Estimate of the dialysis dose using ionic dialysance

The Diascan equipment (Hospal) measures ionic dialysance from which it derives the Kt/V. It is automatic, does not need blood samples and displays the results in real time. The aim of the present study was to compare the Diascan Kt/V with the Kt/V obtained with four simple formulas: two based on a single pool model of urea kinetics (Lowrie 1983 and Daugirdas 1993) and the other based on the two pool model (Maduell formulation applied to Lowrie Kt/V and that proposed by Daugirdas 1995). We have analyzed the inter-method variability, the degree of relationship among the different procedures for Kt/V calculation and the intra-individual variability. The intermethod variability between Kt/V Diascan and Kt/V calculated by the four simple formulas were studied in one hemodialysis session in 19 patients. The Kt/V Diascan was statistically different from that calculated by the four formulas (1,021 +/- 0.140 Diascan vs 1,147 +/- 0.124 for Lowrie-83; vs 1,373 +/- 0.164 for Daugirdas-93; vs 0.963 +/- 0.105 for Maduell and vs 1,173 +/- 0.143 for Daugirdas-95, p < 0.01). The lowest inter-method variability was obtained with the Maduell's Kt/V (relative difference 9%) but even in this case 37% of patients had a variability above 10%. The correlation coefficient was not high enough to allow an estimation of the different Kt/V measurements from the Diascan Kt/V by a regression equation. To study the individual relationship between the Diascan Kt/V and the Kt/V calculated by the four formulations, we have determined the Kt/V every 30 minutes in one hemodialysis session in 30 patients. In all patients we observed a good relationship between the Diascan Kt/V and the other four (correlation coefficient of 0.9952 for Lowrie-83, 0.9976 for Daugirdas-93, 0.9961 for Maduell and 0.9971 for Daugirdas-95); with these correlation coefficientes it was possible to derive regression equations and to obtain an estimation of the four Kt/V's from the Diascan Kt/V. To study the individual variability of each procedure used in the Kt/V calculations we determined the coefficient of variation of the different methods in 5 consecutive hemodialysis sessions performed under identical conditions in 19 patients. The coefficient of variation was 3.7 +/- 1.8% for the Diascan Kt/V; 6.0 +/- 2.8 for the Lowrie-83 Kt/V; 5.8 +/- 2.4 for the Daugirdas-93 Kt/V; 6.5 +/- 2.6% for the Maduell Kt/V; and 5.7 +/- 2.2% for the Daugirdas-95 Kt/V (p < 0.01 between the Diascan Kt/V and the other four). CONCLUSIONS: Although the Diascan Kt/V was statistically different from the other four Kt/V's calculated by the usual formulas, the Diascan Kt/V has an excellent correlation with all of them and showed a lower intra-individual variability. It is possible to obtain an estimation of the calculated Kt/V for each patient by linear regression equation.     

Determination of the dose of dialysis with integrated modules in the same monitor

The "gold standard" method to measure the mass balance achieved during dialysis for a given solute is based on the total dialysate collection. This procedure is unfeasible and too cumbersome. For this reason, alternative methods have been proposed including the urea kinetic modelling (Kt/V), the measurement of effective ionic dialysance (Diascan), and the continuous spent sampling of dialysate (Quantiscan). The aim of this study was to compare the reliability and agreement of these two methods with the formulas proposed by the urea kinetic modelling for measuring the dialysis dose and others haemodialysis parameters. We studied 20 stable patients (16 men/4 women) dialyzed with a monitor equipped with the modules Diascan (DC) and Quantiscan (QC) (Integra. Hospal). The urea distribution volume (VD) was determined using anthropometric data (Watson equation) and QC data. Kt/V value was calculated according to Daurgidas 2nd generation formula corrected for the rebound (eKt/V), and using DC (Kt/VDC) and QC (Kt/VQC) data. The total mass of urea removed was calculated as 37,93 +/- 16 g/session. The VD calculated using Watson equation was 35.7 +/- 6.6 and the VDQC was 35.06 +/- 9.9. And they showed an significative correlation (r:0,82 p < 0.001). The (VDQC-VDWatson) difference was -0.64 +/- 5.8L (ns). Kt/VDC was equivalent to those of eKt/V (1.64 +/- 0.33 and 1.61 +/- 0.26, mean difference -0.02 +/- 0.29). However, Kt/VQC value was higher than eKt/V (1.67 +/- 0.22 and 1.61 +/- 0.26 mean difference 0.06 +/- 0.07 p < 0.01). Both values correlated highly (R2: 0.92 p < 0.001). Urea generation (C) calculated using UCM was 8.75 +/- 3.4 g/24 h and those calculated using QC was 8.64 +/- 3.21 g/24 h. Mean difference 0.10 +/- 1.14 (ns). G calculated by UCM correlated highly with that derived from QC (R2: 0.88 p < 0.001). In conclusion, Kt/VDC and Kt/VQC should be considered as valid measures for dialysis efficiency. However, the limits of agreement between Kt/VQC and eKt/V were closer than Kt/VDC.     

Kt as control and follow-up of the dose at a hemodialysis unit

To ensure our patients are receiving an adequate dose in every dialysis session there must be a target to achieve this in the short or medium term. The incorporation during the last years of the ionic dialysance (ID) in the monitors, has provided monitoring of the dialysis dose in real time and in every dialysis session. Lowrie y cols., recommend monitoring the dose with Kt, recommending at least 40 L in women and 45 L in men or individualizing the dose according to the body surface area. The target of this study was to monitor the dose with Kt in every dialysis session for 3 months, and to compare it with the monthly blood test. 51 patients (58% of our hemodialysis unit), 32 men and 19 women, 60.7+/-14 years old, in the hemodialysis programme for 37.7+/-52 months, were dialysed with a monitor with IC. The etiology of their chronic renal failure was: 3 tubulo-interstitial nephropathy, 9 glomerulonephritis, 12 vascular disease, 7 polycystic kidney disease, 7 diabetic nephropathy and 13 unknown. 1,606 sessions were analysed during a 3 month period. Every patient was treated with the usual parameters of dialysis with 2.1 m2 cellulose diacetate (33.3%), 1.9 m2 polisulfone (33.3%) or 1.8 m2 helixone, dialysis time of 263+/-32 minutes, blood flow of 405+/-66, with dialysate flow of 712+/-138 and body weight of 66.7+/-14 kg. Initial ID, final ID and Kt were measured in each session. URR and Kt/V were obtained by means of a monthly blood test. The initial ID was 232+/-41 ml/min, the final ID was 197+/-44 ml/min, the mean of Kt determinations was 56.6+/-14 L, the mean of Kt/V was 1.98+/-0.5 and the mean of URR was 79.2+/-7%. Although all patients were treated with a minimum recommended dose of Kt/V and URR when we used the Kt according to gender, we observed that 31% of patients do not get the minimum dose prescribed (48.1+/-2.4 L), 34.4% of the men and 26.3% of the women. If we use the Kt individualized for the body surface area, we observe that 43.1% of the patients do not get the minimum dose prescribed with 4.6+/-3.4 L less than the dose prescribed. We conclude that the monitoring of dialysis dose with the Kt provides a better discrimination detecting that between 30 and 40% of the patients perhaps do not get an adequate dose for their gender or body surface area.     

Conventional blood sampling versus On-Line Clearance Monitoring

On-line Clearance Monitoring (OCM) calculates the Kt/V during a dialysis session using a module incorporated into the Fresenius 4008 H/S haemodialysis machine (1). The method is based on repeated increments in dialysate sodium concentrations followed by measuring the change of dialysate sodium concentration after the dialysate has passed through the kidney. OCM is a patient friendly, non-invasive and easy method for measuring Kt/V. Kt/V calculated on single-pool urea kinetics according to Daugirdas was compared to Kt/V measured by OCM in thirty stable patients on chronic haemodialysis. Patients were dialysed using a dialyser with either a high-flux polysulfone or a haemophane membrane. In four patients OCM was measured in ten consecutive sessions to assess the intra-individual variation in OCM. The calculated Kt/V was compared to Kt/Vocm in three patients at five consecutive dialysis sessions to measure the intra-individual correlation. A linear correlation was present between Kt/Vocal and Kt/Vac for both the polysulfone and haemophane membrane. Intra-individual Kt/Vocm showed very stable values with an average variation of less than 5%. Intra-individual correlation between calculated Kt/V and Kt/Vocm was high.     

透析液流量对血液透析充分性的影响

目的：观察增加透析液流量（Qd）对维持性血液透析（MHD）患者透析充分性的影响。方法：随机选择稳定透析6个月以上的MHD患者38例。血透透析液流量定于500ml／min和800ml／min各透析4周，其他透析参数[透析时间，血流量（Qb），超滤量和透析器型号与面积]不变。每种Qd量于第3周和第4周分别测定透析前后血尿素氮（BUN）、血肌酐（SCr）水平，记录每次透析的透析时间、超滤量及透析后体重（W），并根据Kt／V的自然对数公式计算Kt／V、尿素下降率（URR），取2次测定值的平均值作为患者该透析液流量的Kt／V。同时检测第4周及第8周透析前的血红蛋白（Hb）和红细胞压积（Hct）水平。采用成对t检验和卡方检验进行统计学分析。结果：本研究中每例患者构成自身对照，研究前后一般情况完全一致。Qd为800ml／min时URR及Kt／V值均较Qd流量为500ml／min时增加，具有统计学意义（P〈0．05），而SCr下降率、Hb和Hct水平略有增加趋势，无显著性差异。Qd为800ml／min时透析后URR〉65％的百分数明显高于Qd为500ml／min时，具有显著统计学意义（P〈0．001）。结论：将Qd从500ml／min增加至800ml／min，可显著增加URR、增加Kt／V，提高透析充分性达标率。800ml／min透析液流量的MHD可选择性用于不便于延长治疗时间和提高血流量达到透析充分性的患者。     

The adequacy of peritoneal dialysis in a single Chinese center

ObjectiveTo assess the adequacy of peritoneal dialysis in Chinese by analyzing the relationship between weekly urea kinetics (Kt/V) and clinical outcomes.MethodsA total of 146 patients on continuous ambulatory peritoneal dialysis for more than 6 months in the Shanghai Renji Hospital between July 1997 and March 1999 were enrolled into this study. They were assigned to three groups according to weekly Kt/V: Group A, Kt/V less than 1.7; Group B, Kt/V between 1.7 and 2; and Group C, Kt/V greater than 2. Patient and technique survivals were analyzed by using the log rank method.ResultsThe overall 2-year actuarial patient and technique survivals were 90% and 76%, respectively. The 2-year actuarial patient survival was 78% for Group A, 97% for Group B, and 96% for Group C (p<0.05). The 2-year technique survival was 56% for Group A, 88% for Group B, and 88% for Group C. Both actuarial patient and technique survivals in Group A were significantly lower (p<0.05) compared with the other two groups.ConclusionThe study showed that clinical outcomes in Groups B and C patients were similar. However, patients with weekly Kt/V values less than 1.7 had poorer clinical outcomes compared with patients from groups B and C. We conclude that Chinese patients who were receiving peritoneal ambulatory dialysis may benefit from weekly Kt/V greater than 1.7.     

残余肾功能状态对腹膜透析效能的影响

目的:前瞻性观察终末期肾衰(ESRF)患者在腹膜透析(PD)治疗后残余肾功能(RRF)对透析效能及相关临床指标之间的影响。方法:所有患者按残余肾小球滤过率(rGFR)水平将其分为A组(GFR0~2ml/min)、B组(GFR2·1~4ml/min)和C组(GFR>4ml/min)。每3个月进行一次临床随访,全面评估患者的全身情况及透析状态,包括血压、身高、体重、体重指数(BMI)、尿量(UV)、残余肾肌酐清除率(Ccr)、每周总尿素氮表现率(Kt/Vtotal)、每周肌酐总清除率(WCcrtotal)、蛋白氮呈现率(nPNA)、残余肾尿素及Ccr。对比观察不同RRF状态患者透析状况和部分临床及生化指标变化。尿量<100ml/d或Ccr<1·0ml/min视为无尿。结果:三组不同残肾状态患者Kt/vtotal和Ccr分别为1·75±0·35、2·07±0·54、2·46±0·50和53·4±11·2、66·6±11·2、97·6±22·1(L/Wks),各组之间差异非常显著(P<0·001)。三组不同残余肾Kt/v和Ccr分别占总体kt/v的12·4%、27%、45·7%及总体Ccr的18·3%、47·3%和65·3%,三组间相比差异亦显著(P<0·01)。此外,三组间高血压发生率、心胸比例及左心室肥厚(LVH)亦存在一定差异,C组心脏增大的病例明显低于A、B两组。RRF状态与透析效能呈正相关。本组患者除2例在透析治疗时即无尿,128例患者中有31例(24·2%)发生无尿,其中原发病为血管炎综合征及糖尿病肾病各占4例和7例,其无尿发生率分别占本病种的66·7%及25·9%;另20例无尿患者为肾小球肾炎或其它疾病,占此类疾病的20·6%。此外,发生无尿患者中有5例(16·1%)透析时尿量<300ml/d。结论:PD患者的残余肾仍然是清除体内代谢产物的重要途径,同时也影响血压及心血管系统并发症。     

Ionic dialysance and quality control in hemodialysis

Quantification of dialysis is based on the measurement of effective urea clearance (K), dialysis dose (Kt) or normalized dialysis dose (Kt/V). During the last 20 years, Kt/V was the single parameter actually useful for quantifying dialysis efficiency, because it can be calculated from just blood or dialysate urea concentrations at the beginning and at the end of the dialysis session. However the calculation of the normalized dialysis dose (Kt/V) actually delivered to the patient cannot be performed during each dialysis session, because of the need of urea concentration measurements. Ionic dialysance is a new parameter easily measured on-line, non-invasively, automatically and without any cost during each dialysis session by a conductivity method. Because ionic dialysance has been proved equal to the effective urea clearance taking into account cardiopulmonary and access recirculation, it is becoming an actual quality-assurance parameter of the dialysis efficiency.     

Monitoring hemodialysis dose with ionic dialisance in on-line hemodiafiltration

Until now, with the ionic dialysance measurement, it has been possible to determine hemodialysis dose in each session of hemodialysis (HD) and in the conventional hemofiltration (HDF) but not in the modality of on-line HDF. Recently it is possible with a new biosensor that allows to measure the dose in on-line HDF. The aim of this study was to evaluate the value of this biosensor in different dialysis situations comparing the dialysis dose measured in blood in comparison with the values obtained from the sensor. We have analysed 192 hemodialysis sessions performed in 24 patients, 15 male and 9 female, mean age of 70.2 +/- 12 years, included in on-line HDF. All treatments were done using 4008H (Fresenius) monitor equipped with on-line clearance monitoring (OCM), that measure, with non invasive monitoring, the effective ionic dialysance equivalent to urea clearance. Every patient received eight dialysis sessions: one with dialysate flow (Qd) 500 ml/min, two with HD and Qd 800 ml/min and five with on-line HDF. Other habitual haemodialysis parameters were no changed, dialysis time 200 +/- 63 min (135-300) and blood flow 421 +/- 29 ml/min (350-450). Initial and final ionic dialysance values (K), final Kt, Kt/V measured with OCM using V of Watson, and Kt/V determined in blood pre and postdialysis concentrations of urea (Daugirdas second generation), were measured. The mean of initial K was 251 +/- 21 ml/min and the final K was 234 +/- 24 ml/min. The Kt measured with OCM was 50.6 +/- 17 L, 51.2 +/- 17 in men and 49.7 +/- 16 in women. The V (Watson) was 34.5 +/- 6 L. The Kt/V measured with the Kt of OCM and V was 1,499 +/- 0.54 and Kt/V measured in blood samples was 1,742 +/- 0.58. The correlation between both values was 0.956. The Kt was different according to dialysis modality used: in HD and Qd 500 was 44.7 +/- 15 L, in HD and Qd 800 was 50.7 +/- 17 and in on-line HDF (22.1 +/- 7 L of reposition volume), was 51.8 +/- 17 L. The Kt/V from blood samples also shows variation: in HD and QD 500 was 1.60 +/- 0.55, in HD and Qd 800 was 1,726 +/- 0.56 and in on-line HDF was 1,776 +/- 0.59. In this study has been observed a close correlation between the new biosensor OCM with the measures obtained from the blood samples. For this reason this sensor it is useful in all modalities of dialysis treatment, included on-line HDF. The sensor was able to discriminate the efficacy of different dialysis modalities used in this study.     

Monitoring parameters of dialysis dose

In order to deliver a specific dialysis dose (Kt/V) to all patients, their product Kt (urea clearance K multiplied by dialysis time t) should be individually adjusted according to total body water (V) of each patient. With dialysis time being fixed in most centres for organisational reasons, such individualization can be accomplished by individually set blood flow (QB). For a given t, the value of QB also defines the magnitude of the cumulative blood volume (VB = QB*t), i.e. the volume of blood perfused through the dialyser during the whole dialysis time. VB is displayed by every contemporary dialysis machine but not used. The aim of this work was to derive an easy to use approach to QB individualization based on patient's body weight and dialysis time to obtain a desired Kt/V value which would also be easy to check after dialysis by looking at the obtained VB value. Statistically significant correlation was found between the QB-based Kt/V estimation and Kt/V determined by the other two methods demonstrating practical feasibility of the novel approach. Kt/V values obtained with the QB prescribed according to patient's body weight tended to be better in females and patients with higher body mass index.     

Correlates of urea kinetic modeling during hemodialysis in patients with acute renal failure

The current guidelines on dialysis adequacy in acute renal failure (ARF) are loosely defined and have been extrapolated from patients with end-stage renal disease. The objectives of this study were (1) to compare three methods of urea kinetic modeling measurement in patients with ARF receiving intermittent hemodialysis, (2) to compare prescribed to delivered dose of dialysis, and (3) to explore the factors that are associated with dialysis delivery. 'Single-pool' urea kinetic modeling was assessed by the Ureakin) software and the second-generation equation which uses a logarithmic estimate of spKt/V. 'Equilibrated' Kt/V (eKt/V) was calculated using the rate adjustment equation. The prescribed dose was derived using the manufacturer's specifications of the dialyzer clearance, prescribed time, actual delivered blood and dialysate flow, and estimates of volume of urea distribution. A total of 78 consecutive spKt/V measurements were obtained in 24 patients. The mean urea reduction ratio was 51 +/- 1%. The delivered spKt/V was significantly lower than that prescribed (0.87 +/- 0.03 or 0.83 +/- 0.03 vs. 1.28 +/- 0.05; p = 0.0001). The equilibrated Kt/V was markedly lower than the delivered spKt/V (0.73 +/- 0.03 vs. 0.83 +/- 0.03; p = 0.0001). Univariate analyses demonstrated that female gender, low body mass index, low predialysis weight, use of cellulose acetate dialyzers, and increased prescribed time were associated with increased odds of prescribed spKt/V > or =1.2. Similarly, old age, increased delivered time, and high cytokine production were associated with increased odds of delivered spKt/V > or =1.2. In summary, while the impact of delivered intermittent hemodialysis on the survival of patients with ARF remains to be determined, these results indicate that dialysis delivery is suboptimal in ARF, and empiric dosing should strongly consider factors related to lean body mass, including age and gender.     

Patient and technique survival in continuous ambulatory peritoneal dialysis (CAPD) with a basic three 2-liter daily exchanges: a 12- year single center experience in the pre-urea kinetics era

Continuous ambulatory peritoneal dialysis (CAPD) is the prevailing mode of renal replacement therapy in Hong Kong and the routine practice is three 2 L daily exchanges with four exchanges reserved for patients with ultrafiltration problems or clinically inadequate dialysis. In our hospital, Tung Wah Hospital, adequacy of dialysis assessment by urea kinetics was conducted after 1993 and adjustment of dialysis regime according to Kt/V was made only after 1995. This study represented the survival data of CAPD patients in our center before the urea kinetics era. From 1983 to 1994, we have accepted 569 patients into our CAPD program with a mean age ±SD of 47.8 ±15.4 and incidence of diabetes of 17.9%. The overall patient survival rates were 92%, 56% and 26% at 1, 5 and 10 years respectively. The corresponding technique survival rates were 97%, 86% and 60%. A cross-sectional analysis of the CAPD population from 1993 to 1994 showed that only 5% of patients were on four 2 L exchanges and the mean Kt/V was 1.76 ±0.35 and creatinine clearance 58.1 ±23.2 L/week/1.73 m². The patient and technique survival rates were comparable to western centers with a higher mean Kt/V and creatinine clearance. Our data showed that favorable clinical outcome can be achieved with three 2 L daily exchange regime in Chinese patients. This indicates different Kt/V standards may exist for different racial populations.     

El Kt/V alto,a diferencia del Kt,se asocia a mayor mortalidad: importancia de la V baja

Introduction

Kt/V has been used as a synonym for haemodialysis dose. Patient survival improved with a Kt/V > 1; this target was subsequently increased to 1.2 and 1.3. The HEMO study revealed no significant relationship between Kt/V and mortality. The relationship between Kt/V and mortality often shows a J-shaped curve. Is V the confounding factor in this relationship? The objective of this study is to determine the relationship between mortality and Kt/V, Kt and body water content (V) and lean mass (bioimpedance).

Evaluation of methods to calculate dialysis dose in daily hemodialysis

Daily dialysis has shown excellent clinical results because a higher frequency of dialysis is more physiological. Different methods have been described to calculate dialysis dose which take into consideration change in frequency. The aim of this study was to calculate all dialysis dose possibilities and evaluate the better and practical options. Eight patients, 6 males and 2 females, on standard 4 to 5 hours thrice weekly on-line hemodiafiltration (S-OL-HDF) were switched to daily on-line hemodiafiltration (D-OL-HDF) 2 to 2.5 hours six times per week. Dialysis parameters were identical during both periods and only frequency and dialysis time of each session were changed. Time average concentration (TAC), time average deviation (TAD), normalized protein catabolic rate (nPCR), Kt/V, equilibrated Kt/V (eKt/V), equivalent renal urea clearance (EKR), standard Kt/V (stdKt/V), urea reduction ratio (URR), hemodialysis product and time off dialysis were measured. Daily on-line hemodiafiltration was well accepted and tolerated. Patients maintained the same TAC although TAD decreased from 9.7 +/- 2 in baseline to a 6.2 +/- 2 mg/dl after six months, p < 0.01. No significant changes were observed in weekly Kt/V and eKt/V throughout the study. However EKR, stdKt/V and weekly URR were increased during D-OL-HDF in 24-34%, 46% and 50%, respectively. Hemodialysis product was raised in a 95% and time off dialysis was reduced to half. CONCLUSION: Dialysis frequency is an important urea kinetic parameter which there are to take in consideration. It's necessary to use EKR, stdKt/V or weekly URR to calculate dialysis dose for an adequate comparison between different frequency dialysis schedules.     

Assessment of Dialysis Dose in Critically Ill Maintenance Dialysis Patients

Maintenance dialysis patients are admitted more frequently to the intensive care unit (ICU) and have higher ICU mortality than the general population. It is unclear if such dialysis patients receive adequate dialysis in the ICU setting. Using the Daugirdas formula for calculation of spKt/Vurea, single treatment delivered dialysis dose was assessed in 85 critically ill maintenance hemodialysis patients during their first ICU dialysis session. Weekly delivered spKt/Vurea was determined in the surviving 64 patients and compared with their corresponding delivered outpatient dialysis dosages. Outcome measures were ICU and in‐hospital mortality and mortality at 6 and 12 months after discharge. Prescribed dose of the first ICU dialysis was a spKt/Vurea of 1.43 ± 0.11, the single treatment delivered dose was 1.02 ± 0.14. The weekly prescribed ICU Kt/Vurea was 4.25 ± 0.12 and delivered ICU Kt/Vurea was 3.48 ± 0.19. Patients with sepsis had the lowest mean spKt/Vurea values (0.87 ± 0.12). Serial measurements of delivered dialysis dose suggest that this gap is explained by variability of volume of urea distribution. ICU mortality was 25% and was related to APACHE II score, but not to delivered intermittent hemodialysis dose. Critically ill maintenance dialysis patients receive suboptimal dialysis doses. The impact of short‐term underdialysis on survival of hospitalized maintenance dialysis patients remains unknown. Assessment of dialysis adequacy should be routinely performed in these patients and delivered dialysis should be tracked through the initial clinical course.     

Treatment time and ultrafiltration rate are more important in dialysis prescription than small molecule clearance

Chronic hemodialysis sessions, as developed in Seattle in the 1960s, were long procedures with minimal intra- and interdialytic symptoms. Over the next three decades, dialysis duration was shorten to 4, 3, even 2 h in thrice weekly schedules. This method spread rapidly, particularly in the United States, after the National Cooperative Dialysis Study suggested that the time of dialysis is of minor importance as long as urea clearance multiplied by dialysis time and scaled to total body water (Kt/V(urea)) equals 0.95-1.0. This number was later increased to 1.3, but the assumption that hemodialysis time is of minimal importance remained unchanged. However, Kt/V(urea) measures only the removal of low molecular weight substances and does not consider the removal of larger molecules. Nor does it correlate with the other important function of hemodialysis, namely ultrafiltration. Rapid ultrafiltration is associated with cramps, nausea, vomiting, headache, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control leading to left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. Kt/V(urea) should be abandoned as a measure of dialysis quality. The formula suggests that it is possible to decrease t as long as K is proportionately increased, but this is not true. Time of dialysis should be adjusted in such a way that patients would not suffer from symptoms related to rapid ultrafiltration, would not have other uremic symptoms and most patients would have blood pressure controlled without antihypertensive drugs.