***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: This is an interval analysis of the 2-year prospect i ve multicenter Childrens Cancer Study Group study of 1,141 chronic venous access devices in 1,019 children with cancer . Device type was external catheter ( EC ) 72 % , totally implantable ( TID ) 28 % , and did not differ for diagnosis or age except more double-lumen devices in bone marrow transplant protocol s ( 77 % ) and more TIDs in children less than 1 year old ( 17.7 % ) . Insertion characteristics evaluated in 1,078 ( 95 % ) were : operating room placement 99 % ; general anesthesia 98 % ; cutdown 67 % ; percutaneous 33 % ; atrial position 50 % , caval position 50 % ; and perioperative antibiotics 48 % . Vein entry was the external jugular 33 % , internal jugular 22 % , subclavian 35 % , cephalic 7 % , and saphenous 3 % . Insertion was difficult or very difficult in only 10 % and operative complications occurred in only 0.7 % . Degree of difficulty bore no relationship to device type or patient age . The reasons for removal in 736 devices ( 67 % ) were due to complications in 39 % , of which infections were the most frequent . There was some variance between centers ranging from 8.5 % to 31 % for infection ; 2.8 % to 24 % for dislodgment ; and 0 % to 13 % for occlusion .  ECs had a higher risk of dislodgment ; elective removals were more frequent in TIDs ; there was no difference in infection as a cause for removal between ECs and TIDs . Dislodgment was associated with the shortest distance of the cuff to the skin exit ( mean , 4 cm ) : less than or equal to 2 cm , 49 % ; greater than 2 cm , 28 % ( P = .009 ) and occurred most frequently in the younger patient ( 18.9 % , 0 to 1 years ; 0.5 % , greater than 8 years A group of 43 adult patients with acute leukaemia ( AL ) were r and omized to receive a double-lumen totally implantable subcutaneous port system ( PORT , n=19 ) or a double-lumen central venous catheter ( CVC , n=24 )  before induction chemotherapy . Six patients were excluded due to protocol violation ( n=4 , CVC ) and technical difficulties ( n=2 , PORT ) . A st and ardized catheter record form was used for recording of catheter function , local infection and bleeding . The study was prematurely closed due to extensive subcutaneous bleeding after placement in five patients with a PORT . Intention to treat ( n=43 ) or per protocol ( PP ) analysis ( n=37 ) did not reveal a significant difference between the two groups with regard to catheter survival time ( PP PORT , median 113 days , range 2–634 days ; CVC , 55 days , 11–223 days ) . The number of positive blood cultures per 100 central venous access device days was significantly higher in the CVC group ( median 3.6 per 100 days ) than in the PORT group ( 0.9 per 100 days ; P=0.02 ) . In addition , the time to the first blood culture positive for coagulase-negative staphylococcus was shorter in the CVC group ( median 14 days ) than in the PORT group ( 52 days ; P=0.02 ) . Despite fewer infectious complications in the PORT group the use of a double-lumen CVC is advocated in patients with AL undergoing induction treatment due to the risk of extensive local bleeding after placement of the PORT BACKGROUND The incidence of Hickman catheter sepsis is 10 % to 40 % , with result ant catheter loss in one third of infections . Urokinase causes dissolution of colonized intracatheter fibrin thrombi and may improve salvage . STUDY AIMS To evaluate the efficacy of 12-hour-interval slow-push urokinase infusion in addition to st and ard antibiotic therapy in the treatment of catheter sepsis in a pediatric oncology population . METHODS A two-arm r and omized double-blind trial was undertaken , with catheter salvage rate as the end point . Patients with Hickman catheter sepsis were r and omized after culture data confirmed the diagnosis . The study drug was administered by a slow intravenous push and given at 12-hour intervals for a total of four doses . The catheters were aspirated after 1 hour . RESULTS AND CONCLUSIONS The trial was stopped after 41 patients were entered into the study ; 18 patients received a placebo  , and 23 received the urokinase .  In the placebo group , six catheters were lost ; in the urokinase group , eight were lost . The rate of bacterial clearance was equivalent for both . After administration of the study drug , each group had three episodes of fever and chills ; two of these result ed in hypotension ( one in each group ) . The authors conclude that slow-push urokinase infusion during established Hickman catheter sepsis does not result in improved catheter salvage or bacterial clearance . Slow intravenous push infusions in this setting may provoke hemodynamic instability even after initiation of antibiotics From June 1982 until December 1989 , 93 permanent central venous catheters [ 59 external catheters ( ECs ) and 34 implanted catheters ( ICs ) ] were placed in 69 patients . The median age of these patients at placement was 5.6 years for ECs and 8.8 years for ICs ( P less than 0.05 ) . Follow-up evaluation was possible on 86 catheters ( 58 ECs and 28 ICs ) . The median time of insertion was 236 days and 316 days for ECs and ICs , respectively ( P less than 0.05 ) . The median number of open days was 58 for ECs and 66 for ICs ( not significant ) . 17 catheters ( 6 ECs and 11 ICs ) were transiently obstructed ( P less than 0.005 ) . 30 episodes of bacteraemia were documented in 20 patients . The incidence of catheter sepsis and bacteraemia of unknown source was one in 278 and 283 open days for ECs and ICs , respectively ( not significant ) . In this retrospective study , ECs appeared to be as safe as ICs when infection was correlated with use of the catheter , but this finding should be confirmed in a r and omised design Since 1984 , 316 subcutaneous ports ( SP ) and 339 external venous catheters ( EC ) [ Roko Catheter , The Hospital for Sick Children ( HSC ) ]  have been inserted in hematology/ oncology patients at HSC . During a 22-month period ( July 1987 to April 1989 ) , a committed central line nurse ( J.I. ) prospect ively collected clinical and microbiologic data on 144 consecutive SPs and 130 consecutive ECs . Children with the SP had 0.6 infected lines and 0.7 infectious episodes per 1,000 patient days compared to 2.9 infected lines and 4.3 infectious episodes per 1,000 patient days with the EC ( p < 0.001 ) . This lower infectious complication rate with SP was demonstrated in the entire group of unselected patients and in a cohort of children with acute lymphoblastic leukemia ( ALL ) receiving intensive chemotherapy , and it was evident in all age groups . In view of the other advantages of SP – normal activity , absence of the need for home maintenance , improved body image , less expense – these data suggest that SPs are the preferred device in pediatric patients and provide effective venous access with acceptable complication rates PURPOSE To compare the frequency of infectious episodes or other problems occurring with an externalized catheter ( Hickman ) versus a subcutaneously implanted device ( Port-a-Cath , Pharmacia , Piscataway , NJ ) in cancer patients , we performed a prospect i ve , r and omized study in 100 cancer patients ( age range , 5 to 74 years ) . PATIENTS AND METHODS Patients who were chemotherapy c and i date s and required an indwelling catheter were monitored prospect ively and evaluated during the 180 days after the insertion of the catheter and again at time of study closure . The frequency of catheter use , reason for access , and any problems that might have been related to catheter use were noted . All data were collected prospect ively and included the patient 's age , sex , underlying malignancy , temperature , and leukocyte and absolute granulocyte counts at the time of catheter insertion and when complications occurred . The time to and reason for removal of the catheter , as well as any intercurrent infectious or mechanical problems , were also determined . RESULTS Most of the infections that occurred were caused by gram-positive organisms , especially staphylococci or streptococci . A total of 22 complications ( 11 in each group ) result ed in removal of the central line . Only one infection in the Hickman catheter group and four in the Port-a-Cath group led to removal of the central line . All other infectious episodes were successfully treated without removal of the catheters . The mean device life was 230 days for the Hickman catheter and 318 days for the Port-a-Cath ( not significant ) . CONCLUSION There were no differences between the two study groups regarding incidence of documented infections or mechanical or thrombotic complications PURPOSE Infection and thrombosis are serious complications of long-term vascular access devices in children undergoing chemotherapy . Since routine fibrinolytic therapy may decrease these complications , the purpose of this study was to compare the efficacy of an every-2-week administration of urokinase with st and ard heparin flushes in reducing the incidence of device-related infections and occlusions . MATERIAL S AND METHODS This study was a prospect i ve , r and omized phase III multicenter trial conducted by the Children 's Cancer Group , in which patients with implantable ports or tunneled catheters received either urokinase or heparin every 2 weeks for 12 months . Study end points were time to first occlusion or time to first device-related infection . RESULTS Five hundred seventy-seven patients from 29 institutions were enrolled , of whom 51 % had external catheters and 49 % had ports .  Urokinase administration result ed in fewer occlusive events than heparin ( 23 % v 31 % ; P = .02 ) , a longer time to first occlusive event ( log-rank analysis , P = .006 ) , and a 1.6-fold difference in the rate of occlusive events ( Poisson regression , P = .003 ) . Similar results were noted when comparing ports and tunneled catheters . The urokinase group also had a 1.4-fold difference in the rate of infection ( Poisson regression , P = .05 ) and longer time to first infection ( log-rank , P = .07 ) , but the difference was significant only in tunneled catheters . CONCLUSION Urokinase administration every 2 weeks significantly affects the rate of occlusive events in ports and tunneled catheters and of infectious events in external catheters compared with heparin administration Long-term therapy of oncology patients has been facilitated by permanent indwelling central venous catheters , but catheter-related infections remain a serious complication of their use . Using a retrospective matched cohort design , we compared the risk of catheter-related infection in 47 adult solid tumor patients with right atrial Hickman catheters and 94 patients with totally implanted port catheters . Patients were matched for primary solid tumor , presence of metastases , age , gender , and date of catheter insertion . Seven of 47 patients with Hickman catheters developed catheter-related infection ( 1.8 infections/1,000 catheter days at risk ) compared with 10 of 94 patients with implanted port catheters ( 0.4/1000 catheter days , P less than 0.0002 ) . Hickman catheters were used more often for terminally ill patients than were port catheters which was a potential source of bias , but results were unchanged after stratifying patients on lifespan . Our study suggests that there are fewer infections in port than in Hickman catheters in adult patients with solid tumors , but prospect i ve r and omized studies are needed One hundred and forty-eight Hickman-Broviac ( HB ) catheters and 299 Port-a-Cath R ( PAC ) were inserted over the past 5 years at the Institut Jules Bordet . The HB catheter was associated with a complication rate of 4.1/1000 days of access , of which infections were the most common , leading to catheter removal in 22 % of patients . The average PAC remained in situ for 232.9 ( range 1 - 1298 ) days ; the complication rate was only 0.45/1000 days of access . The Hickman-Broviac catheter and the totally implanted port Port-a-Cath achieve safe and reliable venous access in cancer patients We prospect ively studied the continuous function and complication rates of 286 central venous catheters consecutively placed in 264 children and young adults at a single institution over a 19-month period ( median follow-up , 376 days ) .  Externalized catheters ( 91 Hickman [ H ] , 113 Broviac [ B ] ) and implantable ports ( n = 82 ) were compared for complications , including infection and throm 
    Output:
    
Conclusion The findings of this study showed that totally implantable ports are superior to external catheters in terms of catheter-associated complications .