Renal Replacement Therapy - Dialysis Flashcards
Name six function 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 are the clinical features of advanced CKD?
- Until CKD stage 4 or 5 the patient may be asymptomatic
- The syndrome of advanced CKD is called uraemia (high urea)
- Uraemic symptoms can involve almost every organ system but the earliest and cardinal symptom is malaise and fatigue
When is renal replacement therapy indicated?
To sustain life in patient suffering from end-stage renal disease
eGFR < 10ml/min (but can be variable between people)
Name the different types of renal replacement therapy
- Renal transplant
- Haemodialysis
- Peritoneal dialysis
- Conservative kidney management
What are the two types of peritoneal dialysis?
- Continuous ambulatory peritoneal dialysis (CAPD) - four times a day
- Intermittent peritoneal dialysis (IPD)
What are the type types of haemodialysis?
- Home haemodialysis
* Satellite/hospital haemodialysis
What is dialysis?
Dialysis is a process whereby the solute composition of a solution, A, is altered by exposing solutions A to a second solution, B, through a semi permeable membrane
What are the principles of dialysis?
- Diffusion
Waste in blood moves towards dialyse (solution) - Ultrafiltration
Flow of water and dissolved solute down a pressure gradient, removing excess fluid and waste from blood (increases volume of solution B and decrease volume of solution A to equilibrate pressure across membrane)
What are the pre-requisites for dialysis?
- 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
Describe the haemodialysis access routes
Permanent:
• Arteriovenous fistule
• AV prostethetic graft
Temporary
• Tunneled venous catheter
• Temporary venous catheter
Describe the electrolyte loss in dialysis
- Some Na, K, Ca and little HCO3
* All of creatinine and urea
What are the restriction for dialysis patients
Fluid restriction:
• Dictated by residual urine output
• Interdialytic weight gain
Dietary restriction:
• Potassium
• Sodium
• Phosphate
Describe the process of haemodialysis
Blood travels through tubes from body into the dialysis machine. While blood is in the machine, it goes through a filter called a dialyser, which removes waste and extra fluid. Once it has been cleaned, the blood travels through tubes from the dialysis machine back into your body.
Used dialysate is continually removed from dialysed and fresh solution put back in.
How is peritoneal dialysis performed?
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 fluid is used in peritoneal dialysis?
The dialysate contains a balanced concentration of electrolytes. Glucose is the 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
What is the difference between continuous ambulatory PD (CAPD) and automated PD (APD)?
ADP takes place at night, during sleep, over 8-10 hours.
CAPD is done four times a day.
What are possible complications of peritoneal dialysis?
- Exit site infection
- Ultrafiltration failure
- Encapsulating peritoneal sclerosis
PD peritonitis:
• Gram positive – skin contaminant
• Gram negative – bowel origin
• Mixed – suspect complicated peritonitis eg perforation
What are the indications 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
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?
Usually more liberal than haemodialysis intake as continuous ultrafiltration is often achieved
Name dialysis related drugs
Anaemia:
• Erythropoietin injections
• IV iron supplements
Renal Bone Disease
• Activated Vitamin D (eg calcitriol)
• Phosphate binders with meals (CaCo3)
- Heparin
- Water soluble vitamins
What are complications of haemodialysis?
CVS:
• Intra-dialytic hypotension and cramps
• Arrythmias
Coagulation:
• Clotting of vascular access
• Heparin related problems
Other:
• Allergic reactions to dialyses and tubing
• Catastrophic dialysis accidents (rare)
What are complications of peritoneal dialysis?
Infection:
• Exit site infection
• Tunnel infection
• Peritonitis
Mechanical:
• Tube malfunction
• Abdominal wall herniae
• Ultrafiltration problems
How is the choice of dialysis modality made?
- Patient choice through education and shared decision making
- Perception of effectiveness
Describe conservative kidney management for those not suitable for dialysis
Supportive care
• Priority for symptomatic management
• Holistic multi-professional approach
• Anticipatory care planning
