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
Dialysis works across a semipermeable membrane via…
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
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 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)
Peritonitis
Contraindications for PD (5)
Hemodialysis
Hemodialysis components
Problem with temporary catheter
high rate of infection and patient can’t be discharged with a temporary catheter
HD: IV catheter device
HD: Arteriovenous Grafts (AVG)
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
Overtime fistulas..
become tough and may be used for repeated venipuncture for repeated access