Ronco C

Out of hospital outcome and quality of life in survivors of combined acute multiple organ and renal failure treated with continuous venovenous hemofiltration/hemodiafiltration

Objective: To study the out-of-hospital quality of life and long-term survival of critically ill patients with combined multiple organ failure and acute renal failure treated with continuous renal replacement therapy (CRRT). Design: Study based on responses to postal questionnaire and clinical information obtained during treatment in the intensive care unit (ICU). Setting: ICUs of two tertiary institutions. Patients: 85 survivors from a pool of 250 patients with combined acute multiple organ and renal failure who were treated with CRRT. Method and results: Anonymous postal questionnaire based on an activity index, mental function index, and a simplified version of the Nottingham Health Profile. Of the 250 patients, 85 (34 %) survived to be discharged from hospital: 57 males (67 %) and 28 females (33 %), mean age 56.9 years (range 13.4–81). Mean duration of ICU stay was 10.9 days (range 2–52), mean admission Acute Physiology and Chronic Health Evaluation II score was 24.2 (range 15–41), and mean duration of CRRT was 6.2 days (range 1–34). Mean follow-up time was 2.5 years (range 0.1–5.3). Thirty-three of the 85 patients (38.8 %) did not reply to the questionnaire; 35 patients (41.7 %) were alive at the time of response and 17 (20 %) were deceased. Of the 35 responders, 68.5 % were satisfied with their present state of health, despite 60.6 % stating that their mobility had been affected, with 41.9 % being unable to walk more than 200 metres. Most (94.5 %) survivors, however, felt that their treatment had been worthwhile, and 91.2 % said that they would undergo the same treatment again if necessary. The approximate cost for each year of survival was U. S.

Nomenclature for continuous renal replacement therapies

50 000. Conclusions: In the majority of patients who survived to be discharged from hospital after combined acute multiple organ and renal failure, the overall state of health and quality of life seemed acceptable. Most patients felt that their treatment was worthwhile and that they would undergo the same treatment again if necessary. Our findings suggest that the cost and effort associated with CRRT and ICU care in these patients are high but broadly comparable to those associated with the care of other serious illnesses. They are also seen as worthwhile by survivors, who consider their life to be of acceptable quality.

On-Line Urea Monitoring: A Further Step towards Adequate Dialysis Prescription and Delivery

Abstract Continuous renal replacement therapies (CRRTs) have evolved over the last decade, but there is no standard terminology for the defferent methods in use. At an International Conference on CRRT, held in San Diego, CA, November 9–10, 1995, an international panel of experts developed a proposed nomenclature for these therapies. The nomenclature was developed to define common terms and to use a standardized language when papers in the field of CRRT are reviewed and published. This article describes the definition for each technique. It is hoped that these definitions will be used as a framework for subsequent descriptions of new techniques in the literature.

Uremic toxins: a new focus on an old subject.

The Aim Of This Study Is To Present A Clinical Experience Carried Out With A New Device Designed To Measure On-Line Urea Nitrogen Concentration In The Effluent Dialysate. The Biostat 1000® Urea Monitor (Baxter Healthcare, Dirfield, Iii, Usa) Was Utilized In The Present Study. The Monitor Is Based On The Principle That Multiple Urea Measurements In The Dialysate Effluent From The Dialyzer, Permit To Built A Double Exponential Regression Leading To The Urea Kinetic Parameters Of The Dialysis Session. Data Obtained With The Urea Monitor Were, In The Present Study, Compared With Those Obtained By Direct Measurements Carried Out In Blood And Dialysate And By The Collection Of The Whole Amount Of Spent Dialysate. The Monitor Provided An Accurate Value Of Predialysis Bun Without Any Blood Drawing. Urea Kinetics Were Established From Multiple Dialysate Measurements And No Blood Drawing Was Necessary. The Double Pool Kinetics Were Taken Into Account And Kt/V, Pcr And Sri° Obtained Were Comparable To Those Obtained From Direct Measurement. Since A Projected Value Of Kt/V Can Be Obtained, The Monitor Could Represent A Potential Source Of Information To Detect Possible Filter And Machine Dysfunction, As Well As High Rate Of Recirculation.

Inflammation and Subclinical Infection in Chronic Kidney Disease: A Molecular Approach

The uremic syndrome is characterized by an accumulation of uremic toxins due to inadequate kidney function. The European Uremic Toxin (EUTox) Work Group has listed 90 compounds considered to be uremic toxins. Sixty‐eight have a molecular weight less than 500 Da, 12 exceed 12,000 Da, and 10 have a molecular weight between 500 and 12,000 Da. Twenty‐five solutes (28%) are protein bound. The kinetics of urea removal is not representative of other molecules such as protein‐bound solutes or the middle molecules, making Kt/V misleading. Clearances of urea, even in well‐dialyzed patients, amount to only one‐sixth of physiological clearance. In contrast to native kidney function, the removal of uremic toxins in dialysis is achieved by a one‐step membrane‐based process and is intermittent. The resulting sawtooth plasma concentrations of uremic toxins contrast with the continuous function of native kidneys, which provides constant solute clearances and mass removal rates. Our increasing knowledge of uremic toxins will help guide future treatment strategies to remove them.

Dialysate flow distribution in hollow fiber hemodialyzers with different dialysate pathway configurations.

Inflammation and infection seem to be important causes of morbidity and mortality in chronic kidney disease (CKD) patients; subclinical infections have been proposed as an important cause of inflammatory syndrome, but to date this hypothesis remains speculative. We developed a method for the molecular detection of the presence of bacterial DNA in a population of CKD patients in order to correlate the molecular data with the degree and level of inflammation and to evaluate its usefulness in the diagnosis of subclinical infection. The study was divided into two phases: (1) a population of 81 CKD patients was screened for the prevalence and level of inflammation and the presence of possible infection, and (2) a subgroup of 38 patients, without evident clinical causes of inflammation, underwent complete molecular evaluation for subclinical infection using bacterial DNA primers for sequencing. Additionally, complete analysis was carried out in the blood and dialysate compartments of the hemodialyzers used. The general population showed a certain degree of subclinical inflammation and no difference was found between patients with and without evident causes of inflammation. Hemoculture-negative patients were positive for the presence of bacterial DNA when molecular methods were used. We found a correlation trend between the presence of bacterial DNA and the increase in hs-CRP, IL-6 and oxidative stress (advanced oxidation protein product) levels and a reduction in the mean fluorescence intensity for HLA-DR. Hemodialyzer membranes seem to have properties that stick to bacteria/bacterial DNA and work as concentrators. In fact, patients with negative bacterial DNA in the circulating blood displayed positivity in the blood compartment of the dialyzer. The dialysate was negative for bacterial DNA but the dialysate compartment of the hemodialyzers used was positive in a high percentage. Moreover our data suggest that bacterial DNA can traverse hemodialysis membranes. Molecular methods have been found to be far more sensitive than standard methods in detecting subclinical infection. The presence of bacterial DNA seems to influence the variation in some parameters of inflammation and immunity. Apart from the limitations and pitfalls, the molecular method could be useful to screen for subclinical infection and diagnose subclinical sepsis when the hemoculture is negative. However, the identification of the microorganism implicated must be done with species-specific primers.

Basic mechanisms and definitions for continuous renal replacement therapies.

The efficiency of a hemodialyzer is largely dependent on its ability to facilitate diffusion, since 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 dialysate compartment designs on dialysate flow distribution and urea clearances. Eighteen hollow fiber 1.3 m2 hemodialyzers were studied, 6 each of 3 designs: Type A- standard fiber bundle (PAN 65DX Asahi Medical, Tokyo, Japan); Type B - spacing filaments external to the fibers (PAN 65SF Asahi Medical, Tokyo, Japan); Type C - fibers waved to give Moiré structure (FB130 Nissho-Nipro, Osaka, Japan). In vitro studies: 3 dialyzers of each type were studied following dye injection into the dialysate compartment. Dynamic sequential imaging of longitudinal sections of the dialyzer were undertaken, using a new generation helical CT scanner (X-Press/HS1 Toshiba Corporation, Tokyo, Japan). In vivo studies: 3 dialyzers of each type were studied, in randomized sequence, in 3 different patients under standardized dialysis conditions. Blood- and dialysate-side urea clearances were measured at 30 and 150 minutes of treatment. Macroscopic and densitometrical analysis revealed that flow distribution was most homogeneous in the dialyzer with Moiré structure (Type C) and least homogeneous in the standard dialyzer (Type A). Space yarns (Type B) gave an intermediate dialysate flow distribution. Significantly increased urea clearances (p<0.001) were seen with Types B and C, compared to the standard dialyzer. Type C (Moiré) had the highest clearances although these were not significantly greater than Type B (space yarns). In conclusion, more homogeneous dialysate flow distribution and improved small solute clearances can be achieved by use of spacing yarns or waved (Moiré structure) patterns of fiber packing in the dialyzer. These effects are achieved probably as a result of reduced dialysate channeling resulting in a lower degree of mismatch between blood and dialysate flows. The new radiological technique using the helical CT scanner allows detailed flow distribution analysis and has the potential for testing future modifications to dialyzer design.

Comparison of four different short dialysis techniques.

where Pb=hydrostatic pressure of the blood, Puf=hydraulic pressure in the ultrafiltrate/dialysate compartment, and p=oncotic pressure generated by proteins. When ultrafiltration occurs, solutes are carried on the other side of the membrane at various rates according to their membrane rejection coefficient (u), with a being near 1 for albumin and near 0 for small solutes like urea. The sieving coefficient for a solute (S) is correlated with the membrane rejection coefficient and is equal to 1 a, In clinical practice, the sieving coefficient is measured from the ratio between the concentration of solute in the ultrafiltrate and its concentration in plasma water. In convective treatments therefore, the transport (Jc) of a solute x will be governed by the formula: Several forms of renal replacement therapy have been used for the treatment of acute renal failure in the critically ill patient in the last decade (1, 6, 8, 10, 11,13,18,21). The evolution of basic concepts into a more complex clinical approach and the applied technology necessitates a detailed analysis of the various techniques with the aim of establishing a common nomenclature.

Optimizing a kidney stress test to evaluate renal functional reserve.

The goal of shortening dialysis treatment time has stimulated the development of new, highly efficient dialytic strategies. In this study the Authors compared four different short dialysis treatments in terms of efficiency, clinical tolerance, technological investment and costs: 1) Rapid bicarbonate dialysis with 1.5 sq.m. cuprophane membrane; 2) High flux biofiltration with 1.2 sq.m. AN69S hollow fiber membrane; 3) Hemodiafiltration with 1.2-1.9. sq.m. polysulphonic hollow fiber hemodiafilters, and 4) High flux hemodiafiltration with two serial hemodiafilters with AN69s membrane (total 2.4 sq.m.). Hydraulic properties and solute clearances at different blood flows (300-500 ml/min) were tested for each technique. Once the optimal operative level was established three patients were treated with each technique for at least six months. Since BUN clearance averaged 310 ml/min, the treatment duration varied from 120 to 180 min/session with KT/V always higher than 1. The average protein catabolic rate was 0.9 g/kg/24h. Clinical tolerance was generally good, slightly better in treatments with a high convective component. Despite the greater efficiency of treatment No. 4, the technological requirements and costs are such that the others are currently more feasible and acceptable in clinical routine. The study demonstrates that reduction of dialysis treatment time is possible in all centres in a selected population with adequate blood access. Treatment No. 1 can even be performed with standard equipment and cuprophan membranes, while bicarbonate in the dialysate is mandatory. The real limit to shortening treatment time seems to be related to the maximal rate of ultrafiltration achievable in the patient during dialysis.

Principles of solute clearance during continuous renal replacement therapy

BACKGROUND Renal function reserve (RFR) describes the capacity of the kidney to increase glomerular filtration rate (GFR) in response to physiological or pathological stimuli. The scope of our study was to evaluate the optimal level of stimulation using different doses of protein load (PL) for a standard renal stress test (RST). METHODS 18 young healthy individuals were given sessions of PL with 1 and 2 g/kg body weight. Endogenous creatinine clearance was calculated. Baseline GFR (bGFR) and stress GFR (sGFR) (post-PL) were obtained; RFR is the difference between stress and baseline GFR. A p-value < 0.05 was considered statistically significant. RESULTS Mean bGFR was 107.97 ± 12.33 mL/min/1.73m2. sGFR with 1 and 2 g PL were significantly higher than bGFR in all subjects. The sGFR after 2 g PL (141.75 ± 19.90 mL/min/1.73m2) was not statistically different from the sGFR after 1 g PL (142.37 ± 22.35 mL/min/1.73m2). sGFR and therefore RFR were independent from the value of bGFR. CONCLUSIONS We found no difference between 1 and 2 g/kg body weight PL to elicit sGFR. RST may be useful to predict susceptibility and risk of developing acute kidney injury and/or progression to chronic kidney disease. RST uncovers the possible loss of renal functional mass when this condition is not manifested clinically. Further studies are needed to set this hypothesis.