Renal Replacement Therapy Flashcards
What is dialysis?
diffusion across a semipermeable membrane
What is the purpose of dialysis?
removal of toxins which build up-urea, potassium and sodium; infusion of bicarbonate
What blood flow rate do you need for haemodialydid?
300mls/min
What is filtration in haemodialysis?
the removal of water due to a pressure gradient
What is the recommended time of dialysis per week?
4 hours 3xweek
What happens if patients have less than 12 hours a week?
increased 1% risk of death for every 30 minutes les dialysis
What are the dietary restrictions on patients on dialysis?
fluid- 1litre per day; low salt diet; low potassium diet; low phsophate diet
What foods contain high amounts of potassium?
bananas; chocolate; potatoes; avocado
What is the gold standard fr dialysis access?
AV fistula
Waht is an AVfistula?
joins an artery and veine to make an enlarged thick walled vein
What are the pros of AV fistulas?
good bloof flow and unlikely to cause infection
What are the cons of AV fistula?
surgery and 6 weeks maturation; can limit blood flow to distal arm
What is a tunneled venous catheter?
a catheter inserted into a large vein- jugular, subclavian or femoral
What are the pros of a tunneled venous catheter?
easy to insert and can be used immediately
What are the cons of a tunneled venous catheter?
high risk of infection; can cause vein damage making replacements difficult; become blocked
What can untreated infection lead to in tunneled venous catheters?
endocarditis or discitis
What are the investigations if a tunneled venous catheter is suspected infected?
blood cultures; FBC and CRP; exit site swab
What is the treatment for infected tunneled venous catheters?
vancomycin and line removal/exchange
What is intradialytic hypotension?
removing large volumes of water can lead to underfilling of the intravascular space if done too quickly and low BP
How does peritoneal dialysis work?
solute removal by diffusion of solutes across the peritoneal membrane; water removal by osmosis driven by high glucose conc in dialysate fluid
what are the 2 types of peritoneal dialysis?
continuous peritoneal dialysis and automated peritoneal dialysis
How does CAPD work?
4 bag exchanges per day, fluid drained then fresh fluid instilled- 1/2 hour per exchange
How does APD work?
1 bag of fluid stays in all day and overnight machine drains fluid in and out for 9-10 hours per night
What are the sources of infection with peritoneal dialysis?
contamination; gut bacteria translocation
What is the treatment for infection in peritoneal infections?
culture PD fluid; intraperitoneal abx
What are other problems associated with PD?
membrane failure and hernias
What happens if there is membrane failure with PD?
inability to remove enough water so pt becomes fluid overloaded and needs to swithc to haemodialysis
What causes hernias in PD?
increased abdo pressure due to peritoneal fluid
What group of patients doesnt have a decreased survival with PD compared to haemodialysis?
under 60s with no comorbidities
What are the metabolic complications associated with ESRD?
bone mineral metabolism; anaemia; sodium and water retention; accelerated CV disease
What are patients started on dialysis?
if symptoms- fatiuge; itch; unresponsive fluid overload; N &V; LOA; bloods- resistant hyperkalaemia; GFR<5; UR>45; unresponsive acidosis
What causes disequilibrium syndrome?
if dialyse patients too quickly, remove urea from blood but still left in brain so water moves osmotically into brain causing cerebral oedema and seizures
