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