Dialysis

• Dialysis is a method for performing the filtration tasks of the kidneys artificially.
• Dialysis is used in patients with end-stage renal failure or complications of acute kidney injury.
• Dialysis involves removing excess fluid, solutes and waste products.
• The “ AEIOU ” mnemonic can be used for the indications for short-term dialysis: A – Acidosis (severe and not responding to treatment) E – Electrolyte abnormalities (particularly treatment-resistant hyperkalaemia) I – Intoxication (overdose of certain medications) O – Oedema (severe and unresponsive pulmonary oedema) U – Uraemia symptoms such as seizures or reduced consciousness.
• End-stage renal failure (CKD stage 5) is the main indication for long-term dialysis.
• There are two options for dialysis in patients requiring it long-term: Haemodialysis and Peritoneal dialysis.
• The cuff promotes healing and adhesion of tissue, making the catheter more permanent and providing a barrier to infection.
• High-output heart failure is caused by blood flowing quickly from the arterial to the venous system through an A-V fistula.
• Blood is taken out of the body, passed through the dialysis machine, and pumped back into the body.
• A machine continuously replaces the dialysis fluid for 8-10 hours overnight.
• A Dacron cuff surrounds the catheter.
• A special dialysis solution containing dextrose is added to the peritoneal cavity.
• With haemodialysis, patients have their blood filtered by a haemodialysis machine.
• Brachiocephalic fistula at the antecubital fossa (brachial artery to cephalic vein) is a type of AV fistula.
• The main complications are infection and blood clots within the catheter.
• Ultrafiltration occurs from the blood, across the peritoneal membrane, into the dialysis solution.
• 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.
• This plastic tube is inserted into the peritoneal cavity, with one end on the outside, allowing access to the peritoneal cavity to insert and remove the dialysis solution.
• Two tubes are needed, one to remove the blood and one to put the blood back in.
• The dialysis solution is replaced, taking away the waste products that have filtered out of the blood.
• They can stay long-term and be used for regular haemodialysis.
• This leads to hypertrophy of the heart muscle and heart failure.
• It bypasses the capillary system and allows blood to flow under high pressure from the artery directly into the vein.
• Instead, it flows through the fistula and into the venous system.
• The decision about which form to use is based on individual factors, such as preference, lifestyle and co-morbidities.
• An AV fistula is an artificial connection between an artery and a vein.
• The AV fistula “steals” blood from the rest of the limb.
• Haemodialysis requires good access to an abundant blood supply.
• STEAL syndrome occurs when there is inadequate blood flow to the limb distal to the fistula.
• Solutes filter out of the blood, across the membrane and into a fluid called dialysate.
• There are various regimes for changing the solution, for example, two litres of solution replaced four times daily.
• The options for longer-term access are: Tunnelled cuffed catheter and Arteriovenous fistula.
• AV fistula features to examine in an OSCE are: Skin integrity, Aneurysms, Palpable thrill, A “machinery murmur” on auscultation over the fistula, and Complications of AV fistula include: Aneurysm, Infection, Thrombosis, Stenosis, STEAL syndrome, High-output heart failure.
• Creating an A-V fistula requires a surgical operation and a maturation period of 4-16 weeks before it can be used.
• Peritoneal dialysis uses the peritoneal membrane to filter the blood.
• Anticoagulation with citrate or heparin is necessary to prevent blood clotting in the machine and during the process.
• It has two lumens, one for blood exiting the body (usually red) and one for blood entering the body (usually blue).
• Radiocephalic fistula at the wrist (radial artery to cephalic vein) is a type of AV fistula.
• The blood passes along a series of semipermeable membranes inside the dialysis machine.
• Blood is diverted away from the part of the limb it was supposed to supply, leading to ischaemia.