Renal Replacement Therapy Flashcards
When is long term dialysis started?
When it is necessary to manage one or more symptoms of renal failure including:
Inability to control volume status including pulmonary oedema
Inability to control BP
Serositis - inflammation of the serous tissues of the body eg. Tissues of body, lining of lungs and heart
Acid base balance/electrolyte abnormalities
Pruritus
Nausea/vomiting
Cognitive impairment
What is GFR normally at commencement of dialysis?
5 - 10
Name the two types of dialysis
Peritoneal dialysis
Haemodialysis
What is haemodialysis?
Blood is passed over a semi-permenant membrane against dialysis fluid flowing in the opposite direction
Diffusion of solutes occurs down the concentration gradient
Hydrostatic gradient is used to clear excess fluid as required
How is access gained for haemodialysis?
How often is haemodialysis needed?
What is the benefit of daily HD?
AV fistula - which provides increased blood flow and longevity
Required 3 times/week or more
Daily HD increases the ‘dose’ and improves outcomes
Home HD should be offered to all suitable patients
What are the problems of haemodialysis?
Access - AV fistula can have thrombosis, stenosis, steal syndrome
Tunnelled venous line - infection, blockage, recirculation of blood
Dialysis dysequilibrium - between cerebral and blood solutes leading to cerebral oedema
Hypotension
Time consuming
What problems can arise with the AV fistula?
Thrombosis, stenosis, steal syndrome
What is peritoneal dialysis?
Uses the peritoneum as a semi-permeable membrane
Catheter is inserted into the peritoneal cavity and fluid infused.
Solutes diffuse slowly across.
Ultrafiltration is achieved by adding osmotic agents e.g. glucose, glucose polymers
Continuous procures with intermittent drainage and refilling of the peritoneal cavity, performed at home
What are the problems with peritoneal dialysis?
Infection at catheter site
PD peritonitis
Hernia
Loss of membrane function over time
What is haemofiltration?
When is this method of renal replacement therapy used?
Water cleared by positive pressure dragging solutes into the waste by convection
The ultra-filtrate (waste) is replaced with an appropriate volume of (clean) fluid either before or after the membrane
Used - intensive care when HD is not possible due to decreased BP
Outline the difference between haemodialysis and haemofiltration
Haemodialysis - movement of solutes by diffusion down concentration gradient
Haemofiltration - movement of solutes by convection. The positive hydrostatic pressure drives water and solutes across the filter membrane from blood compartment to filtrate compartment where it is drained
What is the advantage of haemofiltration over haemodialysis?
Used in intensive care in patients with low BP to withstand haemodialysis
Haemofiltration - solutes both small and large get dragged through the membrane at similar rate by the flow of water due to the hydrostatic pressure
Convection overcomes the reduced removal rate of larger solutes seen in haemodialysis
What are the complications of renal replacement therapy?
Annual mortality is significant - mostly due to CVS disease
Increased BP, calcium/phosphate dysregulation, vascular stiffness, inflammation
Protein-calorie malnutrition - increases morbidity and mortality
Renal bone disease - high bone turnover, osteoid fibrosa
Infection - uraemia causes granulocyte and T cell dysfunction wth increased sepsis related mortality
Amyloid - Beta2 microglobulin accumulates in long-term dialysis causing carpal tunnel syndrome, arthralgia, visceral effects
When is conservative management used in renal replacement therapy?
What is the focus of conservative management?
For those who opt not to receive RRT due to lack of benefit of quantity/quality of life
Focus is on preserving residual renal function, symptom control and advanced planning with patient and family for end of life care
When should renal transplantation be considered?
For every patient with or progressing towards stage 5 kidney disease
It is the treatment of choice for kidney failure provided risks do not exceed benefits
