What is Peritoneal Solute Transfer Rate? (PSTR)
Rate of solute transfer across the membrane
described as;
a. diffusion capacity
b. mass transfer area coefficient (MTAC)
- maximal rate of clearance by diffusion
c. solute dialysate-to-plasma concentration ratio (D/P ratio)
ISPD peritoneal membrane dysfunction
How to identify Peritoneal Solute Transfer Rate (PSTR) ?
- from 4hrs PET
- use 2.5% / 4.25% glucose solution
- creatinine as index solute
Affects on fast PSTR
- lower survival
- lower UF
- increase net fluid reabsorption
Solution
1. icodextrin
2.prescribe higher glucose conc
low UF capacity
- net UF from 4h PET < 400ml (with 4.25% solution) or < 100ml (with 2.3% solution)
AND / OR - daily UF is insufficient to maintain adequate fluid status
Factors that determine the efficiency of water transport
- peritoneal osmotic conductance to glucose (OCG)
- rate of glucose diffusion from dialysate to blood
- peritoneal lymph flow
- glucose conc at the start of dwell
PET test (peritoneal Equilibration test)
peritoneal membrane clearance and UF characteristic
by measuring
- dialysate to plasma ratio (D/P ratio) of creatinine and glucose
at specific time
under standard condition
How to perform PET test?
0 hr
2 hr
4 hr
dialysate urea / creat / glu 0,2,4 hrs
blood urea / creat / glu 2hrs
Sodium sieving phenomenon
consequence of dissociation between the amount of water and sodium transported over the peritoneal membrane.
decrease of dialysate [Na] (dip) during 1st hour of hypertonic dwell
causes of membrane dysfunction
- type 1: fast PSTR
- type 2: low osmotic conductance to glucose
- type 3: low effective peritoneal surface area
- type 4: High Total Peritoneal Fluid Loss Rate
Type 1: fast PSTR
Def:
D/P ratio > 0.65 (>0.81)
causes: (local inflammation)
a. membrane inflammation cause large effective vascular surface area
b. neovascularization
*post peritonitis
mx:
use short dwell
change to APD
icodextrin with long dwell
rest peritoneum for 2-3 month
Type 2: low osmotic conductance to glucose
def:
sodium dip at 60min < 5mmo/l
sodium sieving ratio < 0.07 with 4.35% glucose (low)
causes:
a. functional alteration of aquaporin
b. aquaporin deficiency
*can happen at start of PD
mx:
? steroid
conversion to HD
type 3: low effective peritoneal surface area
diffuse hypopermeability of the peritoneal membrane results in impairment of both solute transport and ultrafiltration
causes:
a. structural alteration in peritoneum - fibrosis —> EPS
*happen over years on PD
Mx:
conversion to HD
typer 4: High Total Peritoneal Fluid Loss Rate
an increase in the rate of bulk fluid absorption from the peritoneal cavity into lymphatics and into the local tissues
= high ‘effective lymphatic absorption rate’ (due to lymphangiogenesis)
Mx:
conversion to HD
