Unrestricted pore area (A0/Deltax) is a better indicator of peritoneal membrane function than PET.
BACKGROUND
How to measure the peritoneal exchange in uremic patients treated with peritoneal dialysis (PD) is still a matter of controversy. Most clinics use the peritoneal equilibration test (PET), but from a theoretical point of view, it would be more appropriate to determine the "area" parameter, A0/Deltax. The latter reflects the total unrestricted pore area per centimeter diffusion distance and can be obtained by three-pore analysis using, for example, the PD capacity test (PDC). To evaluate the different estimates of peritoneal function, PET data and the A0/Deltax parameters were compared with the independently determined uptake of a small diffusible tracer, iohexol (molecular weight of 821 D), from the abdominal cavity to blood.


METHODS
Fourteen patients on routine PD underwent determinations of PET and A0/Deltax using PDC. Within a month, the two-hour uptake of iohexol (6 mg/mL) was also determined from the plasma iohexol concentration following abdominal filling.


RESULTS
A strong correlation was found between the rate of iohexol plasma concentration increase (k30-120) and A0/Deltax (A0/Deltax = 76,300. k30-120 - 1.56; r2 = 0.799; N = 14) for the 2 L dwell, while the PET data were far less related to iohexol uptake (D/DPurea, r2 = 0.409; D/Pcreatinine, r2 = 0.436; and D/D0glucose, r2 = 0.015, respectively).


CONCLUSIONS
The "area" parameter, A0/Deltax, is superior to the more widely used routine PET as an indicator of peritoneal membrane function. In addition, the concept of A0/Deltax has the virtue of supplying quantitative information about the peritoneal pathophysiology and physiology.
Johnsson
E
E
Departments of Nephrology, Clinical Pharmacology, and Physiology, Göteborg University, Göteborg, Sweden.
Johansson
A C
AC
Andreasson
B I
BI
Haraldsson
B
B
D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000493:pharmacokinetics; D015314:Dialysis Solutions / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007472:Iohexol / Q000493:pharmacokinetics; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000628:therapy*; D008297:Male; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000379:methods* / Q000592:standards; D010537:Peritoneum / Q000378:metabolism*; D014511:Uremia / Q000378:metabolism / Q000628:therapy
D003287:Contrast Media; D015314:Dialysis Solutions; D007472:Iohexol