Haemodialysing small infants is difficult because of vascular access limitations. We show that Poiseuille's law (that flow through a tube varies with its radius4) makes it inevitable that the blood flow that can be achieved in smaller patients will fall disproportionately compared to their need for dialysis. Poiseuille's law also ...

During hemodialysis blood - membrane interaction causes complement activation. During dialysis there may be an electrical current leakage to the dialyzer, especially if there is a broken ground or a defect in another electrical device coupled to the patient. This study investigated whether an electric current of 1.5 mA DC ...

The FASB's Statement of Financial Accounting Concepts No. 7, Using Cash Flow Information and Present Value in Accounting Measurements (Statement No. 7), presents the board's views regarding how cash-flow information and present values should be used in accounting for future cash flows when information on fair values is not available. ...

Dialyzer clearance depends on blood and dialysate flow rates and the product of the membrane surface area and mass transfer coefficient for the solute of interest, K(o)A. K(o)A is usually assumed to be constant for a given dialyzer and solute. Results of two recent studies challenge this assumption. Therefore, we ...

BACKGROUND: Measuring flow in dialysis shunts is recommended to predict imminent thrombosis. Multiple methods for measuring blood flow are in use. Numerous ultrasound protocols exist which determine volume flow using a conventional Doppler (CD) frequency shift analysis technique. All of these are subject to potentially large errors. Quantitative colour velocity ...

As an adjunct to mechanical ventilation, tracheal gas insufflation (TGI) injects gas flow into the trachea to flush carbon dioxide (CO2) from the anatomical and mechanical dead space, but the addition of TGI flow from a catheter may cause problems related to increased flow velocity at the catheter tip. Forward ...

BACKGROUND: Hemodialysis access to the circulation is best provided by native and synthetic arteriovenous fistulae (AVF and AVG). Thromboses caused by venous outflow stenoses prevent the long-term use of AV access. This pilot study was performed to evaluate the ability of ultrasound dilution-derived access blood flows to detect AV access ...

Combined dialysis and ultrafiltration leads to more frequent episodes of hypotension than isolated ultrafiltration. It has been suggested that decreased plasma volume preservation could be responsible for this phenomenon. The present study evaluates the effects of diffusive dialysis on the changes in relative blood volume (RBV). Six stable hemodialysis patients, ...

Dialysate sodium and ultrafiltration profiling are two methods to reduce symptoms during hemodialysis. The objective of the study was to determine the efficacy of combining these techniques to reduce symptoms in chronic hemodialysis patients. Blood volume changes were measured to determine whether any benefit of profiling could be explained through ...

Total dialysis dose (Kt/V) is considered to be a major determinant of morbidity and mortality in hemodialyzed patients. The continuous growth of the blood urea concentration over the 30- to 60-min period following dialysis, a phenomenon known as urea rebound, is a critical factor in determining the true dose of ...

We describe a 56-year-old woman with end stage renal failure, who has an unusual complication in relation to catheter placement. She started hemodialysis in 1992 and until October of 1996 had many arteriovenous fistulas in her upper arms and we placed a lot of grafts. Because she had no vascular ...

Vascular access quality monitoring by means of vascular access blood flow (QVA) evaluated from automated thermodilutional measurement of recirculation with reverse needle position is described. This method provides significant advantages over conventional methods based on simple monitoring of pressures in the extracorporeal circuit and/or measurement of recirculation with normal needle ...

Iron deficiency is a common problem in patients on chronic HD. Earlier studies have shown significant blood loss per HD session. To identify whether the new more biocompatible high-flux or high-efficiency membranes are also responsible for significant blood loss during HD, we quantitated the amount of blood loss associated with ...

Ultrasound dilution technology is emerging as the standard for measuring access recirculation and blood flow in hemodialysis patients. In temporary dialysis catheters, studies using the traditional two-needle urea method have suggested that short femoral catheters are associated with an unacceptably high degree of recirculation. This problem has never been assessed ...

OBJECT: Disturbed ionic and neurotransmitter homeostasis are now recognized as probably the most important mechanisms contributing to the development of secondary brain swelling after traumatic brain injury (TBI). Evidence obtained in animal models indicates that posttraumatic neuronal excitation by excitatory amino acids leads to an increase in extracellular potassium, probably ...

While most commercial ablation units and research systems can provide catheter tip temperature during ablation, they do not provide information about the temperature change inside the myocardium, which determines the lesion size. We present the details of a flow simulation and temperature measurement system, which allows the monitoring of the ...

The activation of monocytes and other immunocompetent cells during hemodialysis can be attributed to their contact with immunogenic structures such as membranes, blood lines, and endotoxins. The simple measurement of cytokines in blood cannot completely describe the whole dimension of this event. Stimulation of monocytes and other immunocompetent cells in ...

BACKGROUND: Doppler ultrasound methods were used during haemodialysis sessions for the detection of microemboli and determination of their origin. METHODS: A 2-MHz ultrasound probe (Multidop X(4) DWL((TM))) was used to assess the number of microembolic signals (MES) in the subclavian vein downstream from the arteriovenous fistula before the dialysis session ...

OBJECTIVE: It was previously observed that infusion of angiotensin II, hypertonic saline and N-methyl-D-aspartic acid (NMDA) causes an increase in vasopressin and cardiodepressant factor release from the posterior pituitary lobe into the blood (Goraca 1998). The aim of present study was to investigate if the cardiodepressant factor and vasopressin are ...

AIMS: The aim of this study was to establish whether changes in parameters reflecting myocardial ischemia QRS vector difference (QRS-VD), ST change vector magnitude (STC-VM) and ST vector magnitude (ST-VM6) during hemodialysis (HD) registered by MIDA (myocardial infarction dynamic analysis) are related to changes in blood volume (BV), extracellular water ...

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 ...

BACKGROUND: The clearance of middle molecules in high-flux hemodialyzers is due to the higher contribution of convection in the overall solute transport. Although net filtration can be maintained low by the machine control, internal filtration in the proximal part of the dialyzer remains high. The final fluid balance is achieved ...

BACKGROUND: Hypotension is caused by a drop in blood volume during ultrafiltration, followed by vasoconstriction and reduced perfusion in some regions of the body. METHODS: We carried out a prospective controlled crossover study on 12 hypotension-prone patients with two different modalities: (A) acetate-free hemodiafiltration with standard ultrafiltration control, and (B) ...

Patients with end-stage renal disease use hemodialysis catheters for either temporary or permanent blood access. Recurrent thrombosis and fibrin sheath formation are common causes of poor or inadequate blood flow rates that require intervention. We studied the effect of tissue plasminogen activator (tPA) in reestablishing adequate blood flow rates through ...

In several circumstances in hemodialysis, the regular direction of blood flow has to be reversed or changed, such as in access dysfunction or insufficient blood flow being obtained through the arterial port, as well as to measure actual access blood flow in fistulas or grafts by using the formula Qa ...

The purpose of this study was to test the pyrogen permeability of the new Asahi polysulfone APS 650 (APS) dialyzer membrane with a high permeability for middle molecules (up to 40 kDa) in comparison with the high-flux Fresenius polysulfone F60S (F60S) membrane. Dialyzers were tested in parallel in vitro dialysis ...

BACKGROUND/AIM: Recirculation measured by thermodilution includes effects caused by access and cardiopulmonary recirculation. The aims of this study were to illustrate the accuracy of thermodilution in measurement of hemodialysis recirculation and also to identify a sensitive and specific threshold to detect access recirculation. METHODS: 110 studies were performed in 19 ...

Metabolic acidosis with an increased anion gap (AG) is frequently seen among patients with end-stage renal failure that is corrected to a variable degree by chronic hemodialysis. The degree of acidosis is generally interpreted from the concentration of total carbon dioxide (tCO(2)) in blood drawn from the vascular access used ...

Urea rebound (UR) after hemodialysis (HD) requires the use of equilibrated urea (Ceq) instead of immediate end-dialysis urea (Ct) for correct quantification of HD, which is impractical. A new formula for predicting Ceq in children is suggested in our study. Thirty eight standard pediatric HD sessions (single pool Kt/V = ...

Acquisition of vascular access in the emergent small animal patient is one of the keys to successful management of a population of patients that are often unstable with regard to their major body systems. Venous and intraosseus cannulation allow for the administration of a variety of fluids and potentially life-saving ...

Two increasingly common characteristics of the American chronic hemodialysis (HD) population, high hematocrit and large body size, may render the currently recommended adequacy targets difficult to achieve, even with very efficient dialyzers. In a group of patients with these characteristics, we assessed the ability of a new high efficiency dialyzer ...

BACKGROUND: Hemolysis associated with hemodialysis is rare. The most frequent causes of hemodialysis-associated hemolysis are chemical contamination, heat, or mechanical injury of erythrocytes from occluded or kinked hemodialysis blood lines. When patients in three states developed hemolysis while undergoing hemodialysis between May 13 and 23, 1998, an investigation was initiated. ...

BACKGROUND: Dialysis efficacy is mostly influenced by dialyzer clearance. Urea clearance may be estimated in vitro by total ion clearance, which can be obtained by conductivity measurements. We have previously used this approach to assess in vitro clearances in a system mimicking predilutional and postdilutional online hemodiafiltration with a wide ...

BACKGROUND: A standardized practical method of post-dialysis blood sampling is required to improve the precision of using urea kinetics in the evaluation of haemodialysis dose and to permit comparative audit. The methods recommended in the Renal Association and Dialysis Outcomes Quality Initiative (DOQI) guidelines reduce the blood pump speed to ...

Microembolic signals (MES) detected by ultrasound, thought to be of gaseous or solid origin, have been described with decompression illness and in the intracranial and cardiopulmonary circulation. We describe the first reported cases of MES occurring in hemodialysis accesses. Two hemodialysis patients, one with a synthetic graft and one with ...

A new dry dialysate concentrate acidified with citric acid (citrate dialysate) has been used in two separate clinical studies of hemodialysis patients. The first compared a single treatment using this dialysate, with one dialysis using regular standard dialysate acidified with acetic acid (regular dialysate) in a prospective, randomized, crossover study ...

Low dialysate to blood flow rate ratios are a unique characteristic of continuous arteriovenous hemodiafiltration (CAVHDF) that should allow complete saturation of dialysis fluid with small-molecular-weight blood solutes. The aim of the investigation was to evaluate the performance of different hemofilters in CAVHDF. In 10 critically ill patients with acute ...

True access recirculation (AR) measured by ultrasound dilution technique is usually absent in well-working shunts. It occurs with low access flows (Qa). High access flow rates are assumed to prevent AR. Two major exceptions to these rules are known: presence of intra-access strictures and inadvertently reversed blood lines. We present ...

The impact of pressure and flow changes in the extracorporeal circuit on dialysis efficiency in response to altered hematocrit is discussed in the light of the known properties of blood, published studies and the author's as yet unpublished measurements. Increasing the hematocrit from 0.35 to 0.45 must be expected to ...

A new polymer-based sorbent cartridge has been recently developed for enhancing middle molecule removal during hemodialysis. The cartridge (Betasorb, Renaltech, New York, USA) has been designed to be placed in series with the dialyzer in the blood circuit. It is therefore important to evaluate the distribution of flow into the ...

Dialysate purity has become a major concern in recent years since it was shown that low levels of endotoxin in dialysate were able to induce the production of proinflammatory cytokines, which were putatively implicated in the development of dialysis-related pathology. On-line haemodiafiltration (HDF; or haemofiltration) using the dialysate as the ...

On-line hemodiafiltration is a technique that relies on the re-injection of pyrogen-free substitution fluid obtained by cold filtration of dialysate. Therefore, safety of this treatment modality depends on the quality of dialysate and, mainly, on the integrity of the ultrafilter(s) employed. Double-chamber on-line hemodiafiltration is a new technique where re-infusion ...

Estimation of body fluid changes during peritoneal dialysis by segmental bioimpedance analysis. BACKGROUND: Commonly used bioimpedance analysis (BIA) is insensitive to changes in peritoneal fluid volume. The purpose of this study was to show, to our knowledge for the first time, that a new segmental approach accurately measures extracellular fluid ...

Access thrombosis remains an enormous problem for patients on hemodialysis. Current evidence suggests that decreasing access blood flow rate is an important predictor of future access thrombosis and failure. This article describes a method for determining access volume flow and detecting access pathology. The Doppler ultrasound signal downstream from the ...

Our goal of maintenance dialysis for the coming millennium is optimal rather than just adequate dialysis. Delivering a large amount of dialysis expressed in terms of urea Kt/V is a necessary but insufficient measure to improve clinical outcome. Cardiovascular morbidity and mortality remain very high in haemodialysis. This is due ...

Selenium (Se) is considered an essential and very important trace element for humans. Blood Se levels in chronic hemodialysis (HD) patients are frequently reported to be lower than in controls. The aim of this study was to evaluate these lower Se blood levels with respect to the basic renal disease, ...

The recommended Kt/V is 1.2. Unfortunately there is no written policy for nurses on the procedure for taking blood urea nitrogen samples post haemodialysis. The aim of this study was to establish the Kt/V variability of haemodialysis patients depending on the method of collection of post-haemodialysis blood urea nitrogen. Twenty-two ...

Parameters such as blood urea nitrogen concentration, normalized protein catabolic rate and Kt/V that are utilized for urea concentration measurements in blood and dialysate for the optimization of the hemodialysis process are reviewed in the paper. Basic methods of urea concentration measurement are described. Urea biosensors of the EnFET type ...

Disturbed ionic and neurotransmitter homeostasis are now recognized to be probably the most important mechanisms contributing to the development of secondary brain swelling after traumatic brian injury (TBI). Evidence obtained from animal models indicates that posttraumatic neuronal excitation via excitatory amino acids leads to an increase in extracellular potassium, probably ...

Tidal peritoneal dialysis (TPD) was introduced in 1990 in the hopes of improving dialysis efficiency. Studies comparing low dialysate flow rates show that tidal peritoneal dialysis has no clearance advantage over intermittent peritoneal dialysis (IPD). With high dialysate flow rates, TPD may be superior or similar to IPD in efficacy, ...