***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: PURPOSE Alteplase is approved for use in the restoration of function to occluded central venous access devices ( CVADs ) ; however , there are few prospect i ve studies in children . This study was undertaken to evaluate the safety and efficacy of alteplase in the treatment of CVAD occlusions in a pediatric population . MATERIAL S AND METHODS A prospect i ve , multicenter , open-label , single-arm study evaluating a maximum of two doses ( < or = 2 mg per dose ) of alteplase was performed in pediatric patients . Inclusion criteria included patient age less than 17 years with an occluded CVAD ( single- , double- , and triple-lumen catheter or implanted port ) . Patients with hemodialysis catheters , those with known mechanical occlusion , or those considered at high risk for bleeding or embolization were excluded . Assessment of function was made 30 and 120 minutes ( if required ) after each dose . The primary objective of the study was to evaluate the safety of alteplase as measured by the incidence of intracranial hemorrhage ( ICH ) ; secondary objectives included the evaluation of specific targeted serious adverse events and efficacy of alteplase in the restoration of catheter function . RESULTS A total of 310 patients ( 174 male patients , 136 female patients ; mean age , 7.2 years ; range , 0.04 - 18.3 y ) were treated ; 55 of the patients ( 17.7 % ) were younger than 2 years of age . No patients experienced ICH ( 95 % CI , 0%-1.2 % ) . Nine serious adverse events were noted in eight patients ( 2.6 % incidence ) , two of which were attributed by the investigator to study drug administration ( one case of sepsis and one case of a ruptured catheter lumen ) . The cumulative rate of restoration of CVAD function after serial administration of a maximum of two instillations of alteplase , each with a maximum dwell time of 120 minutes , was 82.9 % ( 95 % CI , 78.2%-86.9 % ) . Similar rates of catheter function restoration were seen among all catheter types studied ; there were no clinical ly meaningful differences among age or sex subgroups . CONCLUSION The administration of alteplase is safe and effective for the restoration of function to CVADs in pediatric patients BACKGROUND Sodium citrate has antibacterial and anticoagulant properties that are confined to the catheter when used as a catheter lock . Studies of its use as a catheter lock have suggested its efficacy in preventing infection and bleeding complications compared with sodium heparin . STUDY DESIGN Open-label r and omized controlled trial of 2 catheter locks to examine the hypothesis that sodium citrate catheter locks will reduce catheter-related bacteremia and exit-site infection . SETTING S & PARTICIPANTS 232 consenting long-term hemodialysis patients in 4 satellite dialysis units to a large dialysis program with protocol ized treatment and targets . All patients were using twin-catheter single-lumen Tesio-Caths  ( MedComp , Harleysville , PA ) . INTERVENTION 6 months ' use of 46.7 % sodium citrate ( citrate ) or 5 % heparin ( heparin ) locked postdialysis in the dead space of the central venous catheter . OUTCOMES & MEASUREMENTS Primary end point of catheter-related bacteremia and exit-site infection . Secondary end points of catheter thrombosis defined by the use of urokinase lock and infusion , new catheter insertion , catheter-related admission , blood transfusions , parenteral iron , and erythropoietin requirements . RESULTS Catheter-related bacteremia did not differ in the 2 groups , with an incidence of 0.7 events/1,000 catheter-days . There was no significant difference in rates of exit-site infection ( 0.7 versus 0.5 events/1,000 catheter-days ; P = 0.5 ) . The secondary end point of catheter thrombosis defined by the use of a urokinase lock was significantly more common in the citrate group , with an incidence of 8 versus 4.3/1,000 catheter-days ( P < 0.001 ) . Other secondary end points did not differ . Citrate treatment was curtailed compared with heparin because of a greater incidence of adverse events , with a mean treatment duration before withdrawal of 4.8 + /- 2.0 versus 5.7 + /- 1.2 months , respectively ( P < 0.001 ) . LIMITATIONS Low baseline catheter-related bacteremia and exit-site infection event rates may have underpowered this study . High adverse-event rates may have been related to high-concentration citrate that led to increased overspill and reduction in lock volume . This may also explain the increased rates of thrombosis in this group . CONCLUSION Widespread and long-term use of 46.7 % citrate catheter locks with Tesio-Cath access is not justified by this study The most effective and safe method of maintaining peripheral intravenous lock in children is an important clinical question that has been identified by the research ers . The results of recent studies comparing saline versus 10 units/ml of heparin saline flush using a 24-gauge catheter in neonatal and pediatric population s are conflicting and inconclusive . The objectives of this study were to evaluate the effectiveness and safety of three flush solutions : normal saline , 1 unit/ml of heparin saline and 10 units/ml of heparin saline for maintaining peripheral intravenous locks in children , and to establish a research -based practice in the study hospital . In a prospect i ve , r and omized controlled , double-blind trial , one hundred and twenty-three subjects ranging in age from 1 - 10 years with 123 intravenous locks were r and omly chosen to receive 1 unit/ml of heparin saline , 10 units/ml of heparin saline and normal saline to evaluate length of catheter use , survival rate and incidence of intravenous complications . The study found no statistically significant differences in length of catheter use , estimated catheter survival and the incidence of intravenous complications among the three groups . The group that received 1 unit/ml of heparin saline demonstrated the highest rate of survival . The mean length of catheter use of the group that received 1 unit/ml of heparin saline ( 49.8 hours ) was 17 hours longer than the group that received normal saline ( 32.5 hours ) . There are no significant differences among the three types of flushing solution in terms of the catheter longevity and incidence of intravenous complications From January 1986 to December 1990 we studied angiographically the subclavian-brachiocephalic vein of 100 patients dialysed by subclavian catheter for 50 ( first group ) and by internal jugular catheter for the 50 others ( second group ) . These two groups were not statistically different as regards age ( 61.6 + /- 11.3 years in the first and 61 + /- 11.1 in the second ) , sex ( 48 % and 56 % were women ) ,  duration of catheter insertion ( 31 + /- 21.8 and 31.7 + /- 16 days ) , and the number of dialysis sessions ( 13.5 + /- 9.1 and 13.6 + /- 7.1 ) . The type of catheters , the frequency of removal for poor flow ( 16 % in both groups ) or infections ( 6 % in both groups ) , and the local nursing were similar in the two groups . The only difference was the side of cannulation : the right side in 58 % of cases in group 1 and 78 % in group 2 . The angiographic study revealed a stenosis of the vein in 42 % of the subclavian group and in 10 % of the internal jugular group : a dramatic difference in favour of the internal jugular route , whose superiority over the subclavian route is asserted in respect of venous access of dialysed patients Soft , cuffed , implantable central venous catheters such as the Quinton Permcath ( Quinton Instrument Co , Seattle , WA ) are increasingly used as permanent access in patients with end-stage renal disease . Their major limitations , besides infection , are thrombosis and inadequate blood flow . To prevent those complications , heparin is conventionally used for priming the Quinton Permcath between dialysis sessions . In this study , we compared recombinant tissue plasminogen activator ( rTPA ) with heparin for priming the Quinton Permcath in a prospect i ve , r and omized , crossover design . Twelve patients were r and omly assigned to receive 2,000 IU of heparin or 2 mg of rTPA injected into each catheter lumen at the end of each dialysis session over a period of 4 months , followed by a switch to the other substance . Blood flow rate ( flow ) , venous pressure ( VP ) , and arterial pressure ( AP ) were monitored at each dialysis session hourly . Flow was significantly greater ( P = 0.0001 ) with rTPA ( mean + /- SD , 237.7 + /- 18.1 and 231.6 + /- 12.4 mL/min for the first and second 2 months , respectively ) compared with heparin ( 208.5 + /- 10.1 and 206.9 + /- 14.2 mL/min for the first and second 2 months , respectively ) . VP was significantly less ( P = 0.0001 ) with rTPA ( 135.4 + /- 8.2 and 140 + /- 15.2 mm Hg for the first and second 2 months , respectively ) compared with heparin ( 160.5 + /- 16.1 and 159.2 + /- 20.7 mm Hg for the first and second 2 months , respectively ) . AP was significantly greater ( P = 0.0002 ) with rTPA ( -113.5 + /- 11.8 and -115.9 + /- 12.7 mm Hg for the first and second 2 months , respectively ) compared with heparin ( -136.5 + /- 23.3 and -134.7 + /- 25.8 mm Hg for the first and second 2 months , respectively ) . In addition , fewer complications ( flow problems , clotting , and need for fibrinolysis ) occurred in the rTPA period . These results show that rTPA is superior to heparin for priming the Quinton Permcath between hemodialysis sessions and can be used as a valuable alternative to conventional heparin in selected patients BACKGROUND Microinflammation is linked to cardiovascular disease , and is highly prevalent in dialysis patients . It is logical to postulate that septicemia , a common macroinflammatory occurrence in dialysis patients , contributes to their large burden of cardiovascular disease . METHODS The Dialysis Morbidity and Mortality Wave 2 was a r and omly selected prospect i ve cohort of incident dialysis patients . Admission cl aims data were used to define and calculate rates of septicemia or bacteremia and cardiovascular events in those with Medicare as the primary payer . Utilizing Cox proportional hazard models we determined the association between baseline access and the development of bacteremia or sepsis , and also the association between bacteremia or sepsis episodes and subsequent cardiovascular events . RESULTS The 2358 ( 59 % ) patients with Medicare as primary payer were older and more likely to have heart failure  than those with other payers , but had similar comorbidity-adjusted mortality hazards . Rates of first septicemia , bacteremia , or either condition , were 7.0 , 5.9 and 10.4 events per 100-patient years , respectively . Cox regression identified initial dialysis access as the main antecedent of septicemia or bacteremia . Hazards ratios for hemodialysis with permanent catheters , temporary catheters , and grafts were 1.95 ( 95 % CI 1.47 - 2.57 ) , 1.76 ( 95 % CI 1.29 - 2.41 ) , and 1.05 ( 95 % CI 0.82 - 1.35 ) , respectively , while that for peritoneal dialysis was 0.96 ( 95 % CI 0.75 - 1.23 ) ( reference arteriovenous fistula ) . After adjustment for baseline factors , septicemia or bacteremia , as a time-dependent covariate , was associated with subsequent death [ hazards ratio ( HR ) 2.33 , 95 % CI 1.38 - 2.28 ] , myocardial infa rct ion ( HR 1.78 , 95 % CI 1.38 - 2.28 ) , heart failure ( HR 1.64 , 95 % CI 1.39 - 1.95 ) , peripheral vascular disease ( HR 1.64 , 95 % CI 1.34 - 2.0 ) , and stroke ( HR 2.04 , 95 % CI 1.27 - 3.28 ) . CONCLUSION Septicemia appears to be an important , potentially preventable , cardiovascular risk factor in dialysis patients Tinzaparin offers some advantages over unfractionated heparin ( UFH ) for hemodialysis circuit anticoagulation . No study has compared these two molecules as hemodialysis catheter lo 
    Output:
    
In the few r and omized trials that met our inclusion criteria , the use of rt-PA as a locking solution for hemodialysis catheters seems to be associated with fewer adverse events and catheter malfunctioning as compared with heparin .