Dialysis Nursing Care Plan & Management
Description
- Dialysis is primarily used to provide an artificial replacement for lost kidney function (renal replacement therapy) due to renal failure
- Dialysis works on the principles of diffusion of solute through a semipermeable membrane that separates two solutions.
- Direction of diffusion depends on concentration of solute in each solution.
- Rate and efficiency depend on concentration gradient, temperature of solution, pore size of membrane, and molecular size.
Two Mechanisms in Dialysis
- Diffusion – movement of particles from an area of high concentration to one of low concentration across a semipermeable membrane.
- Osmosis – movement of water through a semipermeable membrane from an area of lesser concentration of particles to one of greater concentration.
Indications
The decision to initiate dialysis or hemofiltration in patients with renal failure depends on several factors. These can be divided into acute or chronic indications.
- Indications for dialysis in the patient with acute kidney injury are:
- Metabolic acidosis in situations where correction with sodium bicarbonate is impractical or may result in fluid overload.
- Electrolyte abnormality, such as severe hyperkalemia, especially when combined with AKI.
- Intoxication, that is, acute poisoning with a dialysable drug, such as lithium, or aspirin.
- Fluid overload not expected to respond to treatment with diuretics.
- Complications of uremia, such as pericarditis or encephalopathy.
- Chronic indications for dialysis:
- Symptomatic renal failure
- Low glomerular filtration rate (GFR) (RRT often recommended to commence at a GFR of less than 10-15 mls/min/1.73m2). In diabetics dialysis is started earlier.
- Difficulty in medically controlling fluid overload, serum potassium, and/or serum phosphorus when the GFR is very low
Goals
- Reduce level of nitrogenous waste.
- Correct acidosis, reverse electrolyte imbalances, remove excess fluid.
Two main types of dialysis
I. Hemodialysis
- Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane
- In hemodialysis, the patient’s blood is pumped through the blood compartment of a dialyzer, exposing it to a partially permeable membrane.
- The dialyzer is composed of thousands of tiny synthetic hollow fibers.
- The fiber wall acts as the semipermeable membrane. Blood flows through the fibers, dialysis solution flows around the outside the fibers, and water and wastes move between these two solutions.
- The cleansed blood is then returned via the circuit back to the body.
- Ultrafiltration occurs by increasing the hydrostatic pressure across the dialyzer membrane.
- This usually is done by applying a negative pressure to the dialysate compartment of the dialyzer.
- This pressure gradient causes water and dissolved solutes to move from blood to dialysate, and allows the removal of several litres of excess fluid during a typical 3 to 5 hour treatment.
- Studies have demonstrated the clinical benefits of dialyzing 5 to 7 times a week, for 6 to 8 hours.
- These frequent long treatments are often done at home, while sleeping but home dialysis is a flexible modality and schedules can be changed day to day, week to week.
- External shunt
- Cannula is placed in a large vein and a large artery that approximate each other.
- External shunts, which provide easy and painless access to bloodstream, are prone to infection and clotting and causes erosion of the skin a round the insertion area.
- Arteriovenous fistulas or graft
- Large artery and vein are sewn together (anastomosed) below the surface of the skin (fistula) or subcutaneous graft using the salphenous vein, synthetic prosthesis, or bovine xenograft to connect artery and vein.
- Purpose is to create one blood vessel for withdrawing and returning blood.
- Advantage is greater activity range than AV shunt and no protective asepsis.
- Disadvantage is necessity of two venipunctures with each dialysis.
- Vein catheterization
- Femoral or subclavian vein access is immediate
- May be short or long term duration.