dialysis Flashcards
osmosis
movement of water from an area of lower to higher concentration
diffusion
movement of particles from an area of higher to lower concentration
what is dialysis?
substances move from blood through a semipermeable membrane and into a dialysis solution (dialysate)
hemodialysis
semi-permeable membrane OUTSIDE of body
hooked to an AV fistula
takes ~ 4-5 hours, 3x/week
filtration system in cylinder outside of body (GFR)
90% use
peritoneal dialysis
semi-permeable membrane is the peritoneum
pt can get up and move around
peritoneal catheter into peritoneum –> dialysate infused into peritoneum, stays in, then comes back out
4-6x per day
10% use
dialysate concentrations
if electrolyte levels are high, the dialysate will be less concentration, so the electrolytes diffuse from the pt to the dialysate
if electrolytes are low, dialysate will be more complicated so electrolytes will diffuse to the low concentration in the body
AV fistula
HD access
forearm anastomosis of own artery and vein
(artery and vein sewn together)
permanent and requires months to mature before using (if it does well first 6 months, should last up to 20 years)
expected/unexpected findings of an AV fistula
expected: bruit (swishing sounds heard when stethoscope placed over)
turbulent blood flow
thrill (feels like a cat purring)
unexpected: no bruit/sound –> next best nursing action: call HCP
decrease in peripheral perfusion (pulses, cap refill, tingling & numbness)
nursing implications of an AV fistula
assess for thrill and bruit q shift (confirms patency)
avoid BP, IV sticks in affected arm
assess peripheral perfusion distal to site (cap refill, tingling & numbness, radial and ulnar pulse, pain?)
AV fistula vs. AV graft
fistula: must wait 6 weeks to 2 months to use
*blood supply to dialyzer
*blood return to pt
*basilic vein connected to radial artery
graft: matures quicker than fistula
*looped graft made of synthetic material that connects the antecubital vein to the brachial artery
*body identifies it as a foreign object and it will likely become infected
types of temporary EXTERNAL devices
right internal jugular (IJ) –> tunneled, cuffed cath; lasts 1-3 weeks
femoral (thigh/groin area) –> lasts up to 1 week
*bed rest with minimal leg movement
*NOT ideal site
udall catheter
AKI pt needing dialysis
NOT permanent –> lasts 7-10 days
most common catheter for peritoneal dialysis and insertion is done where?
tenckhoff
peritoneal cath is put in surgically (OR)
and rests in peritoneum
cycles of PD
- inflow (fill)
- dwell
- drain
goes through these 3 cycles for a complete exchange
inflow (“fill”)
2L of dialysate is introduced in abd
takes about 10 minutes
when finished, cath can be rolled up and pt can move around
dwell
diffusion and osmosis take place
time varies
drain
used dialysate is emptied out by gravity flow –> place bag on clean towel on floor to allow it to drain
takes about 15-30 minutes
peritoneal dialysis systems
APD: automated PD
CAPD: continuous ambulatory PD
APD
uses a cycler –> automatically cycles times and controls fill, dwell, and drain phases
used primarily at night during sleep
cycles 4 or so exchanges per night at 1hr per exchange
CAPD
manual exchanges
4x/day
dwell times vary
may be able to disconnect from bag during dwell period
tenckhoff cath use and care
use after healing period of 1-2 weeks - once healed, can shower and pat dry
requires daily care:
-antiseptic solution
-clean dressing (can be removed when healed)
-examination of site for S/S of infection
major complication of PD
PERITONITIS
d/t bad aseptic technique
complications of PD
infection
decreased CO
fluid overload
respiratory insufficiency
abd pain
complications of HD
infection
decreased CO
cardiac dysrhythmias
disequilibrium syndrome –> disorientation, seizures, HA, agitation, N/V
air embolism
advantages of HD
(+) rapid removal of fluid, BUN, Cr, K+
disadvantages of HD
requires vascular access/may require heparin
dietary/fluid restriction more stringent
hypotension during dialysis
which type of dialysis mimics normal UOP?
peritoneal
advantages of PD
less complicated
home dialysis possible
increased mobility
fewer diet restrictions
less CV stress
disadvantages of PD
risk for peritonitis
requires high motivation
body image issues (d/t cath)
nursing considerations for dialysis
monitor VS
I&O/daily weights
monitor S/S complications
monitor lab values
daily catheter/fistula care
nursing considerations for PD
turn side to side to facilitate drainage prn
observe color of dialysate (more concentrated = darker, cloudy)
nursing considerations for HD
no BP, injections, IV insertions on affected limb
do NOT use IV accesses for HD
post-dialysis sub therapeutic levels
some drugs cross semipermeable membrane and are lost during dialysis
what happens to drug levels during dialysis
build up - toxic levels possible
d/t inability to excrete from body, so they circulate in their active form for prolonged periods since not excreted
