Dialysis

Dialysis: What are the two types?

• Haemodialysis → where a machine is used for filtration

• Peritoneal dialysis→ where the patient's peritoneum is used for filtration

Dialysis: What is an ‘arteriovenous fistula’ vascular access?

Arteriovenous fistula:

• An artery and vein are joined surgically, usually the radial artery and cephalic vein

• This increases the flow rate of blood as capillaries are bypassed

• An AV fistula needs to be created at least 4-8 weeks prior to use to give it time to mature

Dialysis: What is an ‘arteriovenous graft’ vascular access?

• A synthetic or natural graft is used to join an artery and vein

• This is more likely to clot or stenose than an AV fistula

Dialysis: What is a ‘tunnelled vascular catheter’ vascular access?

• Usually inserted into the internal jugular vein

• Wider bore access than a normal central line

• Tunnelling under the skin reduces infection risk

• May be used temporarily whilst an AV fistula matures or if a fistula or graft has failed

• Can also provide semipermanent access if a fistula or graft are not suitable

Dialysis: What is a ‘non-tunnelled vascular catheter’ vascular access?

• Temporary access only so often used in emergencies

• Internal jugular catheters may stay in for 2-3 weeks

• Femoral lines need removal within a week due to a higher risk of infection

Dialysis: How does peritoneal dialysis work?

• Peritoneal dialysis involves using the patient's own peritoneal membrane for filtration

• A peritoneal catheter is placed through which dialysate fluid is introduced into the abdominal cavity

• The fluid is then left for 1-4 hours in the abdomen whilst toxins and excess fluid diffuse into the dialysate fluid

• The fluid is then drained out via the peritoneal catheter and discarded

• Each cycle of this is called an "exchange"

Dialysis: What are the two types of peritoneal dialysis?

• Continuous Ambulatory Peritoneal Dialysis (CAPD) → 3-5 exchanges per day

• Automated Peritoneal Dialysis (APD) →involves a machine performing exchanges overnight

• Some people on APD also need to do a CAPD exchange once per day

Dialysis: What are the indications for dialysis?

• eGFR of 5-7 ml/min/1.73m2

• Symptoms of uraemia (e.g. malaise, nausea, pruritus)

• Fluid overload refractory to medical treatment

• Resistant hyperkalaemia

• Resistant acidosis

Dialysis: What are the complications of haemodialysis?

• Hypotension

• Muscle cramps

• Arrhythmias

• AV fistula may bleed

• Bacteraemia due to frequent vascular access → may lead to infective endocarditis

• Heparin-induced thrombocytopenia

Dialysis: What is the main complication of peritoneal dialysis?

Bacterial peritonitis:

• Symptoms include abdominal pain and cloudy dialysis effluent with >100 white cells per ml

• Managed via vancomycin and ceftazidime

Dialysis: What is the prognosis?

• Patients receiving dialysis have a significantly increased risk of death compared to the general population

• The highest risk of death is in the first 90 days after starting dialysis