it involves the diffusion of dissolved particles from one fluid compartment into another across a semipermeable membrane, the client's blood flows through one fluid compartment, + the dialysate is in another fluid compartment
Functions of hemodialysis
1. Cleanses the blood of accumulated waste products.
2. Removes the byproducts of protein metabolism such as urea, creatinine, + uric acid from the blood.
3. Removes excess body fluids
4. Maintains or restores the buffer system of the body
5. Maintains or restores electrolyte levels in the body
Principles of hemodialysis
Semipermeable membrane is made of a thin, porous cellophane
Pore size of the membrane allows small particles to pass through such as urea, creatinine, uric acid, + water molecules.
Proteins, bacteria, and some blood cells are too large to pass through the membrane.
The blood flows through a dialyzer- the movement of substances occurs from the blood to the dialysate
Diffusion is the movement of particles from an area of higher concentration to one of the lower concentration
Osmosis isthe movement of fluids across a semipermeable membrane from an area of lower cont. of particles to an area of higher cont. of particles
Ultrafiltration is the movement of fluid across a semipermeable membrane as a result of an artificially created pressure gradient.
Interventions for dialysis-
Hold HTN meds, any meds that could be removed by dialysis- water soluble vitamins, antibiotics, digoxin
VS- pt's temp may elevate- warming of blood, notify MD for excessive temp. elevations
monitor lab values b4
assess for fluid overload b4 + fluid volume decicit after
weigh client before and after dialysis to determine fluid loss
assess patency of blood access device
monitro for bleeding- heparin added to dialysis
Hypovolemia + shock- blood loss or exccess fluid + E+ removal
Interventions for dialysis cont.
Adequate nutrition- eat before or during dialysis
Identify the pt's reaction to the tx + support coping mechanism, encourage independenc + involvement in care.
Access for hemodialysis- Subclavian + femoral catheter
May be inserted for short- term for ARF
The Catheter is used until a fistula or a graft matures or develops or may be required when the client's fistula or graft access has failed bc of infection or clotting
Interventions for Subclavian/Femoral
Assess site for hematoma, bleeding, dislodgment, and infection.
Should only be used for dialysis.
Maintain dressing over the catheter.
Filled w/ heparin
capped bw tx to maintain patency
Never to be uncapped unless for tx
may be left in place for 6wks
pt should not sit up 45 degrees or lean forward, bc it could kink or occlude
assess extremity for circulation, temperature, + pulses
Perineal care required
External ateriovenous shunt
Two Silastic cannulas are surgically inserted into an artery + vein in the forearm or leg to form an external blood path
The cannulas are connected for for a U shape
Blood flows from the pt's artery through the shunt into the vein
Blood leaves the body through the artery and returns to the body through the vein
When completed, cannulas are clamped reforming to U shape
Advantages of external ateriovenous shunt
Can be used immediately following creation
No venipunture is necessary for dialysis
Disadvantages of external arteriovenous shunt
Disconnection/dislodgment of external shunt
Risk of hemorrhage, infection, or clotting
Potential for skin erosion around site.
Nursing interventions for external shunt
Avoid getting wet
keep dressing around site, C/D/I
Keep clamps at bedside for accidental discon.
No BPs, blood draws, IV lines, or injections in affected site side
Fold back the dressing to expose the shunt tubing for signs of bleeding, infection, or clotting
Look at skin of site
Listen for bruit + feel for thrill
Signs of clotting w/ shunts
1. Fibrin-white flecks noted in the tubing
2. Separation of serum + cells
3. Absence of a previously heard bruit
4. Coolness of the tubing or extremity
5. Client complains of a tingling sensation
Internal arteriovenous fistula
#1 choice for pt's with dialysis
Created surgically by anatomosis of a large artery + large vein in arm
The flow from the artery to the vein- causes the vein to enlarge
Maturity/enlargement takes about 1-2wks- all depends on if pt. can do hand flex exercises- squeeze ball. If they can, then fistula is ready
Advantages of fistula
Risk of clot + bleeding is low
can be used forever
dec. risk of infection
on external dressing
freedom of movement
Disadvantages of fistula
Cannot be used immediately
Needle insertions through the skin and tissues to the the fistula are required for tx
infiltration of the needles during tx can occur and cause hepatomas
arterial steal syndrome can develop-
CHF- can occur from the increased blood flow in the venous system
Arterial Steal syndrome
Too much blood is diverted to the vein, artery perfusion to the hand is compromised
Internal arteriovenous graft
Used primarily for chronic dialysis clients who do not have adequate blood vessels for the creation of a fistula
An artificial graft made of Gore-Tex or bovine(cow) carotid artery is use to create an artificial vein for blood flow
can be used 2 wks after insertion
Advantages of graft
Bc the graft is internal, the risk of clotting and bleeding is low
freedom of movement
Disadvantages of graft
Needle insertions through the skin + tissues for tx