Urea Reduction Ratio Considering Urea Rebound

Abstract

An American National Study shows that survival benefits from higher dialysis doses appear to be present up to a Kt/V level of 1.3 or a urea reduction ratio (URR) of 70%. The effect of increasing dialysis efficiency magnified urea rebound and the error in URR determinations. Several formulas have been developed to calculate URR considering the urea rebound (URRr). Smye and coworkers have proposed a method whereby the equilibrated blood urea nitrogen is predicted by additional intradialytic urea sample. Maduell and colleagues, based on analysis of postdialysis urea rebound, have proposed a method whereby the urea rebound is predicted. To compare measured URRr to estimated by Smye and Maduell formulas, 384 patients were studied, 211 males and 173 females, who received a dialysis session with their habitual parameters. Measurements of plasma urea concentration were obtained at the beginning, 90–100 min following the start of dialysis, at the end, and 45 min after dialysis. The postdialysis urea rebound was 22.4 ± 9.7%. The urea kinetic model Kt/V was 1.365 ± 0.26, and Kt/Vr was 1.14 ± 0.23. URR was 68.7 ± 6.6%, and when it was calculated with urea rebound, it decreased to 61.9 ± 7.4%. The URRr correlated with calculations by Smye and Maduell formulas: 60.7 ± 8.4 (r = 0.722, p < 0.001) and 61.8 ± 6.6 (r = 0.933, p < 0.001), respectively. The precision of estimated limits of agreement and percentage of error by Bland and Altman analysis show that URRr estimated Maduell formula could be used in place of the URRr. Otherwise, the degree of agreement of the Smye method was not clinically acceptable. In conclusion, our results led us to suggest that in actual dialysis, the use of URR is not adequate for delivered hemodialysis dose, and URRr should be used. URRr estimated by Maduell formula could be a simple and accurate method for use in clinical practice. The recommended dialysis dose by the American National Study of URR of 70% could correspond, considering urea rebound, to Kt/Vr 1.18 or URRr of 64%.

Kinetic behavior of urea is different from that of other water-soluble compounds: The case of the guanidino compounds

“…Second, our intercompartmental urea clearance (822 ±345 mL/min) is in good agreement with previous publications reporting K 12 values ranging from 700 up to 960 mL/min [18,19]. Furthermore, it should be remarked that our calculated effective reduction ratio is comparable to the results of previous clinical studies [39].…”

Influence of Physical Exercise on the Dialytic Adequacy Parameters of Patients on Hemodialysis

“…The baseline mean urea rebound in our sample once again provided much higher values than those described in former studies . A rebound of this quantity implies that the dialysis dose achieved at the end of the sessions significantly lowered 30 min after it ended, which we checked when comparing our KtV and final URR values with the rebound calculated with the sample taken after 30 min.…”

“…A rebound of this quantity implies that the dialysis dose achieved at the end of the sessions significantly lowered 30 min after it ended, which we checked when comparing our KtV and final URR values with the rebound calculated with the sample taken after 30 min. Similar results have been obtained in studies by Maduell, Spiegel, and Leblanc . Although the rebounds of creatinine, potassium, and phosphorous have been less studied, we were able to quantify them here and they were even higher than the urea rebound.…”

Update on Postdialysis Rebound by a New Technology in Hemodialysis

“…However, presence of congestive heart failure decreases rebound . Other results about the influence of session time or presence of hypotension have on rebound have been reported .…”