Dialysis

End stage renal disease (ESRD) is a condition when kidneys have lost all or most of their ability to function with GFR < 5ml/minute. The treatment of ESRD includes dialysis – haemodialysis (HD) and peritoneal dialysis (PD) – and Kidney Transplantation.

The process of dialysis involves cleansing the blood of metabolic wastes, based on the principle of osmosis and diffusion. A semi-permeable porous membrane is used in dialysis to separate the patient blood carrying excess fluid and metabolic wastes and the hypotonic “dialysis fluid” called dialysate. Through osmosis and diffusion, the metabolic waste and excess water move into the dialysate. The pores of the semi-permeable membrane do not permit large particles like protein and RBC to pass through, but smaller water-soluble molecules can pass.

In Haemodialysis (HD), patient’s blood circulates outside the body through what is commonly referred to as an “artificial kidney machine”. An opening is created to connect an artery and a vein. Blood leaves the body via the artery, into the dialyser and after cleansing, flow back to the body via the vein as shown in the picture below.

In Peritoneal Dialysis (PD), the patient’s peritoneum is used as the semi permeable membrane and excess water and metabolic wastes are removed by injecting the dialysis fluid into the peritoneal cavity as shown in the picture below. After some time, the fluid with the metabolic waste is drained out from the peritoneum. Peritoneal dialysis is less effective than haemodialysis and can result in loss of intact large molecular proteins also.

For long-term use, continuous ambulatory peritoneal dialysis (CAPD) maybe used based on facilities available. In this, the dialysis fluid is exchanged 4-5 times daily.

The objectives of dietary management in ESRD with dialysis are to maintain balance of protein, energy, fluid and electrolytes, calcium and phosphorus, while making up losses of water-soluble nutrients lost in the dialysate.

The Nutrient requirement for adults with End stage renal disease based on type of therapy is as follows:

Therapy	Energy (Kcal/kg BW)	Protein (g/kg IBW)	Fluid (ml/day)	Sodium (g/day)	Potassium (g/day)	Phosphorus (g/day)
Haemodialysis	35	1	500 + urine	Variable	2- 3	1 – 1.2
Intermittent Peritoneal Dialysis (IPD)	30 (40-50 for repletion)	1.2	500 + urine output	2 – 3	2 – 3	1 – 1.2
Continuous Ambulatory Peritoneal Dialysis (CAPD)	25 (40-50 for repletion)	1.2	Minimum or 2000 ml/day + urine output	6 – 8	3 – 4	1.5 - 2

Also read on other Diseases of the Kidney in the Diet Corner column.

Post by Faiz Lahori