***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: Introduction Central venous cannulation is crucial in the management of the critical care patient . This study was design ed to evaluate whether real-time ultrasound-guided cannulation of the internal jugular vein is superior to the st and ard l and mark method . Methods In this r and omised study , 450 critical care patients who underwent real-time ultrasound-guided cannulation of the internal jugular vein were prospect ively compared with 450 critical care patients in whom the l and mark technique was used . R and omisation was performed by means of a computer-generated r and om-numbers table , and patients were stratified with regard to age , gender , and body mass index . Results There were no significant differences in gender , age , body mass index , or side of cannulation ( left or right ) or in the presence of risk factors for difficult venous cannulation such as prior catheterisation , limited sites for access attempts , previous difficulties during catheterisation , previous mechanical complication , known vascular abnormality , untreated coagulopathy , skeletal deformity , and cannulation during cardiac arrest between the two groups of patients . Furthermore , the physicians who performed the procedures had comparable experience in the placement of central venous catheters ( p = non-significant ) . Cannulation of the internal jugular vein was achieved in all patients by using ultrasound and in 425 of the patients ( 94.4 % ) by using the l and mark technique ( p < 0.001 ) . Average access time ( skin to vein ) and number of attempts were significantly reduced in the ultrasound group of patients compared with the l and mark group ( p < 0.001 ) . In the l and mark group , puncture of the carotid artery occurred in 10.6 % of patients , haematoma in 8.4 % , haemothorax in 1.7 % , pneumothorax in 2.4 % , and central venous catheter-associated blood stream infection in 16 % , which were all significantly increased compared with the ultrasound group ( p < 0.001 ) . Conclusion The present data suggest that ultrasound-guided catheterisation of the internal jugular vein in critical care patients is superior to the l and mark technique and therefore should be the method of choice in these patients 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 BACKGROUND Percutaneous cannulation of the internal jugular vein in infants is technically more difficult and carries a higher risk of carotid artery puncture than in older children and adults . In this prospect i ve study , the authors tested their hypothesis that using an ultrasound scanner would increase the success of internal jugular cannulation and decrease the incidence of carotid artery puncture in infants . METHODS After approval from the institutional review board and receipt of written informed parental consent , 95 infants scheduled for cardiac surgery were r and omized prospect ively into two groups . In the l and marks group , the patients ' internal jugular veins were cannulated using the traditional method of palpation of carotid pulsation and identification of other anatomic l and marks . In the ultrasound group , cannulation was guided using an ultrasound scanner image . The cannulation time , number of attempts , success rate , and incidence of complications were compared for the two groups . RESULTS There were no significant differences between the two groups with regard to weight , age , and American Society of Anesthesiologists physical status classification . The success rate was 100 % in the ultrasound group , with no carotid artery punctures , and 77 % in the l and marks group , with a 25 % incidence of carotid artery punctures . Both differences were significant ( P > 0.0004 ) . The cannulation time was less , the number of attempts was fewer , and the failure rate was significantly lower in the ultrasound group than in the l and mark group . CONCLUSION Ultrasonographic localization of the internal jugular vein was superior to the l and marks technique in terms of overall success , speed , and decreased incidence of carotid artery puncture Context : A 2001 Agency for Healthcare Research and Quality Evidence Report on patient safety addressed point-of-care limited ultrasonography guidance for central venous cannulation and strongly recommended real-time , dynamic guidance for all central cannulas . However , on the basis of one limited study , the report dismissed static assistance , a “ quick look ” with ultrasound to confirm vein location before preparing the sterile field , as unhelpful . Objective : The objective of this trial was to compare the overall success rate of central cannula placement with use of dynamic ultrasound ( D ) , static ultrasound ( S ) , and anatomical l and marks ( LM ) . Design and Setting : A concealed , r and omized , controlled , clinical trial conducted from September 2003 to February 2004 in a U.S. urban teaching hospital . Patients : Two-hundred one patients undergoing internal jugular vein central venous cannulation . Interventions : Patients were r and omly assigned to three groups : 60 to D , 72 to S , and 69 to LM . An iLook25 SonoSite was used for all imaging . Measurements and Main Results : Cannulation success , first-attempt success , and number of attempts were noted . Other measures were vein size and clarity of LM . Results , controlled for pretest difficulty assessment , are stated as odds improvement ( 95 % confidence interval ) over LM for D and S. D had an odds 53.5 ( 6.6–440 ) times higher for success than LM . S had an odds 3 ( 1.3–7 ) times higher for success than LM . The unadjusted success rates were 98 % , 82 % , and 64 % for D , S , and LM . For first-attempt success , D had an odds 5.8 ( 2.7–13 ) times higher for first success than LM , and S had an odds 3.4 ( 1.6–7.2 ) times higher for first success than LM . The unadjusted first-attempt success rates were 62 % , 50 % , and 23 % for D , S , and LM . Conclusions : Ultrasound assistance was superior to LM techniques . D outperformed S but may require more training and personnel . All central cannula placement should be conducted with ultrasound assistance . The 2001 Agency for Healthcare Research and Quality Evidence Report dismissing static assistance was incorrect Background : Portable ultrasound machines are highly valuable in ICUs , where a patient 's condition might not permit shifting the patient to the USG department for imaging . Traditionally central lines are put blindly using anatomical l and marks , which often result in complications such as difficulty in access , misplaced lines , pneumothorax , bleeding from inadvertent arterial punctures , etc . Ultrasonography provides “ real time ” imaging , i.e. , the needle can be visualized entering the vein . Aims : We performed a study to compare USG guided central venous cannulation ( CVC ) and conventional anatomical l and mark approach to CVC , in terms of ease of cannulation , time consumed , and associated complications . Setting s and Design : The study was performed in a 16-bed open ICU . Eighty patients were r and omly divided in two groups . Material s and Methods : The right internal jugular vein ( IJV ) was cannulated in all . In Group I , a portable ultrasound machine was used during cannulation . The vessels were visualized in the transverse section with the internal carotid artery ( ICA ) identified as a circular pulsatile structure , while the IJV as a lateral , oval nonpulsatile structure ) . The needle was inserted perpendicular to the skin under visualization on the US screen . Central venous line was then inserted by the Seldinger technique . In Group II , CVC was performed by the conventional l and mark approach . The parameters studied included time for insertion , attempts required , and complications encountered . Statistical Analysis : The data base of all parameters was analyzed using SPSS software version 10.5 . Results : The mean time to successful insertion was 145 and 176.4 sec in groups I and II , respectively ( p = 0.00 ) . An average of 1.2 attempts per cannulation was required for group I , while 1.53 for group II ( p = 0.03 ) : 10 % witnessed arterial puncture and 2.5 % pneumothorax in group I and none in group II . Conclusion : USG-guided CVC is thus easier , quicker , and safer than l and mark approach 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 Objective : To determine whether ultrasound guidance can help operators to improve the results of jugular vein access in the ICU . Design : Prospect i ve , r and omized study . 
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Based on available data , we conclude that two-dimensional ultrasound offers gains in safety and quality when compared with an anatomical l and mark technique .
Because of missing data , we did not compare effects with experienced versus inexperienced operators for all outcomes ( arterial puncture , haematoma formation , other complications , success with attempt number one ) , and so the relative utility of ultrasound in these groups remains unclear and no data are available on use of this technique in patients at high risk of complications .