RESUMEN
Treatment of severe sepsis and septic shock often focuses on resolving immediate life-threatening problems related to infection (source control, antibiotics) and providing circulatory, ventilatory and other organ support. Neurologic complications, such as sepsis-associated encephalopathy, frequently occur in septic patients and are associated with higher mortality and long-term complications. As case fatalities and overall mortality continue to decline, long-term cognitive problems are becoming more common among survivors. Although the aetiology of septic encephalopathy has not been clearly established, systemic inflammation appears to play a key role in altering both the blood-brain barrier permeability and amplifying the inflammatory response. Several new therapies are now aimed at reducing systemic inflammation. These may eventually play a role in reducing neurologic complications related to the acute pathophysiology of sepsis and may be able to reduce early cerebral dysfunction with the goal of reducing long-term neurologic complications. Coupled plasma filtration adsorption is an extracorporeal therapy aimed at the non-specific removal of cytokines and mediators involved in systemic inflammation and immune suppression by the use of plasma filtration coupled to an adsorbent resin cartridge with high affinity for many cytokines and mediators. Several cytokines that are removed by coupled plasma filtration adsorption have also been implicated in blood-brain barrier permeability, leucocyte recruitment and amplification of the inflammatory response. Current studies are ongoing to determine whether treatments such as coupled plasma filtration adsorption may also be beneficial in reducing long-term neurologic complications.
Asunto(s)
Inflamación , Enfermedades del Sistema Nervioso/terapia , Sepsis/terapia , Adsorción , Animales , Barrera Hematoencefálica , Citocinas/metabolismo , Diseño de Equipo , Hemofiltración , Humanos , Infecciones , Enfermedades del Sistema Nervioso/complicaciones , Sepsis/complicaciones , Transducción de SeñalRESUMEN
BACKGROUND: On-line hemodiafiltration is gaining popularity due to increasing evidence of clinical benefits however it also requires strict attention to hygiene and safety as notable quantities of liquid are reinfused into the patient. Although most centers are improving their attention to water quality, a frequent concern is the inadvertent or accidental contamination of water and whether the redundant safety controls are sufficient to protect the patient. In the present study, in order to simulate a worst-case safety condition, we tested in vitro the reliability of paired hemodiafiltration - (PHF), under low, moderate and high bacterial contamination of the water supply. Tests were performed using various bacterial concentrations (range 85-2000 cfu/mL) of Pseudomonas Aeruginosa. Samples were analyzed from different sites throughout the entire on-line hemodiafiltration circuit for bacteria endotoxin, fungus and ability to stimulate whole blood production of TNFalfa. RESULTS: In the in vitro contamination study, with the three bacterial concentrations tested at various points of the circuit, bacteria were below the level of detection and endotoxins were < 0.01 UE/mL. Addition of dialysate samples taken after the first stage of microfiltration, as well as after the first and second stage of ultrafiltration and incubated with whole blood were not associated with stimulated production of TNFalfa . CONCLUSIONS: PHF appeared to be a safe and feasible method for on-line hemodiafiltration even in the unforeseen presence of bacterial contamination of the feed water or water distribution system.
Asunto(s)
Hemodiafiltración , Higiene , Sistemas en Línea , Seguridad , Abastecimiento de Agua , Endotoxinas/análisis , Contaminación de Equipos , Soluciones para Hemodiálisis , Humanos , Técnicas In Vitro , Pseudomonas aeruginosa/aislamiento & purificación , Factor de Necrosis Tumoral alfa/análisis , Microbiología del Agua , Purificación del AguaRESUMEN
Although hemodiafiltration (HDF) offers the advantage of increased convective clearance for middle molecules, there is still controversy as to whether reinfusion should occur pre- or post-filter. Mid-dilution hemodiafiltration (MD HDF) is a new HDF technique that uses a special dialyzer, MD190, which allows both pre- and post-reinfusion. While externally the dialyzer looks similar to conventional hemodialyzers, the internal fibers are divided into two bundles by a special annular header that first lets the blood pass through the peripheral bundle in post-dilution, mix with the reinfusion fluid at the opposite end of the dialyzer and then proceed (after pre-dilution) to the dialyzer blood exit. The dialyzer is able to support substantially higher reinfusion rates (10-12 l/h). We have compared the removal characteristics of several small solutes and larger middle-molecular-weight toxins by examining instantaneous clearance at 45 min, the dialysis reduction ratio and total mass removal (by spilling) in a three-center prospective cross-over study. Twenty patients were randomized to a treatment sequence of one-week high-flux bicarbonate hemodialysis (HD) followed by MD HDF, or vice versa. The parameters evaluated included urea, creatinine, beta2-microglobulin, angiogenin, leptin, retinol-binding protein, and the effects on sodium, potassium, bicarbonate and calcium. Blood flow rates ranged between 300-450 ml/min (mean 359 +/- 44 HD, 367 +/- 35 MD HDF). The mean reinfusion for MD HDF was 166 +/-17 ml/min. MD HDF had a significantly better instantaneous clearance for urea (328 +/- 28 vs 277 +/- 40); creatinine (292 +/- 32 vs. 212 +/- 66); phosphate (324 +/- 38 vs. 242 +/- 63); beta2-microglobulin (249 +/- 27 vs. 100 +/- 24); angiogenin (173 +/- 27 vs. 28 +/- 32); and leptin (202 +/- 29 vs. 63 +/- 43). Treatments were well tolerated with no adverse reactions occurring during any of the treatments. The MD HDF filter's unique configuration is designed to deliver high-efficiency HDF with a significant improvement in small and middle molecule removal. MD HDF supports substantially higher ultrafiltration rates, and as such, results in a higher removal of middle-molecular-weight toxins.
Asunto(s)
Hemodiafiltración/métodos , Sangre/metabolismo , Convección , Difusión , Diseño de Equipo , Hemodiafiltración/instrumentación , HumanosRESUMEN
PURPOSE: On-line hemodiafiltration (HDF) is gaining popularity due to increasing evidence of clinical benefits. The purpose of this study was to test a new on-line technique paired hemodiafiltration (PHF). In addition, we evaluated the PHF system during in vitro contamination. METHODS: Five patients used the PHF technique over a 6-month period. We performed a disinfection protocol and tested for bacteria, endotoxin, halogenated carbons and metals in the feed water, and we tested for bacteria, endotoxins and fungi in the dialysate after different ultrafiltration stages. In vitro tests were performed using three bacterial concentrations of pseudomonas aeruginosa. Samples were analyzed from different sites throughout the entire on-line HDF circuit for bacteria endotoxins, fungus and the ability to stimulate whole blood production of tumor necrosis factor-alpha (TNF-alpha). RESULTS: The bacteriological control from the feeding machine water and at the entrance to the monitors had a bacterial level of <100 CFU/mL. No bacteria were detected in the dialysate and endotoxin levels were <0.03 EU/mL. In the in vitro contamination study, with the three bacterial concentrations tested at various points in the circuit, bacterial and fungi were below the level of detection and endotoxins were <0.03 UE/mL. The addition of dialysate samples taken after the 1st microfiltration stage, as well as after the 1st and 2nd ultrafiltration stage and incubated with whole blood were not associated with stimulated TNF-alpha production. CONCLUSIONS: PHF appeared to be a safe and feasible method for on-line HDF even in the unforeseen presence of the bacterial contamination of the feed water or in the water distribution system.
Asunto(s)
Contaminación de Medicamentos , Contaminación de Equipos , Hemodiafiltración/métodos , Hemodiafiltración/normas , Humanos , Persona de Mediana Edad , SeguridadRESUMEN
HFR is an integrated hemodiafiltration system that utilizes a double chamber filter to separate convection from diffusion. The ultrafiltrate is regenerated by passage through a sorbent cartridge made up of resin and activated carbon. A small percentage of patients using this technique had gastrointestinal symptoms that included nausea/vomiting, diarrhea and/or stomach cramps approximately 1-2 hours after the start of HFR. We undertook a series of investigations to try and elucidate the cause of these reactions. Since the majority of the patients were taking ACE inhibitors, attention was focused on contact phase activation. Healthy and uremic plasma were incubated with different components of the HFR circuit. The activated carbon caused a moderate activation of factor XII and production of kallikrein, while there was no activation for the lines, double filter or resin. Patients taking ACE inhibitors may be at risk for treatments involved with contact phase activation as ACE inhibitors also block the degradation of bradykinin. A new sorbent cartridge has now been developed that contains only resin.
Asunto(s)
Carbono/fisiología , Hemodiafiltración/métodos , Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Interacciones Farmacológicas , Factor XII/efectos de los fármacos , Hemodiafiltración/efectos adversos , Humanos , Calicreínas/efectos de los fármacosRESUMEN
Adsorbent therapies have become increasingly popular over the last several years as they permit an additional method to selectively or non-selectively remove toxins. Adsorbents offer a unique removal strategy as they have an extremely high adsorption capacity due to their great surface area. This paper describes experiments that utilized a synthetic divinylbenzene styrenic resin cartridge to remove uremic toxins from chronic renal failure patients. The resin-only cartridge was tested as an alternative after a small number of patients (primarily taking ACE inhibitors) experienced gastrointestinal problems using hemodiafiltration with on-line regeneration (HFR). Subsequent laboratory evidence suggested that the particular carbon used in the cartridge was able to activate contact phase activation. This could potentially cause problems in patients taking ACE inhibitors, as they are unable to degrade bradykinin efficiently. The resin-only cartridge was tested in at 6 centers throughout Italy and included patients that had experienced previous reactions to the carbon-resin cartridge. At the conclusion of the study, no adverse reactions were reported and the cartridge exhibited excellent removal of b2 microglobulin and angiogenin.
Asunto(s)
Hemodiafiltración/instrumentación , Adulto , Carbono , Humanos , Uremia/metabolismo , Uremia/terapiaRESUMEN
HFR is a hemodiafiltration method with regeneration of the ultrafiltrate. It consists of a double chamber filter that separates convection from diffusion. The ultrafiltrate exits from the convective filter, passes through a sorbent cartridge where uremic toxins bind to the sorbent. The "purified" ultrafiltrate is then returned to the patient. This study undertook a series of in vitro and ex vivo experiments to optimize the conditions for maximal adsorption and treatment efficacy. An emphasis was placed on a resin only cartridge as previous studies suggested that some patients may be sensitive to the activated carbon, particularly if they are taking ACE inhibitors.
Asunto(s)
Hemodiafiltración/instrumentación , Toxinas Biológicas/metabolismo , Uremia/terapia , Absorción , Diseño de Equipo , Humanos , Peso Molecular , Uremia/metabolismoRESUMEN
We analyse the leucocyte and endothelial cell response to polybromostyrene-polystyrene (PS/PBrS) and the poly-n-butylmethacrylate-polystyrene (PnBMA/PS) systems, both in flat form or nanostructured surfaces consisting of nanohills with increasing hill height (13-95nm). Experiments were carried out first with blood leucocytes alone, endothelial cells (of three different types) alone, and finally, using blood cells and endothelized nanosurfaces. Blocking monoclonal antibodies specific for CD11, CD29, CD31, CD54, CD166 were used to analyse whether and to what extent adhesion molecules could be involved in the adherence of both blood leucocytes and endothelial cells to different nanosurfaces. Expression of CD29 (beta-1 integrin), CD54 (ICAM-1) and CD166 (ALCAM) on blood leucocytes was dependent on the hill height, being most prominent with 13nm (PS/PBrS) and 45nm hill (PnBMA/PS) nanosurfaces. Adherence of a human microvascular endothelial cell line and umbilical primary endothelial cells was also related to hill height, being most prominent with 13nm hill height. An indirect correlation was observed between the extent of endothelization and the degree of leucocyte adherence. In cases of low to medium extent of endothelization, the adherence of monocytes and granulocytes was mediated by the expression of CD166, CD29 and CD11a (alpha-L integrin), CD29, CD31 (PECAM-1), respectively. Scanning electron microscopy studies showed the predominant emission of pseudopodia at the holes of the surfaces and the focal contacts with the nanosurfaces. Our studies emphasize the relevance of testing functional properties in co-culture experiments in the development and optimization of nanosurfaces for biomedical application.
Asunto(s)
Endotelio Vascular/citología , Endotelio Vascular/fisiología , Leucocitos Mononucleares/citología , Leucocitos Mononucleares/fisiología , Nanotecnología/métodos , Poliestirenos , Adhesión Celular/fisiología , Células Cultivadas , Cristalización/métodos , Endotelio Vascular/ultraestructura , Humanos , Leucocitos Mononucleares/ultraestructura , Ensayo de Materiales , Venas Umbilicales/citología , Venas Umbilicales/fisiologíaRESUMEN
BACKGROUND: Based on the increased hydraulic permeability of the new high permeability polyethersulfone membrane, DIAPES HF-800, we investigated the kinetics and handling of albumin in high volume on-line hemodiafiltration (HDF). METHODS: Seven patients on predilutional HDF were studied in two consecutive sessions. Blood flow rate and transmembrane pressure were continuously monitored. Spent dialysate was spilled at 20 ml/h every hour. Albumin was measured in blood and dialysate by immunonephelometry. Albumin and proteins adsorbed onto the dialyzer membrane were eluted after treatment with Triton X. Ultrafiltrates collected at 1 and 2 hours of treatment were pooled from different patients and incubated for 24 hours at 37 degrees C with bovine serum albumin (BSA). Total sulphydryl groups were evaluated using Ellmann's reagent [5, 5'-dithio-bis(2-nitrobenzoic acid)]. RESULTS: In all 7 patients, the total loss of albumin was 3.99 +/- 1.81 g, ranging between 1.09 and 6.82 g/session. Most albumin loss occurred in the first 60 min of pre-dilutional hemodiafiltration (1.92+0.83 g). There was no correlation between transmembrane pressure, urea clearance and the loss of albumin. Plasma water urea clearance values were stable over the treatment (234 +/- 14.3 ml/min). Plasma albumin concentration did not decrease during HDF sessions. Albumin adsorbed onto the dialyzers was 0.7 +/- 1.6 mg but the total amount of adsorbed proteins was much higher (130 + 90 mg). In addition, the ultrafiltrate collected during HDF sessions was able to induce oxidation of bovine serum albumin as measured by total protein sulfhydryl groups: bovine serum albumin incubated in the presence of ultrafiltrate collected at 1 hour had a sulfhydryl loss of 56.3 +/- 5.7% (p < 0.0001 vs control), and bovine serum albumin incubated with ultrafiltrate collected at 2 hours had a loss of 67.5 +/- 3.8% (p < 0.003 vs control). CONCLUSION: The present study shows the high inter- and intra-patient variability of transmembrane passage of albumin in chronically uremic patients undergoing pre-dilutional HDF. Factors involved do not seem to be correlated to transmembrane pressure but rather to an interaction with the polymer surface. Albumin adsorption was minimal and was significantly lower than that of other plasma proteins. Albumin loss during HDF seemed to have no acute impact on plasma albumin. In addition, we demonstrated the presence of prooxidative compounds able to oxidize albumin, of which extracorporeal removal by HDF procedure could be beneficial for HD patients.
Asunto(s)
Hemodiafiltración , Albúmina Sérica/análisis , Adsorción , Anciano , Albúminas/análisis , Soluciones para Diálisis/química , Femenino , Humanos , Técnicas In Vitro , Masculino , Membranas Artificiales , Persona de Mediana Edad , Oxidación-Reducción , Permeabilidad , Polímeros , Albúmina Sérica Bovina/análisis , Compuestos de Sulfhidrilo/análisis , Sulfonas , Urea/metabolismoRESUMEN
Albumin has been considered a "sacrificial plasma antioxidant" due to the high reactivity of the protein sulfhydryl groups with oxidants such as hydrogen peroxide (H2O2) and hypochlorous acid (HOCl). Based on its large quantity and high turnover. It is considered as one of the most important plasma antioxidants for protecting key cellular and regulatory proteins. Since hemodialysis patients have lower overall levels of albumin and possible protein modifications due to uremic toxins, we investigated whether modifications by various uremic toxins would affect the susceptibility of albumin to an oxidative challenge. We incubated bovine serum albumin in the presence of carboxymethyllysine (CML) (10 micromol/L(-1) mmol/L), methyl glyoxal (50 micromol/L(-5) mmol/L), p-cresol (100 micromol/L-10 mmol/L) or hippuric acid (200 micromol/L-20 mmol/L) for 16 hours at 37 degrees C and then subsequently added 0.5 mmol/L(-1) mmol of H2O2/HOCl. We measured the extent of protein modification by the loss of protein sulfhydryl groups, dityrosine formation and the formation of advanced oxidation protein products (AOPP). Incubation of albumin with the uremic toxins caused a loss of protein sulfhydryl groups and an increase in dityrosines and AOPP. The presence of uremic toxins had no effect on the loss of protein sulfhydryl groups after addition of H2O2/HOCl; however, low levels of CML, p-cresol and methyl glyoxal inhibited the formation of AOPP and dityrosines. We suggest that uremic toxins may possibly play a role in mediating free radical initiated protein damage.
Asunto(s)
Albúminas/metabolismo , Uremia/metabolismo , Cresoles/toxicidad , Hipuratos/toxicidad , Humanos , Técnicas In Vitro , Estrés Oxidativo , Piruvaldehído/toxicidad , Toxinas Biológicas/metabolismoAsunto(s)
Proteínas de Fase Aguda , Glicoproteínas de Membrana , Sepsis/terapia , Proteínas Portadoras/fisiología , Complemento C5a/antagonistas & inhibidores , Radicales Libres , Hemofiltración , Humanos , Liposomas/metabolismo , FN-kappa B/fisiología , Factor de Necrosis Tumoral alfa/antagonistas & inhibidoresRESUMEN
The uremic syndrome is a complex mixture of organ dysfunctions, which is attributed to the retention of a myriad of compounds that under normal condition are excreted by the healthy kidneys (uremic toxins). In the area of identification and characterization of uremic toxins and in the knowledge of their pathophysiologic importance, major steps forward have been made during recent years. The present article is a review of several of these steps, especially in the area of information about the compounds that could play a role in the development of cardiovascular complications. It is written by those members of the Uremic Toxins Group, which has been created by the European Society for Artificial Organs (ESAO). Each of the 16 authors has written a state of the art in his/her major area of interest.
Asunto(s)
Toxinas Biológicas/metabolismo , Uremia/metabolismo , Enfermedades Cardiovasculares/etiología , Enfermedades Cardiovasculares/metabolismo , Humanos , Diálisis Renal/métodos , Uremia/complicaciones , Uremia/fisiopatología , Uremia/terapiaRESUMEN
Uremic patients undergoing hemodialysis often have increased oxidant stress and accumulation of uremic toxins. Hemodialysis, per se, often can exacerbate oxidant stress and may be inefficient at removing hydrophobic or protein bound toxins. We describe a new hemodialytic method that incorporates liposomes and antioxidants to remove hydrophobic/uremic toxins and minimize free radical mediated damage. In vitro experiments measured advanced oxidation protein products (AOPP), malonaldehyde, reactive carbonyls, and the removal of platelet activating factor (PAF) and bilirubin during extracorporeal circulation with or without liposomes. We observed a significant reduction of oxidation products as well as a significant removal of PAF and bilirubin compared to normal hemodialysis.
Asunto(s)
Liposomas/uso terapéutico , Estrés Oxidativo/fisiología , Diálisis Renal/métodos , Toxinas Biológicas/sangre , Animales , Antioxidantes/uso terapéutico , Ácido Ascórbico/uso terapéutico , Bilirrubina/sangre , Proteínas Sanguíneas/química , Bovinos , Circulación Extracorporea , Depuradores de Radicales Libres/uso terapéutico , Humanos , Malondialdehído/sangre , Oxidación-Reducción , Fosfatidilcolinas/uso terapéutico , Fosfolípidos/uso terapéutico , Factor de Activación Plaquetaria/química , Diálisis Renal/instrumentación , Albúmina Sérica Bovina/química , Uremia/sangre , Uremia/terapia , Vitamina E/uso terapéuticoRESUMEN
Oxidant stress has been implicated in a number of pathologies associated with uremia and hemodialysis. These patients have an increased incidence of cardiovascular disease, amyloidosis associated with protein modification, and notable changes in both function and structure of many cellular components. Oxidative reactions most frequently involving free radical intermediates play an important role in these processes and participate both directly and indirectly by further amplification of the inflammatory responses or in activation of signaling cascades mediating proliferation, differentiation, and cell death. Proteins and lipids are susceptible to oxidative degradation. These changes can ultimately alter important structural and functional characteristics and lead to pathological changes. This article addresses some of the diverse mechanisms and pathways involved in these changes, and suggests new therapeutic strategies in preventing oxidative damage.
Asunto(s)
Fallo Renal Crónico , Estrés Oxidativo/inmunología , Diálisis Renal/efectos adversos , Humanos , Fallo Renal Crónico/inmunología , Fallo Renal Crónico/metabolismo , Fallo Renal Crónico/terapia , Diálisis Renal/métodos , Uremia/inmunología , Uremia/metabolismo , Uremia/terapiaRESUMEN
OBJECTIVE: To test the hypothesis that nonselective adsorption by a hydrophobic resin of cytokines and other proinflammatory mediators could improve 72-hr survival in a rabbit model of endotoxic shock. DESIGN: Prospective, randomized, controlled animal trial. SETTING: Animal care facility at a research institution. SUBJECTS: A total of 109 New Zealand white male rabbits. INTERVENTIONS: Anesthetized rabbits were cannulated with indwelling femoral arterial and venous lines. Septic shock was induced by a single intravenous injection of Escherichia coli lipopolysaccharide. The dose was experimentally assessed in 40 rabbits receiving 1.0, 0.5, 0.1, and 0.05 mg/kg body weight to determine LD80 at 72 hrs. Extracorporeal circulation consisted of plasma filtration coupled with passage of the plasma filtrate through a hydrophobic sorbent and reinfusion into the venous line. The extracorporeal treatment lasted for 3 hrs. Rabbits injected with endotoxin (0.05 mg/kg) were submitted to plasma filtration with (19 rabbits) or without (20 rabbits) sorbent adsorption. As controls, rabbits injected with vehicle alone were treated with plasma filtration (ten rabbits) or without (ten rabbits) sorbent adsorption. Ten rabbits were monitored under anesthesia to determine basal survival. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations of endotoxin, bioactive tumor necrosis factor, resin-adsorbed platelet-activating factor, mean arterial pressure, base excess, and white cell count were assessed and a global severity score was established. At 72 hrs, cumulative survival was significantly (p = .0041) improved in septic rabbits treated with coupled plasma filtration-adsorption. Circulating tumor necrosis factor bioactivity remained similar in control and treated rabbits. Biologically significant amounts of platelet activating factor were eluted from the sorbent during the entire treatment time. The severity score inversely correlated with survival (p < .001). CONCLUSIONS: Coupled plasma filtration-adsorption improved survival in a rabbit model of endotoxic shock. Coupled plasma filtration-adsorption may be an extracorporeal treatment capable of removing structurally different inflammatory mediators associated with sepsis.