Ionic dialysance and the assessment of Kt/V: the influence of different estimates of V on method agreement.

BACKGROUND: Ionic dialysance was recently introduced as a means to assess Kt/V (K(ID)t/V). With this method, urea distribution volume (V) has to be estimated. The primary aim of the present study was to assess the agreement between equilibrated Kt/V assessed by urea kinetic modelling (eKt/V) with K(ID)t/V taking into account different estimates of V, and to assess the monthly variation in V. Secondly, the mechanisms behind the intra-treatment changes in ionic dialysance and inter-treatment variability of K(ID)t/V were assessed. METHODS: Sixty-six patients were included. eKt/V was estimated using 30 min post-treatment sampling in the second generation Daugirdas equation. V was assessed by the formulae of Watson and Chertow (V(Watson); V(Chertow)), double-pool urea kinetic modelling (V(UKM)) and by ionic dialysance (V(IOD)) [Diascan; Hospal(R)]. RESULTS: The use of V(UKM) or V(IOD) instead of V(Watson) or V(Chertow) improved the relation between eKt/V and K(ID)t/V (both r = 0.93; P < 0.001 vs r = 0.84 and r = 0.81; P < 0.001). Mean values of eKt/V (1.19 +/- 0.21), K(ID)t/V(UKM) (1.19 +/- 0.30) and K(ID)t/V(IOD) (1.21 +/- 0.25) were comparable. Intra-class correlation coefficient of V(IOD) was 0.87 with a 1-month interval and <0.75 after 2 and 3 months. Intra-class correlation coefficient of V(DP) was 0.79 with a 1-month interval and <0.75 after 2 and 3 months. Inter-treatment variation in K(ID)t/V during six consecutive dialysis sessions was 6.1% +/- 0.6%. Changes in blood flow were the main determinant of variations in K(ID)t/V (P < 0.05). During treatment, ionic dialysance decreased by 12 +/- 13 ml/min (P < 0.001). The decline in blood volume was the major determinant of the intra-dialytic change in ionic dialysance (P < 0.05). CONCLUSION: The use of V(IOD) and V(UKM) results in better agreement between eKt/V and K(ID)t/V compared with anthropometric formulae. K(ID)t/V was comparable with eKt/V and thus lower than expected for a single-pool method. V(IOD) and V(UKM), should be assessed at least monthly. K(ID)t/V varies widely between consecutive dialysis sessions, mainly due to differences in blood flow. During treatment, ionic dialysance decreases, which is related to the relative decline in blood volume.

Urine flow cytometry and detection of glomerular hematuria.

BACKGROUND: The UF-100 is a flow cytometer designed for automated cellular urinalysis. In this study, the usefulness of the UF-100 in laboratory investigation into the origin of hematuria was evaluated. METHODS: Results from flow cytometric urinalysis were used to classify urinary red blood cells (RBCs) according to glomerular and non-glomerular origin and the classification was compared to the patient's clinical diagnosis as the gold standard. In parallel, microscopic sediment analysis was carried out. RESULTS: A total of 206 urine samples from 129 patients were analyzed (127 from patients with glomerular hematuria, 79 from patients with non-glomerular hematuria). Of these, 136 samples (92 patients) showed overt hematuria (>or=20 RBC/microL). Urine flow cytometry correctly classified 61% (sediment analysis 69%) of urine samples with overt hematuria. If inconclusive results are excluded, the UF-100 correctly diagnosed 85% (sediment analysis 98%) of urine samples with overt hematuria. The UF-100 and microscopic sediment analysis both showed sensitivity of 99% for the detection of glomerular hematuria. The specificity of the UF-100 for the detection of glomerular bleeding was lower (42%) than the specificity of microscopic sediment analysis (93%). CONCLUSIONS: Owing to its low specificity, the UF-100 showed limited capacity to discriminate glomerular from non-glomerular causes of hematuria in a population with a high incidence of renal disease. Therefore, extensive microscopic urinalysis remains necessary to assess the origin of hematuria.

Effect of icodextrin on volume status, blood pressure and echocardiographic parameters: a randomized study.

Overhydration is a risk factor for hypertension and left ventricular hypertrophy in peritoneal dialysis patients. Recently, a high prevalence of subclinical overhydration was observed in peritoneal dialysis patients. Aim of the present open-label randomized study was to assess the effect of a icodextrin 7.5% solution on fluid status [extracellular water (ECW) bromide dilution], blood pressure regulation (24-hour ambulatory measurements) and echocardiographic parameters during a study period of 4 months, and to relate the effect to peritoneal membrane characteristics (dialysate/plasma creatinine ratio). Forty peritoneal dialysis patients (22 treated with icodextrin, 18 controls) were randomized to either treatment with icodextrin during the long dwell or standard glucose solutions. Thirty-two patients (19 treated with icodextrin, 13 controls] completed the study. The use of icodextrin resulted in a significant increase in daily ultrafiltration volume (744 +/- 767 mL vs. 1670 +/- 1038 mL; P = 0.012) and a decrease in ECW (17.5 +/- 5.2 L vs. 15.8 +/- 3.8 L; P = 0.035). Also the change in ECW between controls and patients treated with icodextrin was significant (-1.7 +/- 3.3 L vs. +0.9 +/- 2.2 L; P = 0.013). The effect of icodextrin on ECW was not related to peritoneal membrane characteristics, but significantly related to the fluid state of the patients (ECW:height) (r = -0.72; P < 0.0001). Left ventricular mass (LVM) decreased significantly in the icodextrin-treated group (241 +/- 53 grams vs. 228 +/- 42 grams; P = 0.03), but not in the control group. In this randomized open-label study, the use of icodextrin resulted in a significant reduction in ECW and LVM. The effect of icodextrin on ECW was not related to peritoneal membrane characteristics, but was related to the initial fluid state of the patient.

Blood volume control by biofeedback and dialysis-induced symptomatology. A short-term clinical study.

In earlier studies, a reduction in intradialytic procedures was observed in patients with severe intradialytic hypotension symptomatology by the use of blood volume controlled biofeedback systems. However, few data are present on the use of biofeedback-controlled treatments in patients experiencing minor intradialytic symptoms. In the present study, 157 standard and 158 biofeedback-controlled treatments were compared during a 2-month period in 16 hemodialysis patients. Both the percentage of hypotensive episodes (6.3 +/- 11.3 vs. 15.8 +/- 18.3%; p < 0.05) as well as other intradialytic symptoms (cramps, nausea, headache, abdominal pain) (11.0 +/- 12.8 vs. 18.1 +/- 16.9%; p < 0.05) were significantly less during biofeedback-controlled treatments compared to standard dialysis treatments, despite a similar decline in relative blood volume (8.8 +/- 3.5 vs. 8.3 +/- 3.1%; p = n.s.). Interdialytic weight gain and intradialytic rise in plasma sodium levels were comparable. Concluding, in this short-term preliminary study, blood volume controlled biofeedback improved dialysis tolerance also in patients with minor intradialytic symptomatology.

Ionic mass balance and blood volume preservation during a high, standard, and individualized dialysate sodium concentration.

BACKGROUND: Although a higher dialysate sodium concentration (DNa) is frequently used to improve haemodynamic stability during haemodialysis, few studies have compared ionic mass balance (IMB) during different DNa. Moreover, DNa is usually a standard prescription, whereas inter-individual pre-dialytic serum sodium levels may differ widely. The aims of the study were to assess IMB and the decline in blood volume (DeltaBV) during isovolaemic HD as well as during HD combined with ultrafiltration (UF) during DNa [140], DNa [144], and an individualized DNa [ind], in which DNa is equal to pre-HD plasma conductivity x 10. METHODS: IMB and plasma conductivity were assessed by on-line conductivity measurements (Diascan; Hospal) in 13 HD patients. After 1 h of isovolaemic HD, measurements were continued during UF+HD until dry weight. DeltaBV was assessed by an optical method (Hemoscan). RESULTS: During isovolaemic HD with DNa [140] and [144], Pre-Na was significantly related to IMB (r=0.83 and r=0.61; P<0.05). Diffusive Na flux into the patient occurred when the difference between DNa and pre-dialytic serum sodium was larger than 5 mmol/l. During UF+HD, IMB was 318+/-166 mmol during DNa [140], 277+/-116 mmol during DNa [ind], and 239+/-111 during DNa [144] (mean+/-SD; P<0.05 compared with the other treatment modalities) whereas DeltaBV did not differ significantly. In the five patients with a pre-dialytic sodium concentration below 140 mmol/l, ionic removal was significantly higher during DNa [ind] (324+/-87) compared with DNa [140] (228+/-127 mmol; P<0.05) without a significant difference in DeltaBV (-9.7+/-1.6 vs -7.8+/-2.3%). CONCLUSION: A large difference in IMB was observed between DNa 144 and DNa 140, without a significant difference in DeltaBV. In patients with low pre-dialytic serum sodium levels, diffusive ionic influx from the dialysate into the patient may occur. In patients with low pre-dialytic sodium levels, DNa [ind] leads to an enhanced ionic removal compared with DNa [140] without large differences in DeltaBV.

Assessment of fluid status in peritoneal dialysis patients.

OBJECTIVES: To assess the influence of abnormalities in fluid status and body composition on agreement between multifrequency bioimpedance analysis (MF-BIA), segmental BIA (sigmaBIA), the Watson formula, and tracer dilution techniques. DESIGN: Cross-sectional. SETTING: Multicenter. PATIENTS: 40 patients (29 males, 11 females) on peritoneal dialysis (PD). MAIN OUTCOME MEASURES: Agreement between the various techniques used to assess total body water (TBW) [MF-BIA, deuterium oxide (D2O), and the Watson formula] and extracellular water (ECW) [MF-BIA, bromide dilution (NaBr), and sigmaBIA], also in relation to the relative magnitude of the body water compartments [ECW (NaBr):body weight (BW) and TBW (D2O):BW] and body composition (DEXA). Second, the relation between body water compartments with echocardiographic parameters. RESULTS: Wide limits of agreement were observed between tracer dilution techniques and MF-BIA [TBW (D2O - MF-BIA) 2.0 +/- 3.9 L; ECW (NaBr - MF-BIA) -2.8 +/- 3.9 L], which were related to the relative magnitude of the body water compartments: r = 0.70 for ECW and r = 0.40 for TBW. sigmaBIA did not improve the agreement [ECW (NaBr-sigmaBIA): 3.7 +/- 2.9 L]. Also, wide limits of agreement were observed between D2O and the Watson formula (-2.3 +/- 3.3 L). The difference between D2O and Watson was related to hydration state and to percentage of fat mass (r = 0.70 and r = -0.53, p < 0.05). Both ECW and TBW as assessed by BIA and tracer dilution were related to echocardiographic parameters. CONCLUSION: Wide limits of agreement were found between MF-BIA and sigmaBIA with dilution methods in PD patients, which were related to hydration state itself. The disagreement between the Watson formula and dilution methods was related to both hydration state and body composition.