Analysis of Urea Distribution Volume in Hemodialysis

Maduell, Francisco; Sigüenza, F; Caridad, A; Miralles, F; Serrato, F.

doi:10.1159/000187829

Cited by 6 publications

(7 citation statements)

References 5 publications

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“…Similar to previous reports [23, 24, 25]differences were found between the V obtained by the single-pool and the double-pool model; these differences may be explained by the fact that in a two-compartmental system, one compartment is cleared faster than the other. It is therefore necessary to wait for the reestablishment of urea equilibrium between compartments to determine V accurately.…”

Section: Discussionsupporting

confidence: 90%

Assessment of the Length of Each Hemodialysis Session by On-Line Dialysate Urea Monitoring

Hernández-Herrera

Martín‐Malo²,

Rodriguez³

et al. 2001

Nephron

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Hemodialysis (HD) prescription is usually based on the periodical measurement of the Kt/V achieved in a midweek dialysis session. The purpose of the study was to assess the duration of each HD session to achieve a target dose of dialysis. This allowed to determine whether a given dialysis session may be considered representative of the other HD sessions. Seventy-two HD sessions were studied in 4 stable patients, who were randomly dialyzed during 3 consecutive periods, each lasting 2 weeks, using a different blood flow rate (Qb) in each period: 400, 300 or 200 ml/min. All HD were prolonged to achieve an on-line dialysate urea monitor (UM) Kt/V of 1.2. The UM Kt/V was compared with the Kt/V calculated using pre-HD, post-HD and rebound (45 min post-HD) plasma water urea concentrations. Comparison of the duration of the second midweek dialysis session with the length of the other HD showed 95% concordance intervals (±2 SD) of ±21.08 min for Qb 400, ±26.88 min for Qb 300 and ±37.02 min for Qb 200 ml/min. The 95% concordance intervals for whole body urea clearance were ±32.0, ±20.36 and ±15.62 ml/min for Qb 400, 300 and 200 ml/min, respectively. No differences were observed between UM Kt/V and blood-based double-pool Kt/V obtained by the second-generation Daugirdas (1.18 ± 0.08) and Garred (1.19 ± 0.08) Kt/V formulas. In conclusion, a great variability was observed between different HD sessions with regard to the whole body urea clearance and the time required to attain a target Kt/V even when the HD characteristics remained constant. The length of every HD required to achieve a target dose of dialysis can be assessed by on-line dialysate urea monitoring.

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Section: Discussionsupporting

confidence: 90%

Assessment of the Length of Each Hemodialysis Session by On-Line Dialysate Urea Monitoring

Hernández-Herrera

Martín‐Malo²,

Rodriguez³

et al. 2001

Nephron

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“…Two points o f discrepancy exist between our data and those of Maduell et al [ 1 ]. The first is the nonconstant V value in our pa tients.…”

contrasting

confidence: 99%

“…patient 1 of our series had a range from 40.8 to 63.8. i.e. a value of 23), we found that the mean value in our 12 patients was 17.4 ± 10.1 versus 4.8 ± 1.5 of the 35 patients of Maduell et al [1] (F 53.08. p < 0.0001). The reason for this dis crepancy is far from being clear.…”

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confidence: 42%

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Urea Distribution Volume Is Not Constant in Hemodialysis Patients

Basile¹

1995

Nephron

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“…When ignored, PDUR can induce an overestimation of dialysis and nutritional indexes. The Kt/V can be overestimated by an average of 15-40% in a conventional 3-to 5-hour dialysis [6,8,9,12,[14][15][16] and the normal protein catabolic rate nPCR can be overestimated by 6-10% [4,17,18]. In our center, long 8-hour dialysis has been in use for more than 30 years with high-dialysis indexes based on pre-and immediate postdialysis urea samples.…”

Section: Introductionmentioning

confidence: 99%

Is Post-Dialysis Urea Rebound Significant with Long Slow Hemodialysis?

Jean

Chazot²,

Charra³

et al. 1998

Blood Purif

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Background: According to previous studies, postdialysis urea rebound (PDUR) is achieved within 30–90 min, leading to an overestimation of Kt/V of between 15 and 40% in 3- to 5-hour dialysis. The purpose of the study was to assess the impact of PDUR on the urea reduction ratio (URR), Kt/V and normal protein catabolic rate (nPCR) with long 8-hour slow hemodialysis. Methods: This study was performed in 18 patients (13 males/5 females), 62.5 ± 11.7 years of age, hemodialyzed for 3–265 months. Initial nephropathies were: 3 diabetes; 2 polycystic kidney disease; 3 interstitial nephritis; 2 nephrosclerosis; 3 chronic glomerulonephritis, and 5 undetermined. Residual renal function was negligible. The dialysis sessions were performed using 1- to 1.8-m² cellulosic dialyzers during 8 h, 3 times a week. Blood flow was 220 ml/min, dialysate flow 500 ml/min, acetate or bicarbonate buffer was used. Serial measurements of the urea concentration were obtained before dialysis, immediately after dialysis (low flow at t = 0), and at 5, 10, 20, 30, 40, 60, 90 and 120 min, and before the next session. The low-flow method was used to evaluate the access recirculation, second-generation Daugirdas formulas for Kt/V, and Watson formulas for total body water volume estimation. The difference between the expected urea generation (UG) and urea measured after dialysis (global PDUR) defines net PDUR (n-PDUR). Results: The n-PDUR usually became stable after 58 ± 25 (30–90) min. Its mean value was 17 ± 10% of the 30-second low-flow postdialysis urea (3.9 ± 2 mmol/l). This small postdialysis urea value and the importance of UG in comparison with shorter dialysis justify the use of n-PDUR. Ignoring n-PDUR would lead to a significant 4% overestimation (p < 0.001) of the URR (79 ± 7 vs. 76 ± 8%), 12% of Kt/V (1.9 ± 0.4 to 1.7 ± 0.38) and 4% of the nPCR (1.1 ± 0.3 to 1.05 ± 0.3). n-PDUR correlated negatively with postdialysis urea (r = 0.45 p = 0.05), positively with URR (r = 0.31 p = 0.01) and Kt/V (r = 0.3 p = 0.03) but not with K, and negatively with the urea distribution volume (r = 0.33 p = 0.05). Mean total recirculation, ultrafiltration rate, predialysis urea levels and urea clearance did not correlate with n-PDUR. Conclusion: We found a significant PDUR in long-slow hemodialysis after a mean of 1 h after dialysis. This PDUR has a less important impact upon dialysis delivery estimation than short 3- to 5-hour hemodialysis, especially for the lower Kt/V or URR ranges. This is explained by the low-flux, high-efficiency, and long-term dialysis. Its inter-individual variability incites us to calculate PDUR on an individual basis.

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Analysis of Urea Distribution Volume in Hemodialysis

Cited by 6 publications

References 5 publications

Assessment of the Length of Each Hemodialysis Session by On-Line Dialysate Urea Monitoring

Assessment of the Length of Each Hemodialysis Session by On-Line Dialysate Urea Monitoring

Urea Distribution Volume Is Not Constant in Hemodialysis Patients

Is Post-Dialysis Urea Rebound Significant with Long Slow Hemodialysis?

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