hemodialysis- mechanism and management.pptx

Haemodialysis

1. HEMODIALYSIS

2. Hemodialysis: Hemodialysis is one of three renal replacement therapies (the other two being kidney transplant and peritoneal dialysis). It is a medical procedure to remove fluid and waste products from blood and to correct electrolyte imbalance. Hemodialysis is done using a hemodialysis machine and dialyzer aslo called as ‘Artificial kidney’ It can be an outpatient or inpatient therapy.

3. Hemodialysis is an extracorporeal process (dialysis membrane is outside of the body). Indication For dialysis: Acidosis (pH <7.1) Electrolyte imbalance (k+ >6.5 mEq/L) GFR<10ml/min Overload of Fluids (pulmonary Oedema) Uremic Symptoms (increased level of nitrogenous waste products)

4. Principle of Haemodialysis Diffusion: Passive movement of solute across a semipermeable membrane. Ultra filtration: solute + Fluid removal across semipermeable membrane down a pressure gradient.

5. Fig: Hemodialysis following diffusion and ultrafiltration

6. Hemodialysis Apparatus Dialyzer Dialysate Blood delivery system

7. Fig: hemodialysis machine

8. 1. Dialyzer (Artificial kidney): Plastic chamber that contains bundles of capillary tube through which blood circulates while dialysis solution travels outside the bundle in opposite counter current direction. Diffusion and Ultrafiltration happens here. Membranes using in dialyser: Cellulose Substituted cellulose: Cellulose acetate Cellulosynthetic: Cellosyn/Hemophan S y nth e tics: Pol y a c rylo n it r il e , p o ly s ulfon e , polymethyl methacrylate

9. 2. Dialysate: Solution used in dialysis which has same solute concentration as those in plasma. Water used in the dialysate is purified by reverse osmosis. Contents of dialysate: Na+ :136-140mmol/L K+ :0-4 mmol/L Mg++ : 0.25-0.75 mmol/L Ca+ : 2.5-3.5mEq/L Chloride: 100-124 mEq/L Bicarbonate: 27-40mmol/L pH: 7.1-7.3 Dextrose: 0-5.5 mmol/L

10. 3. Blood delivery system: Blood pump: Moves blood from access site through the dialyzer and back to the patient. Blood flow rate: 250-500ml/min Heparin syringe pump 2 air traps Air detector Venous line clamp

11. 3. Blood delivery system:

12. Access for Hemodialysis Arterio venous fistula (AVF)-made by joining an artery and vein in arm (first preferred choice for a permanent vascular access). Arterio venous graft (AVG)-made by using a soft tube to join an artery and vein in arm ( second preferred choice for a permanent vascular access). Cuffed tunneled dialysis catheter- a soft tube that is placed in a large vein, usually in neck (temporary access). Temporary access sites Internal jugular vein Femoral vein Subclavian vein

13. Arterio venous fistula: Subcutaneous anastomosis (surgical connection i.e. created between two stuctures) of an artery to an adjacent native vein. Takes 6 weeks for development (arterialization of vein) Both the dialysis needles are inserted into the native vein. Types: Radiocephalic (first choice) Brachiocephalic (second choice) Brachiobasilic (third choice)

14. Procedure Blood flow rate: 300-500 ml/min Dialysate : 500-800 ml/min Usually done 3 times a week and each dialysis lasts for 4 hours.

15. Complications of Hemodialysis Hypotension (22-55%) Muscle cramps (5-20%) Nausea and vomiting (5-15%): due to hypotension Headache (5%)- common Chest pain (2-5%) Back pain (2-5%) Itching (5%)- precipitated by dialysis may be due to hypersensitivity to dialyser membrane Fever & chills (<1%)

16. Management of hypotension: 🞄 Midodrine (10-20mg 30 min. before dialysis), 🞄 S e r t a l i n e (50 - 10 mg da i ly) and IV L- carnitine (20mg/kg at dialysis).

17. Management of muscle cramps: 🞄 Reduced ultrafiltration and infusion of hypertonic saline or glucose to improve circulation, exercise/stretching of affectef limb, or vitamin E 400IU at bedtime with vitamin C 250mg daily for prevention.

18. Less common but serious complication Disequilibrium Syndrome: Set of systemic and neurologic symptoms with characteristics electroencephalographic findings occur either during/following dialysis Early manifestation: nausea, vomiting, restlessness and headache Serious manifestation: seizure, obtundation, coma Cause: Acute increase in brain water content. Treatment: -aimed at prevention by initiating dialysis gradually. - direct treatment involves IV hypertonic saline or mannitol.

19. Aluminum toxicity (dementia, bone disease, anemia): deferoxamine can be used to chelate serum aluminum.

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