***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 
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    Input: Background Central venous access is an essential part of patient management in many clinical setting s and is usually achieved with a blinded , external l and mark-guided technique . The purpose of this study is to evaluate whether an ultrasound technique can improve on the traditional method . Methods and Results We prospect ively evaluated an ultrasound-guided method in 302 patients undergoing internal jugular venous cannulation  and compared the results with 302 patients in whom an external l and mark-guided technique was used .  Ultrasound was used exclusively in an additional 626 patients .  Cannulation of the internal jugular vein was achieved in all patients ( 100 % / ) using ultrasound and in 266 patients ( 88.1 % ) using the l and mark-guided technique ( p<0.001 ) . The vein was entered on the first attempt in 78 % of patients using ultrasound and in 38 % using the l and mark technique ( p<0.001 ) . Average access time ( skin to vein ) was 9.8 seconds ( 2–68 seconds ) by the ultrasound approach and 44.5 seconds ( 2–1,000 seconds ) by the l and mark approach ( p<0.001 ) . Using ultrasound , puncture of the carotid artery occurred in 1.7 % of patients , brachial plexus irritation in 0.4 % , and hematoma in 0.2 % . In the external l and mark group , puncture of the carotid artery occurred in 8.3 % of patients ( p<0.001 ) , brachial plexus irritation in 1.7 % ( p<0.001 ) , and hematoma in 3.3 % ( p<0.001 ) . Conclusions Ultrasound-guided cannulation of the internal jugular vein significantly improves success rate , decreases access time , and reduces complication rate . These results suggest that this technique may be preferred in complicated cases or when access problems are anticipated The internal jugular vein ( IJV ) is a common access route to the central venous system . Anatomical l and marks ( group I ) are normally used for localization of the IJV . We have compared this method with two other methods based on ultrasonic waves to identify the IJV and the carotid artery ( CA ) ( even in atypical positions ) . We employed an ultrasound Doppler device in group II and a real-time ultrasonograph in group III . Central venous catheters were placed into the right IJV by the Seldinger technique .  The IJV could be located in all patients with both ultrasound methods , but the course of the IJV could only be identified by ultrasonography . For this reason , the direction of the IJV was classified as " typical " in 80 % of group I , in 85 % of group II , but in only 45 % of group III . No intergroup differences were found with respect to the number of punctures ( mean value 1.6 + /- 0.83 ) and the incidence of complications . The time required to locate the site and direction of puncture increased with technical sophistication . There was , however , no difference in the total time for catheter placement , because puncture was performed faster when aided by sonography . In four patients in groups I and II , in whom attempts to puncture the IJV had not been successful , this could subsequently be achieved with ultrasonographic aid . One patient ( group I ) displayed a hematoma following inadvertent puncture of the CA . In one patient in group II the IJV and CA could not be distinguished as one was overlying the other . The echocamera provided improved localization of the IJV and the CA in comparison with the Doppler ultrasound . ( ABSTRACT TRUNCATED AT 250 WORDS OBJECTIVE To examine the rate of success and complications of Doppler-guided subclavian vein catheter insertion compared with st and ard insertion in patients considered at high risk for failure . DESIGN Prospect i ve , r and omized , crossover trial . SETTING University-affiliated tertiary care medical center . PATIENTS Two hundred forty patients were enrolled in the study . Patients were stratified for 3 known risk factors : ( 1 ) prior surgery in the subclavian vein region , ( 2 ) prior radiotherapy at the attempted catheterization site , and ( 3 ) an abnormal weight-height ratio . INTERVENTIONS Subclavian vein catheterization was performed either in st and ard or Doppler-guided fashion using the Smart Needle ( Peripheral Systems Group , Mountain View , Calif ) , which is a Doppler probe at the tip of a cannulating needle . If subclavian vein catheterization was unsuccessful after 2 attempts , patients were crossed over to the other technique . MAIN OUTCOME MEASURE Successful cannulation of the subclavian vein . RESULTS The success rate , either as an initial technique or as a salvage technique , and complication rate were not significantly different with use of the Smart Needle . A subgroup of physicians had a significantly lower success rate using the Smart Needle . CONCLUSIONS Doppler guidance did not increase the success rate or decrease the complication rate of subclavian vein catheterization when compared with the st and ard technique in high-risk patients . Doppler guidance was not more useful than the st and ard technique as a salvage technique following a previous failure of catheterization . Furthermore , real-time Doppler guidance of subclavian vein catheterization is a technique that is highly operator dependent STUDY OBJECTIVE To compare the use of real-time-ultrasound guidance with the st and ard l and mark-oriented approach for obtaining femoral vein catheterization in patients requiring intravenous access during CPR . METHODS Prospect i ve , r and omized , paired subject-controlled clinical trial in the setting of an urban teaching county hospital emergency department . The study comprised a convenience sample of 20 patients presenting with apnea and pulselessness in the ED . Each patient received bilateral femoral lines , one by ultrasound guidance and one by the l and mark approach ( control ) . R and omization determined which technique and which side would be attempted first . The following parameters were recorded : time to initial flash of blood , time to completion of catheterization , number of needle passes , and rate of arterial catheterization . CPR and Advanced Cardiac Life Support protocol s were continued during both procedures . RESULTS Real-time ultrasound-guided catheterization had a higher success rate ( 90 % versus 65 % , P = .058 ) , a lower number of needle passes ( 2.3 + /- 3 versus 5.0 + /- 5 , P = .0057 ) , and a lower rate of arterial catheterization ( 0 % versus 20 % , P = .025 ) than the st and ard l and mark-oriented approach . Ultrasound was also slightly faster in time to blood flash and in time to catheterization . An incidental finding of interest was that real-time ultrasound demonstrated the presence of femoral vein pulsations during CPR . CONCLUSION Real-time ultrasound-guided femoral vein catheterization was faster and produced a lower rate of inadvertent arterial catheterization and a higher rate of success during CPR than the st and ard l and mark-oriented approach . Also , ultrasound demonstrated that palpable femoral pulsation during CPR is venous rather than arterial Central venous catheterization can be difficult and can cause serious complications . Ultrasound-guided venous access is increasingly used but reports concern only routine cases . We performed a prospect i ve observational study in ' difficult ' or ' failed ' procedures to assess the usefulness of ultrasound guidance . We used the technique in 33 patients ; 23 had previous failed attempts or had suffered complications from such attempts .  Ultrasound provided an anatomical reason for failure in 16 patients . Ten other patients were expected to be difficult before catheterization .  Ultrasound identified a suitable site for catheterization in all 33 patients .  Real-time ultrasound  was used to successfully catheterize  22 patients . In nine patients , a surface l and mark technique was used , which failed in three patients . In these three patients , ultrasound guidance allowed successful cannulation .  Ultrasound guidance is a useful technique to aid central venous access when difficulties or complications have been encountered or anticipated A prospect i ve , descriptive study is reported on the use and success of ultrasound-assisted internal jugular central vein catheterization ( CVC )  in the emergency department ( ED ) . In patients not in cardiac arrest who had an indication for internal jugular CVC , lines were placed by trained ED staff using ultrasound . Data were collected prospect ively on age , sex , body habitus , indication , vein visibility , number of punctures and needle passes , and success . There were 40 attempts at internal jugular CVC in 34 patients and ultrasound was used in 32 of the 40 ( 80 % ) attempts . Incidences of successful puncture and cannulation using ultrasound were 93.8 % ( 30 of 32 ) and 81.3 % ( 26 of 32 ) , respectively , compared with 62.5 % ( 5 of 8) and 62.5 % ( 5 of 8) in the l and mark group . In 8 patients with no visual or palpable l and marks , cannulation was successful in 100 % ( 7 of 7 ) using ultrasound and in 0 % ( 0 of 1 ) using l and mark technique . Ultrasound-assisted internal jugular CVC is an easily learned technique that is useful in the ED . It may be especially helpful in patients in whom l and marks are not visible and not palpable We prospect ively studied the results of 714 attempts at central venous catheterization during an eight-month period in our intensive care department . We compared the rates of failure of catheterization and early complications among three percutaneous approaches : subclavian , anterior jugular , and posterior jugular veins . The procedures were performed by experienced staff or resident physicians and inexperienced interns and residents under teaching supervision .  Overall rates of failure and complication were similar for each percutaneous approach within each group of physicians . Overall failure rate was 10.1 % for the experienced group and 19.4 % for the inexperienced . The complication was 5.4 % for experienced and 11 % for inexperienced . Among inexperienced physicians , the success rate was 86.7 % and the complication rate 7.6 % in unconscious patients , whereas in conscious patients these rates were 70.5 % and 13.8 % , respectively . The inexperienced physicians caused fewer complications in mechanically ventilated than in spontaneously breathing patients . We suggest that inexperienced physicians should first attempt central vein catheterizations in unconscious and mechanically ventilated patients HYPOTHESIS Real-time ultrasound guidance should increase the success rate and lower the complication rate of central venous access in patients with relative contraindications to having the procedure performed . DESIGN Prospect i ve case series . SETTING A community-based tertiary care hospital . PATIENTS Fifty-two patients were studied . Relative risks to central venous catheter insertion included ( 1 ) thrombosis or stenosis of central veins , ( 2 ) inherent or acquired anticoagulation abnormalities , ( 3 ) inability to assume a supine position , ( 4 ) hypovolemia , ( 5 ) obesity or altered anatomy , and ( 6 ) severe respiratory compromise . INTERVENTIONS Real-time ultrasound evaluation of the proposed vein to be cannulated , followed by real-time percutaneous central vein access . MAIN OUTCOME MEASURES Successful cannulation of a central vein . RESULTS All attempts at central vein cannulation were successful . No bleeding complications occurred . One pneumothorax occurred in an obese patient . CONCLUSIONS Ultrasound-guided central venous access is a helpful technique to gain venous access in difficult cases . Surgeons who perform central venous access procedures should become acquainted with the techniques involved . The techniques should be incorporated into currently developing ultrasound instruction courses for surgeons Background Catheterization of the subclavian vein may lead to severe complications . The current r and omized study compared a technique of pulsed Doppler ultrasonography guidance and the st and ard method for subclavian vein catheterization . Methods St and ard and Doppler ultrasonography guidance methods were performed by the same physician in 286 patients , 143 in each group . Primary end points were immediate complications ( arterial puncture , pneumothorax , wrong position of catheter tip ) , failures , the number of subclavian vein catheterizations with immediate complication or failure , the number of skin punctures per catheterization , and the time to placement of the guide wire . The secondary end points were the determination of predicting factors of successful cannulation in each group . Results Both groups were similar according to morphologic parameters of the patients . A greater number of subclavian vein catheterizations were performed on the right side using Doppler guidance ( 105 vs. 73 , P < 0.01 ) . Doppler guidance decreased complications ( 5.6 % vs. 16.8 % , P < 0.01 ) , largely because of a smaller number of catheters for which the tip was defined to be in incorrect position ( 0.7 % vs. 7.7 % , P < 0.01 ) . The time to catheterization was longer with Doppler guidance ( 300 vs. 27 s , P < 0.001 ) . Failures , catheterizations of the subclavian vein with immediate complications or failure , and the total number of skin punctures per catheterization were similar in both groups . Using Doppler guidance , the presence of a good Doppler signal ( 124 of 143 ) was predictive of successful catheterization ( 123 successful cannulations , P < 0.001 ) . Conclusions Do 
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MAIN RESULTS Practice s with the strongest supporting evidence are generally clinical interventions that decrease the risks associated with hospitalization , critical care , or surgery .
Appropriate use of prophylaxis to prevent venous thromboembolism in patients at risk ; Use of perioperative beta-blockers in appropriate patients to prevent perioperative morbidity and mortality ; Use of maximum sterile barriers while placing central intravenous catheters to prevent infections ; Appropriate use of antibiotic prophylaxis in surgical patients to prevent postoperative infections ; Asking that patients recall and restate what they have been told during the informed consent process ; Continuous aspiration of subglottic secretions ( CASS ) to prevent ventilator-associated pneumonia ; Use of pressure relieving bedding material s to prevent pressure ulcers ; Use of real-time ultrasound guidance during central line insertion to prevent complications ; Patient self-management for warfarin ( Coumadin ) to achieve appropriate outpatient anticoagulation and prevent complications ; Appropriate provision of nutrition , with a particular emphasis on early enteral nutrition in critically ill and surgical patients ; and Use of antibiotic-impregnated central venous catheters to prevent catheter-related infections .
An evidence -based approach can help identify practice s that are likely to improve patient safety .
Such practice s target a diverse array of safety problems .