LESSON 4

AV (artery-vein) FISTULA

• is a connection that’s made between an artery and a vein for dialysis access, and it is connected to a dialysis machine. Minor surgery is needed to create the fistula. This creates a large blood vessel that has a fast flow of blood. Your wrist or elbow is the preferred location for your fistula.

AV (artery-vein) GRAFT

• Minor surgery is done using an artificial tube between a vein and a nearby artery.

• AV graft is a synthetic tube used to surgically connect the artery and vein. This tube functions as a vein, carrying blood through the access.

• An AV graft is usually put inside the bend of your arm or in your upper arm.

IJ CATHETER

• A catheter is most often used for a temporary access

• Catheters are made of soft plastic tubing. The catheter used for hemodialysis is a tunnelled catheter because it is placed under the skin sometimes used for a short time in people who get an AV fistula and need to start dialysis before the fistula is ready. Once the fistula is “mature,” the catheter will be removed.

• Sometimes a catheter is used over a long period of time because a fistula or graft is not possible.

Dialyzer

• A dialyzer is often referred to as an “artificial kidney.” Its function is to remove the excess wastes and fluid from the blood, when the patient’s kidneys can no longer perform that task.

• Dialyzers are made of a thin, fibrous material the fibers form a semipermeable membrane, which allows smaller particles and liquids to pass through.

• Dialyzers are never shared between patients. After your dialysis session is complete, a facility member will take you off the dialysis machine and seal your dialyzer, which is labeled with your name, in a plastic bag.

FEATURES OF HD MACHINE

• Blood pump to achieve a unidirectional flow of up to 500 ml/min

• Heparin pump

• Arterial line and venous line pressure monitors

• Functional air bubble detector

• Mixing proportion unit with bicarbonate dialysis facility, with the rate of dialysate d from 300 to 500 ml/min or more

• Conductivity meter

• Functional blood leak detector

• Dialysate temperature regulator that has a range of temperature from 35°C to 39° C UF control

• Safety devices: Functioning alarms and venous blood clamp

PRINCIPLES OF HEMODIALYSIS

DIFFUSION DIALYSIS

-Is an ion-exchange membrane separation process driven by concentration gradient and has been applied for separation and recovery of acid/alkali waste solutions in a cost effective and environmentally friendly manner.

OSMOSIS DIALYSIS

-During osmosis, the fluid moves from areas of high water concentration across a semi-permeable membrane until equilibrium is reached. In dialysis, excess fluid moves from blood to the dialysate through a membrane until the fluid level is the same between blood and dialysate.

ULTRAFILTRATION DIALYSIS

-Is the removal of fluid from a patient and is one of the functions of the kidneys that dialysis treatment replaces. Ultrafiltration occurs when fluid passes across a semi-permeable membrane due to a driving pressure.

CONVECTION DIALYSIS

-Is a bulk-flow of solute across a semi-permeable membrane together with 

 solvent in a manner that is dependent on transmembrane pressure and membrane characteristics.