Dialysis (renal replacement therapy 1) Flashcards
name 6 functions of the kidney
- 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 is the definition of 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…”
what are some of the clinical features of advanced CKD
- patient may be asymptomatic until stages 4 or 5 CKD
- present with uraemia syndromes - can involve almost every organs system but earliest and cardinal symptoms are malaise and fatigue
what value is indicative of renal replacement therapy
eGFR <10 ml/min
what re the 4 types of renal replacement therapy
- renal transplant
- haemodialysis
- peritoneal dialysis
- conservative kidney management
what is dialysis
a process whereby the solute composition of a solution, A, is altered by exposing solution A to s second solution, B, through a semipermeable membrane
what are the two principles used in dialysis
- diffusion
2. ultrafiltration
define diffusion
the net movement of molecules from a region of high concentration to a region of low concentration until there is an equal concentration - driven by chemical gradient
define ultrafiltration
a variety of membrane filtration in which forces like pressure or concentration gradients lead to a separation through a semipermeable membrane
what are the 4 prerequisites for dialysis
- semipermeable membrane
- adequate blood exposure to the membrane
- dialysis access
- anticoagulation
what are the 2 types of haemodialysis access
- permanent - AV fistula, AV prosthetic graft
2. temporary - tunnelled venous catheter, temporary venous catheters
what are the main things removed from the blood during dialysis
creatinine and urea
what are the two types of restrictions for dialysis patients
Fluid restriction
- Dictated by residual urine output
- Interdialytic weight gain
Dietary restriction
- Potassium
- Sodium
- Phosphate
briefly summarise the process of haemodialysis
blood is removed for cleaning - an arterial pressure monitor keeps track of BP - a heparin pump is attached to prevent clotting - a blood pump pumps the blood through one end of the dialyser - fresh dialysate is pumped through the other end - used dialysate is removed from the dialysed - clean blood leaves the dialyser - a venous pressure monitors keeps track of BP - blood passes through air trap and air detector - clean blood flows back into the patient
briefly summarise 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 are the three kinds of peritoneal dialysis
- Continuous Ambulatory Peritoneal Dialysis (CAPD),
- Automated Peritoneal Dialysis (APD)
- Hybrid
what does the dialysate in peritoneal dialysis contain
contains a balanced concentration of electrolytes
Glucose is the most common osmotic agent for ultrafiltration of fluid
what are complications of peritoneal dialysis
Exit site infection
PD peritonitis
- Gram positive – skin contaminant
- Gram negative – bowel origin
- Mixed – suspect complicated peritonitis eg perforation
Ultrafiltration failure
Encapsulating peritoneal sclerosis
what are the indications for dialysis in end stage renal disease (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 is the fluid balance restriction in haemodialysis patients
Usually restricted to 500-800 ml/24 hours
intake allowed = urine output +insensible loss
what is the fluid balance restriction in peritoneal dialysis patients
Usually more liberal intake as continuous ultrafiltration is often achieved
what drugs are regularly used along with dialysis and what are they for
Anaemia
- Erythropoietin injections
- IV iron supplements
Renal Bone Disease
- Activated Vitamin D (eg calcitriol)
- Phosphate binders with meals (CaCo3)
Coagulation
- Heparin
Water soluble vitamins
? antihypertensives
what are complications of haemodialysis
CVS problems
- Intra-dialytic hypotension and cramps
- Arrythmias
Coagulation
- Clotting of vascular access
- Heparin related problems
Other
- Allergic reactions to dialysers and tubing
- Catastrophic dialysis accidents (rare)
what are the complications of peritoneal dialysis
Infection
- Exit site infection
- Tunnel infection
- Peritonitis
Mechanical
- Tube malfunction
- Abdominal wall herniae
Ultrafiltration problems
how is it chosen what dialysis is ultimately used
Patient choice – most important
- Education
- Shared decision making
Patient related
Perceptions of effectiveness
(Cost and remuneration)
what is conservative kidney management
supportive care
- Priority for symptomatic management
- Holistic multi-professional approach
- Anticipatory care planning
summary: what is the ultimate indication for dialysis
when eGFR less than 10 ml/m or patient symptomatic of uraemia
