Dialysis

Dialysis is a procedure to remove waste products and excess fluid from the blood when the kidneys stop working properly. It often involves diverting blood to a machine to be cleaned.Normally, the kidneys filter the blood, removing harmful waste products and excess fluid and turning these into urine to be passed out of the body.Optimal timing to start dialysis is widely debated guidelines suggest starting when GFR < 15mL / min with symptoms. When eGFR < 5, dialysis indicated in all patients whether symptomatic or asymptomatic.

Indications of Dialysis

• Refractory pulmonary edema
• Persistent hyperkalemia ( K > 7mmol / L )
• Severe metabolic acidosis
• Uraemic encephalopathy
• Uraemic pericarditis.
• Drug overdose like lithium barbiturates, ethylene glycol etc.

Preparation for dialysis

Investigate the patient for HBV, HCV. Medical preparation involves Hep vaccination and creating an arteriovenous fistula or AV graft for haemodialysis , or inserting a Tenchkoff catheter for peritoneal dialysis Choice of haemo vs peritoneal dialysis depends on medical , social personal and psychological factors.

Haemodialysis (HD)

Blood flows on one side of a semi - permeable membrane while dialysis fluid flows in the opposite direction on the other side. Solute transfer occurs by diffusion. Ultrafiltration is the removal of excess fluid by creating -ive transmembrane pressure. In HD double lumen catheter is passed first for temporary dialysis until AV fistula is created and properly matured

Stuff Required for passing Double lumen

• Two pairs of surgical gloves
• Three small sized surgical gauzes
• Normal saline
• Pyodine solution
• Inj - Heparin
• Two 10cc and two 5cc disposable syringes
• Two Inj - lignocaine 2 %
• Small sized Mepore dressing S
• mall sized surgical blades

Haemofiltration

Blood is filtered continuously across a highly permeable synthetic membrane, allowing removal of waste products by a process of convection (not diffusion). The ultrafiltrate is substituted with an equal volume of replacement fluid. It is more expensive and takes longer than HD, but there is less haemodynamic instability and so is used for critically patients.

Peritoneal dialysis (PD)

PD is simple to perform, requires less complex equipment than haemodialysis and is easier at home. It is useful in dialysis fluid introduced into the peritoneal cavity via a Tenchkoff catheter and elderly, those with cardiovascular Ultrafiltration is achieved by adding osmotic agents, e.g., glucose to dialysis fluid.

Peritoneal dialysis (CAPD)

CAPD uses the smallest daily volume of dialysate fluid to prevent uraemia, 2L bags are changed 3-5 times a day to produce, with ultrafiltration, a total dialysate of 10L.

Automated peritoneal dialysis

It uses a cycler machine to enhance solute CCPD), intermittent peritoneal dialysis (IPD), night intermittent and fluid removal. Techniques include continuous cyclic peritoneal dialysis peritoneal dialysis (NIPD), and tidal intermittent peritoneal dialysis (TIPD).

Complications of dialysis

• Cardiovascular disease, e.g. IHD, cardiac failure and stroke are much more common in dialysis patients and are a major cause of mortality
• Hypertension persists in 25-30 % of patients on haemodialysis .
• Hypoglycemia and hypotension.
• Anaemia is common and is treated with erythropoietin.
• Bleeding tendency is due to platelet dysfunction. Acute bleeding is treated with desmopressin and transfusion, as necessary
• Renal bone disease, which is treated with dietary modification, alfacalcidol, Ca2 + supplements, and phosphate binders
• Infection may be due to non - sterility in peritoneal dialysis or intravascular lines in haemodialysis.
• Microglobulin amyloidosis is due to amyloid which accumulates in long - term dialysis patients: it may cause carpal tunnel syndrome, arthralgia, and fractures.
• Acquired renal cysts occur years after dialysis and may present with haematuria or malignant transformation.
• Malignancy is commoner in dialysis patients; this may be related to the cause, e.g, Urothelial tumors in analgesic nephropathy.

Stopping dialysis

Dialysis exerts a big toll on quality of life, and it may all become too much for patients, e.g., if very old or there is co - morbidity (e.g., psychiatric or mobility issues). 8-20 % of deaths in dialysis patients are due its withdrawal