Hemodialysis Blood Research Articles

A prospective observational study of catheter-related bacteraemia and thrombosis in a haemodialysis cohort: univariate and multivariate analyses of risk association

Central venous catheterization is a fundamental component in delivering haemodialysis yet is associated with significantly higher complication rates than other methods of vascular access. In this study, we report results of univariate and multivariate analyses designed to identify and quantify independent risk association for catheterization type, clinical variables and laboratory variables with regard to the development of catheter-related bacteraemia (CRB) and catheter failure due to poor haemodialysis flow. A 2-year prospective study of all incident haemodialysis vascular access catheter insertions was conducted. Laboratory and clinical variables were recorded at catheter insertion, and the clinical course was followed up to the point of catheter removal. CRB and catheter failure due to poor flow were recorded as outcome events. Univariate and multivariate analyses were used to test for association between clinical and laboratory variables and outcome. Forty-four thousand five hundred seventy-six catheter days were accumulated over the study period. Multivariate analysis demonstrated an independent association between non-tunnelled catheterization procedures and adverse outcomes compared with tunnelled central venous catheter insertions. Elevated modified Charlson comorbidity score was independently associated with the development of CRBc. Elevated C-reactive protein and low haemodialysis blood pump flow were independently associated with catheter failure due to poor flow. The data demonstrate that tunnelled central venous catheter insertions have an association with lower complication rates than non-tunnelled central venous catheter insertions that is independent of whether patients have acute or chronic renal failure, or high levels of comorbidity.

Relative Plasma Volume Monitoring and Blood Pressure Control

Establishing dry weight in hemodialysis patients is an inexact science.1 Monitoring changes in blood pressure with volume removal is crude but can be effective in establishing dry weight. Unfortunately, probing for dry weight (eg, reduction of volume on dialysis sufficient to reduce blood pressure to <140/90 mm Hg) can lead to intradialytic hypotension, and this is more common in patients with large intradialytic weight gain. Often clinicians use medication-directed blood pressure control strategies in the hemodialysis patient.2 This paradoxically may interfere with the opportunity to achieve dry weight, because if the patient is on increased amounts of antihypertensive medication, more sizeable reductions in blood pressure with ultrafiltration may occur during dialysis.3 This would limit the opportunity for volume removal. As a consequence, the patient would then be chronically volume overloaded. If antihypertensive medication escalation results from inadequate achievement of goal blood pressure during dialysis, a vicious cycle would ensue. The net result is more risk of adverse events from medications and increased ventricular volume and pressure. Recurrent ventricular volume overload may be one of the most important factors leading to heart failure and increased risk of arrhythmia. Thus, …

Hemodialysis, plea of availability versus adequecy gezira experience

Objectives: This is a prospective cross sectional study carried out in Gezira Hospital for Renal Diseases and Surgery (Sudan) to assess the adequacy of hemodialysis in 206 patients with end stage kidney disease on regular hemodialysis twice per week using.Methods: Pre and post hemodialysis blood sample were obtained from the study group, spKt/V and urea reduction ratio were calculated.Results: Mean Kt/v was found to be 1.19 and urea reduction ratio was 59.55%. None of the patients in this study group achieved the National Kidney Foundation Dialysis Outcomes Quality Initiative (K/DOQI) recommendations for adequate hemodialyis, since it requiresthree hemodialyis sessions per week and our patients are receiving two sessions per week.Conclusion: In order to improve the situation herewith we recommended increased number of sessions from two to three times per week and \or increase the duration of hemodialysis session, increase blood flow rate and dialysate flow rate. Moreover, decrease the number of patients onregular hemodialysis by encouraging the patients to take the other renal replacement therapy (peritoneal dialysis and renal transplantations).

PP-066 Survey of the seroprovalence of HTLV I/II in hemodialysis patients and blood donors in Urmia

PP-066 Survey of the seroprovalence of HTLV I/II in hemodialysis patients and blood donors in Urmia

Comparison of Hemodialysis Blood Access Flow Rates Using Online Measurement of Conductivity Dialysance and Ultrasound Dilution

Routine access flow (AF) surveillance is recommended by the Kidney Disease Outcomes Quality Initiative as one of several components for an arteriovenous vascular access maintenance program. A reliable, but affordable, measurement tool is needed for outpatient hemodialysis facilities. Diagnostic test study. 50 adult patients with 27 grafts and 23 fistulas from a single center who consented to sequential AF measurements, all performed within the first 90 minutes of the hemodialysis treatment. AF measured by using online conductivity dialysance (OLC-AF). AF measured by using ultrasound dilution (UD-AF). Mean UD-AF was 1,086 +/- 629 mL/min, and mean OLC-AF was 951 +/- 575 mL/min, with a mean difference of 135 +/- 229 mL/min. OLC-AF correlated significantly with UD-AF (0.93; P < 0.0001), becoming tighter for flows less than 1,000 mL/min (0.95; P < 0.0001). The coefficient of variation for sequential measurement by using UD was 6.4%, and for OLC, 11.5%, with the difference becoming insignificant (7.6% versus 8.8%; P = 0.5) for flows less than 1,000 mL/min. The average of 2 sequential UD-AF measurements correlated tightly with that of OLC-AF (0.99; P < 0.0001). Tests were performed by 2 highly trained coordinators in a single clinic with a small sample size, and clinical outcomes were not evaluated. The OLC method is a reasonable alternative to UD for flow surveillance of arteriovenous hemodialysis accesses and provides an option for widespread implementation of a vascular access surveillance program. Additional studies are needed to determine whether routine use impacts on clinical outcomes.

Oxidized Low-Density Lipoprotein Biomarkers in Patients with End-Stage Renal Failure: Acute Effects of Hemodialysis

Objective: To assess the effect of end-stage renal failure on oxidized low-density lipoprotein (OxLDL) biomarkers and the acute effects of hemodialysis. Oxidized phospholipids (OxPL) on apolipoprotein B-100 (apoB) particles (OxPL/apoB) have been associated with cardiovascular disease and new cardiovascular events. Patients with end-stage renal failure have increased oxidative stress and are at significantly increased risk of cardiovascular disease. Methods and Results: Fifty-two stable patients with end-stage renal failure undergoing chronic hemodialysis were included in the study. Pre and post hemodialysis blood samples were obtained for measurement of OxLDL biomarkers: oxidized phospholipids (OxPL) on apolipoprotein B-100 (apoB) particles (OxPL/apoB) measured by antibody E06, IgG and IgM autoantibody titers to copper-oxidized LDL (Cu-OxLDL) and malondialdehyde (MDA)-LDL, IgG and IgM apolipoprotein B-100-immune complexes (IC/apoB). Traditional laboratory variables as well as C-reactive protein (CRP) and lipoprotein(a) [Lp(a)] were also measured. For the baseline variables, the distribution of OxPL/apoB and Lp(a) were skewed to lower values, and a strong correlation was noted between OxPL/apoB and Lp(a) (r = 0.94, p < 0.0001). No major associations were noted between OxLDL biomarkers and age, gender or dialytic age. There were also no correlations between OxLDL biomarkers and traditional risk factors, CRP, body mass index, serum creatinine, hypertension or intravenous iron therapy. Following dialysis, there as a significant reduction in OxPL/apoB (–7.5%, p = 0.048) and triglyceride levels (–10.8%, p = 0.005). All other OxLDL biomarkers, CRP, total cholesterol, LDL-C, HDL-C and apoB-100 increased significantly (range 6.3–26.9%, p value range 0.005 to <0.0001). Total protein plasma levels increased 8.8% (p = 0.014 compared to predialysis) following dialysis, consistent with a hemoconcentration effect of hemodialysis. Conclusion: In end-stage renal failure patients undergoing hemodialysis, a reduction in OxPL/apoB levels was noted, despite the hemoconcentrating and strong pro-oxidant milieu of hemodialysis. Studies in larger populations of end-stage renal failure patients are needed to assess whether these findings predict future clinical outcomes.

Hemolysis‐induced acute pancreatitis secondary to kinked hemodialysis blood lines

Hemolytic reactions have become extremely rare in chronic maintenance hemodialysis. We present the case of a young dialysis patient with hemolysis-induced acute pancreatitis secondary to kinked hemodialysis blood lines. With new blood lines on the market, attention to this aspect of dialysis is mandatory.

IS POTENTIAL EQUALISATION IN HD TREATMENTS NECESSARY?

In some cases in haemodialysis blood access is established with a special type of central venous catheter (CVC), sometimes called a central dialysis catheter (CDC), instead of an AV fistula or graft. This central venous catheter tip is placed very close to the heart, increasing the probability of a leakage of electrical current passing through the heart. This may cause arrhythmia or ventricular fibrillation. This current is generally referred to as patient leakage current and has to be kept very low for patient safety. All staff involved in CVC treatments, nursing staff as well as technicians, should be aware of this particular risk to the patient. The purpose of this article is to discuss the background of the above-mentioned safety issue and suggest precautionary measures for minimising this risk. Precautions discussed include potential equalisation, use of separating transformers, periodic maintenance (normally performed by a service technician) and physical placement of the equipment used in the vicinity of the patient (normally the responsibility of the nursing staff).

Hemodialysis Blood Access Flow Rates Can Be Estimated Accurately from On-Line Dialysate Urea Measurements and the Knowledge of Effective Dialyzer Urea Clearance

Measurement of blood flow rate (Qa) is used to monitor arteriovenous fistulas and grafts that are used for hemodialysis blood access. Most Qa measurements use indicator dilution techniques to measure the recirculation that is induced by the reversal of hemodialysis blood lines. R plus the dialysis circuit flow (Qb) allows the calculation of Qa. The principle of needle reversal also can be used with a dialysate urea monitor (e.g., DQM 200 [Gambro]) without injection of diluent; the effect of the reversal on urea concentration is observed. Access blood water flow rate (Qaw) in relation to the effective clearance (K) is found from the urea concentrations in the dialysate with needles in the normal (Cn) and reverse (Cr) positions: K/Qaw = (Cn - Cr)/Cr. Qa is calculated by adjusting Qaw for hematocrit and protein. For testing of this theoretical relationship, 20 patients who were dialyzed on Integra (Hospal) and Centrysystem 3 (Cobe) machines that were fitted with DQM 200 were studied. During each treatment, lines were reversed and Qa was measured by ultrasound velocity dilution (Transonic HD01 monitor); at the same time, Cn and Cr were measured by DQM 200 and K was calculated. K1 was determined from a predialysis blood urea concentration (Cb), initial dialysate urea concentration (Cd), dialysate flow rate (Qd), and the relationship K x Cb = Qd x Cd (K1). K was determined separately from a conductivity step method using Diascan (Hospal) attached to Integra machines only (K2). With the use of K1, 127 comparisons were made; a correlation existed (r = 0.916), although Bland-Altman analysis showed that the dialysate urea method gave a mean value 5.3% +/- 15.3 (+/-SD) higher than that of Transonic (P < 0.001). With the use of K2, there also was a correlation of (r = 0.944; n = 63), and Bland-Altman testing showed an NS difference of +3.5% between the dialysate urea and Transonic methods. Qa can be estimated from on-line dialysate urea measurements that are taken before and after line reversal together with knowledge of K.

COAGULATION TEST METHOD FOR EXTRACORPOREAL BLOOD CIRCUITS

A new method for measuring coagulation in an extracorporeal circuit was developed for biocompatibility tests of 2 hemodialysis blood pumps (roller and Allient™ ventricle pump). Bovine blood was collected in citrate-anticoagulated 450mL blood bags. Heparin was added at 0.5 U/mL and CaCl2 was added to obtain ionized Ca level of 2 mEq/L. Blood was pumped through a blood transfusion filter (Pall Biomedical SQ40S, 40 μ) at ∼300 mL/min and returned to the bag. Pressure on both sides of the filter and the blood flow rate were continuously measured. Hydraulic resistance (HR) of anticoagulated blood is essentially stable. As blood starts to coagulate anywhere in the circuit, slope of HR increases at least 14-fold, usually much more. The tests demonstrated that coagulation properties are similar for the two pumps and that neither has high propensity for coagulation. This test method uses readily available sensors, is sensitive to small amounts of thrombus formation, and detects the onset of coagulation.Figure

Hemodialysis‐induced acute pancreatitis secondary to kinked hemodialysis blood lines

Introduction: Hemolytic reactions developing during hemodialysis usually are caused by oxidant damage, reduction injury, and osmolar, thermal, and mechanical injury to the red blood cells. Mechanical injury due to maloccluded blood pumps, arterial line collapse, and use of subclavian hemodialysis catheters has been reported. We report one episode of acute hemolysis due to kinked hemodialysis blood lines complicated with pancreatitis. Case Report: An 18‐year‐old man with end‐stage renal failure of unknown origin had been on hemodialysis since 2002. His past medical history included asthma and hypertension. He was admitted to the hospital because of severe abdominal pain, nausea, and vomiting during the dialysis session. Laboratory examination showed hematocrit −30 %, platelet count of 131,000 per cubic mL, LDH −5151 U/L, haptoglobin −0.09 g/L, lipase −919 U/L, CPK‐ 260, ASAT −584 U/L, ALAT‐ 316 U/L, bilirubin −36 μmol/L, and visible schistocytes on smear. Examination of the abdomen revealed diffuse discomfort and tenderness in epigastrium. The patient was diagnosed as having hemolysis‐induced acute pancreatitis. He was treated symptomatically and recovered within a few days. We found the arterial blood line tightly kinked at the dialyser inlet port, and we excluded other reported causes of intravascular hemolysis during hemodialysis. Discussion: Until a critical pressure is exceeded, despite a kink in the post pump predialyser blood tubing, the blood pump can maintain sufficient blood flow to prevent an increase in the arterial pressure with a triggering of the arterial alarm and a decrease in the venous pressure with a triggering of the venous alarm. Thus, an excessively high pressure can be maintained in this silent segment of the dialyser tubing without activating the pressure alarms, exposing the red blood cells to high sheer stresses and resulting in clinically significant hemolysis. Acute hemolysis can cause a life‐threatening acute pancreatitis. The literature indicates that acute pancreatitis is a complication of massive hemolysis with a prevalence of about 20%. The important role of inflammatory cytokines in the pathogenesis of acute pancreatitis is well known. Heme released from hemoglobin after episodes of vascular hemolysis has the potential to act as a signalling molecule involved in the triggering of the inflammatory processes associated with massive hemolysis. Hemolysis itself may induce acute pancreatitis by all or some pathways of neutrophil activation and chemoattraction, such as oxidative burst, direct proinflammatory effect, microcirculatory disturbance, and increased expression of proinflammatory and immunoregulatory cytokines.

Molecular Investigation of GB Virus C RNA in Hemodialysis and Thalassemics Patients from Brazil

The GB virus C (GBV-C)/hepatitis G virus (HGV) is a member of the Flaviviridae family. Based on the clinical and epidemiological profiles, this virus could be acquired mainly by parenteral transmission through contaminated blood. We therefore investigated the presence of GBV-C/HGV and its relation with the other blood borne viruses as hepatitis B and C viruses (HBV, HCV) in hemodialysis and thalassemic individuals and blood donors from Ribeirão Preto–-Brazil. Detection of blood borne virus markers including HBV surface antigen (HbsAg), HBV core antibody (anti-Hbc) and HCV antibody was carried out. HIV-1, HIV-2, HTLV-1 and HTLV-2 were also investigated. GBV-C/HGV RNA was detected by reverse transcriptase and polymerase chain reaction (RT-PCR). Ninety-four serum samples from patients with chronic renal failure were analyzed. GBV-C/HGV RNA was identified in 12 (12.8%) patients, anti-HCV antibodies in 28 (29.8%), anti-Hbc in 9 (9.6%), anti-HIV in 1 (1%), HBsAg in 33 (35.1%), and HBsAg/anti-HBc was observed in 2 (2.1%) patients. Thirty-six (38.3%) samples were non-reactive. Seven of the 12 GBV-C/HGV RNA infected samples were co-infected with other viruses: 3 (25%) with HBsAg, 2 (16.7%) with anti-HCV and 2 (16.7%) with anti-HBc/anti-HCV/HBsAg. Among the 42 thalassemic patients, GBV-C/HGV RNA was detected in 6/42 patients (14.2 %). Three patients presented GBV-C/HGV, with other blood borne markers. We also detected GBV-C/HGV in 6/50 (12%) blood donors. In these GBV-C/HGV positive thalassemics patients, 50% (3/6) were young individuals (lesser 15 years old) and 67% (4/6) were female patients. The presence of GBV-C RNA in the absence of hepatitis B and C infection in the young patients and healthy donors could be indicate that this virus is capable of independent transmission and does not contribute to liver disease.

Experience using a New Vascular Port Access Device for Hemodialysis: Preliminary Clinical Results

A new subcutaneous device (Dialock(R), Biolink Corp, Middleboro, MA) provides vascular access to patients who require hemodialysis. The device consists of a port implanted in a subcutaneous pocket in the thoracic area 10 cm below the clavicle. Interdialytic patency is maintained using a priming antithrombotic solution. The device was implanted in 10 outpatients under local anesthesia, and immediately used for he-modialysis. The catheters have been used up to now for a total of 1,480 days ( 24- 248 days), the average being 4.8 months (1-8 months). Survival rate of Dialock (R)was 100% at 8 months. During this period, the device achieved prescription hemodialysis blood flow rates averaging 250-300 ml/min with a venous pressure of 180 +/- 25 mmHg. Malpositioning of the catheters due to their excessive length was observed in the first three patients and led to the repositioning of the catheters' distal tips under local anesthesia. Secondary and delayed hematoma surrounding the Dialock(R)device were observed in 2 patients one or two days after insertion. In one case, a hematoma was surgically removed under local anesthesia. Antibiotic therapy was administered for safety and prophylactic reasons. In one patient spontaneous catheter fracture and distal tip embolization occurred on the 49th day after repositioning. Percutaneous radiological retrieval of the catheter fragment was performed. No infection of the Dialock (R)device occurred and only one episode of bacteremia was observed. Blood cultures were positive for Staphylococcus epidermidis . Infection was cured by appropriate systemic antibiotic therapy combined with gentamicin and sodium citrate lock. The device was well accepted by patients and staff. The Dialock (R)device catheter offers a new vascular alternative for dialysis that deserves further long-term study. In particular, the confidence of structural materials should be tested.

Electrical Current Leakage during Hemodialysis May Increase Blood-Membrane Interaction

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 could alter blood membrane interaction as measured by changes in C3d in the blood. Such a high current leakage could occur because there is no protection in the dialysis machine (Class 1B) against auxiliary current leakage. Such a current could come from a defective external device in contact with the patient during hemodialysis. A dialysis machine (Fresenius 2008C) with a filled blood-line system containing about 350 ml whole blood from each of 8 different donors was used in vitro. Each of the eight test-runs also contained 1000 U added heparin. The dialysis procedure was performed using hemophan membranes (GFS + 12, Gambro) with bicarbonate and potassium 3.0 (D210, Gambro) as dialysate. Two electric poles were placed in the blood line, before and after the dialyzer (connected in parallel) and the ground was placed at entry and exit of the dialysate fluid coming from the machine to the dialysis filter. C3d was measured before the start of "dialysis" and at 15, 30, 45 and 60 min, during dialysis. Thereafter the 1.5 mA current was switched on and additional samples were drawn at 75 and 90 min. The mean C3d values were calculated. Paired non-parametric statistical analyses were performed. There was a significant and continuous increase in C3d as compared to the "predialysis" level. The increase during 0 to 30 minutes was greater than that from 30 to 60 minutes (p=0.018); the increase in C3d during 60 to 90 min, was greater than that from 30 to 60 min (p=0.018) and there was no difference between the 0 to 30 and the 60 to 90 min increases. A current, used in this study, was able to induce a blood membrane interaction during in vitro dialysis. Even a weaker current leakage might have such adverse effects and similar interactions seem possible during regular dialysis depending on the extent of the leakage.

Adverse Events in Chronic Hemodialysis Patients Receiving Intravenous Iron Dextran – A Comparison of Two Products

Background: Parenteral iron therapy is required in a majority of chronic dialysis patients who are receiving recombinant human erythropoietin (r-HuEPO) in order to provide adequate iron for erythropoiesis. At this time, there are only two formulations of parenteral iron dextran available for clinical use in the USA. These two preparations of iron dextran have different physical and chemical characteristics that might affect the adverse events experienced by dialysis patients receiving iron dextran. Methods: We performed a retrospective analysis of all 665 courses of parenteral iron dextran which were administered in our hemodialysis unit from June 1992 through July 1997. An adverse event (AE) was defined as any event which led to interruption of the prescribed course of iron therapy or precluded subsequent administration of parenteral iron in the presence of documented iron deficiency. Database elements included patient age, gender, cause of renal failure, and prior history of drug allergy. The average hemoglobin value and serum iron parameters (iron, total iron binding capacity (TIBC), percent saturation of TIBC, and ferritin) were recorded both pre- and post-iron administration, when available. A course of parenteral iron dextran consisted of a 25-mg test dose, followed by four or five doses of 300 mg each. Iron dextran was infused into the venous limb of the hemodialysis blood circuit over the last 30–60 min of a dialysis treatment. The two forms of iron dextran were designated as Iron A (molecular weight = 165,000) and Iron B (molecular weight = 267,000). Results: Fifty-seven percent of our patients were male, 92% were of white race, and diabetes was the most common cause of renal failure (34%). Sixty-four percent of the patients were 60 years of age or older, and 39% had a history of allergy to one or more drugs. We observed 33 AEs during the administration of parenteral iron dextran, and these AEs occurred in 21 courses of parenteral iron dextran administration. Eighteen of the AEs were gastrointestinal in nature; 7 AEs were cutaneous in nature, 6 AEs had systemic manifestations, while only 2 AEs caused respiratory problems. Two of the AEs were felt to be anaphylactoid in nature. Female gender (p = 0.06) and iron dextran product (p = 0.02) were identified as potential risk factors for the development of an AE. There were 468 courses of Iron A administered, 10 of these courses were complicated by 15 AEs (one or more AE per course). One hundred and ninety-seven courses of Iron B were administered and 11 (5.6%) courses were complicated by the development of 18 AEs (9.1 AEs per 100 courses). Serum iron rose by 22 µg/dl and TIBC saturation increased by 14% after the administration of parenteral iron. The average serum ferritin level rose by 430 µg/l and hemoglobin values rose by an average of 0.8 g/dl. There were no significant differences in the changes of iron parameters or hemoglobin levels between the two iron dextran preparations. Conclusions: The administration of parenteral iron dextran to chronic hemodialysis patients has a relatively high degree of safety. Both iron products were equally efficacious in increasing serum iron parameters and hemoglobin levels. Even when corrected for other factors, there was a significant difference in the observed AEs between the two formulations of parenteral iron dextran. Our observations, if true, may have important implications for the management of anemia in chronic hemodialysis patients. If a significant number of AEs prohibit the administration of a specific iron dextran product to a large number of chronic hemodialysis patients, then anemia management may become suboptimal. In the future, newer iron products may provide even safer alternatives for the administration of parenteral iron to chronic hemodialysis patients.

Differences between Blood Flow as Indicated by the Hemodialysis Blood Roller Pump and Blood Flow Measured by an Ultrasonic Sensor

Background/Aim: The ultrasonic transit time is currently the best method for measuring the blood flow rate in the extracorporeal hemodialysis circuit. The purpose of this study was to analyze the differences between blood flow as indicated by the hemodialysis blood roller pump (prescribed blood flow) and by an ultrasonic flowmeter (delivered blood flow). Methods: The ultrasonic blood flow was measured in 20 patients on chronic hemodialysis who were dialyzed through an arteriovenous fistula. During each dialysis session the ultrasonic blood flow was measured at three different blood roller pump flow rates (300, 350, and 400 ml/min). In order to analyze the influence of inflow and outflow pressures on blood flow, this study was conducted during nine consecutive dialysis sessions during which needles of different sizes were used. Results: The ultrasonic flow was always lower than indicated by the blood roller pump: 265 ± 12, 304 ± 15, and 341 ± 19 ml/min for blood roller pump flow rates of 300, 350, and 400 ml/min, respectively (variability: –11.6, –13.1, and –14.8%, respectively). An univariate regression analysis showed that the reduction in flow recorded ultrasonically correlated with both venous blood line pressure (r = –0.2679, p < 0.001) and negative arterial blood line pressure (r = 0.6773, p < 0.001). By multivariate analysis, only the arterial blood line pressure has a predictive value. When all measurements were grouped by arterial blood line pressure ranges, the variability between ultrasonic blood flow and blood roller pump flow was found to be similar in those groups with the same arterial blood line pressure, regardless of the blood roller pump flow rate. Conclusions: The blood flow indicated by the dialysis blood roller pump is always greater than the delivered blood flow, and this difference is in turn conditioned by the negative pressure induced by the blood roller pump in the arterial blood line.

Multistate outbreak of hemolysis in hemodialysis patients traced to faulty blood tubing sets

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. A case-patient was defined as any patient at healthcare facilities A (Nebraska), B (Maryland), or C (Massachusetts) during May 13 through 23, 1998 (epidemic period), who had hemolysis diagnosed > or =48 hours after undergoing hemodialysis. To identify case-patients and to determine background rates, the medical records of patients from facilities A, B, and C who were undergoing hemodialysis during the epidemic and pre-epidemic (that is, May 5 through 19, 1998) periods were reviewed. Experiments simulating hemodialysis with the same lot numbers of hemodialysis blood tubing cartridge sets used on case- and control-patients were conducted. The rates of hemolysis among patients at facilities A, B, and C were significantly higher during the epidemic than the pre-epidemic period (13 out of 118 vs. 0 out of 118, P < 0.001; 12 out of 298 vs. 0 out of 298, P = 0.001; and 5 out of 62 vs. 0/65, P = 0.03, respectively). All case-patients had hemolysis. Twenty (66%) had hypertension. Eighteen (60%) had abdominal pain, and 10 (36%) were admitted to an intensive care unit. There were two deaths. The only commonality among the three outbreaks was the use of the same lot of disposable hemodialysis blood tubing from one manufacturer. Examination of the implicated hemodialysis blood tubing cartridge sets revealed narrowing of an aperture through which blood was pumped before entering the dialyzers. In vitro experiments with the hemodialysis blood tubing revealed that hemolysis was caused by increased pressure on erythrocytes as they passed through the partially occluded hemodialysis blood tubing. Our investigation traced the multiple hemolysis outbreaks to partially occluded hemodialysis blood tubing produced by a single manufacturer. On May 25, 1998, the manufacturer issued a voluntary nationwide recall of the implicated lots of hemodialysis blood tubing cartridge sets.

Variable flow Doppler for hemodialysis access evaluation: theory and clinical feasibility.

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 arterial needle as a function of the variable hemodialysis blood pump flow rate, is used to determine access blood flow. By using this variable flow (VF) Doppler technique compared with duplex volume flow estimates measured in 18 accesses (16 patients with 12 polytetrafluorethylene [PTFE] grafts and 6 autogenous fistulas), the results showed a correlation of 0.83 (p < 0.0001) between these methods. In grafts with lower blood flow rates, aberrant flow patterns were observed, including stagnant or reversed flow during diastole while forward flow was maintained during systole. When reversed diastolic flow was severe, it was accompanied by access recirculation. In conclusion, we report the theory and clinical feasibility of determining access blood flow by using a VF Doppler technique. Measurements are made without the need to determine the access cross sectional area required for duplex volume flow calculations and without the need to reverse the lines required for various indicator dilution techniques. Important information is also obtained about aberrant flow patterns in patients at risk of access failure.

Adrenomedullin amidation enzyme activities in hypertensive patients.

Adrenomedullin (AM) is a potent vasodilating peptide secreted from the vasculature of various organs. It is biologically active when its C-terminus is amidated. Recently, an RIA method was developed for measurement of the active form of AM, or mature AM. We here employed this method to investigate the significance of amidation of AM in controlling cardiovascular function. Thirty-six patients under hemodialysis were recruited and divided into hypertensive (n = 25; 157/86 mmHg) and normotensive (n= 11; 116/66 mmHg) groups. Mature AM, immature AM and blood pressure were monitored during hemodialysis in all patients. There was a significant reduction in blood pressure during hemodialysis in both groups, although after hemodialysis blood pressure was still higher in hypertensives than in normotensives (139 +/-14.8/76 +/- 2.5 mmHg vs. 110 +/- 5.1/66.7 +/- 3.1 mmHg). Mature AM before hemodialysis were lower in hypertensives than normotensives and it decreased in both groups. Although mature AM decreased more in normotensives than in hypertensives (-27 +/- 8% vs. -17 +/- 5%), at the end point, its level was still higher in normotensives. The ratio of mature AM/immature AM decreased only in normotensives (-11.4 8.7%), whereas it remained stable in hypertensives (0.2 +/- 5.6%). Both groups showed similar changes in ANP, endothelin, catecholamines, cGMP, and NOx. The low level in mature AM level in hypertensives may have contributed to the higher blood pressure in this group. The attenuation of AM amidation in normotensives indicates that an unspecified amidative enzyme of AM was regulated in order to normalize blood pressure.

PDGF-AB release during and after haemodialysis procedure.

During haemodialysis blood membrane contact causes the release of the content of platelet alpha-granules, which contain platelet-derived growth factor (PDGF). In view of its possible role in accelerated atherosclerotic processes, we evaluated the intra- and post-dialytic changes in PDGF-AB serum levels during haemodialysis sessions performed using a cellulosic membrane. Using the ELISA method, PDGF-AB, platelet factor-4 (PF4) and beta-thromboglobulin (beta-TG) levels were determined in peripheral blood, as well as in arterial and venous haemodialyser lines, in 10 patients each of whom underwent five consecutive dialysis sessions with a CU membrane. Blood samples were taken at 0, 15, 30, 60, 120, 180 and 240 min during dialysis and at 1, 4 and 20 h after the end of the session. In the same group of patients the levels of the same molecules were also determined after a heparin bolus injection of 4500 IU, blood samples were taken at 0, 15 and 30 min after injection of the bolus. PDGF-AB serum levels increased, remained consistently high during the haemodialysis session (in particular +134+/-20% after 30 min, P<0.001, and +140+/-5% after 240 min, P<0.001) and returned to basal values only after 20 h following the end of the session. PF4 and beta-TG showed a similar trend to PDGF. The heparin bolus injection caused only a small increase (+15+/-5% at 30 min) in PDGF-AB serum levels. PDGF-AB is released during dialysis mainly as consequence of the blood-membrane contact and it returns only slowly to basal values.