CRITICAL CARE. Editor s key points. R. D. Ball 1, N. E. Scouras 1,2, S. Orebaugh 1,3, J. Wilde 4 and T. Sakai 1,5 *

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1 British Journal of Anaesthesia 108 (1): 72 9 (2012) Advance Access publication 14 November doi: /bja/aer329 CRITICAL CARE Randomized, prospective, observational simulation study comparing residents needle-guided vs free-hand ultrasound techniques for central venous catheter access R. D. Ball 1, N. E. Scouras 1,2, S. Orebaugh 1,3, J. Wilde 4 and T. Sakai 1,5 * 1 Department of Anesthesiology, University of Pittsburgh Medical Center, University of Pittsburgh, Liliane S. Kaufmann Building, 3471 Fifth Avenue Suite 910, Pittsburgh, PA 15213, USA 2 American Anesthesiology, 3100 Spring Forest Road Suite 130, Raleigh, NC 27616, USA 3 Division of Acute Interventional Perioperative Pain and Regional Anesthesia, Department of Anesthesiology, UPMC Southside/Mercy, 2000 Mary Street, Pittsburgh, PA 15203, USA 4 University of Pittsburgh School of Medicine, University of Pittsburgh, M240 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA 5 Department of Anesthesiology, McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, UPMC Montefiore, M469.11, 200 Lothrop Street, Pittsburgh, PA 15213, USA * Corresponding author. sakait@upmc.edu Editor s key points Ultrasound-guided placement of central venous catheters is widely accepted as safe practice. The use of a needle guide paired with the long-axis ultrasound approach facilitated puncture of the target vessel in a simulation model more effectively than similar free-hand techniques. The needle guide used in the long-axis technique did not facilitate puncture of the target compared with free-hand techniques. Background. Short-axis ultrasound-guided placement of central venous catheters (CVCs) is widely accepted as safe practice. However, utilizing the long-axis approach could further improve safety, as it allows for better visualization of the needle as it is advanced to the target vessel. However, the long-axis approach has not widely been used due to the technical difficulty. Recently, a new needle guidance device has become available to aid in the long-axis approach. We hypothesized that the use of a needle guide paired with the long-axis approach would facilitate puncture of the target vessel in a simulation model more effectively than similar free-hand techniques. Methods. A prospective observational study of anaesthesia residents using a CVC partial-task training device was conducted. Each resident performed needle puncture of the target vessel with three different techniques, assigned in random order: short-axis free hand (S-FH), longaxis free hand (L-FH), and long-axis needle guide (NG). To prove the effectiveness of the needle guide, the fraction of time the needle tip remained in view of the ultrasound was recorded and compared. Time required for completing the task and the number of needle sticks and needle re-directions were compared. Results. Thirty-three residents participated in the study. The fraction of time the needle tip remained in view of the ultrasound was significantly higher for the residents using NG [0.90 (0.10)] compared with residents using the other techniques [L-FH: 0.36 (0.20), S-FH: 0.18 (0.10)] (P,0.001). For each resident, the use of the needle guide in the long-axis approach increased visualization by 352 (276)% compared with that of L-FH and by 1028 (1804) % compared with that of S-FH. There was no significant difference in time required to puncture the target between NG [23.7 (14.6) s] and L-FH [30.3 (36.5) s] (P¼0.21); however, both were significantly longer than S-FH [17.0 (13.3) s] (P¼0.012). The numbers of needle sticks and of needle re-directions did not differ among the groups. Conclusions. The needle guide device used in the long-axis approach improved the needle visualization compared with free-hand techniques. The needle guide used in the long-axis technique, however, did not facilitate puncture of the target vessel in this simulation model when compared with free-hand techniques. Keywords: catheterization; central venous; education; ultrasonography Accepted for publication: 9 August 2011 Presented in part at the 105th Annual Meeting of the American Society of Anesthesiologists, San Diego, CA, USA, October 16 20, These authors contributed equally to this work. & The Author [2011]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please journals.permissions@oup.com

2 CIVCO needle guide simulation study BJA Placement of central venous catheters (CVCs) is invasive and has been associated with significant complications, including arterial puncture, haematoma formation, pneumothorax, and haemothorax. 12 At least three meta-analyses comparing the ultrasound guidance technique with the landmark technique showed that success was improved and complications were reduced when the ultrasound-guided technique was used. 1 3 Two ultrasound-guided catheter insertion techniques are used: the short-axis approach (or out-of-plane approach) and the long-axis approach (or in-plane approach), which are defined according to the relationship between the needle direction and the direction of the ultrasound scanning plane. The short-axis approach aligns the two directions in the perpendicular (or transverse) fashion, while the long-axis approach aligns them in the longitudinal direction. The longaxis approach may have a benefit over the short-axis approach, since a practitioner could constantly monitor the tip (or entire length) of the needle under ultrasound image. 4 Despite the theoretical advantage, the long-axis approach has not widely been used due to the technical difficulty in maintaining the linear relationship between the needle and the ultrasound scanning plane. Recently, a new device to assist with the technical challenges of the long-axis approach has become available. A needle guide device attached to the probe of the ultrasound machine has been designed to facilitate the alignment of the needle in the ultrasound scanning plane. However, no study has yet demonstrated the theoretical benefits of using the needle guide device. In this study, we investigated whether the use of a longaxis approach improved resident volunteers performance of ultrasound-guided CVC insertion in a partial-task trainer. Specifically, residents were asked to perform ultrasoundguided needle puncture of the internal jugular vein of the partial-task trainer using three different methods: the shortaxis free-hand (S-FH), the long-axis free-hand (L-FH), and the long-axis needle guide (NG) techniques. We evaluated the effectiveness of the needle guidance in providing more consistent visualization of the needle than the free-hand techniques. We hypothesized that the use of the long-axis approach with a needle guide would allow faster CVC placement (which would indicate the ease of the technique), better success rates, and fewer needle sticks and needle re-directions than the two other techniques. medicine followed by 3 yr of intense study and clinical training focused specifically on anaesthesia, termed clinical anaesthesia (CA) years. A total of 4 yr (CBY CA3) is spent during residency training. Resident volunteers The anaesthesia residents (CA1 3) who had previously completed a mandatory central venous catheterization lecture course at WISER were allowed to participate. This lecture course provides anaesthesia residents the opportunity to get accustomed to ultrasound-guided free-hand short-axis and free-hand long-axis approaches in central venous catheterization using a partial-task trainer. Those residents who had not successfully completed the course were excluded. Study protocol Residents were given an introductory script that described the research study (see Appendix) and were given 15 min to familiarize themselves with the trainer (Central Venous Access Head Neck & Upper Torso Ultrasound Training Model, Blue Phantom TM, Redmond, WA, USA), the ultrasound machine equipped with a 5 10 MHz transducer (ilook w 25 bedside ultrasound unit, SonoSite, Inc., Bothell, WA, USA), and the needle guide device (Infiniti TM, CIVCO Medical Solutions, Kalona, IA, USA). This two-part needle guidance system consists of a custom reusable bracket attached to an ultrasound transducer and a disposable snap-on needle guide with a sterile transducer cover (Fig. 1). During this Methods This prospective observational study was conducted at the Peter M. Winter Institute for Simulation, Education, and Research (WISER) at the University of Pittsburgh School of Medicine. The study was approved by the institutional review board as an exempt study. Volunteer anaesthesia residents from the University of Pittsburgh Medical Center participated in this study. For clarification, the American process of residency training includes an intern or clinical base year (CBY) encompassing training in all fields of clinical Fig 1 Infiniti TM CIVCO Medical Solutions device attached to the ilook w 25 bedside ultrasound unit transducer. 73

3 BJA Ball et al. introduction, the instructor (R.D.B. or N.E.S.) demonstrated how to use the needle guidance device, and the residents were permitted to use the ultrasound on the Blue Phantom TM model with and without the needle guide, practicing shortand long-axis views and inserting the needle into the needle guide. However, they were restricted from actually piercing the model and visualizing the needle on the ultrasound screen. The ultrasound training model contains an insert which simulates the right lateral neck anatomy using two tubings [a superficial one represents the right internal jugular vein (venous tubing) and the other one represents the right carotid artery (arterial tubing)] that can be punctured with a needle (Fig. 2). Each insert only allows a limited number of needle punctures before the red-coloured fluid contained in the tubing leaks and the insert becomes unusable. Based on prior experience at WISER using the training model and inserts, each insert can be used for 100 needle sticks before needing to be replaced with a new one. The residents then performed a needle puncture of venous tubing on the training model, sequentially using all three ultrasound-guided techniques: the S-FH technique, the L-FH technique, and the long-axis technique aided by using the needle guidance device (NG). Each resident was assigned randomly by computer to one of six possible sequences of the three techniques. Ultrasound technique and vessel confirmation were standardized; in the short-axis view, the residents were instructed that the venous tubing was with the larger diameter, located more laterally, and the superficial in depth from the surface compared with the arterial tubing (Fig. 2). In the long-axis view, the residents were instructed to begin in the short-axis position to identify the venous tubing and then rotate to the long axis. The residents were allowed to start advancing the needle only when the target venous tubing was in the centre of the ultrasound Fig 2 Short-axis ultrasound view of the Blue Phantom TM training model. The superficial tubing is venous tubing (V), which simulates the internal jugular vein. The other tubing is arterial tubing (A), which simulates the carotid artery. image in the short-axis approach, or when it was visualized in the ultrasound image in the long-axis approach. A poststudy survey with eight questions was given to the residents after completion of the task (see Appendix). Measurements Resident performance of each technique was closely monitored by the instructor. The following outcomes were measured for each technique: (i) the fraction of time when the needle tip was in ultrasound view, which was observed on the video-taped image obtained on the ultrasound machine during each technique, (ii) the procedure time from the application of the ultrasound probe on the insert until the completion of the task, which was defined as successful puncture of venous tubing by withdrawing 1 ml of the red fluid, (iii) the rate of success in the task, which was defined as completing the task within 10 min, (iv) the incidence of arterial tubing puncture, which was determined by the instructor with verifying the location of the tubing the resident punctured using ultrasound image, (v) the number of skin breaks, (vi) the number of needle re-directions, which were defined as changes in the direction of needle insertion without removing it from the skin, (vii) the incidence of lost view of the target venous tube from the ultrasound view, which resulted in the operator to stop advancing the needle, and (viii) the incidence of the adjustment of ultrasound prove (returning to the short-axis view then rotating the probe to re-image the venous tubing) in the long-axis approaches (NG and L-FH). Calculation of the sample size Based on the study performed by Blavias and colleagues, 5 a two-sample Student s t-test power analysis was conducted based on the primary endpoint of the study, which was the procedure time defined above. In order to possess a power of 80% to avoid b error with significance at the 0.05 level, a sample size of 30 residents would be needed to detect a 50% difference for the procedure time between the NG technique and the L-FH technique. A 50% difference in the time taken to achieve the task was considered practically significant. Statistical analysis Statistical analysis was conducted by Friedman s two-way test with post hoc analysis using Wilcoxon sign-rank test to compare the fraction of time when the needle tip was in the ultrasound view, the procedure time, the rate of success, the incidence of arterial tubing puncture, the number of skin breaks, and the number of needle re-directions among the three techniques. Similar comparisons were performed to investigate the differences in anaesthesia resident training levels (CA classes) using the Kruskal Wallis one-way analysis of variance with post hoc analysis using Dunn s multiple comparison test. The level of significance was set at P,0.05. The randomization of the three procedures and the statistical analyses were performed 74

4 CIVCO needle guide simulation study BJA using the SPSS/PC+ Advanced Statistics Package, version 13.0 (SPSS Inc., Chicago, IL, USA). Results Thirty-three residents participated in the study. The majority (82%, 27 out of 33) had clinical experience of 10 or more prior central line placements and all had experience with ultrasound guidance techniques (Table 1). Less experienced trainees (CA1) accounted for 36% of the residents participating in the study (12 out of 33). Overall, the fraction of time when the needle tip was in view was significantly higher (P,0.001) for the NG technique Table 1 Demographic variables of participating residents. CA, clinical anaesthesia Patient characteristic variables n533 (%) Gender Male 23 (69) Female 10 (31) Clinical year CA1 12 (36) CA2 6 (18) CA3 15 (45) Prior experience of central line insertions (times),10 6 (18) (33) (48) Ultrasound usage in clinical practice,25% 20 (61) 25 75% 7 (21).75% 6 (18) [0.90 (0.10)] compared with the free-hand techniques [L-FH: 0.36 (0.20) and S-FH: 0.18 (0.10)] (Fig. 3). For each resident, the use of the needle guide in the long-axis approach (NG) increased visualization by 352 (276)% compared with that of L-FH and by 1028 (1804)% compared with that of S-FH. There was no significant difference between the fractions of the needle tip visualization among the classes (Fig. 4). The success rate in the task was 100%, regardless of the technique. No inadvertent puncture of arterial tubing was found. There was no significant difference in procedure time noted between NG [23.7 (14.6) s] and L-FH [30.3 (36.5) s] (P¼0.21); however, both were longer than S-FH [17.0 (13.3) s] (P¼0.012) (Fig. 5). The same analysis was performed to investigate the differences in anaesthesia resident training levels (CA classes). The novice operators (CA1) required a significantly longer time period to use L-FH, compared with the other techniques (P¼0.049: P,0.05 vs S-FH) and among the three classes in L-FH (P¼0.031: P,0.05 vs CA3) (Fig. 6). The number of skin breaks and the number of needle re-directions were not significantly different among the three groups (Table 2). There was no incidence of lost view of the target venous tube from the ultrasound view in any of the approaches. There was no incidence of the adjustment of the ultrasound probe (returning to the short-axis view then rotating the probe to re-image the venous tubing) in the long-axis approaches (NG and L-FH). All residents completed the post-task survey and overall evaluation of the needle guide system was positive (Fig. 7). The majority agreed the needle guide kept the needle in view more than the free-hand techniques (Question #1). They agreed even more strongly they would consider using the needle guide in clinical practice (Question #7). Per cent time (%) Per cent time needle tip in view of ultrasound P< Per cent (%) Per cent needle tip in view of ultrasound CA1 CA2 CA NG S-FH Technique L-FH 0 NG S-FH Technique L-FH Fig 3 The fraction of time the needle tip was visualized during each task. NG had significantly higher fraction (P,0.001) compared with the other two techniques. The box plot shows the median, lower and upper quartiles (25 75%), and the minimum and the maximum. NG, long axis with needle guide; L-FH, long-axis free hand; S-FH, short-axis free hand. Fig 4 The fraction of time the needle tip was visualized during the task per class. The column graphs show the mean and standard deviation (SD). There was no statistical difference among the classes per technique. NG, long axis with needle guide; L-FH, long-axis free hand; S-FH, short-axis free hand. 75

5 BJA Ball et al Total time of procedure 10.0 Post-task resident survey Time (s) P=0.012 Response (0 10) NG S-FH Technique L-FH Questions Fig 5 The procedural time required for each task. S-FH had significantly shorter time (P¼0.012) compared with the other two techniques. The box plot shows the median, lower and upper quartiles (25 75%), and the minimum and the maximum. NG, long-axis with needle guide; L-FH, long-axis free hand; S-FH, short-axis free hand. Time (s) Discussion Total time of procedure CA1 CA2 CA3 NG S-FH L-FH Fig 6 The procedural time required for each task per class. The column graphs show the mean and SD. CA1 required a significantly longer time to complete L-FH among the three classes of training (P¼0.031: P,0.05 vs CA3) and among the three techniques (P¼0.049: P,0.05 vs S-FH). NG, long-axis with needle guide; L-FH, long-axis free hand; S-FH, short-axis free hand. Table 2 Number of skin breaks and needle re-directions. Data were described as mean (SD). NG, long-axis with needle guide; L-FH, long-axis free hand; S-FH, short-axis free hand Outcome NG L-FH S-FH P-value Number of skin breaks 1.1 (0) 1.2 (0.6) 1.0 (0.2) 0.6 Number of needle 0.1 (0.8) 0.7 (0.7) 1.0 (0.6) 0.12 re-directions In 1984, the use of ultrasound to locate a vessel by placing a mark on the skin was first described. 6 Since that time, Fig 7 The results of the post-study resident survey (Appendix). The column graphs show the mean and SD. ultrasound-guided central venous line placement has been supported by a number of medical societies, including the ASA. 7 Among the two ultrasound approaches, many users in general find the short-axis technique simpler to use compared with the long-axis approach. 8 When using the shortaxis method, however, the needle tip may be difficult to visualize and one may inadvertently puncture other structures, including the carotid artery, or the needle could travel through the posterior vein wall. 910 Indeed, despite the use of ultrasound guidance during the S-FH approach, an accidental arterial cannulation has been reported. 10 Even the use of a needle guide device in the short-axis approach still carries a chance of arterial puncture (average 4.2%) similar to the short-axis technique without a needle guide in a randomized clinical trial of 429 patients performed by Augoustides and colleagues. 11 The authors postulated that the reason for the lack of protection against arterial puncture might be the lack of control of needle depth under the shortaxis approach, 11 which could be circumvented by better visualization of the needle under the ultrasound image. The visualization of the needle under ultrasound-guided techniques, including vascular access, regional nerve block, and interventional radiology, is a crucial component of patient safety A number of methods to improve needle visualization have been reported; the use of echo-enhanced needles has been proposed, investigations of the ultrasound characteristics to enhance the needle visualization were reported, and the use of the long-axis approach has been advocated. The long-axis technique appears to offer better needle visualization. In a study of emergency medicine residents, the long-axis orientation of the ultrasound transducer allowed the needle tip to be correctly identified, while identification was not possible in the short-axis orientation. 4 In a simulation study on medical students and emergency medicine residents, needle-tip visibility at the time of vessel puncture was higher in the L-FH group (24/39, 62%) as opposed to the S-FH group (9/39, 23%) (P¼0.01). 22 Unfortunately, the L-FH approach requires better hand eye coordination and 76

6 CIVCO needle guide simulation study BJA may be more difficult for novice ultrasonographers. 5 Several techniques have been proposed to solve the technical challenge; however, validation of the efficacy of those techniques remains to be seen. Needle guide use may offer an advantage in providing better visualization of the needle tip in the long-axis view In a simulation study, van Geffen and colleagues 28 reported that resident volunteers using a long-axis needle guidance device achieved shorter procedure time, improved needle visualization, and experienced more satisfaction than when using the free-hand technique on a hand-made porcine ham phantom model. The limitation of van Geffen and colleagues 28 guidance device is its size of cm (length width height), making it unsuitable for the neck region. 10 The Infiniti TM CIVCO needle guide, which was used in our study, is a newer device that went on the market in December Its design is applicable in the neck region. We believe that this is the first reported simulation study to investigate the utility of this device in a right internal jugular venous cannulation model. In this study, we confirmed that the needle-guided long-axis approach provided better needle visualization than the free-hand techniques. Both free-hand techniques resulted in very limited visualization of the needle tip: an average of 36% of the time for the free-hand long-axis technique and only an average of 18% for the free-hand short-axis technique. The needle guide device may further help in confirming the successful cannulation in the venous system of the pilot catheter for the Seldinger technique with a real-time visualization under ultrasound. No statistically significant improvement in the time required for the procedural task was found using the needle guidance long-axis approach in our study. In our study, the long-axis techniques did seem to increase the procedure time length compared with the short-axis technique, as observed in the study by Mahler and colleagues; 8 however, it is important to note that the average time difference was,15 s, which is a relatively small investment for patient safety. In this study, all participants were instructed to start with the short-axis view using the ultrasound probe and rotate it to find the long-axis view in order to standardize the process. This instruction could have contributed to the increase in the procedure time found in this study. Comparison of the individual classes showed that the novice group (CA1) took significantly longer to perform the task with L-FH. It is important to note, however, that the duration that the needle tip was in view of the ultrasound was equal for the CA1, CA2, and CA3 classes. This suggests that needle guide in the long-axis approach has the ability to improve needle-tip visualization in CA1 classes to levels consistent with more advanced trainees, such as CA2 and CA3. Skin breaks and needle re-directions were measured because it was felt that an increase in these numbers would correlate with trauma to the neck, leading to complications. The numbers of skin breaks and needle re-directions were found not to be significantly different among the groups. Visualization of the target is the crucial part of any ultrasound-assisted technique. Although there was no incidence of losing the target venous tubing from the ultrasound view in this simulation model, maintaining visualization of the vein in the clinical setting could be a significant technical challenge, especially in the long-axis approach. A resident survey was completed after study participation. Uniformly, residents were impressed by the ease of use of usability and the reliable needle visibility the needle guides provided. A majority believed that more exposure to the needle guide would lead to faster cannulation times and many would be willing to include the needle guide in their clinical practice. There were several limitations in the study. First, lack of resident familiarity with the new device could have been responsible for the increased length of time for task completion in the needle guide group. To avoid such a potential bias against the new technique, we began with a 15 min period of familiarization, so that residents became comfortable with handling the needle guidance system. It is unclear, however, whether this period was long enough for the residents to feel comfortable using the device in a simulation setting. Secondly, the central venous access trainer is an imperfect model of actual human tissue, despite its closest approximation of human anatomy. In a clinical setting, variance in anatomy and body habitus of the patients would likely come into play. The verification of the findings in our study is required in a clinical setting. Thirdly, we used the time required for task completion as the primary evaluation factor. The reasoning behind using completion time is that the ease and the soundness of the method would be reflected by the duration of the time required; this measure has been used to evaluate the method in other simulation studies. 527 Of course, in the clinical setting, the time per se should not be considered as the best indicator of the best practice; allowing time to ensure that patient safety should be more important. In conclusion, needle guidance for a long-axis ultrasound technique did not decrease the time required to puncture venous tubing in an internal jugular venous cannulation simulator compared with the free-hand long- or short-axis techniques. However, the needle guide permitted significantly more consistent visualization of the needle during the procedure, which suggested the needle guide s potential to improve patient safety by reducing the incidence of inadvertent punctures of adjacent structures. Acknowledgements The authors thank Christine M. Heiner, BA (Scientific Writer, Departments of Anesthesiology and Surgery, University of Pittsburgh School of Medicine) for her editorial assistance with this manuscript. The authors also thank Li Wang, MS, and Clareann H. Bunker, MPH, PhD (Clinical and Translational Science Institute, University of Pittsburgh) and Jim Ibinson, MD, PhD (Department of Anesthesiology, University of Pittsburgh Medical Center) for their statistical assistance. 77

7 BJA Declaration of interest None declared. Funding The study was supported by a Department Seed Grant (Department of Anesthesiology, University of Pittsburgh Medical School) (PI: N.E.S.). Appendix Introductory script (for the participants) The purpose of this research study is to determine whether the use of a needle guide and a long-axis technique will improve performance of central line placement by residents. You will be given 15 min to familiarize yourself with the model, ultrasound, and the needle guide before the study begins. The PI will give you a demonstration of the use of the needle guide during this time. You will be testing three techniques for central line placement: S-FH technique, L-FH technique, and the needle guide (NG) technique. You will be assigned to start with one technique and then move on to the other two techniques. The central line placement will be simulated by using a simulator model, where you will cannulate the right internal jugular vein. When performing the L-FH technique, please maintain your needle in full view of the ultrasound as much of the time as possible. Your total time, number of needle insertions, number of realignments, percentage of time with the needle tip in view, and success will be documented. You will have a time limit of 10 min for each technique. Once you have completed all three techniques, you will be asked to answer a short survey. Post-study resident survey The residents were asked to answer the following questions using a 1 10 scale, where 1 means completely disagree and 10 means completely agree. (1) The needle guide technique allowed me to keep my needle in view with the ultrasound probe more than the free-hand technique. (2) The needle guide technique improved my performance in placing a central line than the free-hand technique. (3) The needle guide technique was cumbersome and difficult to perform than the free-hand technique. (4) With more practice, I think I would get better at the needle guide technique. (5) With more practice, I think I would get better at the L-FH technique. (6) With more practice, I think I would get better at the S-FH technique. (7) I would consider using the needle guide in my clinical practice. References Ball et al. 1 Randolph AG, Cook DJ, Gonzales CA, et al. Ultrasound guidance for placement of central venous catheters. A meta-analysis of the literature. Crit Care Med 1996; 24: Keenan SP. Use of ultrasound to place central lines. J Crit Care 2002; 17: Hind D, Calvert N, McWilliams R, et al. Ultrasonic locating devices for central venous cannulation: meta-analysis. Br Med J 2003; 327: Sierzenski P, Polan D, Baty G, et al. Junior emergency medicine residents demonstrate improved accuracy for the identification of a central venous needle tip with a long-axis ultrasound transducer orientation. Ann Emerg Med 2008; 52(Suppl.): S Blavias M, Brannam L, Fernandez E. 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8 CIVCO needle guide simulation study BJA 18 Hebard S, Hocking G. Echogenic technology can improve needle visibility during ultrasound-guided regional anesthesia. Reg Anesth Pain Med 2011; 36: Karstrup S, Brøns J, Morsel L, Juul N, von der Recke P. Optimal set-up for ultrasound guided punctures using new scanner applications: an in-vitro study. Eur J Ultrasound 2002; 15: Schafhalter-Zoppoth I, McCulloch CE, Gray AT. Ultrasound visibility of needles used for regional nerve block: an in vitro study. Reg Anesth Pain Med 2004; 29: Maecken T, Zenz M, Grau T. Ultrasound characteristics of needles for regional anesthesia. Reg Anesth Pain Med 2007; 32: Stone MB, Moon C, Sutijono D, Blaivas M. Needle tip visualization during ultrasound-guided vascular access: short-axis vs long-axis approach. Am J Emerg Med 2010; 28: Tsui BC. Facilitating needle alignment in-plane to an ultrasound beam using a portable laser unit. Reg Anesth Pain Med 2007; 32: Schofer JM, Nomura JT, Bauman MJ, Hyde R, Schmier C. The Ski Lift : a technique to maximize needle visualization with the long-axis approach for ultrasound-guided vascular access. Acad Emerg Med 2010; 17: e Bluvol N, Sheikh A, Kornecki A, Fernandez Ddel R, Downey D, Fenster A. A needle guidance system for biopsy and therapy using two-dimensional ultrasound. Med Phys 2008; 35: Bluvol N, Kornecki A, Shaikh A, Del Rey Fernandez D, Taves DH, Fenster A. Freehand versus guided breast biopsy: comparison of accuracy, needle motion, and biopsy time in a tissue model. Am J Roentgenol 2009; 192: Phal PM, Brooks DM, Wolfe R. Sonographically guided biopsy of focal lesions: a comparison of freehand and probe-guided techniques using a phantom. Am J Roentgenol 2005; 184: van Geffen G-J, Mulder J, Gielen M, et al. A needle guidance device compared to free hand technique in an ultrasound-guided interventional task using a phantom. Anaesthesia 2008; 63: