Hematocrit and prohepcidin: causation or simply association?
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Antimicrobial Cationic Peptides↗
Biomedical subjects
Pietro Pozzoni
Publications and source records attributed to Pietro Pozzoni.
Dialysis adequacy and response to erythropoiesis-stimulating agents: what is the evidence base?
Despite an increase in the use and average dose of erythropoiesis-stimulating agents (ESA) over the past 15 years, a substantial percentage of patients still do not achieve hemoglobin targets recommended by international guidelines. A clear relationship among hemoglobin or hematocrit levels, ESA dose, and increase in dialysis dose has been pointed out by a number of prospective or retrospective studies. This is particularly true in patients receiving inadequate dialysis. Increasing attention also has been paid to the relationship between dialysis, increased inflammatory stimulus, and ESA response because dialysate contamination and low-compatible treatments may increase cytokine production and consequently inhibit erythropoiesis. The biocompatibility of dialysis membranes and flux are other important factors. However, in highly selected, adequately dialyzed patients without iron or vitamin depletion, the effect of these treatment modalities on anemia seems to be smaller than expected. The role of on-line treatments still is controversial given that it is still difficult to discriminate between the effect of on-line hemodiafiltration per se from that of an increased dialysis dose. Very preliminary results obtained with short or long nocturnal daily hemodialysis on anemia correction are encouraging.
Anemia↗
The relevance of convection in clinical practice: a critical review of the literature.
Convective treatments (high-flux hemodialysis (HD), hemodiafiltration and hemofiltration) are characterized by enhanced removal of middle and large molecular weight solutes compared with conventional low-flux HD. As these molecules are claimed to play an important role in the genesis of many complications of chronic HD, the availability of these techniques represented an intriguing innovation and a possible means to improve the still poor prognosis of HD patients. Here we will critically review the most important published studies comparing convective treatments with low-flux HD on chronic morbidity, preservation of residual renal function, and long-term survival.
Hemodiafiltration↗
A critical assessment of uremia research.
There are considerably fewer randomized controlled trials investigating hemodialysis (HD) than other fields of internal medicine, and no significant improvements have been observed over time. Only the National Cooperative Dialysis Study and the HEMO trial were based on hard endpoints such as morbidity and mortality, but neither considered on-line hemodiafiltration or super-flux membranes, which are thought to provide a number of advantages in terms of the cardiovascular condition of uremic patients. However, results of well-designed clinical trials showing that increasing convection may improve the clinical outcome of HD patients are still lacking. The need for maximizing removal of uremic toxins calls for more frequent HD sessions, but this may be affected by many organizational problems. Therefore, well-designed, long-term clinical trials are urgently needed to investigate which currently available therapeutic instruments can improve the clinical outcome of uremic patients.
Hemodiafiltration↗
Renal manifestations in the metabolic syndrome.
The metabolic syndrome, which is characterized by obesity, serum lipid profile alterations, hypertension, and fasting hyperglycemia, is very common in developed countries, and its prevalence is likely to increase. Chronic kidney disease (CKD) also has become a significant public health problem because it affects a considerable proportion of the adult population and is a major risk factor for cardiovascular disease and premature death. Although it is widely known that the metabolic syndrome is a major risk factor for the development of type 2 diabetes and cardiovascular disease, its precise relationship with the risk for renal impairment only recently has been clarified: Patients with the metabolic syndrome are at significantly higher risk for microalbuminuria and/or CKD, and the level of risk is related to the number of components of the syndrome itself. Although it is difficult to discriminate the detrimental renal effects of the metabolic syndrome from those of hypertension and impaired glucose metabolism, its other aspects (particularly obesity) may favor independently the development of renal abnormalities and may be considered new modifiable risk factors for CKD. These observations provide a rationale for intervention studies that aim to verify whether treating the many components of the metabolic syndrome can effectively prevent the development and progression of renal damage.
Albuminuria↗
Anemia and cardiovascular risk: the lesson of the CREATE Trial.
Anemia has received increasing attention as an independent cardiovascular risk factor in patients with chronic kidney disease (CKD); a number of studies have highlighted its clear relationship with CKD mortality, because its impact on cardiac function leads to the development of left ventricular hypertrophy. However, despite the association between higher hemoglobin levels and better outcomes, a number of clinical studies have failed to demonstrate that fully correcting anemia has a positive effect on morbidity and mortality in patients with CKD. The Cardiovascular Reduction Early Anemia Treatment Epoetin beta (CREATE) study was designed from the hypothesis that, as anemia develops early in the course of CKD and nearly at the same time as cardiovascular disease, its earlier correction may provide better protection against the development of cardiovascular abnormalities. This randomized, multicenter, open-label, parallel-group trial involved 603 patients who had moderate anemia (hemoglobin 11 to 12.5 g/dl) and stage 3 to 4 CKD (estimated GFR 15 to 35 ml/min) and were randomly assigned to attain complete or partial anemia correction. The final results are due to be published within a few months, but the preliminary analyses do not show that complete anemia correction leads to any cardiovascular advantage, although the cardiovascular event rate was half that expected, possibly as a result of patient selection, trial effect, and improved medical care. The baseline findings also indicated that the burden of cardiovascular disease already is very high even in relatively early stages of CKD.
Anemia↗
Anemia and heart failure in chronic kidney disease.
Cardiovascular disease is mainly responsible for the poor long-term survival observed in chronic kidney disease (CKD) patients on dialytic treatment. Anemia is an early complication of CKD and, by inducing important cardiovascular alterations, first of all left ventricular hypertrophy, it does not only impair quality of life, but has also been shown to be an independent risk factor for adverse cardiovascular outcomes in CKD patients. Clinical studies, although with discordant results, have shown that cardiovascular benefits, mainly in terms of left ventricular hypertrophy regression, may be achieved by a partial correction of hemoglobin levels, however, it still is unclear whether starting anemia correction in a very early phase of CKD or aiming for complete normalization of hemoglobin levels higher than the targets recommended by current guidelines may provide further cardiovascular advantages. Results of ongoing, large-scale, prospective, randomized, clinical trials therefore are awaited with much interest to clarify better which practices of anemia correction may provide the best results on the improvement of cardiovascular status and thus of long-term survival of patients with renal disease.
Age Distribution↗
Inflammation and resistance to treatment with recombinant human erythropoietin.
Despite an increase in the use and average dose of recombinant human EPO (rh-EPO) over the last 15 years, a substantial percentage of patients still do not achieve hemoglobin targets recommended by international guidelines. The definition of rh-EPO resistance has been introduced to identify those patients in whom the target hemoglobin level is not attained despite a greater-than-usual dose of erythropoietin-stimulating agent (ESA). In recent years, increasing attention has been paid to the relationship between dialysis, increased inflammatory stimulus, malnutrition, and ESA response. About 35% to 65% of hemodialysis patients show signs of inflammation that could be a cause of anemia through the suppression of bone marrow erythropoiesis by a number of cytokines. A large proportion of chronic kidney disease patients also have protein-energy malnutrition and wasting; low serum albumin levels, together with other more specific nutritional markers, are predictors of rh-EPO response. A diminished nutritional state could then be a feature of patients who are resistant to ESA treatment, with malnutrition probably being a consequence of a chronic inflammatory state. Starting from the hypothesis that anemia, partially attributable to a reduced response to ESA, could be the link among malnutrition, inflammation, and the poor outcome of chronic kidney disease patients, we designed a multicenter observational study, the Malnutrition-Inflammation-Resistance-Treatment Outcome Study (MIRTOS), aimed at evaluating the impact and possible causes of resistance to ESA in a large sample of hemodialysis patients. We hope the results of MIRTOS will represent a step forward toward a better understanding of the factors influencing the response to ESA in hemodialysis patients.
Anemia↗
Relationship between urea clearance and ionic dialysance determined using a single-step conductivity profile.
BACKGROUND: On-line determination of ionic dialysance (ID) has been used to measure the clearance of small solutes like urea. However, attempts to determine the in vivo relationship between ID and urea clearance have led to discordant findings. The aim of this study was to determine the relationship between the mean values of repeated instantaneous determinations of ID throughout a dialysis session ((m)ID), obtained using a single-step inlet dialysate conductivity profile, and the mean values of urea clearance corrected for access recirculation (K(eu1)), total recirculation (access plus cardiopulmonary recirculation, K(eu2)), and the entire postdialysis urea rebound (K(wb)). METHODS: Eighty-two anuric patients on chronic thrice-weekly hemodialysis were studied using an Integra machine equipped with the Diascan module for the automatic determination of ID. The mean values of repeated ID measurements made at 30-minute intervals were compared with K(eu1) (available for only 31 patients), K(eu2), and K(wb). RESULTS: The results in all 82 patients were: (m)ID = 176 +/- 23 mL/min; K(eu2) = 181 +/- 25 mL/min; K(wb) = 159 +/- 22 mL/min. The mean (m)ID/K(wb) and (m)ID/K(eu2) ratios were, respectively, 1.11 +/- 0.06 and 0.98 +/- 0.06. The results in the 31 patients for whom K(eu1) values were available were: (m)ID = 179 +/- 24 mL/min and K(eu1) = 200 +/- 27 mL/min; the mean (m)ID/K(eu1) ratio was 0.90 +/- 0.05. CONCLUSION: The mean value of repeated ID determinations obtained using a single-step conductivity profile underestimates urea clearance corrected for access recirculation, and may be considered an adequate estimate of urea clearance corrected for total recirculation.
Anuria↗
Is it the agent or the blood pressure level that matters for renal and vascular protection in chronic nephropathies?
Over the recent years, it has been clearly documented that hypertension and proteinuria are the major factors responsible for progression of chronic kidney disease (CKD). Therefore, a target BP of at least 130/80 mm Hg has been suggested in order to reduce the rate of progression and cardiovascular mortality. Some antihypertensive agents, such as ACE inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), and perhaps calcium channel blockers (CCBs), may also be capable of reducing CKD progression because they halt some of the pathogenetic mechanisms involved in renal damage, some of which is unrelated to reduction of proteinuria, per se. Although this specific effect seemed to be partially independent of blood pressure reduction, it remains controversial whether these drugs are really superior to other antihypertensive agents when blood pressure values recommended by guidelines are achieved. This issue is still a matter of debate because in published trials, target and achieved blood pressure values were constantly higher than those recommended today. Nevertheless, available findings seem to indicate that the renoprotective effect of these agents is at least partially independent of a better BP control. The only way to definitely solve this issue would be a new randomized trial. However, the clinical relevance of this trial is debatable, considering that we need all the drugs available to reach these recommended BP values.
Animals↗
Clinical benefits of slowing the progression of renal failure.
End-stage renal disease is a social and economic threat worldwide. In this context, any medical intervention that may prevent the progression of chronic kidney disease becomes extremely important. Improving the cardiovascular status is another major objective in the management of this population, because cardiovascular disease is the leading cause of morbidity and mortality among dialysis patients. Moreover, this is only the tip of the iceberg, because many patients die before reaching end-stage renal disease. Today, several interventions are available to delay the progressive loss of renal function and/or prevent the development of cardiovascular disease, but we are still far from being satisfied. These interventions include low protein diets, correction of calcium-phosphate disorders and anemia, blood pressure and proteinuria control, and smoking cessation. Other interventions, such as the administration of lipid-lowering agents, are emerging as particularly promising therapeutic approaches. Recently, growing attention has been paid to polytherapeutic approaches to chronic kidney disease, in order to control different causal factors involved in progression and reduce them as much as possible. However, larger prospective, controlled, randomized clinical trials are needed to demonstrate their actual usefulness. All the interventions are likely to be more effective if performed as early as possible in the course of the disease, because it has been widely demonstrated that early and regular nephrologic care is associated with decreased morbidity and mortality.
Anemia↗
What are we expecting to learn from the MPO study?
High-flux membranes represented a major improvement in dialysis technique, but evidences supporting their clinical superiority over conventional low-flux dialysis are still inconclusive. Although several studies, most of which were observational, showed an association between high-flux dialysis and lower morbidity and mortality, the Hemodialysis (HEMO) study, the first large-scale randomized clinical trial specifically aimed at testing the effect of membrane permeability on patients' outcome, failed to demonstrate a statistical significant benefit of high-flux membranes on all-cause mortality. Although disappointing, these results should however be interpreted in light of some important limitations of the HEMO study, first of all the inclusion of both incident and prevalent hemodialysis patients, the exclusion of sicker patients and the allowance of dialyzer reuse. In this context, much is expected from the Membrane Permeability Outcome (MPO) study, a randomized clinical trial investigating the effect of high-flux membranes in a large population of incident hemodialysis patients across Europe. Inclusion of only incident patients, absence of severe exclusion criteria and no dialyzer reuse are all distinguishing features of this study. Analyses of the baseline data of the MPO study confirm the high burden of cardiovascular disease among incident dialysis patients, although comparison with the Dialysis Outcomes and Practice Patterns Study data provides further evidence of a positive selection of patients in clinical trials.
Equipment Design↗
Epidemiology and prevention of cardiovascular complication in chronic kidney disease patients.
The risk for cardiovascular disease is significantly higher among patients with chronic kidney disease (CKD) than among the general population, considering that cardiovascular disease is the prominent cause of both morbidity and mortality in dialysis patients. This is explained mainly by the considerable prevalence of cardiovascular risk factors among CKD patients since the earliest stages of renal impairment, which include not only the so-called traditional risk factors, but also a number of additional risk factors that are specific to CKD and to the dialytic treatment itself. Considering the multiplicity of cardiovascular risk factors operating in CKD patients, as well as the crucial impact of their cardiovascular condition on long-term outcome, it is mandatory that all the available interventions aimed at the correction of all the modifiable risk factors for cardiovascular disease are performed as early as possible in the progression of the disease. In particular, the results of several controlled clinical trials have shown that a timely correction of anemia and of calcium-phosphate disorders leads to a significant improvement in the cardiovascular conditions of CKD patients. Evidence also is growing regarding the benefits of intervention of newly recognized risk factors for cardiovascular disease such as inflammation and oxidant stress.
Anemia↗
Renal replacement therapy in patients with diabetes and end-stage renal disease.
The number of patients who have diabetes and ESRD and are being admitted to renal replacement treatment (RRT) is increasing dramatically worldwide, and in many countries, diabetes has become the single most frequent cause of ESRD. Although the prognosis of patients who have diabetes and are receiving RRT has greatly improved, survival and medical rehabilitation rates continue to be significantly worse than those of nondiabetic patients, mainly because of preexisting severely compromised cardiovascular conditions. The most common RRT modality in patients with diabetes is still hemodialysis, but it gives rise to a number of clinical problems, in particular difficulties in the management of the vascular access and high frequency of intradialytic hypotension. However, patients who have diabetes and are on peritoneal dialysis have to face a progressive increase in peritoneal permeability, loss of ultrafiltration, and peritoneal fibrosis, all phenomena being accelerated in patients with diabetes and ultimately leading to an increased technique failure. The results of observational studies and national registries, although conflicting, suggest that these two dialytic modalities are somehow comparable in terms of outcomes, whereas accumulating evidence shows that both survival and medical rehabilitation of patients with diabetes are significantly better after renal transplantation, which should be the first-choice option for patients who have diabetes and reach ESRD but unfortunately still accounts for only a limited proportion of RRT treatments in these patients.
Diabetic Nephropathies↗
Epidemiology of cardiovascular risk in patients with chronic kidney disease.
BACKGROUND: Chronic kidney disease (CKD) patients are highly prone to cardiovascular disease for a number of reasons. At the time of starting renal replacement treatment, their cardiovascular condition is already severely compromised, suggesting that cardiovascular risk factors begin to operate very early in the progression of CKD. Moreover, those patients reaching end-stage renal disease without cardiovascular abnormalities have a high probability of developing de novo cardiovascular disease. METHODS: In this review, we analyse the prevalence of the major cardiovascular risk factors in CKD patients and their importance as contributors to the excess cardiovascular disease in this population. We also describe and discuss the main results obtained in the management of these risk factors in terms of preventing cardiovascular morbidity and mortality. RESULTS: Hypertension plays a major role in determining cardiac damage at all stages of CKD, including the dialytic phase. Anaemia is a major determinant of the development of left ventricular hypertrophy and therefore its correction can be expected to improve cardiovascular status and long-term survival, but this needs to be done before changes in cardiac structure become well established. Calcium-phosphate disorders are increasingly acknowledged to be cardiovascular risk factors in CKD, yet their medical control is still far from being satisfactory. Dyslipidaemia is particularly frequent in CKD patients, but the benefit of lipid-lowering treatments still has to be proven. Finally, CKD is associated with newly recognized risk factors for atherosclerosis, although their importance as cardiovascular risk factors is still controversial. CONCLUSIONS: Nephrologists should attempt to give optimal treatment for well-established cardiovascular risk factors, even if this generally fails to prevent the excess cardiovascular disease of CKD patients. Increasing attention is now being paid to newly recognized CKD-related risk factors for atherosclerosis, although their real importance is still under debate and, before therapeutic prescriptions can be applied to CKD patients, further studies in these new fields are needed.
Cardiovascular Diseases↗
The quality of dialysis water.
INTRODUCTION: Every week, haemodialysis patients are exposed to approximately 400 l of water used for the production of dialysis fluids which, albeit with the interposition of a semi-permeable artificial membrane, come into direct contact with the bloodstream. It is therefore clearly important to know and monitor the chemical and microbiological purity of dialysis water. METHODS: In this review, we analyse the sources of chemical and microbiological water contamination, and the problems involved in water purification systems and modalities. We also analyse the compliance of dialysis units with the microbiological standards established by the most widely accepted guidelines relating to the quality of dialysis fluids. RESULTS: The risk of chemical contamination is due mainly to the primary pollution of municipal water, whereas the most important microbiological problem is the control of bacterial growth in the water treatment and distribution system. Dialysis water treatment implies various levels of pre-treatment, a final purification module (which, in many cases, is reverse osmosis: RO) and a hydraulic circuit for the distribution of the purified water. RO-based treatment systems produce water of optimal chemical and microbial quality, and so dialysis units need to concentrate on maintaining this quality level in the long term by means of effective maintenance and disinfection strategies. The most widely accepted standards for water purity are those recommended by the Association for the Advancement of Medical Instrumentation and the European Pharmacopea, which respectively allow bacterial growth of <200 and <100 c.f.u./ml, and an endotoxin concentration of <2 and <0.25 IU/ml. However, a number of multicentre studies have reported that 7-35% of water samples have bacterial growth of >200 c.f.u./ml, and up to 44% have endotoxin levels of >5 IU/ml. CONCLUSIONS: The results of multicentre studies indicate that the microbial quality of dialysis fluids is still a too often neglected problem, particularly as there is evidence of a possible relationship between dialysis fluid contamination and long-term morbidity. The time has now come to take advantage of innovations in water treatment processes and improvements in dialysis machines in order to modify clinical practices and start improvement processes aimed at decreasing the risk of microbial contamination to the minimum, as it has already been successfully done in the case of chemical contamination.
Dialysis Solutions↗
The importance of early detection of chronic kidney disease.
Despite the absence of precise epidemiological data, we know there are a great many patients in the conservative phase of chronic kidney disease (CKD). The incidence and prevalence of renal replacement therapy (RRT) is increasing worldwide. As well as being a large and growing clinical problem, CKD is of an economic and organizational concern, since RRT consumes a considerable proportion of health care resources. In this context, any medical intervention that may prevent the progression of CKD towards end-stage renal disease (ESRD) is extremely important. Improving the patients' cardiovascular status is also a major objective in the management of this population, as cardiovascular disease (CVD) is the leading cause of morbidity and mortality for dialysis patients. Several interventions to delay the progressive loss of renal function and/or to prevent the development of CVD are now available. These include low-protein diets; correction of calcium-phosphate disorders and anaemia; blood pressure and proteinuria control; and smoking cessation. Other interventions, such as the administration of lipid-lowering agents, anti-inflammatory drugs, and anti-oxidant agents are emerging as particularly promising therapeutic approaches, although prospective, controlled, randomized clinical trials are needed to demonstrate their clinical usefulness. Intervention in the conservative phase of CKD is likely to be more effective if performed as early as possible in the course of the disease, since it has been widely demonstrated that early and regular nephrology specialist care is associated with decreased morbidity and mortality.
Anemia↗
High-flux hemodialysis and hemodiafiltration. Impact on outcome.
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Anemia↗