A simple and accurate method to determine equilibrated post-dialysis urea concentration

Canaud, Bernard; Bosc, Jean‐Yves; Leblanc, Martine; Garred, Laurie J.; Vaussenat, Fabrice; Bonardet, A; Mion, C

doi:10.1038/ki.1997.272

Cited by 35 publications

(9 citation statements)

References 23 publications

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“…We have demonstrated that accurate Kt/V results can be obtained in home hemodialysis patients by using blood samples taken before dialysis (C0) and 30 min before the end of dialysis (Ct‐30) to perform the calculations. We and others (19,23) previously demonstrated that blood urea concentrations 30 min before the end of dialysis are almost equivalent to those taken 30 min after dialysis and that this is a convenient way of allowing for the errors introduced by the phenomenon of rebound. Since it is very difficult to convince patients to stay for an extra 30–60 min after dialysis when rebound is almost complete, this method can also be conveniently applied to in‐center dialysis units.…”

Section: Discussionmentioning

confidence: 87%

Quantitating Dialysis in the Home Hemodialysis Patient: A Simple and Practical Approach

Coulis¹,

Gray²,

Saiphoo

et al. 1998

Home Hemodialysis International

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Home hemodialysis is the most cost-effective form of dialysis and is associated with the lowest mortality. Home hemodialysis patients are usually highly motivated, independent, and actively employed. Because of the minimal supervision they require and the fact that they are not in a controlled environment, it is easy to overlook the measurement of their dialysis adequacy. We studied 6 home hemodialysis patients and demonstrated that blood urea measured 30 min before the end of dialysis (Ct-30) is equivalent to that measured 30 min after the end of dialysis (Ct+30). The Kt/V results using Ct-30, Kt/V(Ct-30), were almost equivalent to Kt/V(Ct+30) (p = 0.5). The Kt/V Kt/V(Ct) using blood urea measured at the end of dialysis (Ct) significantly overestimated Kt/V(Ct-30) and Kt/V(Ct+30) (p = 0.007) The calculated percent reduction of urea (PRU) was about 5% less when using Ct-30 compared with Ct (p = 0.001). Taking blood samples 30 min before the end of dialysis for urea kinetics is more convenient for the home dialysis patients, since no other technical aspects of dialysis need their attention. The samples can be delivered to the laboratory the following day, because the blood may be stored in heparinized tubes at 4°C without deterioration of urea and creatinine concentrations. The Kt/V(Ct-30) was almost equal to Kt/V(Ct+30), so there is no longer any concern for the errors introduced by urea rebound. The blood pump must be reduced to 80 mL/min for about 10 sec to eliminate the errors due to fistula and cardiopulmonary recirculation. A simple programmable calculator will facilitate the calculation of accurate results using the Daugirdas second-generation formula.

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Section: Discussionmentioning

confidence: 87%

Quantitating Dialysis in the Home Hemodialysis Patient: A Simple and Practical Approach

Coulis¹,

Gray²,

Saiphoo

et al. 1998

Home Hemodialysis International

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“…The results in the present study lend support to the findings of Canaud et al . [12] and those of Bhaskaran et al . [13] that “–30‐min BUN” and “+30‐min BUN” values are similar.…”

Section: Discussionmentioning

confidence: 99%

“…[13] that “–30‐min BUN” and “+30‐min BUN” values are similar. Because of this similarity, one can use the “–30‐min BUN” level instead of the “+30‐min BUN” value to represent equilibrated, postdialysis BUN concentrations and to compute, for example, the equilibrated urea reduction ratio [15] or the equilibrated Kt/V value [12,13]. As a result of this advantage, there is no need for patients to spend time waiting for blood to be drawn for the measurement of “+30‐min BUN” values.…”

Section: Discussionmentioning

confidence: 99%

“…Because of urea rebound, blood urea nitrogen (BUN) levels of systemic blood samples obtained 30 minutes after the completion of a hemodialysis treatment (+30‐min BUN) are higher than those collected promptly after a dialysis session is over [1,5–11]. Recently, however, it has been shown that the BUN concentrations of systemic blood specimens obtained 30 minutes prior to the end of a dialysis session (–30‐min BUN) are similar in value to their 30‐minute postdialysis (+30‐min BUN) counterparts [12,13]. In an attempt to determine whether such a relationship between BUN concentrations exists in patients dialyzed six times per week, as well as in those dialyzed three‐times weekly, the present study was carried out.…”

Section: Introductionmentioning

confidence: 99%

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Use of Systemic Blood Urea Nitrogen Levels Obtained 30 Minutes before the End of Hemodialysis to Portray Equilibrated, Postdialysis Blood Urea Nitrogen Values

Ing

Blagg

Delano

et al. 2000

Hemodialysis International

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“…As to the prediction of eqBUN, several methods have been suggested. It was reported that it is possible to predict eqBUN using intradialytic BUN sampling (10–12). While there is an advantage in that these methods avoid taking a blood sample after HD and do not detain the patient beyond the treatment time, the accuracy of these methods is influenced by the method and timing of taking the intradialytic blood sample (13,14).…”

Section: Discussionmentioning

confidence: 99%

Mathematical Analysis of Urea Rebound in Long‐term Hemodialysis Patients

et al. 2005

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Quantifying hemodialysis (HD) treatment requires knowledge of the equilibrated concentrations of the post-HD small molecule rebounds. However, measurement of the equilibrated concentrations is only possible after resting in bed after HD for at least 30 min, and this is often impractical. Therefore, we have analyzed mathematically the time course of post-HD urea rebound, and from this, have derived a new formula for predicting its equilibrated concentration. The blood urea nitrogen (BUN) was measured at 10 time points (immediately following HD, and 0.5, 2.5, 5, 7.5, 10, 15, 20, 25, and 30 min post-HD) in 12 anuric HD patients. The absolute change in the urea rebound (DeltaeqBUN) was approximated (DeltaestBUN) using the equation: DeltaestBUN = b -[1-exp x (-c x time (min))] + a x time (min). After the good correlation between DeltaeqBUN and DeltaestBUN, we compared the value of DeltaeqBUN measured at 30 min (DeltaeqBUN(30)) with that calculated (DeltaestBUN(30)) using only four sample points (immediately following HD, and 2.5, 5 and 10 min post-HD). Based on this result, we tried to predict post-HD BUN at 30 min (estBUN(30)). This study was undertaken to determine whether estBUN(30) may be representative of the equilibrated BUN (eqBUN(30)), and to compare with Kt/V using estBUN(30) and eqBUN(30). There was a significant correlation between DeltaeqBUN and DeltaestBUN (0.97 < r < 0.99, P < 0.001). Thus, there was a significant positive linear correlation between eqBUN(30) and estBUN(30) (eqBUN(30): 25.7 +/- 2.25 mg/dL, estBUN(30): 26.3 +/- 2.31 mg/dL; r(2) = 0.99, P < 0.001). A Kt/V measurement was obtained with single pool model using BUN just after HD (Kt/V(sp)), eqBUN(30) (Kt/V(eq)), and estBUN(30) (Kt/V(est)), and with double pool model using Kt/V(sp) (Kt/V(dp)) and was compared with them. Though Kt/V(sp) was significantly higher than Kt/V(eq) (1.26 +/- 0.08 vs. 1.09 +/- 0.07, P < 0.001), there were no differences among Kt/V(eq), Kt/V(est) and Kt/V(dp) (Kt/V(est): 1.06 +/- 0.07, Kt/V(dp): 1.10 +/- 0.07) and all values were clinically acceptable. Furthermore, there was a significant positive linear correlation between Kt/V(eq) and Kt/V(est) (r(2) = 0.98, P < 0.001). In conclusion, we have devised the method to predict equilibrated BUN and calculate double pool Kt/V, which requires samples up to 10 min post-HD.

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A simple and accurate method to determine equilibrated post-dialysis urea concentration

Cited by 35 publications

References 23 publications

Quantitating Dialysis in the Home Hemodialysis Patient: A Simple and Practical Approach

Quantitating Dialysis in the Home Hemodialysis Patient: A Simple and Practical Approach

Use of Systemic Blood Urea Nitrogen Levels Obtained 30 Minutes before the End of Hemodialysis to Portray Equilibrated, Postdialysis Blood Urea Nitrogen Values

Mathematical Analysis of Urea Rebound in Long‐term Hemodialysis Patients

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