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ORIGINAL RESEARCH
Do Echo-Enhanced Needles Make a Difference in Sonographically Guided Vascular Access? Todd Crum, MD, Srikar Adhikari, MD, MS, RDMS, Lina Lander, ScD, Michael Blaivas, MD Objectives—The purpose of this study was to compare sonographically guided vascular access using standard and echo-enhanced needles in a variety of tissue-simulating vascular phantoms. Methods—We conducted a prospective single-blinded observational study at an academic medical center. All participants performed real-time sonographically guided vascular access using both a standard 18-gauge needle and an echo-enhanced needle in both in-plane and out-of plane approaches on 3 different vascular access phantoms. The outcome measures included time to dye flash, first-pass success, visibility of the needle tip at the time of puncture, total number of attempts, number of redirections, and incidence of posterior wall penetration.
Received July 29, 2013, from the Department of Emergency Medicine, Conroe Regional Medical Center, Conroe, Texas USA (T.C.); Department of Emergency Medicine, University of Arizona Medical Center, Tucson, Arizona USA (S.A.); Department of Epidemiology, University of Nebraska Medical Center, Omaha, Nebraska USA (L.L.); and Department of Internal Medicine, University of South Carolina School of Medicine, Columbia, South Carolina USA (M.B.). Manuscript accepted for publication August 19, 2013. This work was presented in abstract form at the Society of Academic Emergency Medicine Annual Meeting; June 2011; Boston, Massachusetts. Address correspondence to Srikar Adhikari, MD, MS, RDMS, Department of Emergency Medicine, University of Arizona Medical Center, PO Box 245057, Tucson, AZ 85724 USA. E-mail: [email protected] Abbreviations
CI, confidence interval; ED, emergency department; IV, intravenous doi:10.7863/ultra.33.4.623
Results—A total of 408 sonographically guided cannulations were performed by 34 participants. The time from needle stick to dye flash, first-pass success, and the total number of attempts were not significantly different between the two needles (P > .05). The tip of the needle was seen at the time of puncture in 79% of attempts with the standard needle (95% confidence interval [CI], 68%–86%) and in 86% of attempts with the echo-enhanced needle (95% CI, 76%–92%), although this difference was not significant (P = .103). The posterior wall was penetrated with the standard needle in 14% of attempts (95% CI, 9.6%–20%) and in 6% of attempts with the echo-enhanced needle (95% CI, 3.5%–11%), and the difference was significant (P < .02). Conclusions—Echo-enhanced needles decreased the incidence of posterior wall punctures when compared to standard needles during sonographically guided vascular access. However, there were no significant differences in other sonographically guided vascular access metrics. Key Words—echo-enhanced needle; emergency ultrasound; posterior wall puncture; vascular access
T
he use of sonographic guidance during central venous catheterization has been identified as one of the patient safety practices and has been endorsed by several medical societies including Agency for Healthcare Research and Quality.1,2 There is ample evidence in the literature supporting the use of sonographic guidance for central venous access, and it has been suggested to be the standard of care.3 A recent meta-analysis showed that central venous catheterization under real-time sonographic guidance was associated with a decreased number of complications compared to the landmark technique.4 Additionally, sonographic guidance is also increasingly being used for peripheral venous access in emergency department (ED) patients with difficult peripheral
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intravenous (IV) access. Sonographically guided peripheral IV cannulation has been shown to be safe and rapid and has a high success rate in patients with difficult peripheral IV access.5 A recent systematic review investigated the clinical effectiveness of sonographic guidance for peripheral IV access and supports the use of sonographic guidance in obtaining venous access in patients with difficult IV access.6 Despite the numerous advantages of the use of sonographic guidance, there is some evidence in the literature suggesting that inadvertent arterial or posterior vein wall puncture still occurs with real-time sonographic guidance.7,8 Reports of accidental arterial cannulation and other associated complications despite the use of sonographic guidance for central venous access placement have been published.9–11 The inability to maintain visualization of the needle tip during the procedure might have contributed to these complications. The success and safety of sonographically guided catheterization is highly dependent on needle tip visualization. Currently, specially designed “echo-enhanced” needles are commercially available, which have the theoretical advantage of better visualization under sonography in comparison to standard needles. A variety of methods are used to make these needles more visible, including but not limited to dimpling, etching, and polymer coating.12–15 Echo-enhanced needles have the potential to increase procedural success and decrease complications. There is limited literature on the use of echo-enhanced needles for sonographically guided central and peripheral venous access in the ED setting. A study comparing echoenhanced needles to standard needles showed no significant differences in vascular access times, numbers of needle sticks, and redirections during sonographically guided vascular access.16 However, the investigators did not objectively assess whether the use of the echo-enhanced needle resulted in superior needle visibility compared to standard needles and whether there was any difference in the frequency of posterior wall puncture between the two needles. Unseen posterior wall puncture is logically the precursor to arterial penetration and cannulation. Additionally, the study was conducted using an out-of-plane (transverse) approach, whereas the in-plane (longitudinal) approach is increasingly recommended for sonographically guided vascular access. The participant experience and level of confidence were also not taken into account in the data analysis of that study. The objective of our study was to compare the visibility of the needle tip, frequency of posterior wall puncture, time to vascular access, total number of attempts, and redirections during sonographically guided vascular access using standard and echo-enhanced needles in a variety of tissue-simulating vascular phantoms.
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Materials and Methods Study Design and Setting We conducted a prospective single-blinded observational study at an academic medical center with an emergency medicine residency training program and an active emergency ultrasound education program. The study was approved by the Institutional Review Board, and written informed consent was obtained from each participant. Selection of Participants All emergency medicine department faculty, residents, and nursing staff were invited to participate in the study. Emergency medicine residents completed a 1-month ultrasound elective in the ED, during which they received training in sonographically guided vascular access. Most of the emergency medicine faculty has experience in common ED point-of-care sonographic applications. The nurses had received formal didactics in sonographically guided vascular access, but most have had limited or no experience in performing sonographically guided vascular access in ED patients. Study Protocol Before attempting cannulation, all participants watched a 5-minute slide show presentation demonstrating the basics of real-time sonographically guided cannulation of vessels in both the transverse and longitudinal axes. All participants performed real-time sonographically guided vascular access using both a standard 18-gauge needle and an echo-enhanced needle (18 gauge, 7 cm; Cook Medical, Bloomington, IN) in both in-plane (longitudinal) and out-of plane (transverse) approaches (Figures 1 and 2) on 3 different vascular access phantoms (2 homemade phantoms and a Blue Phantom branched 2-vessel ultrasound training block model; CAE Healthcare, Sarasota, FL).17,18 The Blue Phantom block was labeled phantom A, and the homemade phantoms were labeled phantoms B and C. Sonographically guided vascular access was performed using an M-Turbo ultrasound system (SonoSite, Inc, Bothell, WA) with a 5–10-MHz linear array transducer. The ultrasound system used in this study was not equipped with needle-enhancing software. A random-number generator was used to assign which needle the participant started with (1, standard; 2, echo enhanced). The participants were blinded to the needle type while performing the cannulation. They were asked to sequentially cannulate the vessels in all 3 phantoms in both out-of-plane and in-plane axes with one needle and then repeat the same process with the other needle. J Ultrasound Med 2014; 33:623–628
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The participants were directly observed by the investigator during cannulation, and all outcomes were recorded in real time on data collection sheets. The outcome measures included time to dye flash, first-pass success, visibility of the needle tip at the time of puncture, total number of attempts, number of redirections, and incidence of posterior wall penetration. After performing the cannulation, all participants completed a 9-item questionnaire. The participants remained blinded to the needle type while filling out the questionnaire. The questionnaire consisted of specific questions regarding the participant’s occupation, experience with sonographically guided vascular access, level of confidence in identifying the needle tip with each needle (needle 1 versus needle 2), comfort level with each needle, difference between the two needles in localizing and following the needle tip, and overall ease of sonographically guided vascular access with each needle. Primary Data Analysis All analyses were performed with SAS version 9.3 software (SAS Institute Inc, Cary, NC). Differences in outcomes of interest were assessed by a repeated-measures analysis of variance model to account for the repeated nature of the data. Analyses were adjusted for model type and approach (in plane and out of plane). P < .05 was considered statistically significant.
Results A total of 408 sonographically guided cannulations were performed by 34 participants. Most of the participants (82%) had received prior training in sonographically guided vascular access. Twenty-four participants (70%) had placed fewer than 10 sonographically guided IV lines; 5 (15%) had placed between 11 and 30; and 5 (15%) had placed more than 30. The time from needle stick to dye flash was not significantly different between the two needles (P = .15), with the standard needle averaging 17.2 seconds to flash (95% confidence interval [CI], 15.1–19.3 seconds) and the echo-enhanced needle averaging 15.6 seconds (95% CI, 13.6–17.6 seconds). Adjusting for the in-plane or out-of-plane approach, the tip of the needle was seen at the time of puncture in 79% of attempts with the standard needle (95% CI, 68%–86%) and in 86% of attempts with the echo-enhanced needle (95% CI, 76%–92%), although this difference was not significant (P = .103). Additionally, it was found that for in-plane approach attempts, the tip of the needle was seen at the time of puncture in 92% of attempts (95% CI, 85%–96%), whereas it was seen in only 66% of out-of-plane approach attempts (95% CI, 55%–75%), and this difference was significant (P < .001). The posterior wall was penetrated in 14% of attempts with the standard needle (95% CI, 9.6%–20%) and in 6% of attempts with the echo-enhanced needle (95% CI, 3.5%–11%), and the difference was significant (P < .02).
Figure 1. Standard needle. A, The tip of the standard needle is shown in the lumen of the vessel in the out-of-plane (transverse) axis. B, The entire length of the standard needle is shown in the in-plane (longitudinal) axis as it enters the vessel. A
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Adjusting for model type, the number of attempts requiring at least 1 redirection of the needle for successful cannulation was significantly higher for the out-of-plane approach, with 42% of attempts requiring at least 1 redirection (95% CI, 30%–58%), when compared to attempts by the in-plane approach, in which only 19% required at least 1 redirection (95% CI, 13%–28%), and this difference was significant (P < .0001). However, there was no significant difference in the number of redirections between the two needles (P = .28). Similarly, first-pass success was not significantly different between needles (P = .43), and there was also no significant difference in the total number of attempts (P = .10). Eighty-eight percent of the participants (30 of 34) were comfortable using both needles for vascular access. However, 41% reported that there was a difference between the two needles with regard to localizing and following the needle tip. Sixty-four percent thought it was easier to localize or follow the needle tip before penetration of the vessel with the echo-enhanced needle. On a scale of 1 to 10 for measuring the confidence level using standard and echoenhanced needles, participants were on average 0.88 points less confident with the standard needle when compared to the echo-enhanced needle (P = .037). Overall, most (62%) thought that sonographically guided vascular access was easier to perform with the echo-enhanced needle compared to the standard needle. When adjusted for participants’ perceived confidence level, the total number of attempts
and the visualization of the needle tip at the time of puncture were significantly different between standard and echo-enhanced needles (P = .024 and .002, respectively). However, the time to dye flash (P = .125), first-pass success (P = .0884), the number of redirections (P = .128), and posterior wall penetration (P = .344) were not significantly different. None of the parameters were significantly different between the standard and echo-enhanced needles when adjusted for participant experience in sonographically guided IV access.
Discussion Real-time sonographically guided vascular access can be challenging when variations in patients’ anatomy, body habitus, and position obscure visualization of the needle on sonography. Despite the use of sonography in vascular access, serious complications such as arterial puncture and pneumothorax can occur when the tip of the needle is difficult to visualize. Echo-enhanced needles are designed with the specific intent to improve visualization of the needle tip on sonography and decrease complications. Our study findings show improved visualization of the needle tip at the time of vessel puncture with echo-enhanced needles compared to standard needles (86% versus 79%). The difference in needle tip visualization was even more significant with the in-plane approach. This improved visualization probably led to the significantly decreased proportion of
Figure 2. Echo-enhanced needle. A, The tip of the echo-enhanced needle is shown in the lumen of the vessel in the out-of-plane (transverse) axis. B, The entire length of the echo-enhanced needle is seen in the in-plane (longitudinal) axis as it enters the vessel. A
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posterior wall punctures with the echo-enhanced needle. These findings are particularly important in the setting of internal jugular central venous access, where penetration of the posterior wall could possibly lead to serious complications such as puncture of the carotid artery. However, in subclavian vein cannulations, it may instead result in pneumothorax due to penetration of the pleura, which lies approximately 5 mm deep to the posterior wall of the vein. Our data suggest that the use of echo-enhanced needles could potentially lessen the occurrence of posterior wall puncture, thereby increasing patient safety. The hallmark of sonographically guided vascular access misadventures is improper needle control. It is logical to suggest that being aware of the location of the needle tip will allow providers to avoid accidental arterial cannulation and injury to adjacent sensitive structures. In our study, there was no significant difference in the time to vascular access, with the echo-enhanced needle only performing approximately 2 seconds better on average than the standard needle. Our results agree with a previous study done by Phelan et al16 in this respect. Generally, sonographically guided vascular access takes several minutes to complete the entirety of the procedure, making a 2-second difference likely not meaningful in a clinical setting. It is logical to expect that novice sonographers would benefit from using echo-enhanced needles. However, participant experience did not affect outcomes in this study. None of the sonographically guided vascular access metrics were significantly different when adjusted for participant experience. However, most of the participants reported a higher level of confidence with the echo-enhanced needle, most likely because of the improved visualization of the needle tip at the time of vessel puncture. Another important finding is the decreased number of required redirections with the in-plane or long axis approach compared to the transverse or out-of-plane approach (19% versus 42%). The difference was greater than 2-fold between the two approaches in this study. Each redirection meant that the needle was initially off course and stood a chance of penetrating unintended sensitive adjacent structures. As emerging data suggest that sonographic guidance does not offer complete immunity from misadventures in central venous access, it is imperative to optimize the technique, and our study offers some useful findings to increase patient safety. This study had several limitations, including a small sample size, which may have limited the conclusions that could be reached. We used a convenience sample for enrollment, which may have introduced a selection bias. The primary investigator directly observed the participants
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and recorded the outcomes. All efforts were made to be consistent between participants, but there was the opportunity for possible error and bias. This study was conducted using tissue-simulating phantoms instead of actual patients. Every effort was made to replicate human tissue, and a variety of phantoms were used to simulate different tissue densities. Additionally, the use of phantoms allowed us to standardize the level of difficulty each participant encountered while performing sonographically guided vascular access. Nonetheless, further studies conducted on humans will be helpful to determine whether echo-enhanced needles can decrease complications and improve patient safety. In conclusion, in our study, echo-enhanced needles decreased the incidence of posterior wall punctures when compared to standard needles during sonographically guided vascular access. However, there were no significant differences in other sonographically guided vascular access metrics.
References 1.
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7.
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Agency for Healthcare Research and Quality. Making health care safer: a critical analysis of patient safety practices [summary]. Evid Rep Technol Assess 2001; 43:i–x, 1–668. National Institute for Clinical Excellence. Guidance on the use of ultrasound locating devices for placing central venous catheters. Technology Appraisal Guidance No. 49, September 2002. National Institute for Clinical Excellence website. http://www.Nice.org.uk. Milling TJ Jr, Rose J, Briggs WM, et al. Randomized, controlled clinical trial of point-of-care limited ultrasonography assistance of central venous cannulation: the Third Sonography Outcomes Assessment Program (SOAP-3) Trial. Crit Care Med 2005; 33:1764–1769. Wu SY, Ling Q, Cao LH, Wang J, Xu MX, Zeng WA. Real-time twodimensional ultrasound guidance for central venous cannulation: a metaanalysis. Anesthesiology 2013; 118:361–375. Costantino TG, Parikh AK, Satz WA, Fojtik JP. Ultrasonography-guided peripheral intravenous access versus traditional approaches in patients with difficult intravenous access. Ann Emerg Med 2005; 46:456–461. Egan G, Healy D, O’Neill H, Clarke-Moloney M, Grace PA, Walsh SR. Ultrasound guidance for difficult peripheral venous access: systematic review and meta-analysis. Emerg Med J 2013; 30:521–526. Moon CH, Blehar D, Shear MA, et al. Incidence of posterior vessel wall puncture during ultrasound-guided vessel cannulation in a simulated model. Acad Emerg Med 2010; 17:1138–1141. Blaivas M, Adhikari S. An unseen danger: frequency of posterior vessel wall penetration by needles during attempts to place internal jugular vein central catheters using ultrasound guidance. Crit Care Med 2009; 37:2345–2349. Blaivas M. A rare look at a cause for vascular access failure after correct needle placement under ultrasound guidance. J Ultrasound Med 2008; 27:311–312. 627
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10. Stone MB, Hern HG. Inadvertent carotid artery cannulation during ultrasound-guided central venous catheterization. Ann Emerg Med 2007; 49:720 11. Adachi YU, Sato S. Four cases of inadvertent arterial cannulation despite of ultrasound guidance. Am J Emerg Med 2010; 28(4):533. 12. Culp WC, McCowan TC, Goertzen TC, et al. Relative ultrasonographic echogenicity of standard, dimpled, and polymeric-coated needles. J Vasc Interv Radiol 2000; 11:351–358. 13. Deam RK, Kluger R, Barrington MJ, McCutcheon CA. Investigation of a new echo-enhanced needle for use with ultrasound peripheral nerve blocks. Anaesth Intensive Care 2007; 35:582–586. 14. Hopkins RE, Bradley M. In-vitro visualization of biopsy needles with ultrasound: a comparative study of standard and echo-enhanced needles using an ultrasound phantom. Clin Radiol 2001; 56:499–502. 15. Jandzinski DI, Carson N, Davis D, Rubens DJ, Voci SL, Gottlieb RH. Treated needles: do they facilitate sonographically guided biopsies? J Ultrasound Med 2003; 22:1233–1237. 16. Phelan MP, Emerman C, Peacock WF, Karafa M, Colburn N, Buchanan K. Do echo-enhanced needles improve time to cannulate in a model of short-axis ultrasound-guided vascular access for a group of mostly inexperienced ultrasound users? Int J Emerg Med 2009; 2:167–170. 17. Kendall JL, Faragher JP. Ultrasound-guided central venous access: a homemade phantom for simulation. CJEM 2007; 9:371–373. 18. Gibson RN, Gibson KI. A home-made phantom for learning ultrasoundguided invasive techniques. Australas Radiol 1995; 39:356–357.
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ORIGINAL RESEARCH
Do Echo-Enhanced Needles Make a Difference in Sonographically Guided Vascular Access? Todd Crum, MD, Srikar Adhikari, MD, MS, RDMS, Lina Lander, ScD, Michael Blaivas, MD Objectives—The purpose of this study was to compare sonographically guided vascular access using standard and echo-enhanced needles in a variety of tissue-simulating vascular phantoms. Methods—We conducted a prospective single-blinded observational study at an academic medical center. All participants performed real-time sonographically guided vascular access using both a standard 18-gauge needle and an echo-enhanced needle in both in-plane and out-of plane approaches on 3 different vascular access phantoms. The outcome measures included time to dye flash, first-pass success, visibility of the needle tip at the time of puncture, total number of attempts, number of redirections, and incidence of posterior wall penetration.
Received July 29, 2013, from the Department of Emergency Medicine, Conroe Regional Medical Center, Conroe, Texas USA (T.C.); Department of Emergency Medicine, University of Arizona Medical Center, Tucson, Arizona USA (S.A.); Department of Epidemiology, University of Nebraska Medical Center, Omaha, Nebraska USA (L.L.); and Department of Internal Medicine, University of South Carolina School of Medicine, Columbia, South Carolina USA (M.B.). Manuscript accepted for publication August 19, 2013. This work was presented in abstract form at the Society of Academic Emergency Medicine Annual Meeting; June 2011; Boston, Massachusetts. Address correspondence to Srikar Adhikari, MD, MS, RDMS, Department of Emergency Medicine, University of Arizona Medical Center, PO Box 245057, Tucson, AZ 85724 USA. E-mail: [email protected] Abbreviations
CI, confidence interval; ED, emergency department; IV, intravenous doi:10.7863/ultra.33.4.623
Results—A total of 408 sonographically guided cannulations were performed by 34 participants. The time from needle stick to dye flash, first-pass success, and the total number of attempts were not significantly different between the two needles (P > .05). The tip of the needle was seen at the time of puncture in 79% of attempts with the standard needle (95% confidence interval [CI], 68%–86%) and in 86% of attempts with the echo-enhanced needle (95% CI, 76%–92%), although this difference was not significant (P = .103). The posterior wall was penetrated with the standard needle in 14% of attempts (95% CI, 9.6%–20%) and in 6% of attempts with the echo-enhanced needle (95% CI, 3.5%–11%), and the difference was significant (P < .02). Conclusions—Echo-enhanced needles decreased the incidence of posterior wall punctures when compared to standard needles during sonographically guided vascular access. However, there were no significant differences in other sonographically guided vascular access metrics. Key Words—echo-enhanced needle; emergency ultrasound; posterior wall puncture; vascular access
T
he use of sonographic guidance during central venous catheterization has been identified as one of the patient safety practices and has been endorsed by several medical societies including Agency for Healthcare Research and Quality.1,2 There is ample evidence in the literature supporting the use of sonographic guidance for central venous access, and it has been suggested to be the standard of care.3 A recent meta-analysis showed that central venous catheterization under real-time sonographic guidance was associated with a decreased number of complications compared to the landmark technique.4 Additionally, sonographic guidance is also increasingly being used for peripheral venous access in emergency department (ED) patients with difficult peripheral
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intravenous (IV) access. Sonographically guided peripheral IV cannulation has been shown to be safe and rapid and has a high success rate in patients with difficult peripheral IV access.5 A recent systematic review investigated the clinical effectiveness of sonographic guidance for peripheral IV access and supports the use of sonographic guidance in obtaining venous access in patients with difficult IV access.6 Despite the numerous advantages of the use of sonographic guidance, there is some evidence in the literature suggesting that inadvertent arterial or posterior vein wall puncture still occurs with real-time sonographic guidance.7,8 Reports of accidental arterial cannulation and other associated complications despite the use of sonographic guidance for central venous access placement have been published.9–11 The inability to maintain visualization of the needle tip during the procedure might have contributed to these complications. The success and safety of sonographically guided catheterization is highly dependent on needle tip visualization. Currently, specially designed “echo-enhanced” needles are commercially available, which have the theoretical advantage of better visualization under sonography in comparison to standard needles. A variety of methods are used to make these needles more visible, including but not limited to dimpling, etching, and polymer coating.12–15 Echo-enhanced needles have the potential to increase procedural success and decrease complications. There is limited literature on the use of echo-enhanced needles for sonographically guided central and peripheral venous access in the ED setting. A study comparing echoenhanced needles to standard needles showed no significant differences in vascular access times, numbers of needle sticks, and redirections during sonographically guided vascular access.16 However, the investigators did not objectively assess whether the use of the echo-enhanced needle resulted in superior needle visibility compared to standard needles and whether there was any difference in the frequency of posterior wall puncture between the two needles. Unseen posterior wall puncture is logically the precursor to arterial penetration and cannulation. Additionally, the study was conducted using an out-of-plane (transverse) approach, whereas the in-plane (longitudinal) approach is increasingly recommended for sonographically guided vascular access. The participant experience and level of confidence were also not taken into account in the data analysis of that study. The objective of our study was to compare the visibility of the needle tip, frequency of posterior wall puncture, time to vascular access, total number of attempts, and redirections during sonographically guided vascular access using standard and echo-enhanced needles in a variety of tissue-simulating vascular phantoms.
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Materials and Methods Study Design and Setting We conducted a prospective single-blinded observational study at an academic medical center with an emergency medicine residency training program and an active emergency ultrasound education program. The study was approved by the Institutional Review Board, and written informed consent was obtained from each participant. Selection of Participants All emergency medicine department faculty, residents, and nursing staff were invited to participate in the study. Emergency medicine residents completed a 1-month ultrasound elective in the ED, during which they received training in sonographically guided vascular access. Most of the emergency medicine faculty has experience in common ED point-of-care sonographic applications. The nurses had received formal didactics in sonographically guided vascular access, but most have had limited or no experience in performing sonographically guided vascular access in ED patients. Study Protocol Before attempting cannulation, all participants watched a 5-minute slide show presentation demonstrating the basics of real-time sonographically guided cannulation of vessels in both the transverse and longitudinal axes. All participants performed real-time sonographically guided vascular access using both a standard 18-gauge needle and an echo-enhanced needle (18 gauge, 7 cm; Cook Medical, Bloomington, IN) in both in-plane (longitudinal) and out-of plane (transverse) approaches (Figures 1 and 2) on 3 different vascular access phantoms (2 homemade phantoms and a Blue Phantom branched 2-vessel ultrasound training block model; CAE Healthcare, Sarasota, FL).17,18 The Blue Phantom block was labeled phantom A, and the homemade phantoms were labeled phantoms B and C. Sonographically guided vascular access was performed using an M-Turbo ultrasound system (SonoSite, Inc, Bothell, WA) with a 5–10-MHz linear array transducer. The ultrasound system used in this study was not equipped with needle-enhancing software. A random-number generator was used to assign which needle the participant started with (1, standard; 2, echo enhanced). The participants were blinded to the needle type while performing the cannulation. They were asked to sequentially cannulate the vessels in all 3 phantoms in both out-of-plane and in-plane axes with one needle and then repeat the same process with the other needle. J Ultrasound Med 2014; 33:623–628
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The participants were directly observed by the investigator during cannulation, and all outcomes were recorded in real time on data collection sheets. The outcome measures included time to dye flash, first-pass success, visibility of the needle tip at the time of puncture, total number of attempts, number of redirections, and incidence of posterior wall penetration. After performing the cannulation, all participants completed a 9-item questionnaire. The participants remained blinded to the needle type while filling out the questionnaire. The questionnaire consisted of specific questions regarding the participant’s occupation, experience with sonographically guided vascular access, level of confidence in identifying the needle tip with each needle (needle 1 versus needle 2), comfort level with each needle, difference between the two needles in localizing and following the needle tip, and overall ease of sonographically guided vascular access with each needle. Primary Data Analysis All analyses were performed with SAS version 9.3 software (SAS Institute Inc, Cary, NC). Differences in outcomes of interest were assessed by a repeated-measures analysis of variance model to account for the repeated nature of the data. Analyses were adjusted for model type and approach (in plane and out of plane). P < .05 was considered statistically significant.
Results A total of 408 sonographically guided cannulations were performed by 34 participants. Most of the participants (82%) had received prior training in sonographically guided vascular access. Twenty-four participants (70%) had placed fewer than 10 sonographically guided IV lines; 5 (15%) had placed between 11 and 30; and 5 (15%) had placed more than 30. The time from needle stick to dye flash was not significantly different between the two needles (P = .15), with the standard needle averaging 17.2 seconds to flash (95% confidence interval [CI], 15.1–19.3 seconds) and the echo-enhanced needle averaging 15.6 seconds (95% CI, 13.6–17.6 seconds). Adjusting for the in-plane or out-of-plane approach, the tip of the needle was seen at the time of puncture in 79% of attempts with the standard needle (95% CI, 68%–86%) and in 86% of attempts with the echo-enhanced needle (95% CI, 76%–92%), although this difference was not significant (P = .103). Additionally, it was found that for in-plane approach attempts, the tip of the needle was seen at the time of puncture in 92% of attempts (95% CI, 85%–96%), whereas it was seen in only 66% of out-of-plane approach attempts (95% CI, 55%–75%), and this difference was significant (P < .001). The posterior wall was penetrated in 14% of attempts with the standard needle (95% CI, 9.6%–20%) and in 6% of attempts with the echo-enhanced needle (95% CI, 3.5%–11%), and the difference was significant (P < .02).
Figure 1. Standard needle. A, The tip of the standard needle is shown in the lumen of the vessel in the out-of-plane (transverse) axis. B, The entire length of the standard needle is shown in the in-plane (longitudinal) axis as it enters the vessel. A
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Adjusting for model type, the number of attempts requiring at least 1 redirection of the needle for successful cannulation was significantly higher for the out-of-plane approach, with 42% of attempts requiring at least 1 redirection (95% CI, 30%–58%), when compared to attempts by the in-plane approach, in which only 19% required at least 1 redirection (95% CI, 13%–28%), and this difference was significant (P < .0001). However, there was no significant difference in the number of redirections between the two needles (P = .28). Similarly, first-pass success was not significantly different between needles (P = .43), and there was also no significant difference in the total number of attempts (P = .10). Eighty-eight percent of the participants (30 of 34) were comfortable using both needles for vascular access. However, 41% reported that there was a difference between the two needles with regard to localizing and following the needle tip. Sixty-four percent thought it was easier to localize or follow the needle tip before penetration of the vessel with the echo-enhanced needle. On a scale of 1 to 10 for measuring the confidence level using standard and echoenhanced needles, participants were on average 0.88 points less confident with the standard needle when compared to the echo-enhanced needle (P = .037). Overall, most (62%) thought that sonographically guided vascular access was easier to perform with the echo-enhanced needle compared to the standard needle. When adjusted for participants’ perceived confidence level, the total number of attempts
and the visualization of the needle tip at the time of puncture were significantly different between standard and echo-enhanced needles (P = .024 and .002, respectively). However, the time to dye flash (P = .125), first-pass success (P = .0884), the number of redirections (P = .128), and posterior wall penetration (P = .344) were not significantly different. None of the parameters were significantly different between the standard and echo-enhanced needles when adjusted for participant experience in sonographically guided IV access.
Discussion Real-time sonographically guided vascular access can be challenging when variations in patients’ anatomy, body habitus, and position obscure visualization of the needle on sonography. Despite the use of sonography in vascular access, serious complications such as arterial puncture and pneumothorax can occur when the tip of the needle is difficult to visualize. Echo-enhanced needles are designed with the specific intent to improve visualization of the needle tip on sonography and decrease complications. Our study findings show improved visualization of the needle tip at the time of vessel puncture with echo-enhanced needles compared to standard needles (86% versus 79%). The difference in needle tip visualization was even more significant with the in-plane approach. This improved visualization probably led to the significantly decreased proportion of
Figure 2. Echo-enhanced needle. A, The tip of the echo-enhanced needle is shown in the lumen of the vessel in the out-of-plane (transverse) axis. B, The entire length of the echo-enhanced needle is seen in the in-plane (longitudinal) axis as it enters the vessel. A
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posterior wall punctures with the echo-enhanced needle. These findings are particularly important in the setting of internal jugular central venous access, where penetration of the posterior wall could possibly lead to serious complications such as puncture of the carotid artery. However, in subclavian vein cannulations, it may instead result in pneumothorax due to penetration of the pleura, which lies approximately 5 mm deep to the posterior wall of the vein. Our data suggest that the use of echo-enhanced needles could potentially lessen the occurrence of posterior wall puncture, thereby increasing patient safety. The hallmark of sonographically guided vascular access misadventures is improper needle control. It is logical to suggest that being aware of the location of the needle tip will allow providers to avoid accidental arterial cannulation and injury to adjacent sensitive structures. In our study, there was no significant difference in the time to vascular access, with the echo-enhanced needle only performing approximately 2 seconds better on average than the standard needle. Our results agree with a previous study done by Phelan et al16 in this respect. Generally, sonographically guided vascular access takes several minutes to complete the entirety of the procedure, making a 2-second difference likely not meaningful in a clinical setting. It is logical to expect that novice sonographers would benefit from using echo-enhanced needles. However, participant experience did not affect outcomes in this study. None of the sonographically guided vascular access metrics were significantly different when adjusted for participant experience. However, most of the participants reported a higher level of confidence with the echo-enhanced needle, most likely because of the improved visualization of the needle tip at the time of vessel puncture. Another important finding is the decreased number of required redirections with the in-plane or long axis approach compared to the transverse or out-of-plane approach (19% versus 42%). The difference was greater than 2-fold between the two approaches in this study. Each redirection meant that the needle was initially off course and stood a chance of penetrating unintended sensitive adjacent structures. As emerging data suggest that sonographic guidance does not offer complete immunity from misadventures in central venous access, it is imperative to optimize the technique, and our study offers some useful findings to increase patient safety. This study had several limitations, including a small sample size, which may have limited the conclusions that could be reached. We used a convenience sample for enrollment, which may have introduced a selection bias. The primary investigator directly observed the participants
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and recorded the outcomes. All efforts were made to be consistent between participants, but there was the opportunity for possible error and bias. This study was conducted using tissue-simulating phantoms instead of actual patients. Every effort was made to replicate human tissue, and a variety of phantoms were used to simulate different tissue densities. Additionally, the use of phantoms allowed us to standardize the level of difficulty each participant encountered while performing sonographically guided vascular access. Nonetheless, further studies conducted on humans will be helpful to determine whether echo-enhanced needles can decrease complications and improve patient safety. In conclusion, in our study, echo-enhanced needles decreased the incidence of posterior wall punctures when compared to standard needles during sonographically guided vascular access. However, there were no significant differences in other sonographically guided vascular access metrics.
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