Our shared responsibility: the urgent necessity of global environmentally sustainable kidney care

In response to Earth's accelerating climate crisis, we, an international group of nephrologists, call on our global community to unite and align kidney care in accordance with United Nation's 26th Conference of the Parties health sector principles. We announce a global and inclusive initiative, "GREEN-K": Global Environmental Evolution in Nephrology and Kidney Care, with a vision of "sustainable kidney care for a healthy planet and healthy kidneys" and mission to "promote and support environmentally sustainable and resilient kidney care globally through advocacy, education, and collaboration." A patient-centric approach that permits climate change mitigation and adaptation is proposed. Multi-stakeholder GREEN-K action and focus areas will include education, sustainable clinical care, and advances toward environmentally sustainable innovations, procurement, and infrastructure. Mindful of the disproportionately high climate impact of kidney therapies, we welcome the opportunity to work together in shared accountability to patients and Earth's natural systems.

Factors influencing kidney transplantation rates: a study from the ERA Registry

BACKGROUND

Large international differences exist in kidney transplantation (KT) rates. We aimed to investigate which factors may explain the total, deceased donor, and living donor KT rates over the last decade.

METHODS

KT experts from 39 European countries completed the Kidney Transplantation Rate Survey on measures and barriers and their potential effect on the KT rate in their country. In the analyses, countries were divided into low, middle, and high KT rate countries based on the KT rate at the start of study period in 2010.

RESULTS

Experts from low KT rate countries reported more frequently to have taken measures regarding staff, equipment and facilities to increase total KT rate compared with middle and high KT rate countries. For donor type specific KT, the largest international differences in measures taken were reported for deceased donor KT, with middle and high KT rate countries taking more measures, such as the use of expanded criteria donor kidneys, the presence of transplantation coordinators, and (inter)national exchange of donor kidneys. Once a measure was taken, experts' opinion on its success was similar across the low, middle and high KT rate countries. Experts from low KT rate countries more often reported potential barriers, such as patients' lack of knowledge and distrust in the health care system.

CONCLUSIONS

In particular in low KT rate countries, KT rate might be stimulated by optimizing staff, equipment, and facilities. In addition, all countries may benefit from deceased and living donor specific measures.

Results of the European EDITH nephrologist survey on factors influencing treatment modality choice for end-stage kidney disease

BACKGROUND

Access to forms of dialysis, kidney transplantation (Tx) and comprehensive conservative management (CCM) for patients with end-stage kidney disease (ESKD) varies across European countries. Attitudes of nephrologists, information provision and decision-making may influence this access and nephrologists may experience several barriers when providing treatments for ESKD.

METHODS

We surveyed European nephrologists and kidney transplant surgeons treating adults with ESKD about factors influencing modality choice. Descriptive statistics were used to compare the opinions of professionals from European countries with low-, middle- and high-gross domestic product purchasing power parity (GDP PPP).

RESULTS

In total, 681 professionals from 33 European countries participated. Respondents from all GDP categories indicated that ∼10% of patients received no information before the start of renal replacement therapy (RRT) (P = 0.106). Early information provision and more involvement of patients in decision-making were more frequently reported in middle- and high-GDP countries (P < 0.05). Professionals' attitudes towards several treatments became more positive with increasing GDP (P < 0.05). Uptake of in-centre haemodialysis was sufficient to 73% of respondents, but many wanted increased uptake of home dialysis, Tx and CCM. Respondents experienced different barriers according to availability of specific treatments in their centre. The occurrence of barriers (financial, staff shortage, lack of space/supplies and patient related) decreased with increasing GDP (P < 0.05).

CONCLUSIONS

Differences in factors influencing modality choice when providing RRT or CCM to adults with ESKD were found among low-, middle- and high-GDP countries in Europe. Therefore a unique pan-European policy to improve access to treatments may be inefficient. Different policies for clusters of countries could be more useful.

International Society of Nephrology Global Kidney Health Atlas: structures, organization, and services for the management of kidney failure in Western Europe

Populations in the high-income countries of Western Europe are aging due to increased life expectancy. As the prevalence of diabetes and obesity has increased, so has the burden of kidney failure. To determine the global capacity for kidney replacement therapy and conservative kidney management, the International Society of Nephrology conducted multinational, cross-sectional surveys and published the findings in the International Society of Nephrology Global Kidney Health Atlas. In the second iteration of the International Society of Nephrology Global Kidney Health Atlas, we aimed to describe the availability, accessibility, quality, and affordability of kidney failure care in Western Europe. Among the 29 countries in Western Europe, 21 (72.4%) responded, representing 99% of the region's population. The burden of kidney failure prevalence varied widely, ranging from 760 per million population (pmp) in Iceland to 1612 pmp in Portugal. Coverage of kidney replacement therapy from public funding was nearly universal, with the exceptions of Germany and Liechtenstein where part of the costs was covered by mandatory insurance. Fourteen (67%) of 21 countries charged no fees at the point of care delivery, but in 5 countries (24%), patients do pay some out-of-pocket costs. Long-term dialysis services (both hemodialysis and peritoneal dialysis) were available in all countries in the region, and kidney transplantation services were available in 19 (90%) countries. The incidence of kidney transplantation varied widely between countries from 12 pmp in Luxembourg to 70.45 pmp in Spain. Conservative kidney care was available in 18 (90%) of 21 countries. The median number of nephrologists was 22.9 pmp (range: 9.47-55.75 pmp). These data highlight the uniform capacity of Western Europe to provide kidney failure care, but also the scope for improvement in disease prevention and management, as exemplified by the variability in disease burden and transplantation rates.

Patient-reported factors influencing the choice of their kidney replacement treatment modality

Background

Access to various kidney replacement therapy (KRT) modalities for patients with end-stage kidney disease differs substantially within Europe.

Methods

European adults on KRT filled out an online or paper-based survey about factors influencing and experiences with modality choice (e.g. information provision, decision-making and reasons for choice) between November 2017 and January 2019. We compared countries with low, middle and high gross domestic product (GDP).

Results

In total, 7820 patients [mean age 59 years, 56% male, 63% on centre haemodialysis (CHD)] from 38 countries participated. Twenty-five percent had received no information on the different modalities, and only 23% received information >12 months before KRT initiation. Patients were not informed about home haemodialysis (HHD) (42%) and comprehensive conservative management (33%). Besides nephrologists, nurses more frequently provided information in high-GDP countries, whereas physicians other than nephrologists did so in low-GDP countries. Patients from low-GDP countries reported later information provision, less information about other modalities than CHD and lower satisfaction with information. The majority of modality decisions were made involving both patient and nephrologist. Patients reported subjective (e.g. quality of life and fears) and objective reasons (e.g. costs and availability of treatments) for modality choice. Patients had good experiences with all modalities, but experiences were better for HHD and kidney transplantation and in middle- and high-GDP countries.

Conclusion

Our results suggest European differences in patient-reported factors influencing KRT modality choice, possibly caused by disparities in availability of KRT modalities, different healthcare systems and varying patient preferences. Availability of home dialysis and kidney transplantation should be optimized.

Inflammation and Erythropoiesis-Stimulating Agent Response in Hemodialysis Patients: A Self-matched Longitudinal Study of Anemia Management in the Dialysis Outcomes and Practice Patterns Study (DOPPS)

Rationale & Objective

Previous studies of inflammation and anemia management in hemodialysis (HD) patients may be biased due to patient differences. We used a self-matched longitudinal design to test whether new inflammation, defined as an acute increase in C-reactive protein (CRP) level, reduces hemoglobin response to erythropoiesis-stimulating agent (ESA) treatment.

Study Design

Self-matched longitudinal design.

Setting & Participants

3,568 new inflammation events, defined as CRP level > 10 mg/L following a 3-month period with CRP level ≤ 5 mg/L, were identified from 12,389 HD patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 4 to 6 (2009-2018) in 10 countries in which CRP is routinely measured.

Predictor

“After” (vs “before”) observing a high CRP level.

Outcomes

Within-patient changes in hemoglobin level, ESA dose, and ESA hyporesponsiveness (hemoglobin < 10 g/dL and ESA dose > 6,000 [Japan] or >8,000 [Europe] U/wk).

Analytical Approach

Linear mixed models and modified Poisson regression.

Results

Comparing before with after periods, mean hemoglobin level decreased from 11.2 to 10.9 g/dL (adjusted mean change, −0.26 g/dL), while mean ESA dose increased from 6,320 to 6,960 U/wk (adjusted relative change, 8.4%). The prevalence of ESA hyporesponsiveness increased from 7.6% to 12.3%. Both the unadjusted and adjusted prevalence ratios of ESA hyporesponsiveness were 1.68 (95% CI, 1.48-1.91). These associations were consistent in sensitivity analyses varying CRP thresholds and were stronger when the CRP level increase was sustained over the 3-month after period.

Limitations

Residual confounding by unmeasured time-varying risk factors for ESA hyporesponsiveness.

Conclusions

In the 3 months after HD patients experienced an increase in CRP levels, hemoglobin levels declined quickly, ESA doses increased, and the prevalence of ESA hyporesponsiveness increased appreciably. Routine CRP measurement could identify inflammation as a cause of worsened anemia. In turn, these findings speak to a potentially important role for anemia therapies that are less susceptible to the effects of inflammation.

Influence of Dialysate on Gastric Emptying Time in Peritoneal Dialysis Patients

Objective

Peritoneal dialysis (PD) patients frequently suffer from dyspeptic complaints such as nausea, vomiting, abdominal distension, early satiety, and anorexia. Gastroparesis might be, at least partially, a source of dyspeptic complaints in PD patients. The aim of the present study was to determine the influence of the presence and composition of dialysate on gastric emptying in PD patients.

Design

Prospective study.

Setting

Renal Division, Department of Internal Medicine, Ghent University Hospital, Belgium.

Patients

Sixty-one PD patients using different dialysate solutions, and 27 healthy volunteers.

Main Outcome Measure

Gastric emptying of solids was assessed by the 13C-octanoic acid breath test.

Results

Gastric emptying was impaired in PD patients, regardless of the composition of dialysate and even if tested with an empty peritoneal cavity. Gastric emptying was significantly slower when glucose-containing dialysate was compared to an empty peritoneal cavity, or when glucose-containing dialysate was compared to icodextrin dialysate. No difference in gastric emptying could be demonstrated between glucose-containing dialysate and dialysate containing a mixture of glycerol and amino acids as osmotic agent.

Conclusions

These findings suggest that the delay in gastric emptying demonstrated in the presence of peritoneal dialysate is not the consequence of a mere volume or pressure effect, but of the absorption of substrate substances with caloric and/or metabolic activity, such as glucose or glycerol and amino acids.

Association between changes in quality of life and mortality in hemodialysis patients: results from the DOPPS

Background

Cross-sectional health-related quality of life (HR-QOL) measures are associated with mortality in hemodialysis (HD) patients. The impact of changes in HR-QOL on outcomes remains unclear. We describe the association of prior changes in HR-QOL with subsequent mortality among HD patients.

Methods

A total of 13 784 patients in the Dialysis Outcomes and Practice Patterns Study had more than one measurement of HR-QOL. The impact of changes between two measurements of the physical (PCS) and mental (MCS) component summary scores of the SF-12 on mortality was estimated with Cox regression.

Results

Mean age was 62 years (standard deviation: 14 years); 59% were male and 32% diabetic. Median time between HR-QOL measurements was 12 months [interquartile range (IQR): 11, 14]. Median initial PCS and MCS scores were 37.5 (IQR: 29.4, 46.2) and 46.4 (IQR: 37.2, 54.9); median changes in PCS and MCS scores were -0.2 (IQR: -5.5, 4.7) and -0.1 (IQR: -6.8, 5.9), respectively. The adjusted hazard ratio (HR) for a 5-point decline in HR-QOL score was 1.09 [95% confidence interval (CI): 1.06-1.12] for PCS and 1.05 (95% CI: 1.03-1.08) for MCS. Adjusting for the second QOL score, the change was not associated with mortality: HR = 1.01 (95% CI: 0.98-1.05) for delta PCS and 1.01 (95% CI: 0.98-1.03) for delta MCS. Categorizing the first and second scores as predictors, only the second PCS or MCS score was associated with mortality.

Conclusions

In our study, only the most recent HR-QOL score was associated with mortality. Hence, the predictive power of a measurement of HR-QOL is not affected by changes in HR-QOL prior to that measurement; more frequent HR-QOL measurements are needed to improve the prediction of outcomes in HD. Further studies are needed to determine the optimal frequency and appropriate instrument to be used for serial measurements.

Future Avenues to Decrease Uremic Toxin Concentration

In this article, we review approaches for decreasing uremic solute concentrations in chronic kidney disease and in particular, in end-stage renal disease (ESRD). The rationale to do so is the straightforward relation between concentration and biological (toxic) effect for most toxins. The first section is devoted to extracorporeal strategies (kidney replacement therapy). In the context of high-flux hemodialysis and hemodiafiltration, we discuss increasing dialyzer blood and dialysate flows, frequent and/or extended dialysis, adsorption, bioartificial kidney, and changing physical conditions within the dialyzer (especially for protein-bound toxins). The next section focuses on the intestinal generation of uremic toxins, which in return is stimulated by uremic conditions. Therapeutic options are probiotics, prebiotics, synbiotics, and intestinal sorbents. Current data are conflicting, and these issues need further study before useful therapeutic concepts are developed. The following section is devoted to preservation of (residual) kidney function. Although many therapeutic options may overlap with therapies provided before ESRD, we focus on specific aspects of ESRD treatment, such as the risks of too-strict blood pressure and glycemic regulation and hemodynamic changes during dialysis. Finally, some recommendations are given on how research might be organized with regard to uremic toxins and their effects, removal, and impact on outcomes of uremic patients.

Health Implications of Antimicrobial Resistance for Patients With Acute Kidney Injury and Bloodstream Infection

Studies have produced conflicting findings on outcomes for patients with antimicrobial-resistant infection. This study evaluated whether infection with an antimicrobial-resistant organism affects outcome in critically ill patients with acute kidney injury treated with renal replacement therapy and whose clinical course is complicated with a nosocomial bloodstream infection. We found that infection with an antimicrobial-resistant organism did not adversely affect clinical outcome in this specific cohort, which already has a high mortality rate.

Associations of self-reported physical activity types and levels with quality of life, depression symptoms, and mortality in hemodialysis patients: the DOPPS

BACKGROUND AND OBJECTIVES

Physical activity has been associated with better health status in diverse populations, but the association in patients on maintenance hemodialysis is less established. Patient-reported physical activities and associations with mortality, health-related quality of life, and depression symptoms in patients on maintenance hemodialysis in 12 countries were examined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In total, 5763 patients enrolled in phase 4 of the Dialysis Outcomes and Practice Patterns Study (2009-2011) were classified into five aerobic physical activity categories (never/rarely active to very active) and by muscle strength/flexibility activity using the Rapid Assessment of Physical Activity questionnaire. The Kidney Disease Quality of Life scale was used for health-related quality of life. The Center for Epidemiologic Studies Depression scale was used for depression symptoms. Linear regression was used for associations of physical activity with health-related quality of life and depression symptoms scores. Cox regression was used for association of physical activity with mortality.

RESULTS

The median (interquartile range) of follow-up was 1.6 (0.9-2.5) years; 29% of patients were classified as never/rarely active, 20% of patients were classified as very active, and 20.5% of patients reported strength/flexibility activities. Percentages of very active patients were greater in clinics offering exercise programs. Aerobic activity, but not strength/flexibility activity, was associated positively with health-related quality of life and inversely with depression symptoms and mortality (adjusted hazard ratio of death for very active versus never/rarely active, 0.60; 95% confidence interval, 0.47 to 0.77). Similar associations with aerobic activity were observed in strata of age, sex, time on dialysis, and diabetes status.

CONCLUSIONS

The findings are consistent with the health benefits of aerobic physical activity for patients on maintenance hemodialysis. Greater physical activity was observed in facilities providing exercise programs, suggesting a possible opportunity for improving patient outcomes.

How to use biomarkers efficiently in acute kidney injury

We discuss the performance of novel biomarkers in acute kidney injury (AKI). Comparison of the areas under the receiver operating characteristic curves of several biomarkers with some clinical and/or routine biochemical outcome parameters reveals that none of the biomarkers has demonstrated a clear additional value beyond the traditional approach in clinical decision making in patients with AKI. Unscrutinized use of these biomarkers may distract from adequate clinical evaluation and carries the risk of worse instead of better patient outcome.

Hurricane Katrina and chronic dialysis patients: better tidings than originally feared?

Besides victims with acute kidney injury, disasters may also affect the destiny of chronic dialysis patients. This Commentary discusses the article by Kutner et al. describing the outcome of chronic dialysis patients who were victims of Hurricane Katrina. The importance of advance disaster plans, including instructions to chronic dialysis patients, is emphasized. In addition, it is expected that specific recommendations, which are currently being prepared, will offer ad hoc advice to rescuers.

Back to the future: middle molecules, high flux membranes, and optimal dialysis

Middle molecules can be defined as compounds with a molecular weight (MW) above 500 Da. An even broader definition includes those molecules that do not cross the membranes of standard low-flux dialyzers, not only because of molecular weight, but also because of protein binding and/or multicompartmental behavior. Recently, several of these middle molecules have been linked to the increased tendency of uremic patients to develop inflammation, malnutrition, and atheromatosis. Other toxic actions can also be attributed to the middle molecules. In the present publication we will consider whether improved removal of middle molecules by large pore membranes has an impact on clinical conditions related to the uremic syndrome. The clinical benefits of large pore membranes are reduction of uremia-related amyloidosis; maintenance of residual renal function; and reduction of inflammation, malnutrition, anemia, dyslipidemia, and mortality. It is concluded that middle molecules play a role in uremic toxicity and especially in the processes related to inflammation, atherogenesis, and malnutrition. Their removal seems to be related to a better outcome, although better biocompatibility of membranes might be a confounding factor.

Evaluation of urine proteome pattern analysis for its potential to reflect coronary artery atherosclerosis in symptomatic patients

Coronary artery disease (CAD) is a major cause of mortality and morbidity. Noninvasive proteome analysis could guide clinical evaluation and early/preventive treatment. Under routine clinical conditions, urine of 67 patients presenting with symptoms suspicious for CAD were analyzed by capillary electrophoresis directly coupled with mass spectrometry (CE-MS). All patients were subjected to coronary angiography and either assigned to a CAD or non-CAD group. A training set of 29 patients was used to establish CAD and non-CAD-associated proteome patterns of plasma as well as urine. Significant discriminatory power was achieved in urine but not in plasma. Therefore, urine proteomic analysis of further 38 patients was performed in a blinded study. A combination of 17 urinary polypeptides allowed separation of both groups in the test set with a sensitivity of 81%, a specificity of 92%, and an accuracy of 84%. Sequencing of urinary marker peptides identified fragments of collagen alpha1 (I and III), which we furthermore demonstrated to be expressed in atherosclerotic plaques of human aorta. In conclusion, specific CE-MS polypeptide patterns in urine were associated with significant CAD in patients with angina-typical symptoms. These promising findings need to be further evaluated in regard to reliability of a urine-based screening method with the potential of improving the diagnostic approaches for CAD.

Costs and length of stay associated with antimicrobial resistance in acute kidney injury patients with bloodstream infection

INTRODUCTION

Antimicrobial resistance negatively impacts on prognosis. Intensive care unit (ICU) patients, and particularly those with acute kidney injury (AKI), are at high risk for developing nosocomial bloodstream infections (BSI) due to multi-drug-resistant strains. Economic implications in terms of costs and length of stay (LOS) attributable to antimicrobial resistance are underevaluated. This study aimed to assess whether microbial susceptibility patterns affect costs and LOS in a well-defined cohort of ICU patients with AKI undergoing renal replacement therapy (RRT) who developed nosocomial BSI.

METHODS

Historical study (1995-2004) enrolling all adult RRT-dependent ICU patients with AKI and nosocomial BSI. Costs were considered as invoiced in the Belgian reimbursement system, and LOS was used as a surrogate marker for hospital resource allocation.

RESULTS

Of the 1330 patients with AKI undergoing RRT, 92 had microbiologic evidence of nosocomial BSI (57/92, 62% due to a multi-drug-resistant microorganism). Main patient characteristics were equal in both groups. As compared to patients with antimicro-4 bial-susceptible BSI, patients with antimicrobial-resistant BSI were more likely to acquire Gram-positive infection (72.6% vs 25.5%, P<0.001). No differences were found neither in LOS (ICU before BSI, ICU, hospital before BSI, hospital, hospital after BSI, and time on RRT; all P>0.05) or hospital costs (all P>0.05) when comparing patients with antimicrobial-resistant vs antimicrobial-susceptible BSI. However, although not statistically significant, patients with BSI caused by resistant Gram-negative-, Candida-, or anaerobic bacteria incurred substantial higher costs than those without.

CONCLUSION

In a cohort of ICU patients with AKI and nosocomial BSI undergoing RRT, patients with antimicrobial-resistant vs antimicrobial-susceptible Gram-positive BSI did not have longer hospital stays, or higher hospital costs. Patients with resistant "other" (i.e. Gram-negative, Candida, or anaerobic) BSI were found to have a distinct trend towards increased resources use as compared to patients with susceptible "other" BSI, respectively.

Exploring the uremic toxins using proteomic technologies

Kidney failure leads to the uremic syndrome that is the clinical expression of the malfunction of vital organs due to the accumulation of uremic toxins, which are normally cleared by the kidneys. Progressively more uremic retention solutes have been identified and their potential toxicity has been characterized. Polypeptides constitute a heterogeneous group of uremic molecules. Therefore, proteome analysis represents a new and promising analytical approach to identify new uremic toxins. Proteomic technologies cover applicability to a broad molecular mass range. For polypeptides >10 kDa classical proteomic techniques, such as two-dimensional gel electrophoresis followed by mass spectrometry, are able to identify uremic polypeptides. In the mass range from approximately 1 to 10 kDa, capillary electrophoresis coupled to mass spectrometry (CE-MS) emerged as a fast possibility to analyze of up to 1,400 compounds in a single step. This chapter will provide an overview about proteomic technologies as efficient tools for the detection of uremic toxins, emphasizing the features of CE-MS. Subsequently, examples of the application of proteomic techniques to define novel biomarkers for renal diseases and uremic toxins will be discussed.

Uremic toxins in chronic renal failure

The uremic syndrome is a complex mixture of organ dysfunctions, which is attributed to the retention of a myriad of compounds that under normal conditions are excreted by healthy kidneys. During recent years major steps have been taken in the area of identification and characterization of uremic retention solutes and in the knowledge of their pathophysiological importance; however, our knowledge remains far from complete. In the present paper the general classification based on their molecular weight and on their protein-binding characteristics, with reflections on their removal, will be discussed. In addition, current knowledge about the main uremic retention products and their clinical and biological effects will be reviewed in detail.

Arterial stiffness and wave reflections in renal transplant recipients

BACKGROUND

Arterial stiffness predicts cardiovascular disease (CVD) events and has been well documented in haemodialysis patients. Information in renal transplant recipients (RTR), however, remains limited despite their higher CVD risk compared to the general population. We aimed to assess arterial stiffening and wave reflections in RTR and healthy controls and to evaluate which factors could explain potential differences.

METHODS

Carotid augmentation index (AI) and carotid-femoral pulse wave velocity (PWV) were measured in 200 RTR and 44 controls using applanation tonometry. The impact of traditional and non-traditional CVD risk factors was assessed using linear regression analysis. Glomerular filtration rate (GFR) was measured by (51)Cr-EDTA (RTR) and estimated using the abbreviated Modification of Diet in Renal Disease formula (RTR and controls).

RESULTS

After correction for age, blood pressure and anthropometry, AI and PWV remained 7.4 +/- 3.6% (P = 0.04) and 0.7 +/- 0.3 m/s (P = 0.01) higher in RTR than controls, corresponding to a difference in vascular age of >10 years. In multivariate analysis, additional independent factors related to AI and PWV were GFR (-1.8% and -0.19 m/s per 10 ml/min) and C-reactive protein (3.2% and 0.21 m/s per logarithm increase).

CONCLUSIONS

Increased arterial stiffness and wave reflections in RTR are attributable to incomplete restoration of GFR and the presence of subclinical inflammation.

Impact of iron sucrose therapy on leucocyte surface molecules and reactive oxygen species in haemodialysis patients

BACKGROUND

It has been suggested that iron increases oxidative stress and that an excess of iron contributes to cardiovascular disease and infections in haemodialysis patients. In the present study, the effects of parenterally administered iron on leucocyte surface molecule expression and the production of reactive oxygen species (ROS) were evaluated.

METHODS

Ten chronic haemodialysis (HD) patients without iron overload were studied. To each patient, four different regimens were applied: placebo; iron sucrose, either 30 or 100 mg, administered via the outflow dialyser line; and 100 mg of iron sucrose infused via the inflow dialyser line. Blood was sampled at different time points: before, during and after infusion and immediately before the next dialysis session. Levels of CD11b and CD45 expression on granulocytes and of CD11b, CD14 and CD36 on monocytes were determined using flow cytometric analysis. The generation of ROS was quantified using chemiluminescence with and without ex vivo stimulation by phorbol myristate acetate (PMA).

RESULTS

No significant differences among the four different treatment regimes were found, neither in chemilumescence activity nor in the expression of CD11b and CD45 on granulocytes, and of CD11b, CD14 and CD36 on monocytes.

CONCLUSIONS

Our results suggest that parenteral infusion of iron sucrose during haemodialysis in patients who have no signs of iron overload has no significant effect on the expression of leucocyte surface molecules and does not increase production of ROS.

Sodium bicarbonate versus THAM in ICU patients with mild metabolic acidosis

BACKGROUND

Sodium bicarbonate is despite its side effects, considered the standard alkali therapy in metabolic acidosis. THAM is an alternative alkalizing agent; however, there are limited data on the use of THAM in metabolic acidosis. The aim of this study was to compare the efficacy and adverse effects of a single dose of sodium bicarbonate and THAM in intensive care unit (ICU) patients with mild metabolic acidosis.

METHODS

18 adult ICU patients with mild metabolic acidosis (serum bicarbonate < 20 mmol/L) were randomized to a single dose of either sodium bicarbonate or THAM, administered over a 1-hour period, and titrated to buffer the excess of acid load.

RESULTS

Sodium bicarbonate and THAM had equivalent alkalinizing effect during the infusion period. This was still present 4 hours after start of infusion of sodium bicarbonate, and until 3 hours after start of infusion of THAM. Serum potassium levels decreased after sodium bicarbonate infusion, and remained unchanged after THAM. After sodium bicarbonate, sodium increased, and after THAM, serum sodium decreased.

CONCLUSIONS

Sodium bicarbonate and THAM had a similar alkalinizing effect in patients with mild metabolic acidosis; however, the effect of sodium bicarbonate was longer lasting. Sodium bicarbonate did decrease serum potassium, and THAM did not; THAM is therefore not recommended in patient with hyperkalemia. As sodium bicarbonate leads to an increase of serum sodium and THAM to a decrease, THAM may be the alkalinizing agent of choice in patients with hypernatremia. Similarly, because sodium bicarbonate increases PaCO2 and THAM may even decrease PaCO2, sodium bicarbonate is contraindicated and THAM preferred in patients with mixed acidosis with high PaCO2 levels.

Assessment of renal function in recently admitted critically ill patients with normal serum creatinine

BACKGROUND

Detection of renal dysfunction is important in critically ill patients, and in daily practice, serum creatinine is used most often. Other tools allowing the evaluation of renal function are the Cockcroft-Gault and MDRD (Modification of Diet in Renal Disease) equations. These parameters may, however, not be optimal for critically ill patients. The present study evaluated the value of a single serum creatinine measurement, within normal limits, and three commonly used prediction equations for assessment of glomerular function (Cockcroft-Gault, MDRD and the simplified MDRD formula), compared with creatinine clearance (Ccr) measured on a 1 h urine collection in an intensive care unit (ICU) population.

METHODS

This was a prospective observational study. A total of 28 adult patients with a serum creatinine <1.5 mg/dl, within the first week of ICU admission, were included in the study. Renal function was assessed with serum creatinine, timed 1 h urinary Ccr, and the Cockcroft-Gault, MDRD and simplified MDRD equations.

RESULTS

Serum creatinine was in the normal range in all patients. Despite this, measured urinary Ccr was <80 ml/min/1.73 m2 in 13 patients (46.4%), and <60 ml/min/1.73 m2 in seven patients (25%). Urinary creatinine levels were low, especially in patients with low Ccr, suggesting a depressed production of creatinine caused by pronounced muscle loss. Regression analysis and Bland-Altman plots revealed that neither the Cockcroft-Gault formula nor the MDRD equations were specific enough for assessment of renal function.

CONCLUSIONS

In recently admitted critically ill patients with normal serum creatinine, serum creatinine had a low sensitivity for detection of renal dysfunction. Furthermore, the Cockcroft-Gault and MDRD equations were not adequate in assessing renal function.

Proteomics: a novel tool to unravel the patho-physiology of uraemia

BACKGROUND

Uraemic toxicity results in the dysfunction of many organ systems, provoking an increase in morbidity and mortality. To date, only approximately 90 uraemic retention solutes have been described. To examine unknown uraemic substances thoroughly, the identification of as many compounds as possible in the ultrafiltrate and/or plasma of patients would lead to a less biased definition of the uraemic retention process compared with what is proposed today.

METHODS

We describe the application of a novel proteomic tool for the identification of a large number of molecules present in ultrafiltrate from uraemic and normal plasma obtained with high- or low-flux membranes. Separation by capillary electrophoresis was coupled on-line to a mass spectrometer, yielding identification of polypeptides based on their molecular weight.

RESULTS

Between 500 and >1000 polypeptides with a molecular weight ranging from 800 to 10,000 Da could be detected in individual samples, and were identified via their mass and their particular migration time in capillary electrophoresis. In ultrafiltrate from uraemic plasma, 1394 polypeptides were detected in the high-flux vs 1046 in the low-flux samples, while in ultrafiltrate from normal plasma, 544 polypeptides vs 490 were found in ultrafiltrate from normal plasma obtained from membranes with comparable cut-off. In addition, polypeptides >5 kDa were virtually only detected in the uraemic ultrafiltrate from the high-flux membrane (n = 28 vs n = 5 with the low-flux membrane). To demonstrate the feasibility of further characterizing the detected molecules, polypeptides present exclusively in uraemic ultrafiltrate were chosen for sequencing analyses. A 950.6 Da polypeptide was identified as a fragment of the salivary proline-rich protein. A 1291.8 Da fragment was derived from alpha-fibrinogen.

CONCLUSION

The data presented here strongly suggest that the application of proteomic approaches such as capillary electrophoresis and mass spectrometry will result in the identification of many more uraemic solutes than those known at present. This could enable the introduction of more direct elimination strategies, since it is possible to obtain an extended appreciation of the removal capacities of particular dialyser membranes.

Effect of nosocomial bloodstream infection on the outcome of critically ill patients with acute renal failure treated with renal replacement therapy

Critically ill patients with acute renal failure (ARF) treated with renal replacement therapy (RRT) have a high mortality. The authors evaluated a cohort of 704 consecutive intensive care unit (ICU) patients with ARF treated with RRT to determine whether there was an increased incidence of nosocomial bloodstream infection and whether this resulted in a worse outcome. The incidence of nosocomial bloodstream infection was 8.8%, higher than that reported in other series of general ICU patients and also higher than the 3.5% incidence of bloodstream infection in non-ARF patients in the same unit (P < 0.001). There were more bloodstream infections caused by Gram-positive species compared with Gram-negative species or fungi. The distribution over the species was comparable to that reported by others for a general ICU population. The outcome was evaluated with matched cohort analysis. With this technique, patients with bloodstream infection (exposed) were closely matched with patients without bloodstream infection (non-exposed) in a 1:2 ratio. Matching was based on the APACHE II system and length of stay before bloodstream infection (exposure time). Length of stay and mortality were equal in exposed and non-exposed patients. There was also no difference in hospital costs. It can be concluded that critically ill patients with ARF treated with RRT were more susceptible to nosocomial bloodstream infection. Nevertheless, the outcome was not influenced by the presence of bloodstream infection. The high mortality observed in ARF patients could therefore not be attributed to the higher incidence of bloodstream infection.

In vitro study of the potential role of guanidines in leukocyte functions related to atherogenesis and infection

BACKGROUND

The blunted immune response upon stimulation in chronic renal failure (CRF) is often coupled to a baseline inflammatory status which has been related to atherogenesis. Uremic biologic fluids and several specific uremic retention solutes alter cell-mediated immune responses, as well as the interaction of calcitriol with the immune system.

METHODS

The present study evaluated the influence of different guanidino compounds on DNA synthesis, chemiluminescence production, and CD14 expression of undifferentiated and calcitriol-differentiated HL-60 cells. In a second setup, these guanidino compounds were evaluated for their specific effect on normal human leukocyte oxidative burst activity and tumor necrosis factor-alpha (TNF-alpha) expression.

RESULTS

First, several guanidino compounds elicited proinflammatory effects on leukocytes. Methylguanidine and guanidine stimulated the proliferation of undifferentiated HL-60 cells and the antiproliferative effect of calcitriol (P < 0.05) was neutralized in the presence of methylguanidine (P < 0.05) and guanidinosuccinic acid (P < 0.05). The phorbol-myristate-acetate (PMA)-stimulated chemiluminescence production of the calcitriol differentiated HL-60 cells was enhanced in the presence of guanidine (P < 0.05). Methylguanidine and guanidinoacetic acid enhanced the lipopolysaccharide (LPS)-stimulated intracellular production of TNF-alpha by normal human monocytes (P < 0.05). Second, several guanidino compounds inhibited the function of leukocytes if they were activated. The PMA-stimulated chemiluminescence production of the calcitriol differentiated HL-60 cells was inhibited by the presence of methylguanidine (P < 0.05), guanidinoacetic acid (P < 0.05) and guanidinosuccinic acid (P < 0.05). After incubation of whole blood in the presence of methylguanidine, the Escherichia coli stimulated oxidative burst activity of the granulocyte population was significantly inhibited (P < 0.05). In addition, guanidinosuccinic acid had an inhibitory effect on the LPS-stimulated intracellular production of TNF-alpha by human monocytes (P < 0.01).

CONCLUSION

Guanidino compounds exert proinflammatory as well as anti-inflammatory effects on monocyte/macrophage function. This could contribute to the altered prevalence of cardiovascular disease and propensity to infection in patients with CRF.

Acute renal failure in patients with sepsis in a surgical ICU: predictive factors, incidence, comorbidity, and outcome

Acute renal failure (ARF) is a common complication in intensive care unit (ICU) patients. Although there are several reports on outcome of septic patients with ARF, there are no data regarding predisposing factors for ARF. Therefore, the incidence of ARF was investigated in 185 sepsis patients admitted in a surgical ICU during a 16-mo period. Variables predisposing to ARF on day 1 of sepsis were evaluated with univariate and multivariable analyses. APACHE II and SOFA scores were compared during a 14-d period. Additionally, the impact of organ failure on mortality was evaluated. ARF developed in 16.2% of the patients, and 70.0% of these needed renal replacement therapy (RRT). Patients with ARF were more severely ill and had a higher mortality. Remarkably, serum creatinine was already increased on day 1. Creatinine > 1 mg/dl and pH < 7.30, both on day 1 of sepsis, were independently associated with ARF. Age, need for vasoactive therapy, mechanical ventilation, and RRT, but not ARF itself, were associated with mortality. In conclusion, ARF was a frequent complication in sepsis. Sepsis patients with ARF were more severely ill and had a higher mortality. Need for RRT was independently associated with mortality. A simple risk model for ARF, on basis of two readily available parameters on day 1 of sepsis, was developed. This model allows initiating specific therapeutic measures earlier in the course of sepsis, hopefully resulting in a lower incidence of ARF and needi for RRT, thereby lowering mortality.

Studies on dialysate mixing in the Genius single-pass batch system for hemodialysis therapy

BACKGROUND

The Genius single-pass batch system for hemodialysis contains a closed reservoir and dialysate circuit of 75 L dialysate. The unused dialysate is withdrawn at the top of the reservoir and the spent fluid is reintroduced into the container at the bottom. Although it has been claimed that both fractions remain unmixed during the dialysis session, no direct proof of this assumption has yet been provided. In the present study, we investigated whether contamination of the unused dialysate with uremic solutes occurred and at which time point it began. Two different dialysate temperatures were compared.

METHODS

Ten chronic hemodialysis patients were dialyzed twice with the Genius system, with dialysate prepared at 37 degrees C and 38.5 degrees C, respectively. The sessions lasted 270 minutes with blood/dialysate flow set at 300 mL/min. Dialysate was sampled at 5, 60, 180, 210, 225, 230, 235, 240, 255, and 270 minutes both from the inlet and outlet dialysate line and blood was sampled from the arterial line predialysis, after 4 hours, and postdialysis. All samples were tested for osmolality, urea, creatinine, p-cresol, hippuric acid, and indoxyl sulfate.

RESULTS

Uremic solutes appeared in the inlet dialysate line between 3 hours 50 minutes and 4 hours 10 minutes after the start of dialysis, corresponding to 68.6 and 74.7 L spent dialysate, respectively (37 degrees C vs. 38.5 degrees C; P = NS). No difference in the amount of removed solutes and in the serum levels was observed between 37 degrees C and 38.5 degrees C. A Kt/V of 1.17 +/- 0.20 and 1.18 +/- 0.26, respectively, was reached with the 37 degrees C and 38.5 degrees C dialysate temperature (P = NS).

CONCLUSION

Contamination with uremic solutes occurred at the dialysate inlet only near the end of the session when small quantities of fresh dialysate were left in the container. Differences in dialysate temperature did not result in a different separation between used and unused dialysate, or in differences in removal of toxins or Kt/V.

No early respiratory benefit with CVVHDF in patients with acute renal failure and acute lung injury

BACKGROUND

There is debate as to whether, in patients with acute lung injury, continuous renal replacement therapy has beneficial effects on pulmonary gas exchange by mechanisms other than fluid removal. Because continuous renal replacement therapy is associated with potential morbidity and mortality, it seems unethical to perform a randomized trial in patients with acute lung injury without renal failure. Therefore, the effects of continuous venovenous haemodiafiltration with zero volume balance on gas exchange were evaluated in patients with acute renal failure and acute lung injury. Because haemofilter conditions should be comparable between patients, we opted for an evaluation of the effects during a 24-h period. Results of this trial can guide future studies in non-renal patients with acute lung injury.

METHODS

In all 37 patients with acute renal failure and acute lung injury, treated with continuous venovenous haemodiafiltration with zero fluid balance during a 1 year period, ventilatory and haemodynamic parameters were measured every 8 h during the 24 h preceding therapy and during the first 24 h of therapy.

RESULTS

We found a slight, although not statistically significant, increase in the PaO(2)/FIO(2) ratio and the oxygenation index, in the total group of patients, and in the subgroups of patients with acute lung injury of extrapulmonary and pulmonary causes.

CONCLUSIONS

During the first 24 h of treatment, continuous venovenous haemodiafiltration with zero volume balance did not result in a significant improvement of the respiratory status in patients with acute renal failure and acute lung injury, nor in the subgroups of patients with acute lung injury with extrapulmonary causes.

Influence of dialysate on gastric emptying time in peritoneal dialysis patients

OBJECTIVE

Peritoneal dialysis (PD) patients frequently suffer from dyspeptic complaints such as nausea, vomiting, abdominal distension, early satiety, and anorexia. Gastroparesis might be, at least partially, a source of dyspeptic complaints in PD patients. The aim of the present study was to determine the influence of the presence and composition of dialysate on gastric emptying in PD patients.

DESIGN

Prospective study.

SETTING

Renal Division, Department of Internal Medicine, Ghent University Hospital, Belgium.

PATIENTS

Sixty-one PD patients using different dialysate solutions, and 27 healthy volunteers.

MAIN OUTCOME MEASURE

Gastric emptying of solids was assessed by the 13C-octanoic acid breath test.

RESULTS

Gastric emptying was impaired in PD patients, regardless of the composition of dialysate and even if tested with an empty peritoneal cavity. Gastric emptying was significantly slower when glucose-containing dialysate was compared to an empty peritoneal cavity, or when glucose-containing dialysate was compared to icodextrin dialysate. No difference in gastric emptying could be demonstrated between glucose-containing dialysate and dialysate containing a mixture of glycerol and amino acids as osmotic agent.

CONCLUSIONS

These findings suggest that the delay in gastric emptying demonstrated in the presence of peritoneal dialysate is not the consequence of a mere volume or pressure effect, but of the absorption of substrate substances with caloric and/or metabolic activity, such as glucose or glycerol and amino acids.

An evaluation of an integrative care approach for end-stage renal disease patients

Studies analyzing the outcome of integrative care of end-stage renal disease (ESRD) patients, whereby patients are transferred from one renal replacement modality to another according to individual needs, are scant. In this study, we analyzed 417 files of 223 hemodialysis (HD) and 194 peritoneal dialysis (PD) patients starting renal replacement therapy between 1979 and 1996, to evaluate the effect of such an approach. Analysis was done for survival of patients on their first modality, for intention-to-treat survival (counting total time on renal replacement therapy, but with exclusion of time on transplantation), and for total survival. Log rank analysis was used and correction for risk factors was performed by Cox proportional hazards regression. Intention-to-treat survival and total survival were not different between PD and HD patients (log rank, P > 0.05). Technique success was higher in HD patients compared to PD patients (log rank, P = 0.01), with a success rate after 3 yr of 61 and 48%, respectively. Thirty-five patients were transferred from HD to PD and 32 from PD to HD. Transfer of PD patients to HD was accompanied by an increase in survival compared to those remaining on PD (log rank, P = 0.001), whereas, in contrast, transfer of patients from HD to PD was not (log rank, P = 0.17). Survival of patients remaining more than 48 mo on their initial modality was lower for PD patients (log rank, P < 0.01). A matched-pair analysis between patients who started on PD and who were transferred to HD later (by definition called integrative care patients), and patients who started and remained on HD, showed a survival advantage for the integrative care patients. These results indicate that patient outcome is not jeopardized by starting patients on PD, at least if patients are transferred in a timely manner to HD when PD-related problems arise.

Cytokine removal during continuous hemofiltration in septic patients

A potential application of the continuous renal replacement therapies is the extracorporeal removal of inflammatory mediators in septic patients. Cytokine elimination with continuous renal replacement therapies has been demonstrated in several clinical studies, but so far without important effects on their serum concentrations. Improved knowledge of the cytokine removal mechanisms could lead to the development of more efficient treatment strategies. In the present study, 15 patients with septic shock and acute renal failure were observed during the first 24 h of treatment with continuous venovenous hemofiltration (CVVH) with an AN69 membrane. After 12 h, the hemofilter was replaced and the blood flow rate (QB) was switched from 100 ml/min to 200 ml/min or vice versa. Pre- and postfilter plasma and ultrafiltrate concentrations of selected inflammatory and anti-inflammatory cytokines were measured at several time points allowing the calculation of a mass balance. Cytokine removal was highest 1 h after the start of CVVH and after the change of the membrane (ranging from 25 to 43% of the prefilter amount), corresponding with a significant fall in the serum concentration of all cytokines. The inhibitors of inflammation were removed to the same extent as the inflammatory cytokines. Adsorption to the AN69 membrane appeared to be the main clearance mechanism, being most pronounced immediately after installation of a new membrane and decreasing steadily thereafter, indicating rapid saturation of the membrane. A QB of 200 ml/min was associated with a 75% increase of the ultrafiltration rate and a significantly higher convective elimination and membrane adsorption than at a QB of 100 ml/min. The results indicate that optimal cytokine removal with CVVH with an AN69 membrane could be achieved with a combination of a high QB/ultrafiltration rate and frequent membrane changes.

Pretransplantation hemodialysis strategy influences early renal graft function

The influence of the pretransplantation hemodialysis strategy on early renal graft function was evaluated in 44 patients receiving hemodialysis in the 24 h preceding kidney transplantation and in 13 patients receiving hemodialysis more than 24 h before transplantation. The patients dialyzed less than 24 h before transplantation were stratified according to treatment with or without complement-activating dialyzers (cuprophane, bioincompatible membrane [BICM] versus polysulfone, biocompatible membrane [BCM]) and with or without ultrafiltration (UF). Serum creatinine (Scr) at days 0, 2, 5, 10, and 30, the time for Scr to decrease 50% (T1/2Scr), the incidence of acute renal failure (ARF; defined as urinary volume < 500 ml/d and/or necessity for posttransplantation hemodialysis), and early graft dysfunction (defined as T1/2Scr > 3.5 d) were registered. Scr was higher in BCM- versus BICM-treated patients (P < 0.0001 by variance analysis) and in patients receiving UF versus those receiving no UF (P = 0.0009). T1/2Scr was higher in treatment with BICM versus BCM (7.4 +/- 7.9 versus 3.1 +/- 2.9 d; P < 0.05) and UF versus no UF (7.1 +/- 7.7 versus 2.7 +/- 2.0 d; P < 0.01). The evolution of Scr was markedly more favorable in the patient group treated with BCM without UF (T1/2Scr 1.7 +/- 0.8 d) compared with the group treated with BICM and UF (T1/2Scr 9.3 +/- 9.1 d; P < 0.01). The remaining groups (BICM without UF and BCM with UF) showed intermediate results. The incidence of ARF and early graft dysfunction was higher in the group on BICM with UF compared to BCM without UF. Functional differences persisted up to 1 mo after transplantation. Patients who underwent dialysis with UF more than 24 h before transplantation had a more beneficial evolution of renal function parameters than those who were dialyzed with UF less than 24 h before transplantation. In conclusion, the use of BICM and the application of UF within 24 h before kidney transplantation enhance the risk of posttransplantation ARF and early graft dysfunction.

Rifampicin-associated acute renal failure: pathophysiologic, immunologic, and clinical features

A 71-year-old woman was treated for a relapsing pulmonary tuberculosis with reinstitution of rifampicin after a medication-free interval of 2 years. After ingestion of the second dose, she developed severe hemolytic anemia and acute renal failure (ARF) necessitating dialysis. We demonstrated the presence in the patient's serum of rifampicin-dependent immunoglobulin G (IgG) and IgM antibodies, which caused red blood cell lysis through interaction with the I antigen on the erythrocyte surface. A review of the literature yielded 48 cases of rifampicin-associated renal failure. A subgroup of 37 patients could be distinguished, which, analogous to our case, suddenly developed ARF and frequently also developed hemolytic anemia and/or thrombocytopenia during intermittent or interrupted treatment. Regarding the pathogenesis of the ARF, renal biopsy consistently revealed tubular lesions. Although intravascular hemolysis with hemoglobinuria may play a role, it is not uniformly present. Our demonstration of an antibody with anti-I specificity provides a possible explanation. The I antigen is also expressed on tubular epithelium and may, therefore, be the target structure through which rifampicin-antibody complexes lead to tubular cell destruction. The other cases of rifampicin-associated ARF were unrelated to this subgroup: two cases of rapidly progressive glomerulonephritis, five cases of acute interstitial nephritis, and four cases of light chain proteinuria were recorded.

Leukocyte CD14 and CD45 expression during hemodialysis: polysulfone versus cuprophane

The expression of CD14 on monocytes and CD45 on monocytes and granulocytes was evaluated during hemodialysis by flow cytometric analysis in the 'resting state' and after in vitro stimulation with phorbol myristate acetate (PMA). A comparison of complement activating cuprophane (CU) versus less complement activating polysulfone (PS) was undertaken. 'Resting state' CD45 expression on granulocytes increased markedly during CU dialysis compared to time 0, whereas this rise was only moderate with PS (CU vs. PS, p < 0.01). When considering the increase in expression upon PMA stimulation, a lower value was obtained during CU dialysis for both CD14 (monocytes at 60 and 240 min) and for CD45 (monocytes and granulocytes at 15 min). In conclusion, granulocytes in the 'resting state' expressed more CD45 on their cell membranes during CU dialysis, whereas CD14 and CD45 upregulation after ex vivo addition of PMA was blunted during CU dialysis.

Recombinant hirudin: a specific thrombin inhibiting anticoagulant for hemodialysis

The first experience with hirudin as an alternative anticoagulant for heparin in hemodialysis is reported. Recombinant hirudin (HBW 023) was administered in 20 patients as a bolus before dialysis with low flux polysulfone dialyzers (PS400), the dosage being adapted stepwise from patient to patient by 0.02 mg/kg to the occurrence of clotting or bleeding. Four different administration schedules were studied. The first three schedules (0.02 mg/kg, N = 1; 0.04 mg/kg, N = 1; 0.06 mg/kg, N = 4) were discontinued because of clotting. The 0.08 mg/kg schedule was maintained without clotting event in 14 patients. Bleeding was not observed. Plasma hirudin averaged 503.9 +/- 214.0 and 527.7 +/- 217.1 ng/ml after two and four hours of dialysis, and decreased during an interdialytic interval of 44 hours to 223.2 +/- 86.2 ng/ml. Modified antithrombin III (P < 0.05) and activated partial thromboplastin times were lower (P < 0.01) under hirudin compared to heparin; these coagulation parameters were closer to normal during hirudin treatment. The patients developing clotting could be distinguished from those without clotting by the registration of the activated clotting times (9.2 +/- 3.0 vs. 18.7 +/- 3.2 min after 2 hr, P < 0.01; 8.1 +/- 3.0 vs. 16.2 +/- 3.8 min after 4 hr of dialysis, P < 0.05); cut-off value below which clotting is to be expected was 12 min). It is concluded that administration of hirudin as a bolus before the start of dialysis, at a dosage of 0.08 mg/kg, is not complicated by clotting or by bleeding. Coagulation tendency can optimally be monitored by the registration of the activated clotting time.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of Urea and Other Uremic Markers for Quantification of Dialysis Efficacy

To validate azotemic markers as an index for intradialytic changes in solute concentration, we compared eight solutes (pseudouridine, xanthine, hypoxanthine, peak 4, peak 5, p-hydroxyhippuric acid, indoxyl sulfate, and hippuric acid) with five classical azotemic markers (urea, creatinine, uric acid, phosphate, and potassium). We determined concentrations by reversed-phase HPLC coupled to ultraviolet absorption or photometrically. Seven compounds showed significant intercorrelation (P less than 10(-5)): urea, pseudouridine, uric acid, peaks 4 and 5, p-hydroxyhippuric acid, and creatinine. The hippuric acid concentration change after dialysis correlated with the change for these seven compounds and also with indoxyl sulfate, hypoxanthine, potassium, and the group of unidentified ultraviolet-absorbing HPLC peaks accumulating in uremia. We conclude that urea only partially represents the concentration changes of other retention compounds after dialysis; alternative markers, e.g., hippurate, should be considered.

Assessment of urea and other uremic markers for quantification of dialysis efficacy

To validate azotemic markers as an index for intradialytic changes in solute concentration, we compared eight solutes (pseudouridine, xanthine, hypoxanthine, peak 4, peak 5, p-hydroxyhippuric acid, indoxyl sulfate, and hippuric acid) with five classical azotemic markers (urea, creatinine, uric acid, phosphate, and potassium). We determined concentrations by reversed-phase HPLC coupled to ultraviolet absorption or photometrically. Seven compounds showed significant intercorrelation (P less than 10(-5)): urea, pseudouridine, uric acid, peaks 4 and 5, p-hydroxyhippuric acid, and creatinine. The hippuric acid concentration change after dialysis correlated with the change for these seven compounds and also with indoxyl sulfate, hypoxanthine, potassium, and the group of unidentified ultraviolet-absorbing HPLC peaks accumulating in uremia. We conclude that urea only partially represents the concentration changes of other retention compounds after dialysis; alternative markers, e.g., hippurate, should be considered.