dialysis and continuous renal replacement therapy (CRRT)

dialysis

technique in which substances move from the blood through a semipermeabile membrane in to a dialysis solution, used to correct fluid and electrolyte imbalances and to remove waste products in kidney failure, maintain fluid balance by removing excess fluid from the blood

osmosis

movement of fluid from an area of lesser concentration to an area of greater concentration

osmosis principle of dialysis

glucose is added to the dialysate and creates a pressure gradient, pulling excess fluid from the blood

diffusion

movement of solutes from an area of greater concentration to an area of lesser concentration

diffusion principle of dialysis

in kidney failure, urea, creatinine, uric acid, and electrolytes move from the blood to the dialysate with the net effect of lowering their concentration in the blood

ultrafiltration

water and fluid removal, mimics the ultrafiltration function of the kidney

ultrafiltration principle of dialysis

results from the osmotic gradient or pressure gradient across the hemofilter membrane

convection

the movement of solutes out of the blood compartment along with movement of water or ultrafiltration

convection principle of dialysis

use therapy fluid to physically pull water across a membrane, the fluid takes anything that can fit through the membranes pores as it rides with the water

adsorption

binding of substances to the surface of the filter/membrane

methods of dialysis

peritoneal dialysis, hemodialysis, continuous renal replacement therapy

peritoneal dialysis

utilizes the patient's peritoneal membrane as the permeable membrane to remove wastes and water, dialysate infused through catheter in patients abdomen and dwells for a specific period of time and is then drained out of the patient, this does not include the ability to remove precise amount of water

PD potential complications

peritonitis, hernias, atelectasis/PNA

intermittent hemodialysis (HD)

access through dialysis catheter for short term or AV fistula or graft for long term

intermittent hemodialysis (HD) indications

BUN > 90 and Cr >9, K > 6, drug toxicity, GFR < 15, metabolic acidosis

intermittent hemodialysis (HD) contraindications

hemodynamic instability, inability to coagulate, no access

special considerations of AV fistulas and grafts

assess patency of AV fistula (thrill, bruit), protect integrity of AV fistula or AV graft, infection and thrombis

CRRT

gradual over 8-24 hrs, uremic toxins and fluid are removed while acid-base status and electrolytes are adjusted slowly and continuously, requires dialysis catheter

CRRT indications

hemodynamic instability, fluid overload, oliguria, electrolyte disturbances, acidosis, sepsis, major burns, drug OD, rhabdomyolysis, contrast induced nephropathy

CRRT nursing management

monitor VS, fluid balance, electrolytes, patency of access, administer medications at appropriate times, fatigue management, teach about renal diet and fluid restrictions, gi disturbances, psychological care