Clinical safety and performance of VIVIA: a novel home hemodialysis system.

Background: The VIVIA Hemodialysis System (Baxter Healthcare Corporation, Deerfield, IL, USA) was designed for patient use at home to reduce the burden of treatment and improve patient safety. It has unique features including extended use of the dialyzer and blood set through in situ hot-water disinfection between treatments; generation of on-line infusible-quality dialysate for automated priming, rinseback and hemodynamic support during hypotension and a fully integrated access disconnect sensor. Methods: The safety and performance of VIVIA were assessed in two clinical studies. A first-in-man study was a prospective, single-arm study that involved 22 prevalent hemodialysis (HD) patients who were treated for ∼4 h, four times a week, for 10 weeks. A second clinical study was a prospective, single-arm study (6-8 h of dialysis treatment at night three times a week) that involved 17 prevalent patients treated for 6 weeks. Results: There were 1114 treatments from the two studies (first-in-man study, 816; extended duration study, 298). Adverse events (AEs) were similar in the two studies to those expected for prevalent HD patients. No deaths and no device-related serious AEs occurred. Adequacy of dialysis ( Kt / V ) urea in both clinical trials was well above the clinical guidelines. VIVIA performed ultrafiltration accurately as prescribed in the two studies. The majority of patients achieved 10 or more uses of the dialyzer. Endotoxin levels and bacterial dialysate sampling met infusible-quality dialysate standards. Conclusion: These results confirm the safety and expected performance of VIVIA.

Recovery time, quality of life, and mortality in hemodialysis patients: the Dialysis Outcomes and Practice Patterns Study (DOPPS).

BACKGROUND: There is limited information about the clinical and prognostic significance of patient-reported recovery time. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: 6,040 patients in the DOPPS (Dialysis Outcomes and Practice Patterns Study). PREDICTOR: Answer to question "How long does it take you to recover from a dialysis session?" categorized as follows: fewer than 2, 2-6, 7-12, or longer than 12 hours. OUTCOMES & MEASUREMENTS: Cross-sectional and longitudinal associations between recovery time and patient characteristics, hemodialysis treatment variables, health-related quality of life (HRQoL), and hospitalization and mortality. RESULTS: 32% reported recovery time shorter than 2 hours; 41%, 2-6 hours; 17%, 7-12 hours; and 10%, longer than 12 hours. Using proportional odds (ordinal) logistic regression, shorter recovery time was associated with male sex, full-time employment, and higher serum albumin level. Longer recovery time was associated with older age, dialysis vintage, body mass index, diabetes, and psychiatric disorder. Greater intradialytic weight loss, longer dialysis session length, and lower dialysate sodium concentration were associated with longer recovery time. In facilities that used uniform dialysate sodium concentrations for ≥90% of patients, the adjusted OR of longer recovery time, comparing dialysate sodium concentration<140 vs 140 mEq/L, was 1.72 (95% CI, 1.37-2.16). Recovery time was correlated positively with symptoms of kidney failure and kidney disease burden score and inversely with HRQoL mental and physical component summary scores. Using Cox regression, adjusting for potential confounders not influenced by recovery time, it was associated positively with first hospitalization and mortality (adjusted HRs for recovery time>12 vs 2-6 hours 1.22 [95% CI, 1.09-1.37] and 1.47 [95% CI, 1.19-1.83], respectively). LIMITATIONS: Answers are subjective and not supported by physiologic measurements. CONCLUSIONS: Recovery time can be used to identify patients with poorer HRQoL and higher risks of hospitalization and mortality. Interventions to reduce recovery time and possibly improve clinical outcomes, such as increasing dialysate sodium concentration, need to be tested in randomized trials.

Simplified phosphorus kinetic modeling: predicting changes in predialysis serum phosphorus concentration after altering the hemodialysis prescription.

BACKGROUND: The KDIGO work group recommends increasing dialytic phosphorus removal in Stage 5D chronic kidney disease patients with persistent hyperphosphatemia; however, optimal prescriptions to enhance phosphorus removal by hemodialysis (HD) therapies have not yet been established. This study evaluated whether phosphorus kinetic modeling based on a pseudo one-compartment model could provide practical clinical guidance for predicting changes in predialysis serum phosphorus concentration after altering the HD prescription. METHODS: Patient-specific phosphorus kinetic parameters determined from thrice weekly HD treatments on 774 patients in the HEMO Study were used to predict changes in predialysis serum phosphorus concentration after altering the HD prescription from thrice weekly to short daily and long nocturnal HD therapies. The effect of changes in the oral phosphorus binder prescription on predicted changes in the predialysis serum phosphorus concentration was also illustrated using the concept of equivalent phosphorus binder dose. RESULTS: Decreases in predialysis serum phosphorus concentration from thrice weekly HD to short daily and long nocturnal HD prescriptions demonstrated strong associations with the predialysis serum phosphorus concentration during thrice weekly HD that were relatively independent of patient-specific phosphorus kinetic parameters. Thus, the percent decrease in predialysis serum phosphorus concentration was approximately the same among patients for a given alteration in the HD prescription. Both increased weekly treatment time and frequency resulted in a reduction in the predialysis serum phosphorus concentration; however, the effect of treatment time was more influential. Simultaneous reduction in the effective phosphorus binder dose blunted the decrease in the predialysis serum phosphorus concentration. CONCLUSIONS: This study demonstrated that a simplified form of phosphorus kinetic modeling based on a pseudo one-compartment model can provide practical clinical guidance for predicting changes in predialysis serum phosphorus concentration after altering the HD prescription. Prospective validation of this approach in future studies is warranted.

Randomized, controlled trial of glucose-sparing peritoneal dialysis in diabetic patients.

Glucose-containing peritoneal dialysis solutions may exacerbate metabolic abnormalities and increase cardiovascular risk in diabetic patients. Here, we examined whether a low-glucose regimen improves metabolic control in diabetic patients undergoing peritoneal dialysis. Eligible patients were randomly assigned in a 1:1 manner to the control group (dextrose solutions only) or to the low-glucose intervention group (IMPENDIA trial: combination of dextrose-based solution, icodextrin and amino acids; EDEN trial: a different dextrose-based solution, icodextrin and amino acids) and followed for 6 months. Combining both studies, 251 patients were allocated to control (n=127) or intervention (n=124) across 11 countries. The primary endpoint was change in glycated hemoglobin from baseline. Mean glycated hemoglobin at baseline was similar in both groups. In the intention-to-treat population, the mean glycated hemoglobin profile improved in the intervention group but remained unchanged in the control group (0.5% difference between groups; 95% confidence interval, 0.1% to 0.8%; P=0.006). Serum triglyceride, very-low-density lipoprotein, and apolipoprotein B levels also improved in the intervention group. Deaths and serious adverse events, including several related to extracellular fluid volume expansion, increased in the intervention group, however. These data suggest that a low-glucose dialysis regimen improves metabolic indices in diabetic patients receiving peritoneal dialysis but may be associated with an increased risk of extracellular fluid volume expansion. Thus, use of glucose-sparing regimens in peritoneal dialysis patients should be accompanied by close monitoring of fluid volume status.

Determinants of phosphorus mobilization during hemodialysis.

Our recent work proposed a pseudo one-compartment model for describing intradialysis and postdialysis rebound kinetics of phosphorus. In this model, phosphorus is removed directly from a central distribution volume with the rate of phosphorus mobilization from a second, very large compartment proportional to the phosphorus mobilization clearance. Here, we evaluated factors of phosphorus mobilization clearance and postdialysis central distribution volume from 774 patients in the HEMO Study. Phosphorus mobilization clearance and postdialysis central distribution volume were 87 (65, 116) ml/min, median (interquartile range), and 9.4 (7.2, 12.0) liter, respectively. The phosphorus mobilization clearance was significantly higher for male patients than for female patients. Both the phosphorus mobilization clearance and the postdialysis central distribution volume were significantly associated with postdialysis body weight but negatively with the predialysis serum phosphorus concentration. The postdialysis central distribution volume was also significantly associated with age. Overall, the postdialysis central distribution volume was 13.6% of the postdialysis body weight. Thus, the phosphorus mobilization clearance during hemodialysis is higher when predialysis serum phosphorus concentration is low and higher in male patients than in female patients. The central distribution volume of phosphorus is a space approximating the extracellular fluid volume.

Phosphorus kinetics during hemodiafiltration: analysis using a pseudo-one-compartment model.

BACKGROUND/AIMS: On-line hemodiafiltration (HDF) has been previously shown to result in modest reductions in predialysis serum phosphorus concentration compared with conventional hemodialysis (HD); however, understanding of phosphorus kinetics during these therapies remains limited. METHODS: Previously published phosphorus kinetic data during HDF and HD were analyzed using a pseudo-one-compartment kinetic model. Phosphorus mobilization clearance (KM) and dialyzer phosphorus clearance (Kd) were simultaneously estimated from measured predialysis and postdialysis serum phosphorus concentrations and total removed phosphorus during each treatment. RESULTS: KM varied among patients between 53 and 173 ml/min. Values of KM during HDF (105 ± 34, mean ± standard deviation, ml/min) and HD (112 ± 44 ml/min) were not different (p = 0.5); however, Kd during HDF (175 ± 23 ml/min) was higher (p = 0.01) than during HD (160 ± 14 ml/min). CONCLUSION: A pseudo-one-compartment kinetic model is useful for the analysis of phosphorus kinetic data during HDF. Lower predialysis serum phosphorus concentrations during HDF are likely due to increased extracorporeal phosphorus clearance.

Association between routine and standardized blood pressure measurements and left ventricular hypertrophy among patients on hemodialysis.

BACKGROUND: Left ventricular (LV) hypertrophy is common among patients on hemodialysis. While a relationship between blood pressure (BP) and LV hypertrophy has been established, it is unclear which BP measurement method is the strongest correlate of LV hypertrophy. We sought to determine agreement between various blood pressure measurement methods, as well as identify which method was the strongest correlate of LV hypertrophy among patients on hemodialysis. METHODS: This was a post-hoc analysis of data from a randomized controlled trial. We evaluated the agreement between seven BP measurement methods: standardized measurement at baseline; single pre- and post-dialysis, as well as mean intra-dialytic measurement at baseline; and cumulative pre-, intra- and post-dialysis readings (an average of 12 monthly readings based on a single day per month). Agreement was assessed using Lin's concordance correlation coefficient (CCC) and the Bland Altman method. Association between BP measurement method and LV hypertrophy on baseline cardiac MRI was determined using receiver operating characteristic curves and area under the curve (AUC). RESULTS: Agreement between BP measurement methods in the 39 patients on hemodialysis varied considerably, from a CCC of 0.35 to 0.94, with overlapping 95% confidence intervals. Pre-dialysis measurements were the weakest predictors of LV hypertrophy while standardized, post- and inter-dialytic measurements had similar and strong (AUC 0.79 to 0.80) predictive power for LV hypertrophy. CONCLUSIONS: A single standardized BP has strong predictive power for LV hypertrophy and performs just as well as more resource intensive cumulative measurements, whereas pre-dialysis blood pressure measurements have the weakest predictive power for LV hypertrophy. Current guidelines, which recommend using pre-dialysis measurements, should be revisited to confirm these results.

Nephrology visits and health care resource use before and after reporting estimated glomerular filtration rate.

CONTEXT: Laboratory reporting of estimated glomerular filtration rate (GFR) has been widely implemented, with limited evaluation. OBJECTIVE: To examine trends in nephrologist visits and health care resource use before and after estimated GFR reporting. DESIGN, SETTING, AND PATIENTS: Community-based cohort study (N = 1,135,968) with time-series analysis. Participants were identified from a laboratory registry in Alberta, Canada, and followed up from May 15, 2003, to March 14, 2007 (with estimated GFR reporting implemented October 15, 2004). MAIN OUTCOME MEASURE: Nephrologist visits and patient management. RESULTS: Following estimated GFR reporting, the rate of first outpatient visits to a nephrologist for patients with chronic kidney disease (CKD; estimated GFR <60 mL/min/1.73 m(2)) increased by 17.5 (95% confidence interval [CI], 16.5-18.6) visits per 10,000 CKD patients per month, corresponding to a relative increase from baseline of 68.4% (95% CI, 65.7%-71.2%). There was no association between estimated GFR reporting and rate of first nephrologist visit among patients without CKD. Among patients with an estimated GFR of less than 30 mL/min/1.73 m(2), the rate of first nephrologist visits increased by 134.4 (95% CI, 60.0-208.7) visits per 10,000 patients per month. This increase was predominantly seen in women, patients aged 46 to 65 years as well as those aged 86 years or older, and those with hypertension, diabetes, and comorbidity. Reporting of estimated GFR was not associated with increased rates of internal medicine or general practitioner visits or increased use of angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers among patients with CKD and proteinuria or the subgroup limited to patients with diabetes. CONCLUSIONS: Reporting of estimated GFR was associated with an increase in first nephrologist visits, particularly among patients with more severe kidney dysfunction, women, middle-aged and very elderly patients, and those with comorbidities. Any effect on outcomes remains to be shown.

Nocturnal hemodialysis does not improve overall measures of quality of life compared to conventional hemodialysis.

We conducted a randomized controlled trial to compare the quality of life of 52 patients undergoing nocturnal hemodialysis and conventional hemodialysis. Quality of life was measured using a number of established methods including the Kidney Disease Quality of Life Short Form and the preference-based Euroqol EQ-5D questionnaire (whose scores varied from 0 to 1). The primary outcome was a change in the Euroqol EQ-5D index scores between baseline and 6 months. We performed additional analyses comparing change in quality of life from pre-randomization (when patients were unaware of treatment allocation) to 6 months. Other analyses considered the impact of nocturnal hemodialysis on four pre-selected Kidney Disease Quality of Life Short Form domains, and the longer term impact of nocturnal hemodialysis on quality of life. Compared with conventional hemodialysis, nocturnal hemodialysis increased Euroqol-EQ-5D index scores by 0.05, which was not significantly different from baseline. When six-month values were compared with pre-randomization values rather than baseline values, the between group difference was larger (0.12) though it was still not statistically significant (P=.06). Nocturnal hemodialysis was associated with clinically and statistically significant improvements in selected kidney-specific quality of life domains (P=.01 for effects of kidney disease; P=.02 for burden of kidney disease). Our primary quality of life analysis did not demonstrate a statistically significant change between nocturnal hemodialysis and conventional hemodialysis, though statistically significant and clinically important changes in some secondary kidney-disease- specific measures were observed.

Overview of the Alberta Kidney Disease Network.

BACKGROUND: The Alberta Kidney Disease Network is a collaborative nephrology research organization based on a central repository of laboratory and administrative data from the Canadian province of Alberta. DESCRIPTION: The laboratory data within the Alberta Kidney Disease Network can be used to define patient populations, such as individuals with chronic kidney disease (using serum creatinine measurements to estimate kidney function) or anemia (using hemoglobin measurements). The administrative data within the Alberta Kidney Disease Network can also be used to define cohorts with common medical conditions such as hypertension and diabetes. Linkage of data sources permits assessment of socio-demographic information, clinical variables including comorbidity, as well as ascertainment of relevant outcomes such as health service encounters and events, the occurrence of new specified clinical outcomes and mortality. CONCLUSION: The unique ability to combine laboratory and administrative data for a large geographically defined population provides a rich data source not only for research purposes but for policy development and to guide the delivery of health care. This research model based on computerized laboratory data could serve as a prototype for the study of other chronic conditions.

Oral estrogen therapy in postmenopausal women is associated with loss of kidney function.

Women are generally protected against progressive loss of kidney function; however, this advantage seems to diminish with menopause. Because of conflicting reports on the association between use of hormone therapy and kidney function we studied 5845 women (1459 on hormone therapy and 4386 non-users) who were over 66 years of age and had at least 2 serum creatinine measurements during the 2 year study period. After adjustment for covariates, hormone use (estrogen-only, progestin-only, or both) was associated with a significant loss of estimated GFR as the primary outcome along with an increased risk of rapid loss of kidney function as the secondary outcome compared to non-users. This increased rate of loss was associated with oral but not transvaginal estrogen use. An increased cumulative dose of estrogen was also associated with a greater decline in estimated GFR. Our study shows an independent association in a dose-dependent manner of estrogen use and loss of kidney function in this elderly population.

Access to health care among status Aboriginal people with chronic kidney disease.

BACKGROUND: Ethnic disparities in access to health care and health outcomes are well documented. It is unclear whether similar differences exist between Aboriginal and non-Aboriginal people with chronic kidney disease in Canada. We determined whether access to care differed between status Aboriginal people (Aboriginal people registered under the federal Indian Act) and non-Aboriginal people with chronic kidney disease. METHODS: We identified 106 511 non-Aboriginal and 1182 Aboriginal patients with chronic kidney disease (estimated glomerular filtration rate less than 60 mL/min/1.73 m(2)). We compared outcomes, including hospital admissions, that may have been preventable with appropriate outpatient care (ambulatory-care-sensitive conditions) as well as use of specialist services, including visits to nephrologists and general internists. RESULTS: Aboriginal people were almost twice as likely as non-Aboriginal people to be admitted to hospital for an ambulatory-care-sensitive condition (rate ratio 1.77, 95% confidence interval [CI] 1.46-2.13). Aboriginal people with severe chronic kidney disease (estimated glomerular filtration rate < 30 mL/min/1.73 m(2)) were 43% less likely than non-Aboriginal people with severe chronic kidney disease to visit a nephrologist (hazard ratio 0.57, 95% CI 0.39-0.83). There was no difference in the likelihood of visiting a general internist (hazard ratio 1.00, 95% CI 0.83-1.21). INTERPRETATION: Increased rates of hospital admissions for ambulatory-care-sensitive conditions and a reduced likelihood of nephrology visits suggest potential inequities in care among status Aboriginal people with chronic kidney disease. The extent to which this may contribute to the higher rate of kidney failure in this population requires further exploration.

Prevalence of chronic kidney disease and survival among aboriginal people.

Globally, it is known that the incidence of end-stage renal disease is higher among Aboriginals, but it is unknown whether this is due to an increased prevalence of chronic kidney disease or other unidentified factors. We studied 658,664 people of non-First Nations and 14,989 people of First Nations and found that the age- and sex-adjusted prevalence of chronic kidney disease was significantly higher among those of non-First Nations compared to those of First Nations (67.5 versus 59.5 per 1000 population; P < 0.0001). However, severe chronic kidney disease (estimated glomerular filtration rate <30 ml/min per 1.73 m2) was almost two-fold higher among people of First Nations (P < 0.0001). Cox proportional hazards models suggested that compared to people of non-First Nations, those of First Nations with chronic kidney disease had a 77% increased risk of death after adjusting for age, gender, diabetes and baseline eGFR. In conclusion, whether the higher incidence of end-stage renal disease among people of First Nations is due to suboptimal management of chronic kidney disease and its associated comorbidities, more rapid loss of kidney function, or other unidentified factors remains to be determined.

Effect of frequent nocturnal hemodialysis vs conventional hemodialysis on left ventricular mass and quality of life: a randomized controlled trial.

CONTEXT: Morbidity and mortality rates in hemodialysis patients remain excessive. Alterations in the delivery of dialysis may lead to improved patient outcomes. OBJECTIVE: To compare the effects of frequent nocturnal hemodialysis vs conventional hemodialysis on change in left ventricular mass and health-related quality of life over 6 months. DESIGN, SETTING, AND PARTICIPANTS: A 2-group, parallel, randomized controlled trial conducted at 2 Canadian university centers between August 2004 and December 2006. A total of 52 patients undergoing hemodialysis were recruited. INTERVENTION: Participants were randomly assigned in a 1:1 ratio to receive nocturnal hemodialysis 6 times weekly or conventional hemodialysis 3 times weekly. MAIN OUTCOME MEASURES: The primary outcome was change in left ventricular mass, as measured by cardiovascular magnetic resonance imaging. The secondary outcomes were patient-reported quality of life, blood pressure, mineral metabolism, and use of medications. RESULTS: Frequent nocturnal hemodialysis significantly improved the primary outcome (mean left ventricular mass difference between groups, 15.3 g, 95% confidence interval [CI], 1.0 to 29.6 g; P = .04). Frequent nocturnal hemodialysis did not significantly improve quality of life (difference of change in EuroQol 5-D index from baseline, 0.05; 95% CI, -0.07 to 0.17; P = .43). However, frequent nocturnal hemodialysis was associated with clinically and statistically significant improvements in selected kidney-specific domains of quality of life (P = .01 for effects of kidney disease and P = .02 for burden of kidney disease). Frequent nocturnal hemodialysis was also associated with improvements in systolic blood pressure (P = .01 after adjustment) and mineral metabolism, including a reduction in or discontinuation of antihypertensive medications (16/26 patients in the nocturnal hemodialysis group vs 3/25 patients in the conventional hemodialysis group; P < .001) and oral phosphate binders (19/26 patients in the nocturnal hemodialysis group vs 3/25 patients in the conventional dialysis group; P < .001). No benefit in anemia management was seen with nocturnal hemodialysis. CONCLUSION: This preliminary study revealed that, compared with conventional hemodialysis (3 times weekly), frequent nocturnal hemodialysis improved left ventricular mass, reduced the need for blood pressure medications, improved some measures of mineral metabolism, and improved selected measures of quality of life. TRIAL REGISTRATION: isrctn.org Identifier: ISRCTN25858715.

Differences in use of peritoneal dialysis and survival among East Asian, Indo Asian, and white ESRD patients in Canada.

BACKGROUND: Racial differences in health outcomes in general are well documented; however, few studies examined the impact of East Asian and Indo Asian race on choice of dialytic modality and survival among patients with end-stage renal disease (ESRD). METHODS: We compared the use of peritoneal dialysis (PD) and survival among East Asian, Indo Asian, and white patients with ESRD initiating dialysis therapy in Canada between January 1, 1990, and December 31, 2000. RESULTS: Of 10,338 patients, 5.7% were East Asian, 3.2% were Indo Asian, and 91% were white. After controlling for sociodemographics and comorbidities, East Asian and Indo Asian patients were significantly more likely to initiate dialysis therapy on PD compared with white patients (odds ratio, 1.63; 95% confidence interval [CI], 1.36 to 1.96; odds ratio, 1.52; 95% CI, 1.21 to 1.93, respectively), with no difference in likelihood of technique failure. East Asian and Indo Asian patients had a lower risk for death after the initiation of dialysis therapy (irrespective of modality) compared with white patients, with adjusted hazard ratios of 0.66 (95% CI, 0.58 to 0.76) for East Asian patients and 0.63 (95% CI, 0.53 to 0.75) for Indo Asian patients. The survival benefit for East Asian and Indo Asian patients was similar in the subgroup that initiated dialysis therapy with PD. CONCLUSION: We found that Asian patients with ESRD were more likely to initiate dialysis therapy using PD, with improved survival after the initiation of dialysis therapy, compared with white patients. Elucidation of factors in East Asian and Indo Asian ESRD populations that result in improved outcomes may have implications for ESRD treatment for other racial groups.

Performance of the automated BpTRU measurement device in the assessment of white-coat hypertension and white-coat effect.

OBJECTIVES: BpTRU (VSM MedTech Ltd, Vancouver, Canada) is an automated oscillometric device that provides serial blood pressure measurements in an office setting in the absence of a healthcare professional. We sought to determine whether the white-coat effect is reduced by a blood pressure measurement protocol using BpTRU compared with casual office measurements. Secondarily, we also sought to determine whether a blood pressure measurement protocol using BpTRU reduced white-coat hypertension compared with the casual office measurements, and reduced white-coat effect and white-coat hypertension compared with blood pressure obtained by a research nurse. METHODS: Blood pressure was measured in 107 adult hypertensive patients referred for ambulatory blood pressure monitoring using an ambulatory blood pressure monitor, a standardized protocol by a trained research nurse, and a protocol using BpTRU (five readings over 25 min, using the 5-min blood pressure measurement interval setting). Casual office blood pressure was also recorded in the family physicians' offices. Using the mean daytime ambulatory blood pressure as the reference standard, the proportion of patients with white-coat effect and white-coat hypertension were determined for measurements obtained by BpTRU, the research nurse, and the family physicians' offices. RESULTS: Casual office blood pressure measurements demonstrated a white-coat effect in 39 (36.4%) patients; seven (6.5%) patients demonstrated a white-coat effect using BpTRU (P<0.0001). White-coat hypertension was also less common using BpTRU than with the casual office readings (13 vs. 1 patient, P<0.0001). White-coat effect was also reduced with BpTRU compared with the research nurse measurements. Unfortunately, percentage agreement for the diagnosis of hypertension between the protocol using BpTRU and the reference standard was only 48%. This resulted in substantial misclassification of hypertension by the BpTRU measurement protocol. CONCLUSIONS: Although BpTRU reduces white-coat effect and white-coat hypertension, blood pressure is underestimated by the device, leading to misclassification of hypertension. BpTRU, when set at 5-min blood pressure measurement intervals, should not be used in clinical practice.

The effects of nocturnal hemodialysis compared to conventional hemodialysis on change in left ventricular mass: rationale and study design of a randomized controlled pilot study.

BACKGROUND: Nocturnal hemodialysis (NHD) is an alternative to conventional three times per week hemodialysis (CvHD) and has been reported to improve several health outcomes. To date, no randomized controlled trial (RCT) has compared NHD and CvHD. We have undertaken a multi-center RCT in hemodialysis patients comparing the effect of NHD to CvHD on left ventricular (LV) mass, as measured by cardiac magnetic resonance imaging (cMR). METHODOLOGY/DESIGN: All patients in Alberta, Canada, expressing an interest in performing NHD are eligible for the study. Patients enrolled in the study will be randomized to either NHD or CvHD for a six month period. All patients will have a full clinical assessment, including collection of biochemical and cMR data at baseline and at 6 months. Both groups of patients will be monitored biweekly to optimize blood pressure (BP) to a goal of <130/80 mmHg post-dialysis using a predefined BP management protocol. The primary outcome is change in LV mass, a surrogate marker for cardiac mortality, measured at baseline and 6 months. The high sensitivity and reproducibility of cMR facilitates reduction of the required sample size and the time needed between measures compared with echocardiography. Secondary outcomes include BP control, anemia, mineral metabolism, health-related quality of life, and costs. DISCUSSION: To our knowledge, this study will be the first RCT evaluating health outcomes in NHD. The impact of NHD on LV mass represents a clinically important outcome which will further elucidate the potential benefits of NHD and guide future clinical endpoint studies.

Prescriptions of dialysate potassium concentration during short daily or long nocturnal (high dose) hemodialysis.

The prescription of dialysate potassium concentration during short daily and long nocturnal (high dose) hemodialysis (HD) is challenging due to limited clinical experience with such modalities. The aim here is to propose a quantitative approach for prescribing dialysate potassium concentrations during high-dose HD. Potassium kinetic parameters based on a pseudo one-compartment model from 547 patients participating in the HEMO Study were used for prediction purposes in this study. Patients were categorized based on the prescribed dialysate potassium concentration during thrice weekly HD as 1K (mean of 1.02 mEq/L, N = 60), 2K (2.01 mEq/L, N = 437), or 3K (3.01 mEq/L, N = 50). Dialysate potassium concentrations were then predicted for each patient during short daily and long nocturnal HD based on a pseudo one-compartment model to maintain the identical weekly dialytic potassium removal and predialysis serum potassium concentration as during thrice weekly HD. Predicted prescribed dialysate potassium concentrations for short daily HD were 0.18-0.45 mEq/L higher than during thrice weekly HD but were approximately 4 (3.72-4.26) mEq/L for all patients during long nocturnal HD. The intradialytic decrease in serum potassium concentration was predicted to be reduced by more than one-half during short daily HD and by approximately three-quarters during long nocturnal HD of that during thrice weekly HD. Prescribed dialysate potassium concentration during high-dose HD modalities can be quantitatively predicted using a pseudo one-compartment kinetic model. High-dose HD modalities may improve clinical outcomes by reducing intradialytic decreases in serum potassium.

Survival after coronary revascularization among patients with kidney disease.

BACKGROUND: The optimal approach to revascularization in patients with kidney disease has not been determined. We studied survival by treatment group (CABG, percutaneous coronary intervention [PCI], or no revascularization) for patients with 3 categories of kidney function: dialysis-dependent kidney disease, non-dialysis-dependent kidney disease, and a reference group (serum creatinine <2.3 mg/dL). METHODS AND RESULTS: Data were derived from the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH), which captures information on all patients undergoing cardiac catheterization in Alberta, Canada. Characteristics and patient survival in 662 dialysis patients (1.6%) and 750 non-dialysis-dependent kidney disease patients (1.8%) were compared with the remainder of the 40,374 patients (96.6%). For the reference group, the adjusted 8-year survival rates for CABG, PCI, and no revascularization (NR) were 85.5%, 80.4%, and 72.3%, respectively (P<0.001 for CABG versus NR; P<0.001 for PCI versus NR). Adjusted survival rates were 45.9% for CABG, 32.7% for PCI, and 29.7% for NR in the nondialysis kidney disease group (P<0.001 for CABG versus NR; P=0.48 for PCI versus NR) and 44.8% for CABG, 41.2% for PCI, and 30.4% for NR in the dialysis group (P=0.003 for CABG versus NR; P=0.03 for PCI versus NR). CONCLUSIONS: Compared with no revascularization, CABG was associated with better survival in all categories of kidney function. PCI was also associated with a lower risk of death than no revascularization in reference patients and dialysis-dependent kidney disease patients but not in patients with non-dialysis-dependent kidney disease. The presence of kidney disease or dependence on dialysis should not be a deterrent to revascularization, particularly with CABG.

Potassium kinetics during hemodialysis.

Hyperkalemia in hemodialysis patients is associated with high mortality, but prescription of low dialysate potassium concentrations to decrease serum potassium levels is associated with a high incidence of sudden cardiac arrest or sudden death. Improved clinical outcomes for these patients may be possible if rapid and substantial intradialysis decreases in serum potassium concentration can be avoided while maintaining adequate potassium removal. Data from kinetic modeling sessions during the HEMO Study of the dependence of serum potassium concentration on time during hemodialysis treatments and 30 minutes postdialysis were evaluated using a pseudo one-compartment model. Kinetic estimates of potassium mobilization clearance (K(M)) and predialysis central distribution volume (V(pre)) were determined in 551 hemodialysis patients. The studied patients were 58.8 ± 14.4 years of age with predialysis body weight of 72.1 ± 15.1 kg; 306 (55.4%) of the patients were female and 337 (61.2%) were black. K(M) and V(pre) for all patients were non-normally distributed with values of 158 (111, 235) (median [interquartile range]) mL/min and 15.6 (11.4, 22.8) L, respectively. K(M) was independent of dialysate potassium concentration (P > 0.2), but V(pre) was lower at higher dialysate potassium concentration (R = -0.188, P < 0.001). For patients with dialysate potassium concentration between 1.6 and 2.5 mEq/L (N = 437), multiple linear regression of K(M) and V(pre) demonstrated positive association with predialysis body weight and negative association with predialysis serum potassium concentration. Potassium kinetics during hemodialysis can be described using a pseudo one-compartment model.