instilled into the peritoneal cavity using the peritoneal mesothelium as a dialysis membrane

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

Question 11

What are the mechanisms of peritoneal dialysis?

Answer 11

Continuous ambulatory peritoneal dialysis (CAPD)

Automated peritoneal dialysis (APD)

Hybrid

Question 12

Describe the peritoneal dialysis fluids

Answer 12

Dialysate contains a balanced concentration of electrolytes

Glucose - most common osmotic agent for ultrafiltration of fluid

•The peritoneal transport characteristics can vary from high transporter to low transporter

–Dwell times can be adjusted according to transport characteristics

Question 13

What are the comlpications of peritoneal dialysis?

Answer 13

Exit site infection

Tunnel infection

PD peritonitis - gram positive - skin contaminant

Gram negative - bowel origin

mixed - suspect complicated peritonitis - e.g perforation

Ultrafiltration failure

Encapsulating peritoneal sclerosis

Mechanical:

• Tube malfunction, abdominal wall herniae

Question 14

What are the indicatinos for dialysis in ESRD? - end stage renal disease

Answer 14

• 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 15

What is the difference in fluid restriction between haemodialysis and peritoneal dialysis?

Answer 15

Haemodialysis - restricted to 500 - 800 ml/24 hours intake allowed = urine output and insensible loss

Peritoneal dialysis - more liberal intake as continuous ultrafiltration is often achieved

Question 16

What are dialysis related drugs?

Answer 16

•Anaemia

–Erythropoietin injections

–IV iron supplements

•Renal Bone Disease

–Activated Vitamin D (eg calcitriol)

–Phosphate binders with meals (CaCo3)

•Heparin

•Water soluble vitamins

•? antihypertensives

Question 17

What are the complications of haemodialysis?

Answer 17

Cardiovascular problems: Intradialytic hypotension and cramps, arrythmias

Coagulation: Clotting of vascular access, heparin related problems

Other: Allergic reactions to dialysers and tubing, catastrophic dialysis accidents (rare)

Patients on (any type) of dialysis have increased morbidity and mortality