Accuracy of using 30-minute post-dialysis BUN to determine equilibrated Kt/V.

BACKGROUND: The equilibrated Kt/V (eKt/V), a clinical index of hemodialysis adequacy, can be calculated by several means. The commonly used methods are second generation of natural logarithm by Daugirdas and rate adjustment methods. However these two methods used immediate post-dialysis blood urea nitrogen (BUN) (C0). The authors investigated the accuracy of 30-minute post-dialysis BUN (C30), equilibrated BUN at the end of urea rebound time, to determine the eKt/V MATERIAL AND METHOD: We measured 7 values of eKt/V in 30 hemodialysis sessions by using the 5 following methods: 1). Empirical method (Emp) 2). Smye method (Sm) 3). Daugirdas method using C0 and C30 (Dau0, Dau30) 4). Rate adjustment method using C0 and C30 (Rate0, Rate30) 5). Double Pool urea kinetic model (DP), and compared with the gold standard values calculated by the modified Direct Dialysate Quantitative method (mDDQ). RESULTS: All patients had adequate hemodialysis with eKt/V (mDDQ) = 1.80 + 0.22. Compared with mDDQ, the median of absolute difference of eKt/V were Rate30 (0.10); Dau30 (0.11), Rate0 (0.11), Sm (0.11); Emp (0.13); DP (0.15); Dau0 (0.35) while the correlation coefficient (r2) were 0.926, 0.948, 0.785, 0.629, 0.551, 0.833,and 0.806 respectively. CONCLUSION: By using 30-minute post-dialysis BUN to calculate, the values of eKt/V by Daugirdas and rate adjustment methods were associated with better accuracy and correlation than immediate post-dialysis BUN. In the demand of the accurate eKt/V measurement, the Dau30 and Rate30 may be the suitable method to determine the eKt/V in clinical hemodialysis.

The efficacy of single-needle versus double-needle hemodialysis in chronic renal failure.

OBJECTIVE: The purpose of the present study was to assess single-needle dialysis adequacy and other parameters of dialysis efficiency, such as recirculation, hematocrit, calcium and phosphorus level. The complications and adverse events were also evaluated. Time to achieve maximal adequacy of dialysis were compared between 4, 4.5, and 5.0 hours of dialysis session. DESIGN: Prospective, cross-over trial. SETTING: Renal Unit, Department of Medicine, Bangkok Metropolitan Administration Medical College and Vajira Hospital. MATERIAL AND METHOD: Seven stable chronic renal failure patients who regularly used standard hemodialysis (HD) technique with double-needle (DN) were recorded for baseline data including Kt/V percent recirculation, calcium and phosphorus level, hematocrit, and LDH level. Subsequently, all the patients were placed on single-needle dialysis (SN) for 3 consecutive duration, 4 hours, 4.5 hours and 5.0 hours respectively for 3 weeks in each period. The same parameters were recorded at the end of each period. RESULTS: Prior to the single-needle phase, the adequacy of dialysis in DN dialysis were within the acceptable range. After switching to SN mode, the Kt/V did not change significantly from the baseline value. However, subgroup analysis in twice weekly dialysis revealed some degree of reduction in Kt/V value albeit not significant. In the thrice weekly group, the Kt/V did not differ from the baseline value and achieved the target level according to the DOQI guideline. The other parameters such as hematocrit, calcium, phosphorus and LDH were not different from the DN group. SN dialysis did not cause more recirculation than the DN group and both were less than 10 percent. There were no other major complications during the SN phase. The outcome of the fistulas were excellent. CONCLUSION: The SN dialysis has the same efficacy as the conventional DN technique in terms of Kt/V and other parameters such as calcium, phosphorus and LDH values. Both DN and SN caused less than 10% recirculation. There were no reports of adverse events during the treatment period. The double-pump system therefore could be suitable for routine thrice weekly HD in a selected group of patients.