Presence of a biomaterial implant facilitates induction of experimental infective endocarditis due to streptococci and staphylococci

Infective endocarditis (IE) usually is studied using animals with catheters inserted into the heart, which causes formation of platelet-fibrin thrombi (vegetations, VGs). We used two rabbit models to study the respective roles of the catheter and the VGs in the development of IE. The influence of the catheter was studied by either removing the catheter before bacterial challenge, or leaving the catheter in place. In all cases, removal of the catheter caused a strong decrease in the frequency of IE. The presence of the catheter stimulated population increase of streptococci within 4 h after challenge. As most catheters were sterile 4 h after challenge, they did not serve as a reservoir of bacteria. To study the requirement of a preformed VG catheters were inserted either 24 h or 30 min before bacterial challenge. In the former model VGs were present, in the latter VGs were not yet formed when bacteria were injected. The frequencies of IE due to 2 S. sanguis and 2 S.epidermidis strains in the 24 h model or 30 min model were similar, indicating that a preformed VG is not necessary for development of IE. Five coagulase-negative stains were shown to vary in their capacity to cause IE in the 30 min model. Variation was not caused by differences in early adhesion or colonization of the aortic valve, but reflects differences in persistence after initial colonization. Like in the 24 h model, persistence of the bacteria was greatly enhanced by the continuous presence of the catheter. Possible mechanisms of the infection-potentiating effect of the catheters are discussed.     

Case report of Capnocytophaga canimorsus septicemia with infective endocarditis in a hemodialysis patient: A not widely known dog pathogen

Keeping pets as a companion is a global phenomenon. This relationship, however, is not entirely free of risk as some diseases can be transmitted to human beings. It is important to emphasize safety among pet owners, particularly in people with chronic illness as they may have increased vulnerability to infection which could arise from an intimate relationship. We report an uncommon etiology of sepsis complicated with infective endocarditis in a 63-year old dog-owner who was on hemodialysis. To the best of our knowledge, this is the first case of Capnocytophaga canimorsus infective endocarditis (IE) ever reported in a patient undergoing hemodialysis.     

The level of C‐reactive protein in chronic hemodialysis patients: A comparative study between patients with noninfected catheters and arteriovenous fistula in two large Gulf hemodialysis centers

Hemodialysis (HD) patients have greater morbidity and mortality when they have a central venous catheter (CVC) rather than an arteriovenous fistula (AVF) access. Inflammation associated with dialysis catheter use and resultant higher C‐reactive protein (CRP) levels could have an independent adverse effect on patient outcomes. In this prospective study, we investigated whether HD catheters induce inflammation independent of infection. We compared the mean levels of the inflammatory marker (CRP) in 67 patients on maintenance HD using noninfected catheters with 86 HD patients using AVFs at Prince Salman Center for Kidney Diseases, Saudi Arabia (KSA), and Jahra Hospital, Kuwait, who met our inclusion criteria. C‐reactive protein levels were measured every 2 months over a period of 6 months using immunoturbidimetric assay. One hundred fifty‐three patients on maintenance HD for more than 6 months were included in the study, with mean age of 52.19 ± 16.06 years; 66% were males and 34% were females. Serial levels of mean CRP were statistically and significantly higher in group with noninfected catheters (1.33, 1.24, and 1.10 mg/dL) compared to those with AVFs (0.65, 0.59, and 0.68 mg/dL) with P value of 0.000. In our study, we found no relation between CRP level and age, sex, hemoglobin, albumin, calcium, phosphorus, and iPTH level in both groups. Hemodialysis patients with a catheter have a heightened state of inflammation independent of infection, and thus our study supports the avoidance of catheters and a timely conversion to AVFs with catheter removal.     

Infective spondylodiscitis in patients on high‐flux hemodialysis and on‐line hemodiafiltration

Infective spondylodiscitis (ISD) is a rare but potentially devastating condition in hemodialysis (HD) patients. Reports are limited especially in patients receiving high‐flux HD and hemodiafiltration (HDF). In a retrospective analysis, 13 patients on our maintenance high‐flux HD/HDF program were identified as having has infective spondylodiscitis over a 10‐year period (1997–2006), an incidence of approximately 1 episode every 215 patient‐years. The incidence was around 3 times higher in patients dialyzing with tunnelled central venous catheters (TCVC) than in those with arteriovenous fistulae. Affected patients were elderly (mean age 70 years) and had multiple comorbidities. Access problems, particularly TCVC infection, were common in the months preceding it's onset. Tunnelled central venous catheter removal during these episodes did not necessarily prevent it. Diagnosis was based on a history of back pain, raised C‐reactive protein, positive blood cultures, and characteristic magnetic resonance findings. Many patients were apyrexial and had normal white cell counts. In our patients on high‐flux HD/hemodiafiltration, its incidence appears comparable to that in conventional HD settings. No patients had infection with waterborne organisms. Blood cultures were positive in 77%. Gram‐positive organisms predominated, particularly Staphylococcus aureus. The major route of infection was hematogenous, with the most likely source the venous access. All received antibiotics for 6 to 12 weeks or until death. Only 2 patients underwent surgical drainage. Mortality was high (46%) and predicted by the development of complications, and by pre‐existing cardiovascular comorbidity. Prevention, using strategies to reduce the prevalence of bacteremia, including limiting the use of TCVC, should be an overriding aim.     

Late acceleration of glomerular filtration rate decline is a risk for hemodialysis catheter use in patients with established nephrology chronic kidney disease care

Chronic kidney disease (CKD) patients with established nephrology care have a high rate of tunneled dialysis catheters (TDC) as first vascular access when transitioning to hemodialysis (HD). We sought to identify factors associated with this problem. Patients who started HD and had prior CKD care within our renal clinic were categorized according to access type at incident HD. Clinical factors, all estimated glomerular filtration rates (eGFR), renal clinic attendance records, hospital admissions in the 6 months preceding HD start, and patient participation in predialysis education course were analyzed. Three hundred thirty‐eight patients initiated HD, 107 received pre‐HD CKD care within our clinics. Seventy patients started with a TDC. All groups started HD at similar eGFR values. The trajectory of eGFR decline in the 6 months prior to HD start was significantly more rapid in the TDC group. Patients in the TDC group had more acute health events in the prior 6 months. Multivariate modeling showed that failure to attend a predialysis education course and having a more rapid rate of eGFR decline in the 6 months prior to dialysis initiation were both associated with TDC use. Patients with CKD nephrology care who initiated HD with a TDC as first vascular access had a more rapid rate of decline in eGFR in the months preceding dialysis start and were less likely to have attended our predialysis education course. This appears to correspond with the observed increased number of emergency and hospital visits in the 6 months prior to end‐stage renal disease.     

Effectiveness of a computerized decision support system for anticoagulation management in hemodialysis patients: A before–after study

Introduction The risk‐benefit profile for warfarin anticoagulation in hemodialysis (HD) patients differs compared with the non‐HD population. HD patients are at increased risk of both thromboembolism and bleeding related to anticoagulation therapy. In addition, anticoagulation control may be more difficult to achieve in the HD population due to frequent comorbidities, subclinical Vitamin K deficiency, altered pharmacokinetics due to uremia and the concurrent use of multiple medications. While computerized decision support systems (CDSS) to assist with anticoagulation management are safe and effective in the non‐HD population, they have not been well studied in HD outpatients. Methods A before–after study compared anticoagulation control for HD outpatients receiving warfarin at a tertiary medical center in Canada during two time periods: an initial period of nephrologist‐led anticoagulation management and a second period after implementation of a pharmacist‐led, CDSS‐assisted anticoagulation management strategy. Findings Forty‐two patients were included. Following implementation of the CDSS‐assisted strategy, there was no significant change in median therapeutic time‐in‐range (3.7% difference (IQR, ?9.5% to 20.6%); P = 0.247). Median change in INR testing frequency was 1.2 (IQR, 0.1–2.2; P = 0.0001) fewer tests per patient per month, which equates to approximately 15 fewer tests per patient per year. Adverse events were similar. Discussion Implementing a CDSS‐assisted strategy for anticoagulation management in HD outpatients is effective. Doing so may lead to modest cost savings related to less frequent INR testing.     

Effects of enoxaparin on myeloperoxidase release during hemodialysis

Myeloperoxidase (MPO) is a proteolytic and prooxidant enzyme largely assembled with the vascular wall, and a heparin‐binding protein. We studied if low‐molecular‐weight heparin enoxaparin administered for hemodialysis (HD) anticoagulation causes systemic MPO activation. Plasma MPO levels were measured in patients undergoing maintenance HD with an intravenous bolus of enoxaparin. Patients were retested during HD employing dialyzers with heparin‐grafted polyacrylonitrile membrane and no systemic enoxaparin administration. During enoxaparin‐anticoagulated HD plasma MPO levels strikingly increased in all patients (8.6‐fold at 10 minutes and 3.3‐fold at 120 minutes, both P < 0.0001). The increments were directly associated with the enoxaparin dosage and strongly inversely with the predialysis levels of the enzyme. The increase in plasma MPO during systemic heparin‐free HD was significantly less pronounced. Enoxaparin administered for HD anticoagulation induces a marked and dose‐dependent increase in plasma MPO as a plausibly favorable result of the liberation of the enzyme from the vascular wall.     

Hemodialysis access-related survival and morbidity in an elderly population in South West Thames, UK

Elderly patients form the most rapidly expanding group of hemodialysis (HD) patients in Europe and the United States. There are initiatives to promote an increase in arteriovenous fistula (AVF) formation. There are concerns that elderly patients may have lower rates of surgical vascular access compared with younger patients due to risks of higher co-morbidities, surgical complications, and higher AVF nonuse rates. The aim of this study was to compare access-related survival and morbidity for dialysis catheters and AVFs and to evaluate the AVF nonuse rate in an elderly population. We have performed a retrospective analysis of access survival and morbidity in patients > or = 70 years of age, either on maintenance HD or predialysis with preemptive formation of surgical access. One hundred and forty-six patients had permanent HD access created during the 18-month study period, from 1 January 2006 to June 2007. There were 89 male and 57 female patients in whom 78 AVFs and 137 tunneled venous catheters were inserted. There was a significantly greater loss of vascular access due to infection in the catheter group compared with the AVF group (P<0.016). Access survival was also significantly prolonged in the AVF group (446 days, 95% confidence interval 405-487) compared with the catheter group (276 days, 95% confidence interval 240-313), P=0.001. The rate of nonuse of AVFs was low (16%). We conclude that an AVF is the preferred form of vascular access in elderly HD patients.     

Antibiotic lock: In vitro stability of vancomycin and four percent sodium citrate stored in dialysis catheters at 37°C

Catheter-related bacteremia (CRB) is a major cause of morbidity and mortality especially among patients receiving hemodialysis (HD). Antibiotic lock therapy represents a promising technique in the treatment of CRB. Several studies have evaluated antibiotics in combination with heparin as an interdialytic locking solution as adjunctive therapy for CRB. The objective of this study was to evaluate the chemical stability of the vancomycin in 4% sodium citrate in HD catheters as an interdialytic lock. Vancomycin was prepared and diluted with sodium citrate 4% and stored in polyvinyl chloride syringes, 2 carbothane dialysis catheters (Hemostar^®) and 2 dual floating HD catheters (CardioMed^®). Syringes were stored at 4 °C or 23 °C and the catheters were stored in an incubator at 37 °C for 72 hours. Samples underwent daily chromatographic analysis and the luminal concentration of vancomycn was determined on study days 0, 1, and 3. When vancomycin is reconstituted with normal saline to achieve a concentration of 50 mg/mL, and then further diluted in 4% sodium citrate, to achieve concentrations of either 1 or 3 mg/mL, and then stored at 4 °C, room temperature, or 37 °C, solutions were observed to retain >92% of the initial concentration for the study period of 3 days. Based on the fastest degradation rate determined with 95% confidence interval, >90% is retained for 6.53 days. We conclude that vancomycin—4% citrate solutions stored in polyvinyl chloride syringes or HD catheters are not significantly affected by temperature or concentration within the 72 hours storage period. Therefore, these solutions can be anticipated to be suitable as a HD interdialytic antibiotic lock in standard HD catheters.     

Free dialysis in Nepal: Logistical challenges explored

Nepal's Ministry of Health began offering free lifetime hemodialysis (HD) in 2016. There has been a large growth in renal replacement therapy (RRT) services offered in Nepal since 2010, when the last known data on the subject was published. In 2016, 42 HD centers existed (223% increase since 2010) serving 1975 end stage renal disease patients (303% increase since 2010); 36 nephrologists were registered (200% increase since 2010), 12 were trained in transplantation, and 790 transplants had been performed to date. We estimate the incidence of end stage renal disease to be 2900 patients (100 per million population). With an annual cost of approximately US$2300 per dialysis patient, offering free dialysis could potentially cost the government US$6.7 million per year, suggesting that 2.1% of the annual health budget would be allocated to 0.01% of the population. The geographic zone surrounding the capital city, Kathmandu, contains 50% of HD centers, but only 14.5% of Nepal's population. Forty‐eight percent of the population lives within zones without HD service, therefore infrastructure challenges exist in providing equitable access to RRT. The aim of this article is to summarize the current statistics of RRT in Nepal.     

Necrotizing fasciitis and infective endocarditis caused by Escherichia coli in a hemodialysis patient

Patients with uremia are often immunocompromised and uremia patients undergoing maintenance dialysis are often vulnerable to uncommon infections. We report a 40‐year‐old man who was undergoing maintenance hemodialysis and was initially diagnosed with monomicrobal necrotizing fasciitis of the lower limbs, based on blood and pus cultures that yielded Escherichia coli. His condition improved after surgical debridement and antibiotic therapy. However, he eventually died of intracranial hemorrhage related to septic emboli. Concurrent infective endocarditis was diagnosed based on an echocardiogram that indicated vegetation in the left ventricular region. Escherichia coli‐related necrotizing fasciitis and infective endocarditis is rarely seen in clinical practice. There should be a high index of suspicion for multiple infections when a hemodialysis patient presents with an uncommon infection.     

Relationship of Hypoalbuminemia to Multiple Clinical Factors in Hemodialysis Patients

Research shows that low albumin is correlated with higher morbidity and mortality in the dialysis population. The reasons for this are multi‐factorial and may be related to inadequate protein intake, infection and sepsis, inadequate dialysis, or catabolism of uremia. USRDS data show that ESRD Network 16 tends to have lower albumins compared to other ESRD Networks. Objective: To evaluate albumin status of HD patients at Puget Sound Kidney Centers, Everett, WA (ESRD Network 16) and identify potential factors that may put patients at risk of hypoalbuminemia. Methods: Clinical and biochemical data were collected for 3 months on 221 HD patients. Data included serum albumin (bromcresol purple), calcium, phosphorus, CO₂, Hct, % saturation, ferritin, PTH, BUN, Kt/V, URR, nPCR, hours of HD treatment, interdialytic fluid weight gains, DW changes, incidence of infection and hospitalization, catheter use for dialysis access, presence of diabetes and other co‐morbidities, dialyzer reuse, social/psychological status, and use of nutrition supplements. All biochemical data were collected after the longest interdialytic period and analyzed at the same reference laboratory. Data were averaged for each patient for the 3 months and correlations between parameters were determined using Chi‐square analysis. Results: 25% of all patients had albumins <3.2 g/dL (reference range for normal population 3.5–5.0 g/dL). Patients with lower albumins were significantly more likely to have DM (p < 0.02), use catheters for HD access (p < 0.001), had infections during the previous month (p < 0.001), been hospitalized during the previous month (p < 0.002), have co‐morbid issues (p < 0.001), and use nutrition supplements (p < 0.002). No other factors were significantly correlated with lower albumin. Conclusion: Factors other than nutrition seem to be related to hypoalbuminemia. This study has prompted improved protocols for catheter care and use, infection control, and early intervention for nutrition supplement use. Increased screening and monitoring at‐risk patients (those with diabetes and other co‐morbid conditions) has resulted in improved patient care.     

Enterococcus faecalis endophthalmitis as a metastatic complication of hemodialysis vascular access‐related sepsis: A case report and review of the literature

Catheter and/or arteriovenous (A‐V) graft‐related bacteremia is an important cause of morbidity and mortality among hemodialysis (HD) patients. Endocarditis, septic arthritis, epidural abscess, septic embolism, and osteomyelitis are the most common complications of catheter and/or A‐V graft‐related bacteremia; however, endogenous endophthalmitis is rarely seen. To the best of our knowledge, Enterococcus faecalis is the first case report in this population. We hereby report a case of endogenous endophthalmitis caused by E. faecalis as a complication of catheter and/or A‐V graft‐related bacteremia in a diabetic patient, who was undergoing HD for 5 years. We also discuss the etiology, clinical features, and outcomes of endogenous endophthalmitis in HD patients with a brief review of the literature. Although broad‐spectrum parenteral (intravenous and intravitreal) antibiotics were used for 4 weeks, evisceration of the left eye could not be avoided. Endogenous endophthalmitis is a rare but rapidly blinding complication of catheter and/or A‐V graft‐related bacteremia in HD patients. It can develop as a result of silent catheter and/or A‐V graft infections, which may lead to recurrent bacteremia. E. faecalis should be considered as a pathogen in this population who had recent history of catheter or A‐V graft procedure.     

Central Venous Catheter Access in Children on HD

Central venous catheters (CVC) remain a frequently used form of vascular access in children receiving chronic hemodialysis (HD). Whereas standard dual-lumen catheters (DL) are used in many centers, the Tesio catheter has proven to be superior to the DL catheter in terms of catheter survival and infection rates in at least one pediatric study (Sheth RD et al . Am J Kidney Dis. 2001). Recently, the Ash Split catheter became available which, while similar to the Tesio internally, being comprised of 2 separate catheters, may be preferable because of the requirement for only one skin puncture for placement vs. two for the Tesio. However, no pediatric data pertaining to the Ash Split catheter have been published to date. Therefore, we reviewed and compared our experience with a small number of Ash Split (# 16) and Tesio (# 8) catheters used for semipermanent vascular access in our chronic HD population with reference to survival, infectious complications, patency, and dialysis adequacy. The results of this experience are as follows:  

     

Factors predicting failure of AV “fistula first” policy in the elderly

An arteriovenous fistula (AVF) is the preferential hemodialysis (HD) access. The goal of this study was to identify factors associated with pre‐dialysis AVF failure in an elderly HD population. We used United States Renal Data System + Medicare claims data to identify patients ≥67 years old who had an AVF as their initial vascular access placed pre‐dialysis. Failure of the AVF to be used for initial HD, was used as the outcome. Logistic regression model was used to identify factors associated with AVF failure. The study cohort consisted of 20,360 subjects (76.2 ± 6.02 year old, 58.5% men). Forty‐eight percent of patients initiated dialysis using an AVF, while 52% used a catheter or an AVG. The following variables found to be associated with AVF failure when an AVF was created at least 4 months pre‐HD initiation: older age (odds ratio [OR] 1.01; 95% confidence interval [CI] 1.00–1.02), female gender (OR 1.69; 95% CI 1.55–1.83), black race (OR 1.41; 95% CI 1.26–1.58), history of diabetes (OR 1.22; 95% CI 1.06–1.39), cardiac failure (OR 1.26; 95% CI 1.15–1.37), and shorter duration of pre–end‐stage renal disease (ESRD) nephrology care (OR for a nephrology care of less than 6 months prior to ESRD of 1.22 compared with a pre‐ESRD nephrology follow up of more than 12 months; 95% CI 1.07–1.38). OR for AVF failure for the entire cohort showed similar findings. In an elderly HD population, there is an association of older age, female gender, black race, diabetes, cardiac failure and shorter pre‐ESRD nephrology care with predialysis AVF failure.     

Neutrophil and monocyte activation in chronic kidney disease patients under hemodialysis and its relationship with resistance to recombinant human erythropoietin and to the hemodialysis procedure

The aim of the present work was to further clarify leukocyte activation due to hemodialysis (HD) procedures and to investigate its relationship with recombinant human erythropoietin resistance. Therefore, we studied the expression of CXCR1 and CD11b on neutrophils, as well as the monocyte expression of CD11b, HLA‐DR, and CD14. We studied 34 chronic kidney disease (CKD) patients under HD and recombinant human erythropoietin treatment (26 responders and 8 nonresponders to recombinant human erythropoietin therapy). All CKD patients' blood samples were collected before and immediately after the HD procedure. Eighteen healthy individuals (blood donors) were also studied as a control group. Hematological data, neutrophil (CD11b and CXCR1), and monocyte (CD11b, HLA‐DR, and CD14) cell surface markers were measured in all patients (before and after the HD procedure) and controls. When compared with the controls, CKD patients presented a significant decrease in CXCR1 neutrophil expression, and in CD14 monocyte expression, accompanied by a significant increase in HLA‐DR monocyte expression. When comparing the 2 groups of patients, we found that nonresponders showed an additional decrease in CXCR1 neutrophil expression. After the HD procedure, a statistically significant increase in CD14 and CD11b monocyte surface markers and a decrease in CXCR1 neutrophil expression and in HLA‐DR monocyte expression was found. These data further strengthen our previous studies, showing that neutrophils and monocytes are activated in CKD patients, particularly in nonresponder patients. Moreover, this activation is due, at least in part, to the HD procedure, although we should not exclude that it can also be due to the enhanced inflammatory process observed in nonresponder patients.     

Enhanced expression of hemoglobin scavenger receptor and heme oxygenase‐1 is associated with aortic valve stenosis in patients undergoing hemodialysis

A high prevalence and a rapid progression of aortic valve stenosis (AS) in patients undergoing hemodialysis (HD) has been reported. In these circumstances, intraleaflet hemorrhage of aortic valve may be related to the development of AS in HD patients. We immunohistochemically examined the relationship among intraleaflet hemorrhage, neovascularization, hemoglobin scavenger receptor (CD163), and heme oxygenase‐1 (HO‐1) using surgically resected aortic valve specimens from AS patients undergoing HD. The study population consisted of 26 HD patients and 25 non‐HD patients with severe AS who had undergone aortic valve replacement. Frozen aortic valve samples surgically obtained from AS patients were stained immunohistochemically with antibodies against smooth muscle cells, macrophages, glycophorin‐A (a protein specific to erythrocyte membranes), CD31, CD163, and HO‐1. Morphometric analysis demonstrated that the CD163‐positive macrophage score, the number of CD31‐positive microvessels, and the percentage of glycophorin‐A and HO‐1‐positive area were significantly higher in HD patients than in non‐HD patients (CD163‐positive macrophage score, P < 0.0001; CD31‐positive microvessels, P < 0.0001; glycophorin‐A, P < 0.0001; HO‐1, P < 0.0001). Double immunostaining for CD163 or HO‐1 and macrophages revealed that the majority of CD163‐ or HO‐1‐positive cells were macrophages. Furthermore, CD163‐positive macrophage score was positively correlated with glycophorin‐A, HO‐1‐positive area, and the number of CD31‐positive microvessels (glycophorin‐A, R = 0.66, P < 0.0001; HO‐1, R = 0.50, P < 0.0005; microvessels, R = 0.38, P < 0.01). These findings suggest a positive association among intraleaflet hemorrhage, neovascularization, and enhanced expression of CD163 and HO‐1 as a response to intraleaflet hemorrhage in stenotic aortic valves in AS patients undergoing HD.     

Alteplase vs. urokinase for occluded hemodialysis catheter: A randomized trial

Introduction Thrombosis of tunneled central venous catheters (CVC) in hemodialysis (HD) patients is common and it can lead to the elimination of vascular sites. To compare the efficacy of alteplase vs. urokinase in reestablishing adequate blood flow through completely occluded vascular catheters. Methods In this randomized study, patients with completely occluded tunneled HD catheters received 40 minutes intracatheter dwell with alteplase (1 mg/mL) or urokinase (5000 IU/mL). Primary endpoint was the proportion of patients with occluded catheters achieving post‐thrombolytic blood flow of ≥250 mL/min. Safety endpoints included the incidence of hemorrhagic and infectious complications. Findings Eligible adult patients (n = 100) were treated with alteplase (n = 44) or urokinase (n = 56). The two groups were similar in gender (male: 51.8% vs. 56.8%, P = 0.35), age (60 ± 12 vs. 59 ± 13 years, P = 0.71), time on dialysis (678 ± 203 vs. 548 ± 189 days, P = 0.77), diabetes and cardiovascular disease (55.6% vs. 70.4%, P = 0.08 and 17.8% vs. 22.7%, P = 0.38, respectively), jugular vein as main vascular access (54.8% vs. 62.5%, P = 0.57), and time of CVC (278 ± 63 vs. 218 ± 59 days, P = 0.67). Primary success with alteplase and urokinase occurred in 42/44 (95%) vs. 46/56 (82%), P = 0.06. Success was not achieved after the second dose of alteplase and urokinase in 1 and 7 cases, respectively (2% vs. 12%, P = 0.075). Serious adverse effects were not observed in both groups. There was no difference between the two groups in infectious complications (P = 0.94). Discussion Alteplase and urokinase are effective thrombolytic agents for restoring HD catheter patency. Our study has revealed a likely slight superiority of alteplase over urokinase for unblocking central lines, but which has enrolled too few patients to be able to detect a difference of this size.