What is the cardinal symptom of Chronic Renal Failure?
A syndrome known as uraemia. characterised by severe malaise and fatigue
How does dialysis work?
The solute composition of Solution A (Blood) is altered by exposing it to Solution B (dialysate) through a semipermeable membrane.
Based on two principles:
How is blood exposed to the membrane in each type of dialysis?
Extra-corporeally in haemodialysis
Mesenteric circulation in Peritoneal
What are the types of dialysis?
Haemodialysis (home, satellite or hospital)
Peritoneal (CAPD & APD)
How do you gain blood access in haemodialysis?
Native AV fistula
AV prosthetic graft
Temporary access through a tunnelled or temporary venous catheter
What are the types of peritoneal dialysis?
Continuous Ambulatory Peritoneal Dialysis:
- Patient changes their own fluid ~4x a day
Automated Peritoneal Dialysis
- Patient hooked to a machine which changes their fluid while they sleep
What is used as a SPM in Peritoneal dialysis?
The peritoneal mesothelium
Explain the difffusion principle?
Dialysate is designed with a solute composition that will equilibriate with that of the blood at the target solute conc.
E.g. it contains more bicarb so it diffuses into blood, less Na so some moves out the blood and no urea so lots of it is diffused out.
Explain the ultrafiltration principle
The method by which excess fluid is drained out the blood.
In haemodialysis pressure is applied to the SPM to drain fluid from the blood
In PD osmotic agents (mainly glc) in the dialysate cause movement of water out the blood
What indicates dialysis is appropriate?
Advanced Uraemia (<10ml/min GFR). Particularly when symptomatic
Severe acidosis (<10mmol/l Bicarb)
Fluid/Na retention uncontrolled by diuretics
How is diet affected by dialysis?
Water soluble vit supplements Phosphate restriction (+binders) Na/K restriction Calorie and protein restriction
How is fluid gain measured during dialysis?
Measure body weight after dialysis and before the next treatment, tells you how much fluid to drain off
How is fluid restricted in dialysis patients?
Haemo is strictly limited to their UO + insensible loss. (500-800ml/24 hrs depending on the patient)
PD is more liberal as continuous ultrafiltration is often achieved
What meds would you put a dialysis patient on?
- Erythropoietin stimulating Agents (ESA)
- Phosphate binders with meals
- Water soluble vit supplement
- Fe supplements
- Anti-hypertensives/Lipid control as relevant
(Haemo gets heparin during treatments)
Complications of Haemodialysis?
- Clotting of vascular access point
- Heparin problems
- Hypotension & Cramps (excess fluid drained)
Allergic reaction to dialysis
Catastrophic Dialysis Accient
Complications of Peritoneal dialysis?
PD Peritonitis Exit site or tunnel infection Ultrafiltration failure (Usually membrane damaged by infection, need to move them onto haemo) Abdominal wall hernia Tube problems Encapsulating Peritoneal Sclerosis
What organisms cause PD peritonitis?
Gram +ve if skin contaminant
Gram -ve if bowel origin
Other than dialysis how else do we manage renal failure?
Conservative Kidney Management (CKM) - Using meds to treat the symptoms of uraemia