Dialysis

• Dialysis involved removing excess fluids, solutes and waste products
• Short term dialysis indications:

  • Acidosis (severe and not responding to treatment)
  • Electrolyte abnormalities - resistant hyperkalaemia
  • Intoxication - e.g. paracetamol overdose
  • Oedema - resistant pulmonary oedema
  • Uraemia - seizures and reduced GCS
• End stage renal failure (CKD stage 5) is the main indication for long-term dialysis
• Haemodialysis:

  • typically 4 hours a day, 3 days a week
  • Blood passes along a series of semipermeable membranes
  • Solutes filter out of blood into dialysate
  • Anticoagulation with citrate or heparin is needed to prevent blood clotting in the machine
  • Via tunnelled cuffed catheter or AV fistula
• A tunnelled cuffed catheter is a tube inserted into the subclavian or jugular vein, with a tip in the superior vena cava or right atrium

  Has two lumens - one for blood entering the body and one for blood leaving the body
• AV fistula:

  • Artificial connection between an artery and a vein
  • Bypasses the capillary system and allows blood flow under high pressure from the artery directly into the vein
  • Permanent, large, easy access blood vessel with high pressure arterial blood flow
  • Requires operation and maturation period of 4-16 weeks
  • Radiocephalic fistula - radial artery to cephalic vein
  • Brachiocephalic fistula - at the antecubital fossa
• AV fistula complications:

  • Aneurysm
  • Infection
  • Thrombosis
  • Stenosis
  • STEAL syndrome
  • High output heart failure
• STEAL syndrome is when there is inadequate blood flow to the limb distal to the fistula
• High output heart failure:

  • Blood flowing quickly from the arterial system to the venous system
  • Rapid return of the blood to the heart, increasing pre-load
  • Leads to hypertrophy of the heart muscles and therefore heart failure
• Peritoneal dialysis:

  • Dextrose solution is added to the peritoneal cavity
  • Ultrafiltration occurs from the blood, across the peritoneal membrane and into the dialysis solution
  • Dialysis solution is replaced, removing waste products
• Peritoneal dialysis complications:

  • Bacterial peritonitis
  • Peritoneal sclerosis
  • Ultrafiltration failure - dextrose is absorbed, reducing the filtration gradient
  • Weight gain - absorption of dextrose
  • Psychosocial implications