Search PubMed⌕ Search

Biomedical subjects

Claudio Ronco

Publications and source records attributed to Claudio Ronco.

At least 19 recordsLinked to original sources
PubMed2007

Disinfection of dialysis monitors.

In recent years the concept of biocompatibility is not limited to the dialytic membranes, but has been substituted by a more general viewpoint where all the parameters of the dialytic treatment are taken into consideration: the interaction of blood-surfaces (the dialyzer in all its components and the hematic lines), the sterilization of all materials, the quality of the solutions utilized for dialysis and reinfusion. Numerous studies have shown that the inflammatory response in dialysis is the cause of many of the side effects of dialytic treatment itself both acute and chronic. Hypoxemia, 'first use' syndrome, hypotension, allergic-anaphylactic reactions (short-term side effects); microinflammation, malnutrition, accelerated arteriosclerosis, anemia, beta2 microglobulin amyloidosis, immunodeficiency, bone mass loss (long-term side effects), have all been reported. In this review, we will focus on the fluids utilized for hemodialysis (HD) and hemodiafiltration (HDF); we will describe the process of disinfection of the machines which produce the dialytic solutions.

Disinfectants↗
PubMed2007

Effectiveness of sodium hypochlorite in the prevention of catheter related infections.

Vascular access in hemodialysis is a major point of concern in the management of chronic patients. Although arteriovenous fistula remains as the access of first choice, tunneled central venous catheters are still commonly used. Infection remains the principal cause of catheter dysfunction or loss. Many protocols have been used in order to prevent exit site infections and bacteremia. We describe our experience with the use of sodium hypochlorite, an electrolytic chloroxidizer used as a topical disinfectant. It has been shown to be active against a broad spectrum of potential pathogens and has other specific advantages compared to other cleansing agents, including its non-toxic, non-irritating nature and its low cost. We conclude that sodium hypochlorite solution in different concentrations (10 and 50%) is effective in preventing exit site infections and bacteremia associated with tunneled central venous catheters in chronic hemodialysis patients.

Bacteremia↗
PubMed2006

Guidelines for guidelines.

Practice guidelines are proliferating in medicine. In addition to methodological problems that cause guidelines to be outdated rapidly, they are plagued by conflicts of interest. They are largely consensus opinions of panels of experts, most of whom are supported by industry. Professional societies, health insurers, Centers for Medicare and Medicaid Services, and dialysis providers also benefit from guidelines. Little attention is paid to the potential for harm to patients, and to the profession of medicine, from the widespread use of guidelines.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed2006

Haemodialysis fluid: composition and clinical importance.

Dialysis fluid is produced by the blending of treated water with electrolytes at the patients bed side. Its preparation and composition are important elements of treatment optimisation since many of the constituents play a role in patient well-being. Ideally the composition of the dialysis fluid should match that of plasma, but due to differences between patients, as well as the increasing number of elderly patients receiving treatment, have resulted in a move towards individualisation of the electrolyte and buffer composition to patient needs. Such individualisation is facilitated by the availability of technology, however it is not yet possible to individualise minor electrolytes, such as K(+), Ca(2+) and Mg(2+). Early dialysis treatments were frequently accompanied by pyrogen reactions arising from bacterial contamination of the dialysis fluid. Today the focus is on the stimulation of mononuclear cells by bacterial fragments contributing to chronic inflammation associated with long-term haemodialysis therapy, and which has led to suggestions regarding the desirability of using ultra-pure dialysis fluid to prevent or to delay complications associated with their presence.

Bacteria↗
PubMed2006

Usefulness of a molecular strategy for the detection of bacterial DNA in patients with severe sepsis undergoing continuous renal replacement therapy.

INTRODUCTION: Sepsis is a major cause of morbidity and mortality in critically ill patients. Sepsis is associated with cell necrosis and apoptosis. Circulating plasma levels of DNA have been found in conditions associated with cell death, including sepsis, pregnancy, stroke, myocardial infarction and trauma. Plasma DNA can also derive from bacteria. We have recently implemented a method to detect bacterial DNA and, in the present study, we validated this technique comparing it to standard blood culture in terms of diagnostic efficacy. METHODS: We examined a cohort of 9 critically ill patients with a diagnosis of severe sepsis and acute renal failure requiring continuous renal replacement therapy (CRRT). We analyzed bacterial DNA in blood, hemofilters, and ultrafiltrate (UF) by polymerase chain reaction amplification of 16S rRNA gene sequence analysis. Standard blood cultures were performed for all patients. RESULTS: The blood cultures from 2 of the 9 (22%) patients were positive. However, bacterial DNA was identified in the blood of 6 patients (67%), including the 2 septic patients with positive blood cultures. In 9 (100%) patients bacterial DNA was found on the filter blood side, whereas in 7 (78%) subjects it was found in the dialysate compartment of the hemofilters. Bacterial DNA was never detected in the UF. CONCLUSIONS: Using the 16S rRNA gene, the detection of bacterial DNA in blood and adsorbed within the filter could be a useful screening tool in clinically septic, blood culture-negative patients undergoing CRRT. However, the identification of the etiologic agent is not feasible with this technique because specific primers for the defined bacteria must be used to further identify the suspected pathogenic organisms.

Acute Kidney Injury↗
PubMed2006

Defining and classifying acute renal failure: from advocacy to consensus and validation of the RIFLE criteria.

Until recently, more than 30 different definitions of acute renal failure (ARF) had been used in the literature. This lack of a common reference point created confusion and made comparisons difficult. It also led to strong advocacy of a consensus definition. In response to the need for a common definition and classification of ARF, the Acute Dialysis Quality Initiative (ADQI) group of experts developed and published a consensus definition of ARF. This definition goes under the acronym of RIFLE to indicate that it classifies patients with renal dysfunction according to the degree of impairment into patients at risk (R), with injury (I), with failure (F), with sustained loss (L) and with end-stage (E) status in relation to their renal function. This editorial aims to summarize and interpret recent findings concerning the application of the RIFLE criteria to the assessment of the epidemiology and the prediction of the outcome of ARF.

Acute Kidney Injury↗
PubMed2006

A new semiempirical mathematical model for prediction of internal filtration in hollow fiber hemodialyzers.

The potential of convective solute transport for blood purification has been widely explored. New techniques (such as hemodiafiltration), based on a combination of diffusion and convection techniques, have been developed. Owing to the internal filtration/backfiltration (IF/BF) phenomenon, high-flux dialysis also relies on a convective component, which, however, is hard to quantify and thus optimize. In this work, we developed a mathematical model designed to supply the clinician with a quantification of the IF/BF fluxes taking place during high-flux dialysis. IF fluxes are predicted based on the machine settings and blood hematocrit/protein concentration. The hydraulic characteristics of commercial dialyzers were derived from bloodless bench tests. Moreover, an in vitro blood test was conducted on a 1.8 m(2) polysulfone dialyzer using an established scintigraphic analysis, for verification of model prediction accuracy. Results of simulations show that the IF/BF rate is sensitive to the blood flow rate and (to a lesser extent) to the dialysate flow rate. Increasing net ultrafiltration rates resulted in parallel increases of direct filtration and simultaneous decreases of BF. IF/BF is rather influenced by blood composition, due to the complex dependence of oncotic pressure and blood viscosity upon hematocrit and plasma protein concentration. Simulation results showed an excellent agreement with the experimental results obtained with scintigraphy, with only a 3% prediction error. With respect to some previous works, this model is simpler in its theoretical approach. It allows implementation into a user-friendly software tool and might be used to predict the convective component in high-flux dialysis and possibly to optimize it.

Computer Simulation↗
PubMed2006

Recent clinical advances in the management of critically ill patients with acute renal failure.

BACKGROUND: Significant progress has been made in the field of renal replacement therapy for critically ill patients with acute renal failure (ARF) over the past few years. This review highlights these developments. METHODS: Recent studies assessing the clinical utility of the RIFLE classification system for the diagnosis of ARF were reviewed. Clinical outcome studies evaluating the effect of continuous renal replacement therapy (CRRT) dose and timing of initiation were assessed. The final review topic was the effect of dialysis modality on the recovery of renal function in ARF patients. CONCLUSIONS: Based on recent clinical studies, the increasing use of the RIFLE criteria is justified, as this approach appears to be a robust method for both the diagnosis of and prognostication in ARF. A large randomized trial involving convective CRRT supports the commonly used prescription of 35 ml/ kg/h in clinical practice. Moreover, numerous recent outcome studies, also largely involving convective CRRT, provide a clinical rationale for the increasingly common clinical practice of earlier initiation. Finally, several recent studies suggest CRRT, relative to conventional hemodialysis, results in a greater rate of renal recovery in ARF patients.

Acute Kidney Injury↗
PubMed2006

Ethical, political, and social aspects of high-technology medicine: Eos and care.

OBJECTIVE: We discuss biosocial aspects of high-technology medicine (HTM) to provide a global view of the current model of medicine in the developed world and its consequences. METHODS: We analyze changes in the concept of death and in the use and cost of HTM. The consequences of HTM on the delivery of basic medical care within and among countries are discussed. Concepts derived from Greek mythology are used to illustrate the problems associated with HTM. RESULTS: HTM can be extremely effective in individual cases, but it poses important bioethical and biosocial problems. A major problem is related to the possibility of manipulating the process of dying and the consequent alteration in the social concept of death, which, if not carefully regulated, risks transforming medicine into an expensive way of pursuing pointless dreams of immortality (myth of Eos). Another problem is related to the extraordinary amount of resources necessary for HTM. This model of medicine (which is practiced daily) has limited sustainability, can work only in highly developed countries, may contribute to unequal access to health care, and has negligible positive impact on global health and survival. CONCLUSIONS: HTM poses very important biosocial questions that need to be addressed in a wider and transparent debate, in the best interest of society and HTM as well.

Biotechnology↗
PubMed2006

Extracorporeal blood purification therapies for prevention of radiocontrast-induced nephropathy: a systematic review.

BACKGROUND: Radiocontrast-induced nephropathy (RCIN) causes acute kidney injury and increases mortality. Studies have examined the capacity of various forms of extracorporeal blood purification therapies for the prevention of RCIN, with conflicting results. We conducted a systematic review of published trials to determine whether periprocedural extracorporeal blood purification prevents RCIN. METHODS: We searched PubMed, the Cochrane Collaboration Database, EMBASE, and CINAHL through January 2006 and bibliographies of retrieved articles and consulted with experts to identify relevant studies. Published studies of extracorporeal blood purification for the prevention of RCIN in patients receiving radiocontrast were included. Two authors reviewed all citations. The primary end point is the incidence of RCIN, defined as an increase in serum creatinine concentration (>or=0.5 mg/dL [>or=44 micromol/L]). Results were combined on the risk ratio scale. Random-effects models were used. Sensitivity analyses were performed to evaluate the effects of extracorporeal blood purification modality, study design, and sample size. RESULTS: Eight trials (6 randomized controlled trials, 2 nonrandomized trials) were included in the analysis (pooled sample size, 412). Six trials assessed hemodialysis, whereas 1 trial each assessed continuous venovenous hemofiltration and continuous venovenous hemodiafiltration. The incidence of RCIN was 35.2% in the standard-medical-therapy group and 27.8% in the extracorporeal-blood-purification group. Extracorporeal blood purification did not decrease the incidence of RCIN significantly compared with standard medical therapy (risk ratio, 0.97; 95% confidence interval, 0.44 to 2.14); however, intertrial heterogeneity was high. Limiting analysis to only randomized trials did not eliminate heterogeneity, but limiting analysis to only hemodialysis trials did. Periprocedural hemodialysis did not decrease the incidence of RCIN. CONCLUSION: This critical analysis of the published literature suggests that periprocedural extracorporeal blood purification does not decrease the incidence of RCIN compared with standard medical therapy.

Contrast Media↗
PubMed2006

An assessment of the RIFLE criteria for acute renal failure in hospitalized patients.

OBJECTIVE: The Acute Dialysis Quality Initiative (ADQI) Group published a consensus definition (the RIFLE criteria) for acute renal failure. We sought to assess the ability of the RIFLE criteria to predict mortality in hospital patients. DESIGN: Retrospective single-center study. SETTING: University-affiliated hospital. PATIENTS: All patients admitted to the study hospital between January 2000 and December 2002. Patients were excluded if they were younger than 15 yrs old, were on chronic dialysis, or had kidney transplant or if their length of hospital stay was <24 hrs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We included 20,126 patients. Mean age was 64 yrs, 14.7% of patients required intensive care unit admission, and hospital mortality was 8.0%. According to the RIFLE criteria, 9.1% of all patients were in the Risk category for acute renal failure, 5.2% were in the Injury category, and 3.7% were in the Failure category. There was an almost linear increase in hospital mortality from Normal to Failure (Normal, 4.4%; Risk, 15.1%; Injury, 29.2%; and Failure, 41.1%). Multivariate logistic regression analysis showed that all RIFLE criteria were significantly predictive factors for hospital mortality, with an almost linear increase in odds ratios from Risk to Failure (odds ratios, Risk 2.5, Injury 5.4, Failure 10.1). CONCLUSIONS: The RIFLE criteria for acute renal failure classified close to 20% of our study patients as having some degrees of acute impairment in renal function and were useful in predicting their hospital mortality.

Acute Kidney Injury↗
PubMed2006

Current worldwide practice of dialysis dose prescription in acute renal failure.

PURPOSE OF REVIEW: The practice of renal replacement therapy for acute renal failure varies greatly around the world. This is especially true for the dose of renal replacement therapy. This review describes the epidemiology of dialysis prescription and delivery around the world based on recent observational studies and international surveys. Furthermore, a brief speculation on the concept of adequacy of therapy is provided. RECENT FINDINGS: Following the publication of the first large prospective randomized trial on the effects of treatment dose on outcome of patients with acute renal failure a certain consensus has been achieved on the adequacy of 35 ml/kg/h of clearance in continuous therapies. Surveys conducted in 1998 had demonstrated that such adequate therapy was only prescribed in a minority of patients. Recent observations based on questionnaires and surveys confirm that the number of centers prescribing adequate dialysis dose is increasing, but there is still a large number of institutions where prescription is made with no specific adequacy targets and effective delivery is not measured. Several barriers have been identified to reach adequacy targets including logistics, costs, personnel and others. SUMMARY: The analysis of the epidemiology of dialysis dose around the world shows a complex picture. Wide variations in practice are present although a significant effort has been made to standardize the prescription and delivery of therapy.

Acute Kidney Injury↗
PubMed2006

Flow distribution analysis by helical scanning in polysulfone hemodialyzers: effects of fiber structure and design on flow patterns and solute clearances.

The efficiency of a hemodialyzer is largely dependent on its ability to facilitate diffusion, as this is the main mechanism by which small solutes are removed. The diffusion process can be impaired if there is a mismatch between blood and dialysate flow distribution in the dialyzer. The objective of the paper was to study the impact of different fiber bundle configurations on blood and dialysate flow distribution and urea clearances. The Optiflux 200 NR hemodialyzer was studied and the standard F 80 A hemodialyzer was used as a control for the study. Six dialyzers of each type were studied in vitro in the radiology department utilizing a new generation of helical computed tomography (CT) scan following contrast medium injection into the blood and dialysate compartment. Dynamic sequential imaging of longitudinal sections of the dialyzer was undertaken to detect flow distribution, average and peak velocities, and calculate wall shear rates. Six patients were dialyzed with 2 different dialyzers in random consecutive sequence. In these patients, 2 consecutive dialyses were carried out with identical operational parameters (Qb = 300 mL/min, Qd = 500 mL/min). In each session, blood and dialysate side urea clearances were measured at 30 and 150 min of treatment. Macroscopic and densitometrical analysis revealed that flow distribution was most homogeneous in the dialyzer with a new bundle configuration. Significantly increased urea clearances (p < 0.001) were seen with the Optiflux dialyzer compared with the standard dialyzer. In conclusion, more homogeneous dialysate blood and dialysate flow distribution and improved small solute clearances can be achieved by modifying the configuration of the filter bundle. These effects are achieved probably as a result of reduced blood to dialysate mismatch with reduction of flow channeling. The used radiological technique allows detailed flow distribution analysis and has the potential for testing future modifications to dialyzer design.

Blood Flow Velocity↗
PubMed2006

Dialyzer and machine technologies: application of recent advances to clinical practice.

Although hemodialysis is a mature therapy, a growing population of patients with more complex medical problems and limitations on resources will require technological innovations to improve the safety, reliability and efficiency of the therapy. The past several years have seen design changes to dialyzers that have provided incremental improvements in small solute clearance and more substantial improvements in the clearance of large solutes. New functions have been added to dialysis machines that help ensure reliable delivery of the dialysis prescription and enable full advantage to be taken of improvements in dialyzer clearance of large molecules. In addition, feedback control systems have been developed that may help reduce the untoward side effects which many patients experience during hemodialysis. Whether or not a particular innovation enters routine clinical use will depend on demonstrating that it improves clinical outcomes, its cost, and, in some cases, on a more enlightened approach by regulatory authorities.

Dialysis Solutions↗
PubMed2006

The importance of water quality and haemodialysis fluid composition.

Treatment of renal failure by haemodialysis uses dialysis fluid to facilitate the normalization of electrolyte and acid base abnormalities and the removal of low molecular weight uraemic compounds present in the plasma such as urea. The dialysis fluid is a continuously produced blend of treated tap water and a concentrated solution containing electrolytes, buffer, and glucose. The water used originates as drinking water but undergoes additional treatment. Recent surveys have indicated that the chemical and microbiological content of such water frequently fails to meet the requirements of established standards, and its bacterial content arising from the presence of a biofilm in the water distribution network or the hydraulic circuit of the dialysis machine is a contributory factor to the chronic inflammatory state in patients undergoing regular dialysis. The composition of the dialysis fluid plays an important role in the modulation of complications associated with end-stage renal disease, as well as those associated with the treatment itself. The avoidance of complications arising from water contaminants requires a constant and vigorous attention to water quality, whilst with the composition of electrolytes and buffer there is a trend towards greater individualization to provide a high degree of treatment tolerance.

Biofilms↗
PubMed2006

Dialysis patients and cardiovascular problems: Can technology help solve the complex equation?

Patients with end-stage kidney disease undergoing chronic hemodialysis (HD) present higher mortality rates compared with the general population. Once patients are on HD, the risk of cardiovascular death is approximately 30 times higher than in the general population and remains 10-20 times higher after stratification for age, gender, and the presence of diabetes. About half the deaths of patients on dialysis are attributed to cardiovascular causes including coronary heart disease, cerebrovascular disease, peripheral vascular disease, and heart failure. The cardiovascular burden of the HD patient arises from three different sources: risks inherent to the patient and the uremic syndrome, traditional risk factors, and risk factors related to the dialysis therapy. Based on these considerations and the fact that several aspects of the dialysis procedure can either add to the cardiovascular burden or modify the existing burden, new technologies should be directed towards the approach of a potential 'cardioprotective dialysis therapy'; such an approach may be facilitated by the application of new techniques and advanced dialysis machines. Created to make dialysis easy and safe, new machines feature several options that make patient monitoring and online hemodiafiltration therapy routine procedures. These and other features will possibly make dialysis better tolerated and more efficient in protecting patients from undesirable or potentially fatal cardiovascular events.

Age Factors↗