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
What are the contraindications for renal transplant?
Absolute - Cancer with mets
Temporary - Active infection, HIV with viral replication, unstable CVD
Relative - congestive heart failure, CVD
What are the two types of renal transplant available?
Which gives the best graft function and survival?
Living donor - best graft function and survival, especially if HLA matched
Deceased donor
- donor after brain death
- expanded criteria donor is from an older kidney from a patient with history of CVA, BP or CKD - impacts on long term prognosis of transplant but offers a better outcome than remaining on dialysis
- donor after cardiac death with increased risk of delayed graft function
What types of immunosuppression are used for renal transplant?
Combination of drugs at lowest effective dose
Monoclonal antibodies e.g Bailiximab - selectively block activated T cells - used at time of transplant. Decrease acute rejection and graft loss
Calcineurin inhibitors e.g. ciclosporin - inhibit T cell activation and proliferation. Narrow therapeutic index. Requires monitoring. Clearance dependent on CYP450
Antimetabolites e.g. myclophenolic acid - prevents acute rejection and graft survival. DONT USE IN PREGNANCY
Glucorticosteroids - decrease transcription of inflammatory cytokines. First choice treatment for acute rejection. Significant side effects e.g. BP, hyperlipidaemia, impaired wound healing
What is the first choice treatment for acute transplant rejection?
What is their mechanism of action?
Name some side effects
Glucocorticosteroids - decrease transcription of inflammatory cytokines.
Significant side effects e.g. hyperlipidaemia, BP, impaired wound healing, oestoporosis
Name 4 surgical complications for renal transplant
Bleed
Thrombosis
Infection
Urinary leaks
Lymphocele
Hernia
How can rejection of a kidney transplant be classified?
Acute - divided into antibody mediated (rare) or cellular (common)
Treatment = high dose steroids and increased immunosuppression
Chronic - antibody mediated rejection causes progressive dysfunction of the graft
What types of infection are renal transplant patients prone to?
Hospital acquired infection derived in 1 month
Opportunistic infection 1- 6 months - give prophylactic treatment for CMV and pneumocystis jirovecii
Community acquired 6 - 12 months
What is the risk of cancer with immunosuppression?
Increased by 25 times - particularly skin, post transplant lymphoproliferative disorder and gynaecological
What CVS effects can a renal transplant have?
Increased risk of premature CVD compared to general population
BP, rejection and renal history contribute
