***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: BACKGROUND Cannulation of the radial artery in infants and small children can be challenging , even for the most experienced providers . Utilizing Doppler to aid in radial artery cannulation has been well described . Recent studies have demonstrated the efficacy of ultrasound ( US ) image-guided vascular access techniques in the paediatric population . The utility of these two techniques , when used by non-expert personnel , has not been studied . METHODS This is a r and omized prospect i ve study to compare the utility of two different radial arterial cannulation techniques in paediatric patients weighing < 12 kg :  US-guided technique ( US group ) vs Doppler-assisted technique ( Doppler group ) when used by trainees with limited experience . The primary objective was to compare the first-attempt success rate between each group . As a secondary objective , success rate within 10 min was compared . RESULTS The trial was prematurely terminated after 50 % of paediatric patients ( n=104 ) were included in the study and 52 of each were r and omized to the US or Doppler group . A total of 12 anaesthesia trainees performed radial arterial cannulations . The first-attempt success rate was greater in the US group compared with the Doppler group [ 17/52 ( 33 % ) vs 8/52 ( 15 % ) , P=0.039 , odds ratio ( OR ) : 2.67 , confidence interval ( CI ) : 1.03 - 6.91 ] . The overall success rate within 10 min was 34/52 ( 65 % ) in the US group and 24/52 ( 46 % ) in the Doppler group ( P=0.048 , OR : 2.20 , CI : 1.00 - 4.85 ) . CONCLUSIONS US-guided radial arterial cannulation in infants and small children provided a greater chance for success at the first attempt compared with the Doppler-assisted technique Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more Objective : To compare ultrasound (US)-guided radial artery cannulation with the traditional palpation technique . Design : Prospect i ve r and omized study . Setting : Operating room in a tertiary care pediatric center . Patients : One hundred fifty-two children under 18 yrs of age requiring radial artery cannulation . Interventions : Patients were r and omized to either 1 ) palpation or 2 ) US guidance technique for radial artery cannulation .  Measurements and Main Results : The primary end point of the study was the time taken for attempted cannulation by the first operator at the first site . Secondary end points included the number of attempts at arterial cannulation , the number of cannulae used , and the need for additional assistance from another anesthesiologist .  Eighty and 72 children were r and omized to the palpation and the US-guided groups , respectively . There were no statistically significant differences in age , gender , weight , and systolic blood pressure between the two study groups . The design ated first operator ( 20 pediatric subspecialty trainees and eight consultant anesthesiologists ) had previous experience in US-guided arterial cannulation in < 10 cases , with 94 % having experience in < 5 cases . Although the radial artery was eventually cannulated in all patients , the design ated operator was successful at the first site of cannulation in only 66 % and 69 % in the palpation and US groups , respectively . There were no statistically significant differences between the groups in time to successful cannulation , total number of attempts , number of successful cannulations during the first attempt , or in the number of cannulae used for catheterization . Conclusions : US guidance did not facilitate faster cannulation of the radial artery in children in our study Objective : To determine whether ultrasound guidance increases the success rates , decreases the complication rates , and shortens the time to successful radial artery catheterization in infants and small children . Design : R and omized study . Setting : Single university-affiliated hospital . Patients : Infants and children weighing 3–20 kg , undergoing cardiac surgery for congenital heart disease . Intervention : We r and omly assigned the right and left radial arteries of patients undergoing arterial catheterization to ultrasound-guided technique versus the usual palpation technique . Measurements : The primary study endpoints were the rates of successful cannulation at first and within three attempts . The secondary endpoints were time to radial artery identification , number of attempts for successful cannulation , and rate of complications . Main Results : Compared with palpation , ultrasound-guided radial artery catheterization was successful in 76.3 % versus 35.6 % of first attempts and in 94.9 % versus 50.8 % of arteries after three attempts ( both comparisons , p < 0.01 ) . The median time [ interquartile range ] to identification of the arteries ( 18.5 seconds [ 11.25–27.25 ] vs 30 seconds [ 17.75–39.5 ] ) was significantly shorter ( p < 0.01 ) , the number of attempts [ interquartile range ] at successful cannulation ( 1 [ 1–1 ] vs 2 [ 1–2 ] ) was significantly fewer ( p < 0.01 ) , and the proportion of hematomas ( 5.1 % vs 25.4 % ) was significantly lower ( p < 0.01 ) in the ultrasound group than those in the palpation group . Conclusions : In infants and small children , ultrasound-guided radial artery catheterization was more successful and expeditious than the usual palpation technique Background and objective : In small children , the placement of arterial catheters can be technically challenging for even the most experienced anaesthetist . We investigated whether ultrasound imaging would improve the success rate and reduce time dem and and complications of radial artery cannulation . Method : In this prospect i ve r and omized study , we performed radial artery cannulation in 30 small children ( age 40 ± 33 months ) using two different techniques for localization of the vessel . In Group 1 ( n = 15 ) , the traditional palpation method was used , while in Group 2 ( n = 15 ) cannulation was directed by vascular ultrasound imaging . In addition , we used ultrasound to determine the cross‐sectional area of the radial artery with and without dorsiflexion . For statistical analysis , the non‐parametric U‐test for non‐paired data and the Wilcoxon signed rank sum test for paired data were used . Differences were considered significant , when P < 0.05 . Results : Ultrasound‐guided puncture was successful in all children of Group 2 compared to only 12 of 15 ( 80 % ) children in Group 1 . Fewer attempts with the imaging technique were required than with the traditional technique ( 20 vs. 34 , P < 0.05 ) . Dorsiflexion significantly reduced the mean cross‐sectional area of the artery by 19 % . Conclusion : The current pilot study suggests that ultrasound guidance is appropriate for radial artery catheter insertion , sharing many of the benefits of ultrasound‐guided central vein catheter insertion BACKGROUND Arterial cannulation for continuous blood-pressure measurement and frequent arterial-blood sampling commonly are required in critically ill patients . OBJECTIVES To compare ultrasound (US)-guided versus traditional palpation placement of arterial lines for time to placement , number of attempts , sites used , and complications . METHODS This was a prospect i ve , r and omized interventional study at a Level 1 academic urban emergency department with an annual census of 78,000 patients . Patients were r and omized to either palpation or US-guided groups . Inclusion criteria were any adult patient who required an arterial line according to the treating attending . Patients who had previous attempts at an arterial line during the visit , or who could not be r and omized because of time constraints , were excluded . Enrollment was on a convenience basis , during hours worked by research ers over a six-month period . Patients in either group who had three failed attempts were rescued with the other technique for patient comfort . Statistical analysis included Fisher 's exact , Mann-Whitney , and Student 's t-tests . RESULTS Sixty patients were enrolled , with 30 patients r and omized to each group . Patients r and omized to the US group had a shorter time required for arterial line placement ( 107 vs. 314 seconds ; difference , 207 seconds ; p = 0.0004 ) , fewer placement attempts ( 1.2 vs. 2.2 ; difference , 1 ; p = 0.001 ) , and fewer sites required for successful line placement ( 1.1 vs. 1.6 ; difference , 0.5 ; p = 0.001 ) , as compared with the palpation group . CONCLUSIONS In this study , US guidance for arterial cannulation was successful more frequently and it took less time to establish the arterial line as compared with the palpation method Objective To assess the role of a portable ultrasound device in the insertion of radial artery catheters . Design Prospect i ve , r and omized , comparative study . Setting Tertiary university hospital . Patients Elective surgery patients requiring arterial catheter insertion for intraoperative monitoring . Interventions A portable ultrasound device was used to visualize the radial artery at the wrist and to direct arterial catheter insertion . This new technique of arterial catheter insertion was compared with the classic palpation technique . Measurements and Main Results A total of 69 patients requiring an arterial catheter were r and omized to either the  ultrasound  ( 34 patients ) or palpation technique  ( 35 patients ) . The time taken from skin puncture to successful arterial catheter insertion , the time taken per insertion attempt , the number of attempts required , and the number of cannulae used were recorded for each group . The arterial cannula was inserted on the first attempt in 21 ( 62 % ) cases using ultrasound vs. 12 ( 34 % ) cases by palpation ( p = .03 ) . Significantly fewer attempts were required for catheter insertion using ultrasound as compared with palpation ( mean ± sd , 1.6 ± 1.0 vs. 3.1 ± 2.4;p = .003 ) ; however , the time taken for each successful attempt was longer ( 26.1 ± 2.0 vs. 17.3 ± 1.6 secs , p = .001 ) . A trend toward shorter overall time required for catheter insertion was found for the ultrasound group ( 55.5 ± 63.8 vs. 111.5 ± 121.5 secs , p = .17 ) . There were four failures in the ultrasound group and one in the palpation group ( not significant ) . Conclusions Ultrasound is a useful adjunct to arterial catheter insertion and increases the rate of success at first attempt . The technique is easy to learn and may reduce the time taken to insert the catheter We r and omly allocated 749 participants to radial artery cannulation by anaesthetic trainees , guided by Doppler ( 244 ) , palpation ( 256 ) or ultrasound ( 249 ) . Ultrasound  increased the rate of cannulation at the first attempt by 14 % ( 95 % CI 5–22 % ) , from 39 % with Doppler or palpation , p = 0.002 for both . There were no differences in the rates of cannulation 5 min after the procedure started : 147/244 ( 60 % ) with Doppler ; 160/256 ( 63 % ) with palpation ; and 171/249 ( 69 % ) with ultrasound , p = 0.13 UNLABELLED STUDY OBJECTIVE AND BACKGROUND : Arterial puncture for blood gas analysis is a frequent procedure and could be difficult in the emergency setting . The aim of the study was to compare ultrasonographically guided arterial radial puncture vs conventional sampling . MATERIAL S AND METHODS This is a prospect i ve , r and omized study . The inclusion criteria are all patients needing arterial blood gas at admission in the emergency unit . The exclusion criteria are the following : Hallen test positive , local sepsis , local trauma , known sever local arteriopathy , refusal of consent by the patient , participation in another study , and cardiac arrest . Patients were r and omized into 2 groups : radial arterial puncture obtained through an ultrasonographically guided technique ( group 1 ) or radial arterial puncture by conventional method ( group 2 ) . The main objective is the number of attempts after enrollment . The secondary objectives are time to success , patient satisfaction and pain , and physician satisfaction . Immediate complications were collected . Groups were compared with nonparametric analysis . RESULTS The data were usable for 72 of 74 patients included . Lung disease ( acute exacerbation of chronic obstructive pulmonary disease and pneumonia ) at 45 % ( n = 32 ) and suspicion of pulmonary embolism in 31 % ( n = 22 ) were the most common reasons . Demographics data were comparable in the 2 groups . In group 1 , the number of attempts significantly increased ( 2.35 [ 1 - 3 ] vs 1.66 [ 1 - 2 ] [ P = .017 ] ) , and the sample was 2.4 times longer ( 132 seconds [ 50 - 200 ] vs 55 [ 20 - 65 ] [ P < .01 ] by st and 
    Output:
    
In both the adult and paediatric population s , there was high-level evidence for significantly improved first-attempt success rate and number of attempts with the use of ultrasound guidance .
This is the first level one systematic review to demonstrate strong evidence for the use of ultrasound guidance in radial artery cannulation in adult and paediatric population s. In the adult population , ultrasound use significantly increased first-attempt success rate , which subsequently result ed in a significant reduction in the number of attempts .
The benefits of ultrasound were also shown in the paediatric population , with a significant increase in first-attempt success rate and reduction in the number of attempts .