Dialysis - two compartment model

Question 1

What is the LRD for the two-compartment model?

Answer 1

Question 2

intracellular extracellular
intracellular compartment = ___ TBW
extracellular compartment = ___ TBW

Answer 2

2/3
1/3

Question 3

What is the compartment transfer rate? (2)

Answer 3

• compartment transfer coefficient rate = given based on literature 450ml/min
• concentration difference

Question 4

initial urea concentration =

Answer 4

45 mmol/L

Question 5

dialyzer clearance + urea production =

Answer 5

same as single compartment example

Question 6

Intracellular urea =
Extracellular urea =

Answer 6

Question 7

due to 2/3 + 1/3 diff between extra. + intra.

Answer 7

different initial conditions (level)

Question 8

What is the assumption?

Answer 8

assume = steady state - same concentration
- ≠ transfer between compartments

Question 9

What does the graph look like for urea concentration?

Answer 9

Question 10

What does the arrow represent?

Answer 10

= transient rebound before linear increase

Question 11

What happens if dialysis stops?

Answer 11

dialysis stops
outflow stops
amt. urea = higher
transfer rate = overshoot

Question 12

blue =
red =

Answer 12

blue = extracellular concent of urea
red = intracellular concent of urea

Question 13

Which model to use? (2)

Answer 13

• trade off: complexity vs accuracy
• complex model = captures behaviours that the simple model does not
  = only necessary where simple model ≠ capture
  desired behaviour