Dialysis Flashcards
What are the functions of the kidneys?
- Excretion of nitrogenous waste products
- Maintenance of acid and electrolyte balance
- Control of blood pressure
- Drug metabolism and disposal
- Activation of vitamin D
- Production of erythropoietin
What functions of the kidneys cannot be replaced by dialysis?
- Activation of vitamin D
- Production of erythropoietin
End stage renal disease (ESRD)
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
When may a patent with CKD be asymptomatic?
-Until CKD stage 4 or 5 the patient may be asymptomatic
What is the syndrome of advanced CKD called?
Uraemia
How do uraemic symptoms manifest?
Uraemic symptoms can involve almost every organ system but the earliest and cardinal symptom is malaise and fatigue
What is renal replacement therapy?
The means by which life is sustained in patients suffering from end-stage renal disease.
When is renal replacement therapy usually indicated?
Usually indicated when eGFR <10ml/min
What types of renal replacement therapy are there?
- Renal transplant
- Haemodialysis
- Peritoneal dialysis
- Conservative kidney management
How can haemodialysis be delivered?
- Home haemodialysis
- Satellite/hospital haemodialysis
How can peritoneal dialysis be administered?
- Continuous ambulatory peritoneal dialysis (CAPD)
- Intermittent peritoneal dialysis (IPD)
Dialysis
Dialysis is a process whereby the solute composition of a solution, A, is altered by exposing solution A to a second solution, B, through a semipermeable membrane.
What are the principles of dialysis?
- Diffusion
- Ultrafiltration
What are the pre-requisites for dialysis?
- Semipermeable membrane (artificial 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 haemodialysis
What types of access are there for haemodialysis?
Permanent
- AV fistula
- AV prosthetic graft
Temporary
- Tunnelled venous catheter
- Temporary venous catheter
What is the name of the solution used in dialysis?
Dialysate
How is maximum efficiency of the removal of waste products achieved?
- Blood and dialysate run in opposite directions
- This means that the concentration difference is maintained at either side.
- This means waste will continue to filter into the dialysate maximising removal from the blood
What intake restrictions are there for dialysis patients?
- Fluid restriction dictated by residual urine output checked by interdialytic weight gain
- Dietary restriction of potassium, sodium and phosphate
How is clotting prevented in the dialysis machine?
Heparin pump
What is involved in the process of peritoneal dialysis?
- 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
What does the dialysate used in peritoneal dialysis contain?
- The dialysate contains a balanced concentration of electrolytes
- Glucose is the most common osmotic agent for ultrafiltration of fluid
Why do dwell times need to be adjusted in peritoneal dialysis?
The peritoneal transport characteristics can vary from high transporter to low transporter
What are the possible complications of peritoneal dialysis?
- Exit site infection
- Tunnel infection
- PD peritonitis
- Technical
- Ultrafiltration failure
- Encapsulating peritoneal sclerosis
What technical complications may there be in peritoneal dialysis?
- Tube related problems
- Abdominal wall hernia
Where can the bacteria come from in PD peritonitis?
- Gram positive usually a skin contaminant
- Gram negative usually bowel origin
- Mixed: suspect complicated peritonitis e.g. perforation
What are the indication for dialysis in ESRD?
- 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
How is fluid balance maintained in haemodialysis patients?
- Usually restricted to 500-800 ml/24 hours
- Intake allowed = urine output +insensible loss
How is fluid balance maintained in peritoneal dialysis patients?
- Usually more liberal intake as continuous ultrafiltration is often achieved
- Less restriction on fluid intake
What drugs are dialysis patients usually on?
- Erythropoietin injections
- IV iron supplements
- Activated vitamin D
- Phosphate binders
- heparin
- Water soluble vitamins
- Antihypertensives
What are the possible complications of haemodialysis?
CV problems
- Intra-dialytic hypotension and cramps
- Arrhythmias
Coagulation
- Clotting of vascular access
- Heparin related problems
Other
- Allergic reactions to dialysers and tubing
- Catastrophic dialysis accidents (rare)
What factors contribute to the choice of dialysis modality?
- Patient choice (involves education and shared decision making)
- Patient related factors
- Perceptions of effectiveness
- Cost and remuneration (not applicable in Scotland)
What are the limitations of dialysis?
- It is a woeful substitute for the kidneys
- It is not right for everyone
- Mortality rates
What type of care is involved in conservative kidney management?
Supportive care
What supportive care is available in conservative kidney management?
- Priority for symptomatic management
- Holistic multi-professional approach
- Anticipatory care planning
- Randomised control trial ongoing for dialysis versus CKM for older adults with co-morbidity
