Dialysis

what is the primary purpose of DIALYSIS

managing fluid + electrolyte balance with CKD/AKI

what are the 3 major types of DIALYSIS

1. peritoneal dialysis

2. intermittent hemodialysis

3. continuous renal replacement therapy (CRRT)

for either PERITONEAL/INTERMITTENT DIALYSIS, what 3 principles are used to balance fluid + electrolyte levels

1. diffusion

2. osmosis

3. ultrafiltration

what is DIFFUSION

is the movement of solutes (Cr, urea/electrolytes) from an area of higher concentration to an area of lower concentration

what is OSMOSIS

is the movement of fluid from an area of lesser solute concentration to an area of greater solute concentration

what is ULTRAFILTRATION

is the removal of water + fluid

how is ULTRAFILTRATION accomplished

by creating pressure gradients between arterial blood + dialyzer membrane/compartment

what 2 types of DIALYSIS are indicated for AKI cases

1. intermittent hemodialysis

2. CRRT

what setting is CRRT implemented in

critical care settings in patients with AKI

- stabilize patients

what does PERITONEAL DIALYSIS involve

using the peritoneal cavity as a semipermeable membrane to exchange soluble substances + water between the dialysate fluid + blood vessels in abdominal cavity

what is the duration range for PERITONEAL DIALYSIS

45 minutes to 9 hours

what is the PERITONEAL DIALYSIS exchange range that patients can have anywhere from

4-24 exchanges per day

what are the 3 major steps involved in PERITONEAL DIALYSIS

1. dialysate fluid instilled into peritoneal cavity through an indwelling catheter

2. after dialysate is instilled into peritoneum, there's an equilibrium period when water + solutes pass through semipermeable membrane

3. once equilibrium is complete, peritoneal cavity is drained of excess fluid + solutes that the failing kidney can't remove

what are the 3 phases of PERITONEAL DIALYSIS

1. instillation

2. equilibration

3. drainage

what are the 2 types of PERITONEAL DIALYSIS

1. automated PD (APD)

2. continuous ambulatory PD (CAPD)

what is the difference between APD vs CAPD

APD: uses an automatic cycling device

CAPD: carried out by patient at home + doesn't require a machine; manually performed

what does AUTOMATED PD (APD) include

use of an automatic cycling device to control the instillation, equilibration + drainage phases

what type of setting can CAPD be completed in

at home

does CAPD require a machine

no, doesn't require a machine + is performed manually

what is involved in CAPD

dialysate left in peritoneal cavity for 6-8 hours allowing for equilibrium then drained out + fresh dialysate instilled

how many times a day is CAPD performed

3-4 times/day

what does fluid removal rely on regarding CAPD

creating an osmotic gradient across membrane using varying concentrations of glucose in dialysate

what patients is PERITONEAL DIALYSIS indicated for

patients with CKD who may/may not be hospitalized

what is the purpose of INTERMITTENT HEMODIALYSIS

control kidney functions (fluid volume, electrolyte balance, acid-base balance + filtration of nitrogenous wastes)

what are 2 steps involved in INTERMITTENT HEMODIALYSIS

1. patient's arterial blood is mechanically circulated through semi-permeable tubing surrounded by a dialysate solution in dialyzer (artificial kidney)

2. as patient's arterial blood is being filtered through dialyzer, "clean" blood is returned to patient's venous circulation

what are patient required to replace per dialysis session regarding INTERMITTENT HEMODIALYSIS

patients required to replaced 2-3L of fluid per dialysis session

why are patients require to replace 2-3L of fluid per dialysis session with INTERMITTENT HEMODIALYSIS

to fully achieve clear waste products + achieve osmotic balance

what does CRRT (Continuous Renal Replacement Therapy) provide

a continuous mechanism that balances fluid + electrolytes and small + medium solutes from the body in a manner that mimics the natural function of the patient's native kidney

what is CRRT beneficial for

patients with positive fluid balance

what are 6 predictable outcomes with CRRT

1. hemodynamic stability

2. continuous control of fluid status

3. control of acid-base status + electrolyte, calcium + phosphate balance

4. provision of protein-rich nutrition with excellent uremic control

5. prevention of intracerebral water fluctuations

6. minimal risk of infection

what are the 6 types of CRRT

1. slow continuous ultrafiltration (SCUF)

2. continuous veno-venous hemofiltration (CVVH)

3. continuous veno-venous hemodialysis

4. continuous veno-venous hemodiafiltration (CVVHDF)

5. continuous high-flux dialysis (CVVHFD)

6. continuous plasma-filtration adsorption (CPFA)

what is slow continuous ultrafiltration ONLY USED FOR

fluid control

what 2 types of MODES does slow continuous ultrafiltration have

1. arteriovenous modes

2. venovenous modes

what does continuous venovenous hemofiltration include

convective blood purification through a high-permeability membrane

what MODE is available with continuous venovenous hemofiltration

arteriovenous mode

what does continuous venovenous hemodialysis include

diffusive purification of blood through a low-permeability dialyzer

what is continuous venovenous hemodialysis ONLY USED FOR

small molecule clearance

what does continuous venovenous hemodiafiltration include

diffusive + convective blood purification with a highly permeable membrane

what does continuous high-flux dialysis include

diffusive + convective blood purification with a highly permeable membrane

- accessory pump to control ultrafiltration

what does continuous plasma-filtration adsorption include

a highly permeable plasma filter filters plasma, allowing it to pass through a bed of adsorbent material (carbon/resins)

what is MAINTAINED during continuous plasma-filtration adsorption

fluid balance