Topic 15 Flashcards
Dialysis=
filtering metabolic waste products from blood
–separation of dissolved substances from a solution by allowing the solution to diffuse through a semipermeable membrane
Hemodialysis=
Removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure
Peritoneal Dialysis (PD) =
A treatment for patients with severe chronic kidney disease. The process uses the patient’s peritoneum as a membrane across which fluids and dissolved substances (electrolytes, urea, glucose, albumin and other small molecules) are exchanged
Continuous Ambulatory Peritoneal Dialysis (CAPD)=
Fluid is introduced through a tube in the abdomen and flushed out either every night while the patient sleeps or via regular exchanges throughout the day
PD is used as an alternative to what?
hemodialysis (especially in kidlets)
what is in the Dialysate Solution
Contains chemicals in concentrations similar to blood, a
mixture of purified water and measured chemicals, which flows counter current on the outside
Substances that must remain in the bloodstream, such as (4), are in the dialysate in concentrations similar to blood
glucose, sodium, calcium, and magnesium
The composition of the dialysate determines what?
which solutes pass out of and which stay in the blood during dialysis.
Dialyzer=
an artificial kidney filter designed to provide controllable transfer of solutes and water across a semi permeable membrane separating flowing blood and dialysate streams
The transfer processes for dialysis and ultrafiltration are by what means?
diffusion (dialysis) and convection (ultrafiltration).
what are three basic dialyzer designs?
coil
parallel plate
hollow fiber configurations
Convection=
transport of a constituent by bulk motion of fluid.
–one of the major modes of mass transfer.
Diffusion=
transport due to gradients in concentrations
–another major mode of transfer (Diffusive transport)
REVIEW BLOOD CHEMISTRY VALUES
now :)
Acute renal failure (ARF)=
a sudden loss of kidney function (hypovolemia).
- -Causes include low blood volume
- -Exposure to harmful substances
- -May be obstruction of the urinary tract
- -what we can cause on CPB
Chronic kidney disease (CKD)=
A long a slow process of kidneys losing their function
–is identified by significantly elevated creatinine
End-Stage renal disease (ESRD)=
when kidneys have completely shut down
Renal failure is described as what?
a decrease in glomerular filtration rate (GFR)
how is renal failure is typically detected?
by an elevated serum creatinine level
what 3 things are used to Diagnose on the basis of lab findings for Acute Renal Failure?
- elevated blood urea nitrogen (BUN)
- Elevated creatinine
- inability of the kidneys to produce sufficient amounts of urine.
name 5 Complications of ARF
metabolic acidosis, high potassium levels, uremia changes in body fluid balance effects to other organ systems.
what do Higher levels of creatinine indicate?
falling glomerular filtration rate and as a result a decreased capability of the kidneys to excrete waste products
name 6 Problems frequently encountered in kidney malfunction
- abnormal fluid levels in the body
- deranged acid levels
- abnormal levels of potassium, calcium, and phosphate
- anemia.
- hematuria (blood loss in the urine)
- proteinuria (protein loss in the urine)
Long-term kidney problems have significant repercussions on other diseases, such as?
cardiovascular disease
what is used for removed total body water on the principle of hydrostatic pressure gradients
Ultrafilters/Hemoconcentrators
what is used for utilized to treat renal failure removal of
diffusable solutes based on the principle of a concentration gradient and solute drag established by a dialysate solution
Dialysis
what is known as The influence exerted by a flow of solvent through a membrane on the simultaneous movement of a solute through the membrane
SOLVENT DRAG (CONVECTION)
describe the COIL DIALYZER
Blood compartment consisted of one or two long membrane tubes placed between support screens and
wound around a plastic core
what is the disadvantages of using the coil dialyzer
Serious performance limitations, which gradually restricted its use as better designs evolved.
–Coil design did not produce uniform dialysate flow distribution across the membrane
described the PARALLEL PLATE DIALYZE
Sheets of membrane are mounted on plastic support screens, and then stacked in multiple layers ranging from 2 to 20 or more
what is the most effective dialyzer design
HOLLOW FIBER DIALYZER
describe the HOLLOW FIBER DIALYZER
low-volume high efficiency with low resistance to flow. The fiber bundle are potted in polyurethane at each end
of the fiber bundle in the tube sheet, which serves as the membrane support
Hemodialysis machines use a ______ where the dialysate _____ through the dialyzer once and is then _____
single pass system
circulates
discarded
All systems require what 3 same basic components? KNOW
- dialysate heater to warm dialysate to body temperature (37C)
- dialysate pump and flow meter to regulate the rate of dialysate delivery
- sensors and alarms to monitor dialysate pressure, temperature, conductivity, and air or blood leaks
when you dialyze someone, what are you essentially putting on each side of the membrane?
- you put their blood (hypertonic–very full of stuff that needs removing) on one side of a membrane
- you put some hypotonic solution on the other side
(that’s the dialysate)
what is PERITONEAL DIALYSIS less effective in and more effective in?
Less efficient at removal vs. hemodialysis
Effective in very labile cardiac states
what form of dialysis is the Treatment of choice in
kidlets and Allows more patient freedom?
PERITONEAL DIALYSIS
what are the 2 ALTERNATIVE HEMODIALYTIC TECHNIQUES that are Convection based?
CAVH (continuous arteriovenous hemofiltration)
CVVH (continuous venovenous hemofiltration)
what are the 2 ALTERNATIVE HEMODIALYTIC TECHNIQUES that are Diffusive Therapy based?
CAVHD (continuous arteriovenous hemodialysis)
CVVHD (continuous venovenous hemodialysis)
describe CAVH (continuous arterio-venous hemofiltration)
- -Blood circulates with or without a blood pump through a small hollow-fiber hemofilter
- -Blood circulates through the hemofilter wherein the plasma and water is filtered and collected in the collection bag
for CAVH, where do we cannulate
Access-femoral artery and vein
for CAVH, where is heparin infused
Heparin is infused proximal to the dialyzer.
for CAVH, where is replacement volume infused
venous return line
describe CVVH (continuous veno-venous hemofiltration)
–Pump assisted and achieves higher clearance. Because of its effectiveness, it is replacing the pumpless CAVH mode
–Continuous diffusive solute transport is achieved by infusing
a dialysis fluid
for CVVH, where do you cannulate
Access-double lumen catheter in the femoral, SC, or IJ vein
for CVVH, what is the counter-current rate
15 ml/min or 1 L/hr.
describe CAVHD (continuous arteriovenous hemodialysis)
–This technique uses an infusion pump, dialyzer
membrane and dialysate solution.
–An infusion pump pushes a flow of dialysis fluid dialyzer.
The blood/dialysate interfaces on the membrane. CAVHD uses the process of diffusion dialysis to rid the body of fluid, electrolytes, and nitrogenous wastes
for CAVHD, where do you cannulate
preferred arterial access site is the common femoral artery
describe CVVHD (continuous veno-venous hemodialysis)
The process of continuous diffusion dialysis in CVVHD is less effective than the CAVHD because the lower pressure venous system does not filter as much blood per unit of time
ARTERIOVENOUS FISTULA=
Surgically created arteriovenous fistulas are
preferred over catheters for patients with chronic renal
failure for ease of access and a lower infection risk
what is One of the most common errors of dual lumen catheters
placement of the arterial and venous ports on the catheters
what are the 2 Citrate (CPD) Citrate advantages
- citrate has the effect of anticoagulating the CVVH system itself.
- Citrate interrupts the clotting cascade by soaking up
(chelating) free ionized calcium. the citrate is cooked off
(metabolized) into the form of bicarb
what is used with both CVVH and CVVHD
heparin
REVIEW THE CIRCUITS
DRAW THEM
