in most emergency departments , nursing personnel or medical technicians attempt initial intravenous catheter placement . if the initial attempts are unsuccessful , physicians are then asked to either assist or attempt a line placement . in cases
where initial attempts have been unsuccessful , ultrasound can be used as an adjunctive technique .
ultrasound - assisted vascular access has been shown to provide a greater margin of safety in central venous cannulation and is an efficient means to obtain both peripheral and central venous access [ 13 ] .
ultrasound - guided vascular access is an acquired skill , with a steep learning curve .
there are few studies looking at the best approach to ultrasound - guided vascular access .
traditionally this procedure is taught and performed in the short axis with a standard needle .
manufacturing technology has the ability to produce intravenous catheter needles with an enhanced ultrasonographic image .
an echo - enhanced needle has a tip that produces a high - intensity echo so that it creates a very bright echogenic focus at the needle tip on the ultrasound screen .
commercially available echo - enhanced needle tips are used in radiology for ultrasound - guided procedures to assist localizing the needle on the ultrasound screen by enhancing the reflectivity of the needle itself .
the theoretical advantage of the echo tip is that enhanced visualization , compared to standard needles , should therefore improve procedural ease and success .
while ultrasound - guided vascular access has been encouraged in emergency departments , there have been few studies evaluating echo - enhanced needles and their usefulness in performing vascular access .
our purpose was to perform a prospective , randomized , observational study to evaluate the effect of echo - enhanced needles on venous cannulation in a vascular access phantom .
we presumed that participants using an echo - enhanced needle would have a significant reduction in time to cannulate because the needle should have been easier to visualize . to determine if these needles provided any benefit we utilized a standard vascular access model , standard short - axis vessel visualization , and measured the number of needle sticks , number of redirects , and time to dye flash .
this was a prospective , randomized , observational study evaluating ultrasound - guided vascular access in the short axis of the vessel using an echo - enhanced needle ( echotip needle , cook , bloomington , in , usa ) compared to a standard needle using a phantom vascular access model ( blue phantom , advanced medical technologies , llc , kirkland , wa , usa ) .
this study was reviewed and approved by the institutional review board for verbal consent for all participants .
this study was conducted in the emergency departments of two midwestern urban tertiary care centers with a shared emergency medicine residency program .
as part of their training , emergency medicine residents are instructed in ultrasound techniques through a combination of didactic lectures , lab time , and a 1-month dedicated rotation in emergency medicine ultrasound . following this baseline training ,
skills in ultrasound - guided vascular access are taught through lectures and direct supervision by attending physicians certified in the technique .
a random number generator with a ten - subject block design was used to randomly assign which needle each participant would use first .
each subject was then shown a 10-min video describing ultrasound - guided vascular access ( produced by blue phantom , advanced medical technologies , llc , kirkland , wa , usa ) .
they then attempted to obtain vascular access with both standard and echo - enhanced needles .
ultrasound imaging was performed with the sonosite titan ultrasound machine ( sonosite , bothell , wa , usa ) , with a 38-mm broadband ( 10 - 5  mhz ) linear array transducer ( titan l38 , sonosite , bothell , wa , usa ) .
the blue phantom vascular access model is a durable anthropomorphic phantom that images similar to real tissue with ultrasound and contains simulated blood vessels . for this study ,
the phantom was modified to further obscure the embedded vessel such that there were no visual or palpable anatomic clues for vascular access .
this was done by placing a separate rectangular flap made of the same material as the phantom over the phantom obscuring any visualized vessels .
this added approximately 1.0  cm extra depth , an insignificant amount , but provided excellent camouflage of the vessel .
we did our best to reposition the flap after multiple uses to hide obvious needle sticks .
the vessel was 8  mm in diameter and was filled with a blood simulation material ( water colored with red food dye ) .
participants attempted to obtain vascular access with the 18-gauge standard needle and echo - enhanced needle in the short axis view .
residents and staff members were not allowed to observe others attempting to gain vascular access .
physicians were directly observed by a trained research assistant during all of their attempts to gain vascular access . using a stopwatch , time from ultrasound probe placement on the phantom until dye flash within the cannula was measured .
the research assistant also recorded the number of needle sticks required and the number of needle redirections .
median differences between echo - enhanced and standard needles for the variables  time to dye flash , number of sticks , and number of redirects were calculated by subtracting the standard needle tip value from the echotip value .
a positive value corresponded to higher echo - enhanced needle values and negative values indicated a higher standard needle value .
wilcoxon rank sum testing was used for analysis with a p  <  0.05 taken to indicate statistical significance .
all analyses were done using the sas software , version 9.1 ( cary , nc , usa ) .
this was a prospective , randomized , observational study evaluating ultrasound - guided vascular access in the short axis of the vessel using an echo - enhanced needle ( echotip needle , cook , bloomington , in , usa ) compared to a standard needle using a phantom vascular access model ( blue phantom , advanced medical technologies , llc , kirkland , wa , usa ) .
this study was reviewed and approved by the institutional review board for verbal consent for all participants .
this study was conducted in the emergency departments of two midwestern urban tertiary care centers with a shared emergency medicine residency program .
as part of their training , emergency medicine residents are instructed in ultrasound techniques through a combination of didactic lectures , lab time , and a 1-month dedicated rotation in emergency medicine ultrasound . following this baseline training ,
skills in ultrasound - guided vascular access are taught through lectures and direct supervision by attending physicians certified in the technique .
a random number generator with a ten - subject block design was used to randomly assign which needle each participant would use first .
each subject was then shown a 10-min video describing ultrasound - guided vascular access ( produced by blue phantom , advanced medical technologies , llc , kirkland , wa , usa ) .
they then attempted to obtain vascular access with both standard and echo - enhanced needles .
ultrasound imaging was performed with the sonosite titan ultrasound machine ( sonosite , bothell , wa , usa ) , with a 38-mm broadband ( 10 - 5  mhz ) linear array transducer ( titan l38 , sonosite , bothell , wa , usa ) . the blue phantom vascular access model is a durable anthropomorphic phantom that images similar to real tissue with ultrasound and contains simulated blood vessels . for this study ,
the phantom was modified to further obscure the embedded vessel such that there were no visual or palpable anatomic clues for vascular access .
this was done by placing a separate rectangular flap made of the same material as the phantom over the phantom obscuring any visualized vessels .
this added approximately 1.0  cm extra depth , an insignificant amount , but provided excellent camouflage of the vessel .
we did our best to reposition the flap after multiple uses to hide obvious needle sticks .
the vessel was 8  mm in diameter and was filled with a blood simulation material ( water colored with red food dye ) .
participants attempted to obtain vascular access with the 18-gauge standard needle and echo - enhanced needle in the short axis view .
residents and staff members were not allowed to observe others attempting to gain vascular access .
physicians were directly observed by a trained research assistant during all of their attempts to gain vascular access . using a stopwatch , time from ultrasound probe placement on the phantom until dye flash within the cannula was measured .
the research assistant also recorded the number of needle sticks required and the number of needle redirections .
median differences between echo - enhanced and standard needles for the variables  time to dye flash , number of sticks , and number of redirects were calculated by subtracting the standard needle tip value from the echotip value .
a positive value corresponded to higher echo - enhanced needle values and negative values indicated a higher standard needle value .
wilcoxon rank sum testing was used for analysis with a p  <  0.05 taken to indicate statistical significance .
all analyses were done using the sas software , version 9.1 ( cary , nc , usa ) .
overall there were 69 participants with a median of 3  years [ interquartile range ( iqr ) : 27 ] of clinical experience ( including residency ) .
of the participants , 46.4% ( 32/69 ) were staff emergency medicine physicians and 53.6% ( 37/69 ) were residents .
most [ 82.6% ( 57/69 ) ] reported that they had little or no experience ( zero to nine actual attempts ) with ultrasound - guided vascular access before participating in this study ; 100% of placement attempts were successful , and no placement required more than three attempts .
the overall median time from needle stick to flash was 17.56 s ( iqr : 12.3733.15 ) for the standard needle and 19.22  s ( iqr : 10.1931.10 ) for the echo - enhanced needle .
there was no difference for number of needle sticks , redirects , or time to dye flash ( tables  1 and 2 ) . 

table  1median number of sticks , redirects , and time to dye flash  nmedian25th , 75th percentileecho sticks691.001.00 , 1.00standard sticks691.001.00 , 1.00echo redirects691.000.00 , 2.00standard redirects691.000.00 , 2.00echo time to dye flash6919.2212.37 , 33.15standard time to dye flash6917.5610.19 , 31.10table  2median differences between needle sticks , redirects , and time to dye flash  nmedian25th , 75th percentilep valuestick diff.690.000.00 , 0.000.99redir .
diff.690.00 - 1.00 , 0.000.35time diff.692.06 - 9.22 , 14.500.35median of the difference between echo and standard ( calculated by echostandard ) . thus , positive numbers correspond to higher echo values and negative values indicate higher standard valuesp value from wilcoxon rank sum test , testing the median difference ( echostandard )  =  0 median number of sticks , redirects , and time to dye flash median differences between needle sticks , redirects , and time to dye flash median of the difference between echo and standard ( calculated by echostandard ) .
thus , positive numbers correspond to higher echo values and negative values indicate higher standard values p value from wilcoxon rank sum test , testing the median difference ( echostandard )  =  0
our study showed that there was no significant difference in vascular access metrics for ultrasound - guided intravenous catheter placement between echo - enhanced or standard needles using a vascular access surrogate with the vessel in the short axis .
as ultrasound becomes more prevalent in emergency departments , physicians will increasingly be using this device for both peripheral and central vascular access .
some of these procedures may benefit from having a needle tip that is more easily localized .
there are several commercially available needles that have been altered to improve needle visibility [ 7 , 8 ] . the potential to facilitate placement of a needle into a vessel with a needle that shows up brighter on the ultrasound screen seems obvious .
when performing ultrasound - guided procedures using a non - echo - enhanced needle tip , it is often challenging to visualize the needle tip especially in the short axis .
visualization of the needle is one of the most common difficulties encountered during ultrasound - guided vascular access .
the steeper the angle of the needle to the probe the more difficult it is to visualize .
studies have shown that at a decreasing angle of insonation , it is more difficult to visualize the needle ; some echogenic needles are advantageous and show significantly improved visibility .
optimization of conditions , like angle of insertion , are sometimes limited because of anatomy and when unfavorable conditions exist , utilizing a needle that has been echo - enhanced can make it more visible . often the physician placing the needle estimates its location by watching for changes in the soft tissue or vessel itself during insertion , never fully seeing the needle tip as a reflection on the screen .
the advantages of an echo - enhanced needle tip for ultrasound localization , especially for teaching purposes , seem obvious .
many practitioners of ultrasound , like interventional radiologists and gynecologists , have been using echo - enhanced products when performing their ultrasound - assisted procedures .
echo enhancement can come in a number of different categories including a chemical coating or even etches in the wall of the needle [ 11 , 12 ] .
most of the participants had little or no experience with ultrasound . despite this fact and with minimal training all participants successfully cannulated the vascular access phantom . moreover , despite a core curriculum that includes ultrasound lectures , we did not control or document who actually completed the lectures .
most of the residents ( especially upper level ) had some previous ultrasound education / lectures while the emergency medicine staff did not , but all participants watched the same brief video .
a group of experienced ultrasound - guided vascular access participants may have performed better with the echo - enhanced needle knowing how to better localize the tip .
the ultrasound phantom , although a good approximation of human tissue , does not in fact mimic actual human tissue , and this needs to be taken into consideration when extrapolating the data .
the visibility of the needle is much more obvious in the phantom than during ultrasound - guided vascular access in human tissue .
we used a vascular access phantom for ease of study and to avoid subjecting patients to training procedures .
the results found here may have been different had we studied real patients or cadavers . while this phantom represented our best available vascular access model ,
the differences with human tissue and the location of deeper vessels make extrapolation of this study difficult in a live human setting .
however , it still appears that inexperienced ultrasound users may not benefit from the advantages of an echo - enhanced needle until further along in their training and understanding of ultrasound - guided vascular access .
in a group of mostly ultrasound inexperienced participants attempting ultrasound - guided vascular access visualizing the vessel in the short axis , the echo - enhanced needle did not improve measures of successful vascular access .
 backgroundvascular access is a critical skill for emergency physicians . 
 however , it can be unpredictably challenging in some patients . 
 while ultrasound - guided vascular access has been encouraged in emergency departments , there have been few studies evaluating echo - enhanced needles and their usefulness in performing vascular access.aimsour purpose was to determine if the use of an echo - enhanced needle tip results in faster vascular access times , with fewer needle sticks , fewer redirections , and improved needle visualization in ultrasound - guided vascular access with the vessel in the short axis.methodsthis is a prospective , randomized , observational study of ultrasound - guided vascular access on a vascular phantom comparing an echo - enhanced needle with a standard needle . 
 each participant viewed a teaching video demonstrating typical ultrasound - guided vascular access and then attempted ultrasound - guided vascular access using both a standard and an echo - enhanced needle with the vessel in the short axis . 
 the numbers of needle sticks , redirections , and time to dye flash were measured.resultsthe 69 participants attempted 69 short - axis ultrasound - guided vascular cannulations with no difference in time to dye flash between needle types : the median time from needle stick to flash was 17.56 s [ interquartile range ( iqr ) : 12.3733.15 ] for the standard needle and 19.22 s ( iqr : 10.1931.10 ) for the echo - enhanced needle . 
 there was no difference between needle types for number of needle sticks or redirects.conclusionecho-enhanced needles did not provide objective performance improvement compared to standard needles during ultrasound - guided vascular access with a vascular access model in the short axis . 
Introduction
Methods
Study design
Study setting and population
Study protocol
Measurements/outcome measures
Data analysis
Results
Discussion
Conclusion