Renal Replacement Therapy Flashcards
What are the functions of the kidneys?
Excretion of nitrogenous waste products Maintenance of acid/base balance Control of BP Drug metabolism and excretion Vitamin D activation Production of erythropoietin
When is CKD typically symptomatic?
At stage 4/5
What is uraemia?
The syndrome of advanced CKD
What is the earliest and most cardinal symptoms of uraemia?
Fatigue
What are the symptoms of CKD?
Typically asymptomatic until stage 4/5
When is RRT usually indicated with eGFR?
<10ml/min
What are 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
Nephrologist’s clinical judgment is important
What are the types of RRT?
Renal transplant
Haemodialysis
Peritoneal dialysis
Conservative kidney management
What are the 2 types of haemodialysis?
Home
and satellite/hospital
What are the 2 types of peritoneal dialysis?
Continuous ambulatory peritoneal dialysis (CAPD)
Intermittent peritoneal dialysis (IPD)
What are the 2 molecular processes crucial for haemodialysis?
Ultrafiltration
Diffusion
Describe diffusion in haemodialysis
Process whereby solute composition of a solution A is altered by exposing solution A to solution B through a semi-permeable membrane
With time solution A equilibrates with solution B
Describe the process of ultrafiltration in haemodialysis/
Take the same semi-permeable membrane and apply a pressure gradient
to regulate fluid balance
Are ultrafiltration and diffusion applied at the same time or separately?
Same time
What are the pre-requisites for dialysis?
Semi-permeable membrane
Adequate blood exposure to membrane
Dialysis access
Anticoagulation
What are the permanent types of haemodialysis access?
Arteriovenous fistula
AV prosthetic graft
What are the temporary types of haemodialysis access?
Tunnelled venous catheter
Temporary venous catheter
What is an arteriovenous fistula?
When artery is anastomosed to a vein
Pressure is transmitted from artery to the vein causing hypertrophy
Has strong blood flow through it
When is AV prosthetic graft indicated?
In failed AV fistula
What is the disadvantages of AV prosthetic graft?
Foreign body
So increased risk of infectioqn
What direction does the dialysate move in?
Opposite to the blood flow to pull the solutes out of the blood
What is the fluid restriction in haemodialysis patients?
500-800ml/24 hours
What is the fluid restriction in peritoneal dialysis?
Usually more liberal as continuous ultrafiltration is often achieved
What restrictions are dialysis patients under?
Fluid restriction Dietary restriction of Potassium Sodium Phosphate
What are potential complications of haemodialysis?
CVS problems - arrhythmias, hypotension and cramps
Coagulation - clotting or heparin related problems
Other - allergic reactions to dialysis and tubing, catastrophic dialysis accidents
What is the predominant home therapy for RRT?
Peritoneal dialysis
What type of access is present in peritoneal dialysis?
Tunnelled cuffed catheter into the pelvic region
How does peritoneal dialysis work?
Balanced dialysis solution is instilled into the peritoneal cavity using the peritoneal mesothelium as a dialysis membrane
How does peritoneal dialysis control ultrafiltration?
Through glucose in the solution being an osmotic agent
Remember there is no pressure from the apparatus like in haemodialyis with the dialysis machine
Describe CAPD peritoneal d?
Involves several exchanges of fluid throughout the day
Describe APD peritoneal D?
Occurs at night with a machine
drains same amount of times but quicker with less filtration at each time
What are the complications of peritoneal D?
Exit site infection
PD peritonitis
Ultrafiltration failure
Technical related problems - tube related or abdominal hernia
What is the most commonest route of infection with gram positive PD peritonitis?
Skin contamination
What is the commonest route of infection with gram negative PD peritonitis?
Bowel origin
What other drugs should be considered in dialysis?
Erythropoietin injections
IV iron supplements for anaemia
- Activated Vitamin D (eg calcitriol)
- Phosphate binders with meals (CaCo3)for Vit D deficiency
Heparin
Water soluble vitamins
? antihypertensives
Why does activated vitamin D have to be given in CKD?
Because activation of vitamin D occurs in the kidney
In cDK kidney not working so have to activate prior
What considerations have to be made when putting a patient on dialysis?
Patient choice
Perceptions of effectiveness
What are the limitations of dialysis?
It is a woeful substitute for the kidneys
Where are kidney transplaneted?
Into the iliac fossa
What is used as the membrane in peritoneal dialysis?
Peritoneal membrane
What is the problem with using the peritoneal membrane for dialysis?
It does not apply pressure for ultrafiltration
What happens to the native kidneys in transplantation?
They remain in situ
How does cold ischaemic time of the kidney related to the success of the transplant?
The longer the cold ischaemia time - less successful
What are potential surgical complications of renal transplant?
Bleeding Arterial thrombosis Venous thrombosis Urine leak Hernia Infection - more common
What are the contraindications for renal transplant?
Cancer with metastases
Active infection
HIV with viral replication
Congestive heart failure
What immunosuppression drugs are given after transplantation?
Calcineurin inhibitors Anti-proliferative agents mTOR inhibitors Glucocorticosteroids monoclonal antibodies
What are the types of deceased donors?
Donation after brain death
Donation after cardiac death
What are the types of living donors?
Living related donor
Living unrelated donor
What is the criteria for brain death?
Coma - unresponsive to stimuli Absence of cephalic reflexes Apnoea of ventilator Body temperature above 34 degrees Absence of drug intoxication
What is paired donation?
When donor A want to donate to recipient B but is not an exact match
Donor B is in the same position with recipient B
Donor A is a match with recipient B and vice versa so switch
What is pooled donation?
Pooled donation is where more than two pairs of donors and recipients are involved in the swap.
Who is transplantation not usually suitable for?
Elderly
What are the types of risk involved with transplantation?
Rejection
Infection
Malignancy
Delayed graft function
How is rejection treated with?
High dose steroids and immunosuppression
What are the two types of transplantation rejection?
Antibody mediated
Cell mediated
What is cytomegalovirus?
Most important transplant related infection
Affects around 8% of transplant recipients
Despite prophylaxis treatment
high mortality and morbidity if left untreated
What is the best way to treat ESRD?
Renal transplantation
Are there enough donors for transplantation?
No demand is much higher than supply
What are Extended criteria donors?
Donors with medical complexities
Donor aged >60yrs
Or donor aged 50-59 years with history of hypertension, death from cerebrovascular accident or terminal creatinine of >132umol/L
