Dialysis Flashcards
Dialysis
Solutes and water move across the membrane form the blood into dialysate or from dialysate into the blood based on the concentration gradient.
Glucose is added to dialysate to create an osmotic gradient across the membrane to remove excess fluid from blood
Dialysis in AKI
Urea, creatinine, uric acid and electrolytes form from the blood to the dialysate –> decreased concentration of the blood
Start dialysis if
- GFR <15 ml/min/1.73m2
- Lack of donated organs
- Unable to get a transplant
- Don’t want a transplant
Dialysis works across a semipermeable membrane via…
- Diffusion: moves urea, creatinine, uric acid and electrolytes
- Osmosis: add glucose pulls fluid from the blood
Peritoneal dialysis membrane
the peritoneal membrane is the semipermeable membrane
Hemodialysis membrane
there is an artificial membrane
Ultrafiltration
water and fluid removed by adding glucose in PD and increasing the pressure in HD
Peritoneal dialysis
Surgically insert a catheter through the anterior abdominal wall - takes a few weeks for fibrous tissue to grow to hold catheter in place
Tip of the catheter rests in the peritoneal cavity and there are many perforations for fluid to flow in and out of the catheter
PD three phases
- Inflow (2L infused over 10 minutes)
- Dwell (let sit for 4-6 hours for osmosis to occur)
- Drain (15-30 minutes)
An exchange
all three phase are called an exchange, typically patients have several exchanges during the night
Automated PD
uses a cycler that times and controls the fill, dwell and drain times. Allows patient to do dialysis while sleeping. Sometimes can disconnect in the day but might need to do 1-2 cycles
- Continuous Cycle PD
- Intermittent PD
- Nightly PD (4 or more times/night)
Continuous ambulatory
PD
manually exchanging 2L of peritoneal dialysis usually 4X/day with dwell times of 4hrs. Done every few hours throughout the day
PD complications (7)
- Infection at catheter site
- Peritonitis
- Hernias: due to the pressure from the dialysate
- Lower back problems: due to increased intraabdominal pressure
- Bleeding: at the catheter site especially after the first few exchanges
- Pulmonary complications: atelectasis, PNA, and bronchitis due to the upward placement of the diaphragm
- Protein loss: can be worse if someone gets peritonitis
Peritonitis
- Due to improper technique
- Abdominal pain, rebound tenderness, cloudy peritoneal effluent, maybe a fever
- Formation of adhesions can occur after repeated infections
Contraindications for PD (5)
- History of multiple abdominal surgeries or abdominal pathologies
- Recurrent abdominal wall or inguinal hernias
- Excessive obesity
- Preexisting vertebral disease
- Severe obstructive pulmonary disease
Hemodialysis
- Pump driven system
- outpatient therapy or bedside
- Requires AV fistula for large bore IV access
- Emergent can use jugular or femoral vein at the bedside
Hemodialysis components
- Dialyzer
- Dialysis solution (dialysate)
- Tubing for transport of blood and dialysis solution
- machine: power and mechanically monitor hemodialysis
Problem with temporary catheter
high rate of infection and patient can’t be discharged with a temporary catheter
HD: IV catheter device
- Acute, temporary access
- Red = “arterial”
- Blue = “venous”
- DO NOT use for other lab draws unless OK by protocol
- DO NOT use for IV access
ONLY USED FOR DIALYSIS
HD: Arteriovenous Grafts (AVG)
- Synthetic graft implanted under the skin
- Connect both artery and vein
- Faster healing, 2-4 four weeks to heal/access
- Can be used right away
- More likely to become infected and form clots
- Can palpate a thrill and auscultate a bruit
- Use large needles to access for HD
What patients do you use a AVG in?
patient with a history of severe PAD, prolonged IV drug abuse, obese women
HeRO
Last resort for patient who can used upper AV fistula and AV graft sites
HD Arteriovenous Fistula
- common access
- Forearm by a side-to-side end-to-side or end-to-end anastomosis between an artery and a vein
- fistula provides arterial blood flow, rapid blood flow through the vein (which dilates the vein)
- feel thrills and hear bruit
Overtime fistulas..
become tough and may be used for repeated venipuncture for repeated access
Naive fistulas..
have best overall patency rates, least complications, can only be used if pt has good vascular health
common issue with HD Arteriovenous Fistula
Central venous stenosis or occlusion
Nursing consideration for AV Fistulas and Grafts
- Assessment: Palpate for a thrill at site of anastamosis, listen for bruit (both created by arterial blood rushing through vein)
- Never perform BP or venipuncture on affected extremity
- sing above HOB no right arm use for BP or venipuncture, can also wear a arm restriction bracelet
Prior to hemodialysis
- Large bore required
- Pre-dialysis RN care
- In-center HD
- Home HD
Why is heparin add when the blood comes in contact with the dialyzer?
The blood tends to clot when it comes in contact with the dialyzer
Prior need an order for heparin and as the nurse, may have to grab heparin from med room for the dialysis team
Nursing care pre dialysis
Weight, BP, temp, peripheral edema, auscultate lung sounds and heart sounds, assess fluid status, how fast/long HD will run and the
Difference between post dialysis and predialysis weight - detainees amount of weight removed
Vital signs during dialysis
taken every 30-60 minutes by the dialysis nurse
HD frequency
3 times per week for 3-4 hours
Home HD
daily or nocturnal with less complications
Increase patient autonomy
Requires a good support system
less medication, less side effects
Dialyzer
is a long plastic cartridge that contains many parallel hollow tubes or filters that are semipermeable membranes.
How does dialyzer work?
- Blood is pumped into the top of the cartridge and is dispersed to all of the fibers.
- Dialysate is pumped into the cartridge and bathes the outside of the filters w/ dialysis fluid.
- Ultrafiltration, diffusion and osmosis occur across the pores of the semipermeable membrane.
- When the dialyzed blood reaches the end of the thousands of semipermeable filters, it converges into a single tubing that returns to the patient
Dialysis procedure preformed by dialysis nurse
- Primed w/ NS, displaced by blood as it is drawn from the fistula (heparin added to blood as flows to dialyzer)
- Ultrafiltration controller equalizes positive and negative pressures to regulate amount of fluid removed
- Blood is returned to pt via venous line
- Dialysis is terminated by flushing dialyzer w/ NS
- Firm pressure to graft site after removal of needles
HD complications (9)
- Hypotension
- Muscle cramps
- Blood loss
- Hepatitis
- Sepsis
- Clot at graft site
- Aneurysm
- infections
- Disequilibrium syndrome
HD complication: hypotension
D/t: Rapid removal of vascular volume, ↓ CO, and ↓SVR:
S/S: light headedness, N/V
seizures, vision changes
coronary ischemia
TX: decrease fluid volume being removed, infusion of NS, hold BP meds prior HD if pt has hx of ↓BP
HD complication: muscle cramps
D/t: from rapid removal of Na and H20 or from neuromuscular sensitivity,
TX:↓ ultrafiltration rate, NS bolus, glucose, mannitol
HD complication: blood loss
inadequate rinsing of dialyzer, separation of blood tubing or dialysis membrane rupture or bleeding out of fistula after dialysis –> increased risk because of heparin
HD complication: hepatitis
D/t: from blood transfusions
Hep C more common (10% in dialysis patients)
Hep B less common now because of HepB vaccine
HD complication: sepsis
D/t: infection of vascular access sites during dialysis
TX: aseptic technique is essential
Dialysis Disequilibrium syndrome (DDS)
- usually during first treatment or if patient has missed consecutive treatments
- Range of neurological symptoms that patients on HD experience that is caused by cerebral edema
- Rapid changes in extracellular fluid (urea, Na and other solutes from blood then from the CSF and the brain)
- differential creates increase in osmotic gradient in brain –> increased fluid shifts in the brain –> cerebral edema
Disequilibrium Syndrome mild manifestations (12)
N/V, confusion, restlessness, HA, twitching and jerking, seizures, muscle cramps and hypotension, blurred vision, somnolence, disorientation, mania
Disequilibrium Syndrome severe manifestations
seizures, stupor, coma, and death
Disequilibrium Syndrome treatment
- slowing or stopping dialysis
2. Infuse hypertonic saline solution albumin or mannitol to draw fluid from the brain cells back into circulation
Peritoneal Dialysis short
fluid is removed by increasing the osmolality of dialysate (by adding glucose)
Hemodialysis short
fluid is removed by creating a difference in pressure between the blood compartment (positive) and the dialysate compartment (negative pressure)
Continuous renal replacement therapy (CRRT)
- slow removal of toxins and fluids from patients who are hemodynamically unstable
or if slow continuous removal of toxins is desired - Toxins and fluids are removed while acid-base status and electrolytes are adjusted slowly and continuously
- Pts must not have life-threatening hyperkalemia or pericarditis that would require rapid resolution
How is CRRT different from hemodialysis?
- continuous rather than intermittent
- solute removal mechanism is by convection, osmosis and diffusion
- causes less hemodynamic instability like hypotension d/t slower fluid removal
- ICU RN can perform CRRT, but does not require a specialized nurse like what is needed with HD
- Different equipment: doesn’t use a dialyzer, but a blood pump is needed for venovenous therapies
Potassium and CRRT
cannot have any emergent situation with potassium
CRRT set up
- Vascular access like HD like jugular or femoral vein
- Exchange is slow, but continuous
- Rate of ultrafiltration (removal of fluid/solutes) around 150mL/min
typically on the lower side as system relies on patient’s BP to push blood through unit - Newer units have a blood pump that increases the pressure gradient and fluid flow
- Anticoagulation to prevent blood clotting
Nursing considerations for CRRT
Patient can have it for 30-40 days
Hemofilter changed every 24-48 hours
