Renal replacement therapy Flashcards
Outline briefly how haemodialysis works.
Blood flows on one side of a semipermeable membrane while dialysis fluid flows in the opposite direction on the other side. Solute transfer occurs by diffusion
What is mainly excreted in haemodialysis?
Urea, creatinine, potassium, other toxins
What are the constituents of the dialysis fluid?
Water, sodium, bicarbonate, potassium, glucose
How is water removed in haemodialysis?
Ultrafiltration (due to negative transmembrane pressure)
What is the minimum time spent on dialysis per week?
4 hours x 3 times per week
What dietary restrictions are placed on the patient?
Fluid intake, salt, potassium, phosphate (require phosphate binders with meals)
How is vascular access achieved in haemodialysis? What are the pros and cons of these approaches?
Arteriovenous fistula- requires surgery which takes 6 weeks to mature, good blood flow and low risk of infection.
Tunnelled venous catheter- easy to put in, can be used immediately but high risk of infection, can cause damage to veins making replacement difficult, and can block
How is infection of a tunneled venous catheter managed?
Vancomycin, line removal/replacement
What are the possible complications of haemodialysis?
Loss of vascular access; fluid overload; hypotension; cardiac arrythmias (hypokalaemia)
Briefly describe how peritoneal dialysis works.
PD fluid is introduced into the peritoneum via a Tenckhoff catheter and uraemic solutes diffuse into it across the peritoneal membrane
How is ultrafiltration achieved in PD?
Adding glucose to the fluid- acts as an osmotic agent
What are the advantages of peritoneal dialysis?
Simple, requires less complex equipment, easier at home
What are the two main methods of PD?
Continuous ambulatory peritoneal dialysis (4 bag exchanges per day) and automated peritoneal dialysis (one bag- need to be connected up to a machine at night)
What is the most common complication of PD? How is it treated?
Peritonitis either from contamination or gut bacteria. Culture PD fluid and treat to sensitivities
Other than infection, what are two possible complications of PD?
Membrane failure- causes fluid overload, requires switch to haemodialysis.
Hernias due to increased intraabdominal pressure
