Renal replacement therapy - dialysis Flashcards
What are the symptoms of uraemia?
Malaise and fatigue Nausea Vomiting Fatigue Anorexia Weight loss Muscle cramps Pruritus Mental status changes
What are the clinical signs of uraemia?
Muscle atrophy Loss of appetite Tremors Abnormal mental function Frequent shallow respiration Metabolic acidosis
What are the functions of the kidneys?
- Excretion of nitrogenous waste products (urea)
- Maintenance of acid and electrolyte balance
- Control of blood pressure
- Drug metabolism and disposal
- Activation of vitamin D
- Production of erythropoietin
What is uraemia?
Uremia is the condition of having “urea in the blood”. Urea is one of the primary components of urine. It can be defined as an excess of amino acid and protein metabolism end products, such as urea and creatinine, in the blood that would be normally excreted in the urine. The Uremic Syndrome can be defined as the terminal clinical manifestation of kidney failure (also called renal failure)
Define end stage renal disease
“…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…”
When is renal replacement therapy indicated?
Usually indicated when eGFR <10 ml/min.
What types of RRT are available?
Renal transplant
Haemodialysis
• Home haemodialysis
• Satellite / hospital haemodialysis
Peritoneal dialysis
• Continuous ambulatory peritoneal dialysis (CAPD)
• Intermittent peritoneal dialysis (IPD)
Conservative Kidney Management
What is dialysis?
Dialysis is a process whereby the solute composition of a solution, A, is altered by exposing solution A to a second solution, B, through a semipermeable membrane
List the 2 basic principles of dialysis
Diffusion
Ultrafiltration
What prerequisites are required for dialysis?
- Semipermeable membrane (artificial 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 haemodialysis
How can we acquire access to the bloodstream for haemodialysis (both permanent and temporary options)?
Permanent
– Arteriovenous fistula
– AV prosthetic graft
Temporary
– Tunnelled venous catheter
– Temporary venous catheter
List the restrictions required while on dialysis
Fluid restriction
– Dictated by residual urine output
– Interdialytic weight gain
Dietary restriction
– Potassium
– Sodium
– Phosphate
How often is haemodialysis carried out?
3-5 times a week
Describe 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. Check drained fluid for signs of infection e.g. cloudiness, then pour away
Describe haemodialysis
- In haemodialysis, the patient’s blood is pumped through the blood compartment of a dialyzer, exposing it to a partially permeable membrane. The dialyzer is composed of thousands of tiny hollow synthetic fibers. The fiber wall acts as the semipermeable membrane.
- Blood flows through the fibers, dialysis solution flows around the outside of the fibers, and water and wastes move between these two solutions. The cleansed blood is then returned via the circuit back to the body.
- Ultrafiltration occurs by increasing the hydrostatic pressure across the dialyzer membrane. This usually is done by applying a negative pressure to the dialysate compartment of the dialyzer.
- This pressure gradient causes water and dissolved solutes to move from blood to dialysate and allows the removal of several litres of excess fluid during a typical 4-hour treatment.
How often is peritoneal dialysis carried out?
Continuous Ambulatory Peritoneal Dialysis (CAPD) - carried out by patient at home, 4 cycles a day usually
Automated Peritoneal Dialysis (APD) - carried out as you sleep, runs around 8 cycles every night
What types of peritoneal dialysis are available?
- Continuous Ambulatory Peritoneal Dialysis (CAPD)
* Automated Peritoneal Dialysis (APD)
How long is a typical haemodialysis session?
4hrs
What is the most important osmotic agent for ultrafiltration in peritoneal dialysis?
Glucose
What complications are associated with peritoneal dialysis?
Exit site infection/tunnel infection
Tube malfunction
Abdominal wall hernia
PD peritonitis
– Gram positive – skin contaminant
– Gram negative – bowel origin
– Mixed – suspect complicated peritonitis eg perforation
Ultrafiltration failure - failure of peritoneal fluid removal to match the volume balance needs of the patient being treated by peritoneal dialysis.
Encapsulating peritoneal sclerosis – fibrosis of peritoneum which encapsulates and obstructs the bowel
Where would you suspect a gram negative infection came from in PD peritonitis?
Bowel origin
Where would you suspect a gram negative infection came from in PD peritonitis?
Skin contaminant
What are the indications for dialysis for ESRD patients?
- 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
How much fluid is allowed to be taken in daily by dialysis patients?
Haemodialysis - Usually restricted to 500-800 ml/24 hours
Peritoneal dialysis - Usually more liberal intake as continuous ultrafiltration is often achieved
What drugs are required to be given alongside dialysis and why?
Anaemia
– Erythropoietin injections
– IV iron supplements
Renal Bone Disease
– Activated Vitamin D (eg calcitriol)
– Phosphate binders with meals (CaCo3)
Heparin
Water soluble vitamins
? antihypertensives
List some complications of haemodialysis
Cardiovascular 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 influences choice of dialysis modality?
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 – Randomised control trial ongoing for dialysis versus CKM for older adults with co-morbidity
When is dialysis ultimately indicated?
Indicated when eGFR less than 10 ml/m or patient symptomatic of uraemia.
What are the major disadvantages of dialysis?
Patients on dialysis have increased morbidity and mortality and are faced with dietary and fluid restrictions
Infections can happen and are often very serious complications
