Two spent dialysate samples are sufficient for hemodialysis efficacy assessment.
BACKGROUND
The measure of dialysis efficacy is expressed as Kt/V value (calculated from predialysis and postdialysis blood urea concentration). The aim of this study was to assess the possibility of direct calculation of Kt/V value from two spent dialysate samples by using the regular blood-based Kt/V calculation formula with dialysate samples used as surrogates for blood samples, and to detect the most appropriate couple of dialysate samples for Kt/V estimation.


METHODS
Fifty-two single hemodialysis treatments in 34 anuric patients on chronic bicarbonate low-flux hemodialysis were observed. Kt/V values according to Daugirdas formula from two blood samples and from two dialysate samples were calculated.


RESULTS
Kt/V values calculated according to Daugirdas 2 nd generation formula from blood samples (Kt/V sp Daugirdas) were in significant correlation with all Kt/V values obtained from two spent dialysate samples. The highest correlation coefficient (r = 0.74, p < 0.001) and the least standard error of mean of the differences were found between Kt/V sp Daugirdas and value obtained with substitution of urea concentration from dialysate samples taken 60 minutes after dialysis start and at the end of the dialysis into Daugirdas 2 nd generation formula (Kt/V D C D(60) -C D(e) ), which can be expressed as a equation of linear regression y = 0.47 + 0.86x. The highest correlation coefficient (r =0.74, p < 0.001) was found between Kt/V sp Daugirdas values equilibrated according to Daugirdas rate formula, and Kt/V D C D(60) -C D(e) value, which can also be expressed as an equation of linear regression y = 0.43 + 0.73x.


CONCLUSIONS
The results of this study clearly show the sufficiency of only two spent dialysate samples for direct estimation of the Kt/V values, with no blood sample required.
Kovacic
V
V
Clinical Hospital Split, Department of Internal Medicine, Division of Nephrology and Dialysis, Split, Croatia. vedkovac@inet.hr
Ljutic
D
D
D000328:Adult; D000367:Age Factors; D000368:Aged; D000465:Algorithms; D001835:Body Weight; D015314:Dialysis Solutions / Q000032:analysis*; D005260:Female; D017583:Hemodiafiltration; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000379:methods / Q000592:standards*; D013997:Time Factors; D016896:Treatment Outcome; D014508:Urea / Q000032:analysis / Q000097:blood
D015314:Dialysis Solutions; D014508:Urea