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Biomedical subjects

C Ronco

Publications and source records attributed to C Ronco.

At least 37 records · Page 2Linked to original sources
PubMed2005

Management of fluid balance in CRRT: a technical approach.

BACKGROUND: The possibility of making fluid balance errors during continuous renal replacement therapy has been identified since the beginning of this modality of treatment. The advent of automated machines has partially overcome this problem. Nevertheless, there are conditions and operation modes in which the potential for fluid balance errors is still present. OBJECTIVE: To analyse fluid balance management in CRRT therapies across a range of currently marketed machine. METHODS: The tests were conducted in vitro, utilizing saline solution for the blood circuit and regular dialysate/reinfusate for the dialysate/reinfusion circuit. The methodology used was based on the voluntary creation of a fluid balance error by altering the correct flow in the circuit of the different machines. Subsequently, the time for alarm occurrence and the threshold value for fluid balance error was evaluated. The alarm was overridden and the overall fluid error allowed by the machine was evaluated. Each machine was tested in conditions of different dialysate/filtrate flow rates and in different simulated treatment modalities. RESULTS: Fluid balance errors can be easily avoided not only by a correct and careful adherence to the protocols of use of the current CRRT machines, but also by the compliance to prescriptions and programmed controls during therapy. Most importantly, if an alarm appears on the machine, one can try to override it without major problems; major problems may occur when multiple override commands are operated without identifying the problem and solving it adequately. CONCLUSION: Machines seem to be designed with adequate safety features and accurate alarm systems. However, features and alarms can be manipulated by operators creating the opportunity for serious error. Physicians and nurses involved in prescription and delivery of CRRT should have precise protocols and defined procedures in relation to machine alarms to prevent major clinical problems.

Acute Kidney Injury↗
PubMed2005

Plasma acid-base changes in chronic renal failure: a Stewart analysis.

The bicarbonate centered approach to acid-base physiology involves complex explanations for the metabolic acidosis associated with chronic renal failure. We used the alternate Stewart approach to acid-base physiology to quantify the acid-base chemistry of patients with chronic renal failure. We examined the plasma and urine chemistry of 19 patients with chronic renal failure who were predialysis and 20 healthy volunteers. We compared the plasma strong-ion-difference due to sodium,potassium,and chloride ions as well as the weak acids albumin and phosphate. We used a simplified Fencl-Stewart approach to quantify the effects of sodium-chloride, albumin, and unmeasured ions on base-excess. The chronic renal failure group had a greater metabolic acidosis, with a base-excess that differed from the healthy group by a mean of -2.7 mmol/L, p = 0.04. This was associated with a strong ion acidosis due to both increased chloride and decreased sodium. The anion gap, strong-ion-gap, and base-excess effect of unmeasured ions were similar in both groups suggesting that unmeasured ions had only a minor role in the acid-base status in this group of patients.

Acid-Base Equilibrium↗
PubMed2005

Dialytic performance evaluation of Rexeed: a new polysulfone-based dialyzer with improved flow distributions.

New dialyzers are designed to optimize the convective and diffusive components of solute transport. Asahi Kasei Medical Co.,Ltd.has developed a new high flux dialyzer series called Rexeed with improved flow distributions. We evaluated the in vivo dialytic performance of two dialyzers of the Rexeed series: Rexeed-18A and Rexeed-25A (1.8 m2 and 2.5 m2 ). We calculated the clearance for urea,creatinine,phosphate and b2-microglobulin both in high flux dialysis (HFD)and in 15 liter postidiluitional on-line hemodiafiltration (HDF)mode. With n = 3 patients in high flux HD at blood flow 450, 400, 350 and 250 ml/min we found remarkably high clearance for urea (347 +/- 4%, 305 +/- 0%, 288 +/- 5%, 230 +/- 3%, for Rexeed-18A and 361 +/- 3%, 329 +/- 0%, 313 +/- 1%, 234 +/- 3%for Rexeed-25A),creatinine (282 +/- 10%, 234 +/- 0%, 221 +/- 8%, 174 +/- 8%, for Rexeed-18A and 276 +/- 6%, 245 +/- 0%, 226 +/- 9%, 172 +/- 13% for Rexeed-25A),phosphate (347 +/- 0%, 316 +/- 0%, 275 +/- 4%, 202 +/- 16%, for Rexeed-18A and 364 +/- 3%, 365 +/- 0%,286 +/- 3%, 224 +/- 2% for Rexeed-25A)and b2-microglobulin (133 +/- 21%, 124 +/- 0%,118 +/- 12%, 98 +/- 11%, for Rexeed-18A and 159 +/- 8%, 169 +/- 0%,157 +/- 8%, 129 +/- 7% for Rexeed-25A) With n = 2 patients in HDF at blood flow 300 ml/min we found remarkably high clearance for urea (268 +/- 2%, for Rexeed-18A and 283 +/- 2% for Rexeed-25A),creatinine (183 +/- 6%for Rexeed-18A and 205 +/- 9% for Rexeed-25A),phosphate (245 +/- 3%, for Rexeed-18A and 270 +/- 2% for Rexeed-25A)and b2-microglobulin (166 +/- 12%, for Rexeed-18A and 192 +/- 4% for Rexeed-25A). Our preliminary evaluation describes the characteristics and the performances of a new polysulfone-based hemodialyzer series called Rexeed. Several innovative features have been implemented by the manufacturer. These constructive approaches seem to have produced a positive effect on the dialyzer performance at the bedside.

Blood Flow Velocity↗
PubMed2005

Recent insights into the pathogenesis of severe sepsis.

OBJECTIVE: Severe sepsis remains the dominant challenge in the care of critically ill patients. Over the last 10 years a large body of research has modified our understanding of this condition. In this article, we review the evolution of our understanding of the molecular mechanisms responsible for the development of this clinical syndrome. DATA SOURCES: The authors undertook a critical review of the literature on the molecular basis of the pathogenesis of sepsis with particular emphasis on the role of cytokines, toll-like receptors, adhesion molecules, coagulation cascade molecules and the possible role of in-vitro experimental models of blood-endothelium interaction. SUMMARY OF REVIEW: Recent insights into the molecular mechanisms responsible for the pathogenesis of the severe sepsis syndrome suggest that pro- and anti- inflammatory pathways are simultaneously activated and interact in a dynamic way. Pro-inflammatory cytokines previously considered as targets for intervention have typically been already activated and de-activated by the time the clinical diagnosis is made and intervention is possible. Cellular activity involving white cell-endothelial interactions occur later, making them a more attractive option for therapeutic intervention. Immunological incompetence rather than over-activity may be the most common state of cell function in critically ill patients. CONCLUSIONS: Our understanding of the the pathogenesis of severe sepsis continues to grow. Expression of membrane surface molecules such as toll-like receptors, adhesion molecules and cytokine receptors induce a high degree of redundancy and amplification. Cell responsiveness is reduced in an attempt to circumvent the amplification loop. However, the ensuing interaction between the host and the pathogen(s) may lead to an immune deficiency, leaving the field open to further invasion by the original bacteria or to superimposed infection agents. Endothelium-white cell interactions might be an appropriate target for future interventions.

Journal Article↗
PubMed2004

Ultrafiltration in patients with hypervolemia and congestive heart failure.

Fluid overload may occur in patients with myocardial dysfunction and different clinical problems. Myocoardial dysfunction may be a consequence of heart dilatation with reduced contractility, ventricular stiffness with diastolic dysfunction or the consequence of myocardial injury or circulating myocardial depressant factors as seen in sepsis. In all cases, cardiac support can be achieved by the optimization of fluid balance, the reduction in organ edema and the restoration of desirable levels of pre- and afterload. Several reports have shown that myocardial elastance can improve after hemofiltration with restoration of adequate fluid balance. In such conditions, continuous extracorporeal therapy may result in remarkable cardiovascular stability with maintenance of hemodynamic parameters, including mean arterial pressure, heart rate and systemic vascular resistance. Such stability, which is achieved through the slow continuous ultrafiltration and continuous refilling of the intravascular volume from the interstitium, enables the stability of the circulating blood volume and the preservation of organ perfusion. This is also crucial for renal recovery during acute renal failure.

Blood Volume↗
PubMed2004

Cytokine removal during continuous renal replacement therapy: an ex vivo comparison of convection and diffusion.

BACKGROUND AND OBJECTIVES: It is unknown whether cytokine adsorption to the membrane during continuous renal replacement therapy is affected by the technique. Such knowledge might affect the choice of technique in vivo. Accordingly, we conducted an ex vivo study to test whether continuous veno-venous hemofiltration (CVVH) or continuous veno-venous hemodialysis (CVVHD) affect cytokine adsorption differently. SETTING: Laboratory attached to the Intensive Care Unit of a tertiary hospital. DESIGN: Six healthy human volunteers donated blood, which was incubated with endotoxin. Control blood was left at room temperature, and treatment blood was recirculated for eight hours through closed circuits using polyacrylonitrile membranes (AN69). The effect of CVVH and CVVHD on cytokine removal from the circuits was compared. MEASUREMENTS: The concentrations of interleukins (IL)-1beta, 6, 8, 10 and TNF were measured in the control samples, pre-and post-filter and in the effluent at baseline and hourly thereafter. The clearances by adsorption, and filtration were calculated. RESULTS: Control cytokine concentrations remained the same or increased slightly. Adsorption was the major mechanism of removal for all cytokines with the exception of IL-1beta, but the effect was short-lived. Peak adsorption generally occurred at baseline before the start of CVVH and CVVHD, with clearances ranging from 43.7 ml/min (for IL-8) to 7.6 ml/min (for IL-10). The time-weighted average total clearances during CVVH were 23.3, 4.3, 3.8, -2.0, and 15 ml/min for IL-8, IL-1beta, TNF, IL-6, and IL-10 respectively. The corresponding clearances during CVVHD were 19.0, 10.7, 2.7, 2.4, and 0.3 ml/min. IL-10 clearances were greater during CVVH than CVVHD (p=0.03). Non adsorptive CVVH clearance of IL-1beta was greater than CVVHD clearance, but this advantage was outweighed by an increased tendency of the membrane to release IL-1beta into the circuit during HF. CONCLUSIONS: The technique of solute removal had only a minor effect on the magnitude of cytokine adsorption, and neither technique had the advantage for all the measured cytokines.

Adsorption↗
PubMed2004

Pulse high volume hemofiltration.

The sepsis syndrome is the most common cause of acute renal failure and multiple organ dysfunction in critically ill subjects and continues to have an alarmingly high mortality. Normal immune homeostasis is interrupted by a complex storm of inflammatory mediators responsible for the deleterious effects. Extracorporeal blood purification techniques can confer benefits in sepsis by proven non-specific removal of these mediators (pro- or anti-inflammatory), and provide a logical and adequate approach to treat this syndrome. High volume hemofiltration (HVHF) has had the most dramatic effect conferring benefits in hemodynamics, reduction in vasopressor doses and improvement in survival. "Pulse HVHF" is the latest approach which may offer the most efficient results: a daily schedule of 6-8 hours followed by standard CVVH. This paper describes the rationale and potential of this technique. Reliability and tolerance of this technique and biological effects are described.

Acute Kidney Injury↗
PubMed2004

First clinical trial for a new CRRT machine: the Prismaflex.

A new CRRT machine has been designed to fulfill the expectations of nephrologists and intensivists operating in the common ground of critical care nephrology. The new equipment is called "Prismaflex" (Gambro-Dasco, Mirandola, Modena) and it is the natural evolution of the Prisma machine that has been utilized worldwide for CRRT in the last decade. We performed a preliminary "alfa trial" to establish usability, flexibility and realiability of the new device. Accuracy was also tested by recording various operational parameters during different intermittent and continuous renal replacement modalities. Forty-one runs were conducted on 13 patients and the difference between delivered and prescribed parameters was always lower than 2%. We concluded that the new Prismaflex is a well designed new machine for CRRT and can be safely and effectively utilized in the critical care nephrology setting.

Acute Kidney Injury↗
PubMed2004

Continuous renal replacement technology: from adaptive devices to flexible multipurpose machines.

OBJECTIVE: To review the evolution of technologies in the development of renal replacement therapies. DATA SOURCES: Articles and published reviews on renal replacement therapies. SUMMARY OF REVIEW: Continuous arterio-venous haemofiltration (CAVH) was the first continuous renal replacement technique capable of overcoming the traditional haemodialysis-related side effects, making possible the treatment of critically ill patients safely and with less physiological instability. The evolution of technology and the progress experienced in intensive care units (ICUs) has made it possible to start renal replacement therapy programs in the absence of a chronic dialysis facility or a trained nephrological team. Initial limitations and draw-backs of CAVH, stimulated the ICU staff to explore new avenues for better therapy. Extracorporeal therapies are today a routine experience in the ICUs: continuous renal replacement therapies are a broadly accepted treatment for acute renal failure. Furthermore, alternative indications for extracorporeal blood circulation (e.g. sepsis, liver failure, congestive heart failure, drug intoxications, hyperthermia, immuno-mediated syndromes) are becoming more and more popular. The ideal machine has yet to be completed, but progress has occurred and has opened a new era for critical care nephrology and the further expansion of blood purification technology in the ICU. CONCLUSIONS: Technical advances in renal replacement therapies have increased their functionality (i.e. used in hepatic failure, sepsis, cardiac failure and immuno-mediated syndromes), are easier to operate and have less side-effects compared with their standard extracorporeal counterparts. Further improvements may see them become a routine part in the management of the critically ill patient.

Journal Article↗