[Central venous access for hemodialysis: no one likes it but everyone uses it].
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Catheterization, Central Venous↗
Biomedical subjects
B Canaud
Publications and source records attributed to B Canaud.
[Dialysis Outcomes and Practice Patterns Study: data on the use of central venous catheters in chronic hemodialysis].
Central venous catheters are widely used as vascular accesses for chronic haemodialysis. Different factors may lead to catheter use, whether clinical such as emergency dialysis, or related to practices specific to each dialysis unit or country. The Dialysis Outcomes and Practice Patterns Study is an observational study of more than 10,000 representative patients treated by haemodialysis followed over a two-year period in the United States, Japan, and in five European countries (France, Germany, Italy, Spain, United Kingdom). DOPPS data from the United States and Europe about catheters are reported in this paper. Catheter use is less frequent in Europe than in the US, both in incident and prevalent patients, and in patients who have been seen by a nephrologist in the pre-dialysis period. Tunneled and untunneled catheters are each associated with a significantly higher frequency of access infection compared to native arteriovenous fistulae and grafts. Patients with important comorbidities such as diabetes, cardiovascular diseases, malnutrition or dementia are more likely to be dialysed with tunneled catheters. Furthermore, patients initiating hemodialysis with a tunneled catheter display higher mortality risk compared to patients starting hemodialysis with a permanent access. In summary, DOPPS data indicate that central venous catheters are used for chronic haemodialysis in patients with a high level of morbidity, and that their utilisation is associated to an additional risk, particularly of infection, and to a lower survival for tunneled catheters. Appropriate care should limit the utilisation of central venous catheters to clinically undisputable indications.
Catheterization, Central Venous↗
[Permanent catheters for hemodialysis: indications, methods and results. French national survey 1998-2000].
A national survey on permanent hemodialysis catheters was conducted in 99 hemodialysis centers between january 1998 and january 2000. It was a prospective, national and multicentric study. Data were gathered in 1552 patients (mean age 65 +/- 15 years) with chronic end stage renal failure. A questionnaire was filled out each time a permanent hemodialysis catheter was inserted. Two permanent catheters (72%) were inserted under local anesthesia (92%), using the right internal jugular vein (81%) with a percutaneous technique (96%). The two main indications were: end stage chronic renal failure without creation of a vascular access (52%) and dysfunction of a preexisting vascular access (35%). Patients have been followed a mean time period of 58 days and 179 cases of death have been reported. The median duration of catheters was 500 days. The two main causes of catheter removal were creation of a functional A-V fistula (40%) and death of the patient (28%). The incidence of bacteriemia/septicemia was 0.74 episode/patient/1000 days of follow-up while that of any type of infection was 0.85 episode/patient/1000 days. The risk of infection increased with time especially in type 2 diabetes patients.
Aged↗
[Dialock: results of a French multicenter study].
INTRODUCTION: By offering a rapid and convenient vascular access option for hemodialysis, permanent catheters are increasingly used in ESRD patients. Indeed, permanent catheters are associated with an increased risk for complications. Moreover, catheter bearing spoils the self body image and may alter the quality of life of dialysis patients. Implantable port catheter device, recently introduce in dialysis, may offer an attractive option, able to reduce most of infectious risk and inconveniences of the permanent catheters. PATIENT AND MATERIAL: The Dialock (Biolink) device was evaluated in a multicenter French trial. Twelve dialysis facilities enrolling 51 ESRD patients (male 28, female 23, age 56 +/- 2 years) participated in this trial. Dialock devices were inserted in patients for whom a permanent venous catheter was indicated. The cumulative experience was 56.8 years-patient. The technical survival (intent to treat) of Dialock devices was 85% at two years. Blood flow were 299 +/- 7 ml/min. Dialysis adequacy was achieved in all patients without altering dialysis schedule (3 sessions per week, 240 +/- 30 min each). Dialysis dose (K(/Vdp) delivered was 1.3 +/- 0.2. Satisfaction of patients and nursing staff was achieved in 75% of cases. Normalized incidence of complications (events for 1000 patient-days) in the evaluation phase (II) were as follows: hematoma and/or small bleeding (2.1), bacteremia (1.1), device infection (0.2), skin necrosis (0.1). A significant reduction of the infection and hematoma incidence rate was noticed when heparin lock was substituted for an non hemorrhagic antithrombotic locking solution (fragmented heparin or sodium citrate). This observation tend to accreditate the hypothesis that port catheter infection occurs via a transluminal bacteria passage. CONCLUSION: The Dialock device, offers a new and comfortable hemodialysis vascular access for ESRD patients. Performances are in agreement with those needed to achieve adequate dialysis. The regular use of dual antithrombotic-antiseptic catheter locking solution seems to be necessary to prevent any bacterial contamination.
Anticoagulants↗
[Surveillance of permanent central venous access for hemodialysis].
Central venous catheters have emerged as a valuable alternative for permanent access in hemodialysis. Thanks to steady improvements of materials and design they have been successfully used as bridging solution until another vascular access became available or even long term solution for patients with limited or insuffisant vascular resources. Since the use of central venous catheters is affiliated with a higher dysfunction rate and morbidity, special attention is indicated. This should include regular surveillance, clinical examination and intervention using specific methods, bacteriological exams and regular dialysis quantification. Such a constant quality control followed by strict and adapted rules for catheter handling are essential necessities to reduce catheter-related complications and assure an adequate dialysis.
Catheterization, Central Venous↗
Urea as a marker of adequacy in hemodialysis: lesson from in vivo urea dynamics monitoring.
BACKGROUND: "Dialysis dose," a concept developed by Sargent and Gotch based on urea kinetic modeling, is a useful and recognized tool that is used to quantitate and optimize a dialysis-efficacy program. However, it has been shown that oversimplification of the "dialysis adequacy" concept to the Kt/V index might lead to dramatic underdialysis and subsequent deleterious consequences on morbidity and mortality of dialysis patients. With this perspective, the determination of Kt/V must be very cautious and rely on accurate measurement of postdialysis urea concentration and its use integrated as a tool in a quality-assurance process. METHODS: In this study, we analyzed urea dynamics by means of a blood side (ultrafiltrate) continuous online urea monitoring system interfaced with a two-pool model hosted in a microcomputer. The study was designed to provide instantaneous dialysis performances (body and dialyzer clearances, dialyzer mass transfer coefficient) and to determine the in vivo functional permeability characteristics of the patient [intercompartment urea mass transfer coefficient (Kc)]. Thirteen end-stage renal disease patients (age 54 +/- 16 years; 12 male and 1 female) were studied during nine consecutive dialysis sessions (3 weeks). RESULTS: Urea kinetics obtained from the urea monitoring system fitted closely the urea kinetic modeling prediction, confirming the validity of the double-pool model structure. Effective in vivo urea mass transfer coefficient averaged 912 +/- 235 mL/min/1.73 m2, a value close to those reported with more invasive methods. Large variations ranging from 363 to 1249 mL/min were observed among patients, confirming very large interindividual patient permeability differences. Interestingly, the urea mass transfer coefficient was inversely correlated with the postdialysis rebound values. Intraindividual variations were also noted as a function of time denoting functional changes in urea mass transfer coefficient values. The urea distribution volume was 38.1 +/- 7, 8 L (53 +/- 8% body weight). V1 referring to the extracellular volume and V2 to the intracellular volume were 9 +/- 2 L (13 +/- 2% body weight) and 29.2 +/- 6.6 L (41 +/- 1.3% body wt), respectively. The extracellular/intracellular volume ratio was 0.31 (approximately one third) and was not as usually defined by the paradigm 1/2 ratio. CONCLUSION: Online double-pool urea kinetic modeling gave a new insight in urea kinetic modeling approach. Urea dynamics fit perfectly a double-compartment model structure. Accessible extracellular volume to hemodialysis is smaller than expected. The in vivo urea mass transfer coefficient must be considered as an individual and variable characteristic of ESRD patients that should be taken into consideration when prescribing the hemodialysis schedule.
Adult↗
Temporary vascular access for extracorporeal therapies.
Central venous catheters provide at the present time the basic and ideal method to perform acute extracorporeal blood purification. Rapid launch of extracorporeal therapy is indicated in two situations: first, renal conditions presenting as a recognized acute organic renal failure (ARF) and acute decompensation of end stage renal disease (ESRD) without permanent vascular access; second, non-renal conditions presenting as urgent clinical situations requiring isolated ultrafiltration for chronic congestive heart failure, plasmapheresis or selective immunoadsorption for immune diseases, cytapheresis for hematological disease, and selective detoxification for certain types of poisoning. Central venous catheters are classified into 2 categories according to the duration of use: temporary catheter (less than 90 days) and permanent catheter (more than 90 days). A temporary catheter, including rigid (polyethylene, teflon) and semirigid (polyurethane) material, is indicated in emergency situations and for short-term use. A permanent catheter, made usually of soft silicone rubber with a subcutaneous anchoring system, has a subcutaneous tunnel and is indicated in medium and long-term use. Catheter design has benefited greatly from technical advances and material hemocompatability. However, catheter-related morbidity still remains high and is associated with an unacceptable incidence rate of infection and/or vein thrombosis. This article covers our present knowledge regarding catheter indications, technical aspects of catheter insertion and care, functional limitation of central venous catheters, and catheter-related complications. It is also our intent to provide the reader with optimal indication and catheter care in order to prevent and reduce the burden of catheter-related morbidity.
Blood Component Removal↗
Protective effects of high-density lipoprotein against oxidative stress are impaired in haemodialysis patients.
INTRODUCTION: Cardiovascular diseases represent the major cause of mortality in haemodialysis (HD) patients. Oxidized low-density lipoprotein (Ox-LDL) is a major cardiovascular risk factor, implicated in atherosclerotic plaque formation. It has been suggested that high-density lipoprotein (HD) has the capacity to reduce the oxidative modifications of LDL. The aim of this study is to analyse the protective effects of HDL in HD patients. METHODS: In vitro copper-induced LDL oxidation was evaluated in 12 patients with chronic renal failure (mean age 61.0+/-12.8 years) and compared to 25 healthy subjects (mean age 57.3+/-19.2 years). LDL were incubated in oxygen-saturated PBS, LDL oxidation was initiated by Cu (II) in the presence and absence of HDL and assessed by measuring the absorbance (abs) increase at 234 nm due to conjugated diene formation. Duration of lag time, maximum velocity (V(max.)) of lipid peroxidation, oxidation slope and half-time of maximum diene formation (T (1/2)) were obtained by kinetic modelling analysis. RESULTS: HDL (1.06+/-0.31 vs 1.23+/-0.39 mmol/l) and Apo AI (1. 17+/-0.39 vs 1.49+/-0.20 g/l) levels were decreased in HD patients. In the absence of HDL, LDL obtained from HD patients showed an enhanced susceptibility to oxidation in vitro as demonstrated by the significant decrease in lag time (54.5+/-22.2 vs 79.4+/-37.8 min) and a significant increase in V(max.) (0.026+/-0.006 vs 0.017+/-0. 005 abs/min). In all cases, HDL (from 0.1 to 2 microM) prevented LDL oxidation in vitro; however, this effect was significantly reduced in HD patients: increase in lag time 54.2% vs 150.4% in HD vs controls; increase in T (1/2) 52.2% vs 124.6% in HD vs controls; decrease in V(max). 13.5% vs 38.5% in HD vs controls. CONCLUSIONS: These results suggest that qualitative abnormalities such as an impairment of HDL-associated enzymes are associated with a decrease of HDL levels during HD. Hence, in addition to the known impairment of reverse cholesterol transport, the reduction of HDL protective capacity against oxidative stress could be involved in the development of HD-induced atherosclerosis.
Adult↗
Intradialytic glucose infusion increases polysulphone membrane permeability and post-dilutional haemodiafiltration performances.
INTRODUCTION: During real-time monitoring of the ultrafiltration coefficient (Kuf) in haemodiafiltration (HDF), it was noticed that the ultrafiltration performance of polysulphone membrane dialysers increased when hypertonic glucose (D50%) was administered through the venous blood return. METHODS: This observation was explored in six non-diabetic chronic dialysis patients during 48 HDF sessions using 1.8 m(2) polysulphone membrane dialysers. In all six patients, 24 sessions were performed with glucose supplementation (as a continuous D50% (500 g/l) infusion at 40 ml/h) and 24 sessions without supplementation. RESULTS: Glucose supplementation led to a marked increase in Kuf from 22.8+/-2.2 (without D50%, n=24) to 32. 1+/-3.9 ml/h/mmHg (with D50%, n=24) (P<0.0001). An increase in percentage reduction ratios for urea and creatinine were also consistently observed during the sessions with glucose administration (from respective mean values of 75+/-5 and 68+/-4% to 79+/-4 and 74+/-10%). Mean double-pool Kt/V, calculated from serum urea concentrations, rose from 1.65+/-0.24 (n=24) to 1.86+/-0.24 (n=24) (P<0.005). Similar results were observed in a subgroup of 18 HDF sessions (nine with glucose and nine without) monitored with an on-line urea sensor of spent dialysate. No detrimental effects were induced at any time. CONCLUSIONS: We conclude that intravenous glucose administration during high-flux HDF using polysulphone membranes increases significantly both ultrafiltration capacity and dialysis dose delivery.
Adult↗
On-line haemodiafiltration. Safety and efficacy in long-term clinical practice.
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Adult↗
Why hemodialysis patients are in a prooxidant state? What could be done to correct the pro/antioxidant imbalance.
Oxidative stress which results from an imbalance between reactive oxygen species production and antioxidant defense mechanisms is now well recognized in hemodialysis (HD) patients and could be involved in dialysis-related pathologies such as accelerated atherosclerosis, amyloidosis and anemia. In order to evaluate the rationale for preventive intervention against oxidative damage during HD, we review the factors that are implied and may be responsible for the imbalance between pro- and antioxidative mechanisms. The inflammatory state mainly due to hemobioincompatibility of the dialysis system plays a critical role in the production of free oxygen radical species contributing by this way to worsen the prooxidant status of uremic patients. Two factors largely contribute to the stimulation of the NADPH oxidase: hemoreactivity of the membrane and trace amounts of endotoxins. The antioxidant system is severely impaired in uremic patients and gradually altered with the degree of renal failure. HD could further impair this antioxidant system mainly by losses of (a) hydrophilic unbound small-molecular-weight substances such as vitamin C, (b) trace elements and (c) enzyme-regulatory compounds. Two main axes may be proposed in order to prevent and/or to decrease oxidative stress in HD patients. One consists in improving the hemocompatibility of the dialysis system mainly by using a dialyzer with low hemoreactivity and ultrapure, sterile, nonpyrogenic dialysate. The other consists in supplementing the deficiency patients with antioxidants. This could be achieved by oral or perdialytic supplementation. Vitamin E could be bound on dialyzer membrane. Alternatively, hemolipodialysis consists in loading HD patients with vitamin C or E via an ancillary circuit made of vitamin E-rich liposomes. The presence of liposomes could also facilitate the removal of hydrophobic prooxidative substances.
Antioxidants↗
Microbiologic purity of dialysate: rationale and technical aspects.
Dialysate purity has become a major concern in hemodialysis since it has been shown that microbial-derived products were stimulating the production and the release of proinflammatory cytokines in hemodialysis patients. This chronic microinflammatory state induced by hemodialysis has been putatively implicated in the development of dialysis-related pathology. In order to prevent risk related to these offenders and to reduce patient/dialysis interaction, it appears highly desirable to use ultrapure dialysis fluid aiming at sterility and apyrogenicity on a regular basis. Ultrapure dialysate results from a complex chain of production where purity grade relies on the weaker link of this chain. Technical aspects and pitfalls in the production of ultrapure dialysate are summarized in this paper. Production of ultrapure dialysate may be achieved on a routine basis, provided adequate components are used, and hygienic handling is regularly ensured. It includes the use of ultrapure water, clean and or sterile electrolytic concentrates (liquid or powder), implementation of ultrafilters on hemodialysis machines, microbiologic monitoring and hygienic handling of the chain with frequent disinfection. Safety and reliability of ultrapure dialysate production relies on a continuous quality assurance process, where results are coupled to corrective action in a feedback loop process.
Dialysis Solutions↗
[Quality control in hemodialysis: quality assurance process].
The development of a quality assurance step in hemodialysis replies to the needs of the accreditation process defined in the hospital reform and the related ordinances edited in April 1996. This global concept is set to continuously improve the quality care and the outcomes of the hemodialysis patients. The thought behind this work has two objectives: provide guidelines to guaranty quality and adequacy of hemodialysis treatment schedule in ESRD patients; anticipate standard rules edited by regulatory authorities for quality indices and control process in hemodialysis. The final aim of this work is also to demonstrate that the quality assurance process in hemodialysis should not be perceived as an extra administrative burden but rather as a new opportunity to establish good medical practice rules in the peculiar domain of renal replacement therapy.
Accreditation↗
Haemodialysis catheter-related infection: time for action.
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Bacterial Infections↗
Dialock: a new vascular access device for extracorporeal renal replacement therapy. Preliminary clinical results.
BACKGROUND: Vascular access, a vital tool for end-stage renal disease patients, remains a weak component of extracorporeal renal replacement therapy (RRT) and the first cause of morbidity. Permanent catheters proposed as an alternative to permanent AV fistulae are associated with a significant risk of infection. A subcutaneously implantable chamber connected to permanent catheter appears highly desirable to reduce such hazards. METHODS: Dialock, a metallic port-like valve device connected to permanent silicone twin catheters has been developed (Biolink Corp, Middleboro, MA, USA). After being implanted subcutaneously below the clavicle, Dialock provides a linear flow passage to two Silastic catheters placed in the right atrium via the right internal jugular vein. The valve is accessed percutaneously each dialysis session with needle cannulae that functionally convert the device into twin catheters. Interdialytic patency of the catheters is ensured by antithrombotic lock (heparin or low-molecular-weight heparin). RESULTS: Dialock was implanted in 10 ESRD patients (64+/-12 years) under general anaesthesia, with almost immediate use for HD. RRT consisted of three HD sessions per week lasting 4 h; 699 HD sessions were performed. Average duration of use was 5.7 patient-months (1.3-9.6 months). Patient satisfaction was evident in all cases. Three episodes of bacteraemia occurring in the early phase of the study were cured by appropriate antibiotics. No device was removed because of infection. Skin condition at the puncture sites has remained satisfactory in all patients. Nurse training for cannulating was brief (2-3 x). Effective blood flow was 307+/-3.3 ml/min, with a venous pressure of 195+/-39 mmHg and a recirculation rate of 6.7+/-0.8%. Effective Kt/V dp delivered was 1.36+/-0.03 with a nPCR of 1.20+/-0.005 g/kg/day. Haematoma and a small amount of bleeding of the skin puncture sites observed in the initial period of the study were effectively prevented by reducing heparin lock volume. CONCLUSIONS: The Dialock device offers a new and interesting vascular access alternative for haemodialysis bridging the 'gap' between permanent catheters and arteriovenous fistulae. Dialock's place in the vascular access strategy for haemodialysis patients deserves further long-term clinical studies.
Adult↗
Nutritional status of haemodialysis patients: a French national cooperative study. French Study Group for Nutrition in Dialysis.
BACKGROUND: Despite the severity and the prognosis value of undernutrition in haemodialysed patients, no large study is available as yet in Europe. Hence, this French National Cooperative Study aimed to determine the prevalence of undernutrition and its relationship to dialysis efficacy. METHODS: Nutritional status was determined in 7123 patients (i.e. one-third of the French haemodialysis population) using body mass index (BMI), predialysis haemoglobin, albumin, pre-albumin, cholesterol, and also normalized protein catabolic rate (nPCR) and lean body mass (LBM) calculated from pre- and postdialysis urea and creatinine. Dialysis treatment was estimated from weekly dialysis time and KtV determination. RESULTS: Dialysis time was 12.4+/-2.7 h/week and KtV 1.36+/-0.36. BMI was below 20 kg/m2 in 24% and the observed/expected LBM ratio below 90% in 62%. Albumin, pre-albumin and nPCR were below the high-risk thresholds of 35 g/l, 300 mg/l and 1g/kg/day in 20%, 36% and 35% of patients, respectively. Pre-albumin was the most representative nutritional parameter. Albumin, pre-albumin and LBM correlated with nPCR. A dialysis time above 12 h/week was associated with higher BMI, albumin, pre-albumin and LBM. LBM was higher in patients with a KtV value >1.1. CONCLUSION: This study showed life-threatening undernutrition in 20-36% of the studied population, according to nutritional parameters. Protein intake (estimated by nPCR) and dialysis efficacy (estimated by dialysis time and KtV) appeared to be major determinants of nutritional status in this population.
Adult↗
Ultrafiltration and convective-based dialysis modalities: new trends and applications for renal replacement therapy in ESRD patients.
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Hemodiafiltration↗
Imbalance of oxidants and antioxidants in haemodialysis patients.
Dialysis-related pathology (DRP) observed in long-term haemodialysis patients is increasingly reported. Among DRP manifestations, cardiovascular disease is the most frequent, being the first cause of mortality in haemodialysis patients. Alterations in lipid metabolism and oxidative stress are recognised as major risk factors that could be prevented or reduced by optimal therapy. In order to evaluate the rationale for preventive intervention against oxidative damage we review the factors that are implied and may be responsible for the imbalance between prooxidative and antioxidative mechanisms in haemodialysis patients. Oxidative stress resulting from this imbalance is responsible for increasing stress markers and enhancing susceptibility to LDL oxidation. Factors implied in this prooxidative state belong to four groups: (1) uremia and comorbid status of the end stage renal disease (ESRD) patient; (2) losses of antioxidant substances via the dialysis; (3) haemoincompatibility of the dialysis system; (4) adjuvant therapy. Such prooxidant status could have further deleterious consequences since it has been recently shown that antioxidant status could modulate cell functions such as reactive oxygen species (ROS) production, adhesive molecule expression and/or cell proliferation. Preventive modalities, including use of biocompatible membrane, ultrapure dialysate, exogenous supplementation of antioxidant vitamins, extracorporeal removal of ROS and oxidatively-modified substances, would appear highly desirable to reduce complications of long-term dialysis patients.
Antioxidants↗