RRT Flashcards
What are the three types of dialysis?
Haemodialysis (HD)
Haemodiafiltration (HDF)
Peritoneal dialysis (PD)
What does RRT stand for?
Renal Replacement Therapy
Why do we need dialysis?
To remove toxins that build up because the kidney’s cannot excrete them.
What is the blood flow rate in HD?
300-350mls/min
How does dialysis get rid of solutes?
Toxins diffuse from high conc in blood to low conc in dialysis fluid
How does dialysis get rid of water?
Negative pressure gradient between blood and dialysis fluid forces water out of plasma
What does adsorption affect?
Plasma proteins and molecules bound to them
What role does adsorption play in dialysis?
Removes small proteins from the blood by binding them to the membrane
How does HDF differ from HD?
HD just relied on conc gradient
HDF relies on pressure gradient too
When is HDF used?
AKI
What things can affect HFD rate?
Water flux (rate and volume)
Membrane pore size (big or little holes, and their respective ratios)
The pressure difference (hydrostatic pressure) applied to and across the membrane
Viscosity of the fluid within the membrane pores
The size, shape and electrical charge of each molecule
What additional thing needs done in HFD?
Fluid replacement
What restrictions are caused by dialysis?
Fluid, Na, K and P intake
What kinds of venous access are available for dialysis?
Scribner Shunt
Tunneled Venous Catheter
Fistula
Describe a Tunneled Venous Catheter
Catheter inserted into large vein such as internal jugular
What are some advantages of Tunneled Venous Catheter?
Easy access
What are some disadvantages of Tunneled Venous Catheter?
High infection risk
Can be blocked easily
Can damage veins and cause thrombosis etc
Describe a fistula for dialysis
Link artery to vein to cause Arteriovenous Fistula (AVF)
What are some advantages of a fistula?
Good blood flow
Less chance of infection
What are some disadvantages of a fistula?
Requires surgery
6-12 weeks before it can be used
Limit blood flow to distal arm
Thrombose or stenose
What are some potential side effects of dialysis?
Hypotension Haemorrhage Loss of vascular access Arrhythmia- Electrolyte imbalance Cardiac arrest
How does PD work?
Use peritoneum as membrane for diffusion and filtration. Fill with high glucose solution to draw out water.
What two forms of PD are available?
Continuous Ambulatory Peritoneal Dialysis (CAPD)
Automated Peritoneal Dialysis (APD)
How do Continuous Ambulatory Peritoneal Dialysis (CAPD) and Automated Peritoneal Dialysis (APD) differ?
CAPD- 4x2L bags per day each taking 30 mins
APD- 1 bag of fluid that’s removed over 10hr at night
What are some problems with PD?
Infection- Skin or gut
Peritoneal membrane failure- Results in fluid overload and uraemic
Hernias
When should dialysis be started?
Based on bloods or symptoms
What bloods suggest starting dialysis?
Resistant hyperkalaemia
eGFR < 7 ml/min
Urea > 40 mmol/L
Unresponsive metabolic acidosis
What symptoms suggest starting dialysis?
Nausea Anorexia Vomiting Profound fatigue Itch Unresponsive fluid overload
How long of a session do you start with HD?
60-90mins
How long is a standard HD session?
4h
What can happen if you HD to quickly?
Disequilibrium syndrome
What are some signs of Disequilibrium syndrome?
Cerebral oedema
Confusion
Seizures
Death
How long after inserting a PD catheter can you start dialysis?
3-6 weeks
Why give a patient a renal transplant?
Better survival than dialysis
Improves quality of life
Cost effective
What are the two sources of organs for transplant?
Cadaveric
Live donor
What is the main issue with organ transplant?
Immune attack by host
What is the main barrier to organ transplant?
Comorbidities
What must you be to receive a renal transplant?
Life expectancy >5y
Ability to survive surgery
What are some contraindications to transplant?
Untreated malignancy or solid tumour in last 3-5 y Active HIV or TB Severe IHD or airway disease Vasculitis Hostile bladder
What two immunological things must you try to match for a transplant to be successful?
Blood and tissue group
What are sensitising events?
Events that lead to preformed Ab in the blood against nonself
Give some examples of sensitising events
Blood transfusion
Pregnancy/miscarriage
Previous transplant
What is desensitisation?
Removal of blood group or donor specific antigens
How id desensitisation done?
Plasma exchange
B cell antibody (rituximab)
What are the types of organ rejection?
Hyperacute- Due to preformed antibodies. Unsalvageable
Acute- Due to Ab. Increase immunosuppression
Chronic- Slow decline in function.
What is an important complication of immunosuppression?
Cytomegalovirus disease
