- Email: [email protected]
Lightly Embalmed Cadavers as a Training Tool for Ultrasound-Guided Procedures Commonly Used in Interventional Radiology
ARTICLE IN PRESS
Radiologic Resident Education
Lightly Embalmed Cadavers as a Training Tool for Ultrasound-Guided Procedures Commonly Used in Interventional Radiology TagedPMary E. (Mollie) Meek, MD, James C. Meek, DO, Blake Hollowoa, BS, Ruizong Li, MD, Linda A. Deloney, EdD, Kevin D. Phelan, PhD
TagedPAbbreviations US Ultrasound IR Interventional Radiology WA Washington USA United States of America
Rationale and Objectives: TagedPCompetency in ultrasound (US) imaging and US-guided procedures is often difficult for medical students and residents to master. The use of simulation training has been strongly encouraged but the quality of phantom models available for US-guided procedures is limited. As a feasible alternative, we describe the innovative use of a lightly embalmed cadaver for realistic practice of common interventional radiology (IR) procedures prior to direct patient care. Materials and Methods: L TagedP ightly embalmed cadavers were positioned as patients would be in the IR suite: supine, prone, and erect seated position. Lidocaine was injected and visualized under standard percutaneous techniques and sonographic guidance was used to simulate common US-guided procedures performed in IR including liver biopsy, kidney biopsy, thoracentesis, and vascular access. Results: TagedPThe ability to position cadavers was a key factor that allowed entire procedures to be simulated. Medical students with very limited exposure to US imaging and diagnostic radiology residents with minimal exposure to US imaging successfully completed common US-guided procedures. Arterial and venous vascular access was obtained. Wires were passed and catheters easily placed via both access sites. The texture of the tissue layers provided realistic feedback for the trainees as they advanced the needle or dilated the tissues. Images from each simulated procedure resembled images expected in a living patient. Conclusion: L TagedP ightly embalmed cadavers are an innovative and feasible tool to simulate common IR USguided procedures in a realistic fashion for deliberate practice in advance of first-attempt encounters with patients. TagedPKey Words: Radiology; Image-guided procedures; Interventional radiology; Lightly embalmed cadaver; Medical education; Simulation; Ultrasound-guided procedures. © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
Acad Radiol 2018; &:1 7 Grant Funding: None. Preliminary findings were presented as Educational Exhibit Abstract No. 521 at the Society of Interventional Radiology Annual Meeting in Vancouver British Columbia, Canada, April 2-7, 2016 by Sam McMurry, DO, Diagnostic Radiology Class of 2016. From the University of Arkansas for Medical Sciences, Little Rock, Arkansas (M.E.(M.)M.); Interventional Radiology Division, University of Arkansas for Medical Sciences, Little Rock, Arkansas (J.C.M., R.L.); College of Medicine, MS4, University of Arkansas for Medical Sciences, Little Rock, Arkansas (B.H.); Department of Radiology, University of Arkansas for Medical Sciences, 4301 W. Markham, #556, Little Rock, AR 72205 (L.A.D.); Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas (K.D.P.). Received February 15, 2018; revised May 23, 2018; accepted May 24, 2018. Address correspondence to: L.D. e-mail: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected] © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.acra.2018.05.019
TAGEDH1INTRODUCTIONTAGEDN
C
ompetency in ultrasound (US) imaging and USguided procedures is a fundamental skill required for interventional radiology (IR) physicians but often difficult for trainees to master. Although the use of USguided procedures in the field of medicine has drastically increased in recent years, students are minimally exposed to US during medical school (1,2). IR procedures are classically taught via literature, simulations, and demonstration before trainees attempt procedures under direct observation. Attempting IR procedures when patients are awake or minimally sedated creates apprehension in patients which in turn increases the resident’s anxiety and can lead to mistakes in technique, medical errors, and less effective teaching. As a 1
ARTICLE IN PRESS MEEK ET AL
learning experience, this approach limits open communication, instruction, and experimentation the resident needs to develop the appropriate skill set. TagedPThe use of simulation to achieve excellence and safety in IR patient care has been strongly encouraged (3). Hours spent in deliberate practice, intentionally repeating an activity in order to improve performance or master a task, have correlated with the development of expertise. Simulation allows deliberate practice in a safe environment, as often as needed for mastery learning, without jeopardizing patient safety (4,5). Combined with immediate feedback and self-evaluation, deliberate practice requires effort, and, though not innately enjoyable, can reduce training time and be more effective than nonfocused training (4). With permission to fail and correct mistakes remote from patients, novice operators can practice common percutaneous procedures that range in complexity from superficial skin punctures to biopsies, aspirations, and central venous access. Likewise, experts can refresh old skills and learn new ones. TagedPAs time for training and practice becomes increasingly limited, simulation can maximize the productivity of educational time. Obstetric/gynecology residents significantly improved laparoscopic surgical techniques in a relatively short amount of time in a cadaver training program (6). Radiology residents who had a 30-minute training session with an abdominal imaging phantom reported improved overall procedure time, number of skin punctures, and needle adjustments, and subjective performance compared to residents who did not have the training session (7). Simulation allows trainees to master basic skills through deliberate practice and then use their time with patients to learn complex skills. For example, a trainee might perform 10 procedures in 1 hour of simulation while the same number of procedures on live patients could take 10 hours or more. TagedPSuccessful adoption of a simulation strategy requires understanding the strengths and limitations of simulators, determining and improving their effectiveness, and establishing standards for documentation (3). In medical education, simulation uses lifelike mannequins, physical models, standardized patients, or computers to replicate real health encounters (8). A variety of US simulators have been used in IR with differing degrees of sophistication. Primitive simulators, such as home-made or manufactured gelatin molds, have been used to replicate image guided biopsy and USguided vascular access training has been achieved with phantom models (CAE Blue Phantom, Redmond, Washington) (3,7,9,10). Computer-based simulators are the most sophisticated, providing a virtual reality where trainees must complete complex tasks. The Vascular Interventional Surgical Trainer (VIST-VR, Mentice, Gothenburg, Sweden) and ANGIO Mentor (Simbionix Ltd, Lod, Israel) allow catheterbased endovascular simulation. Benefits of computer simulators include: use of virtual fluoroscopy, physical manipulation of guidewires, ability to replicate complex vasculature, and providing objective measures (ie time) useful in evaluating trainees. Compared to no intervention, simulation training 2
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TagedPhas shown improvements in knowledge, skill, and patientrelated outcomes (11). While these endovascular simulators are suitable to train cognitive steps, evidence supporting their validity in training fine motor actions is insufficient (12). Phantom models bear little resemblance to live patients and the replication of real human tissue is subpar (1). Despite advancements in simulation, the human body remains the best tool for mastering a skill (12). TagedPCadaveric dissection has been used in medical education for centuries and is an essential tool for understanding the human body, but applications are limited. Fresh cadavers are most realistic but, because they only last about two weeks, they cannot feasibly be used for multiple training sessions (13). Unembalmed bodies deteriorate rapidly, and possible associated health hazards are usually considered unacceptable. Although unembalmed cadavers can be frozen for later use, freezing spoils their texture and deterioration is suspended only as long as they remain frozen (13). TagedPTraditional embalming techniques are also unable to produce high-fidelity training models. They leave the body stiff and fail to preserve the tissue in a life-like manner. Their inflexibility prevents appropriately positioning the cadavers as needed in IR training (14). In traditionally embalmed cadavers preserved with formaldehyde, tissues become rigid and organs and structures are difficult to distinguish, and this leads to poor image quality (14). TagedPThe light embalming technique preserves the cadaver in a life-like manner and provides the most realistic training model available. Tissue of lightly embalmed cadavers is much more like living tissue and provides a better model for simulating surgical procedures and techniques, allowing entire procedures to be replicated (13). In particular, the light embalming technique maintains the US anatomy and the ability to manipulate the cadaver into a variety of positions, simulating patient mobility (1). These cadavers can be kept in a refrigeration unit with negligible loss of tissue quality and color. Lightly embalmed cadavers typically last 8 10 weeks before deterioration begins to make them unsuitable for training purposes (13). TagedPThe technique, as first described by Anderson, consists of three major components: a preinjection chemical, embalming fluid, and a dye (13). The technique differs from traditional embalming in three ways: weaker embalming fluid is used, lower volumes are used, and the fluid is not allowed to accumulate (13). This allows for the cadaver to be positioned as needed,. The method is cost-effective, comparable to the traditional embalming method. The lightly embalmed cadavers must be refrigerated between uses. TagedPThe literature on lightly embalmed cadavers in medical education is sparse. Reports of lightly embalmed cadavers as patient simulators include realistic simulation of central venous access (15) and orotracheal intubation (16). First-year medical, physician assistant, and physical therapy students reported increased confidence and clinical competence after hands-on cadaver training (17). Surgical residents consistently rated an open surgical skills program using lightly embalmed
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TagedPcadavers the highest among their training activities (14). Lightly embalmed cadavers created an excellent model for mimicking the sonographic appearance of pneumothorax (18). The use of lightly embalmed cadavers in IR training has not been previously described. TagedPFor this pilot study, we investigated the feasibility of using lightly embalmed cadavers in a controlled environment as a training model to improve the knowledge, technical ability, and confidence of novice trainees performing common IR procedures. This single-center study, conducted at an academic medical center, was conducted in a gross anatomy laboratory using normal educational practices. The study was classified exempt by the university’s Institutional Review Board. TAGEDH1MATERIALS AND METHODSTAGEDN TagedPTraining workshops using lightly embalmed cadavers were conducted. First-year medical students were recruited via email to participate in training using US-guided placement of central venous lines (2014) and for US-guided kidney and liver biopsy (2018). The medical students had some familiarity with positioning techniques since radiologists in our department facilitate an introductory US-guidance session in their first-year Gross Anatomy Human Structures Course. Diagnostic radiology residents with minimal exposure to US imaging and IR procedures were recruited to perform simulated biopsies, thoracentesis, and vascular access (2016). TagedPLightly embalmed cadavers were prepared as previously reported (13) from anatomical gift donors acquired within 3 days of death. Blood work was obtained on each cadaver to exclude any cadaver with evidence of HIV or hepatitis A, B, or C. All cadavers were stored in the refrigeration unit between uses.
TRAINING WITH LIGHTLY EMBALMED CADAVERS
TagedPFor each workshop, cadavers were positioned on a dissection table as they would be in the IR department including supine, prone, and erect seated positions. Due to the flexibility of the tissue, lidocaine was injected and visualized under US. Standard percutaneous techniques and US-guidance were used to simulate liver biopsy (supine) and kidney biopsy (prone). The cadaver was placed in a seated position for USguided thoracentesis. The Seldinger wire technique to obtain access to blood vessels and other hollow organs was reviewed before vascular access was attempted. Hands-on performance was supervised by IR faculty, fellows, and senior residents. Trainees controlled the US probe with the assistance of experienced IR practitioners. Attempts for medical students were time limited due to the size of the class, but the learning objective was to introduce them to US-guided techniques, not to master procedures. In general, participants simulated each procedure one time. TagedPAt the conclusion of each medical student workshop, participants were asked to evaluate the learning experience by rating their perception of the session’s organization and structure, satisfaction with the lightly embalmed cadaver as a learning tool, the clinical relevance of the training, the presenter’s knowledge of the topic, and the overall quality of the session. TAGEDH1RESULTSTAGEDN TagedPUS images from each simulated procedure resembled images expected from a living patient (Figs 1 5). Some were not as clear and detailed of those of live patients, but were comparable overall. The ability to position the cadavers in various positions was a key factor that allowed entire procedures to be simulated. Arterial vascular access was obtained in the
Figure 1. (a) Common carotid artery (green arrow) and partially compressed internal jugular vein (red arrow). (b) Common carotid artery (green arrow) and echogenic needle in the internal jugular vein (red arrow) of a lightly embalmed cadaver. (Color version of figure is available online.)
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Figure 2. (a) Common femoral artery (red arrow). (b) Echogenic needle in the common femoral artery (red arrow) of a lightly embalmed cadaver. (Color version of figure is available online.)
TagedPcommon femoral artery. Wires were passed and catheters easily placed via both access sites. The texture of the tissue layers provided realistic feedback for the learners as they advanced the needle or dilated the tissues. Pleural fluid was easily identified and needle passage was visualized under US guidance with the cadaver in a seated position. Images of the kidneys showed remarkable US anatomy preservation that allowed for training in US-guided renal procedures. TagedPIn our first workshop, 31 first-year medical students successfully completed US-guided placement of a central venous line. Of these students, 16 (61% response rate) provided information regarding their experience (Table 1) Notably, 100% “strongly agreed” the lightly embalmed cadaver was a “great” learning tool (5.00 § 0.00). In our second workshop, 8 diagnostic radiology residents successfully completed US-guided biopsy of the liver. They
TagedPprovided anecdotal information about their experience, agreeing with medical students that the lightly embalmed cadaver was a “great” learning tool. Our third workshop attracted 55 first-year medical students to perform USguided liver and kidney biopsies. Satisfaction with the training was again high. Of the 55 participants, 29 completed the evaluation (53% response rate) and “strongly agreed (93%) or “agreed (7%) the lightly embalmed cadaver was a “great” learning tool. (Table 2). One self-efficacy question was added to their evaluation and, with the exception of one medical student, participants “strongly agreed” (62%) or “agreed” (35%) they were more confident of their ability to perform US-guided procedures after the session. We also asked the medical students to offer comments and suggestions for improvement. Representative comments are displayed in Appendix A.
Figure 3. (a) US of a liver in a lightly embalmed cadaver. (b) Echogenic needle in the liver of a lightly embalmed cadaver (red arrow). (Color version of figure is available online.)
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TRAINING WITH LIGHTLY EMBALMED CADAVERS
Figure 4. (a) US showing the right pleural space in a lightly embalmed cadaver. (b) Echogenic needle in the right pleural space (red arrow) of a lightly embalmed cadaver. (Color version of figure is available online.)
TAGEDH1DISCUSSIONTAGEDN TagedPOur experience confirms that lightly embalmed cadavers are realistic simulators for practicing common US-guided procedures prior to direct patient care. The ability to position the cadavers was a key factor that allowed entire procedures to be simulated. For medical students, the combination of cadaveric and radiographic anatomy makes these preclinical lessons particularly relevant to future clinical training. TagedPLimitations of this pilot study are its small size and the single site. No demographic information was collected and it is impossible to account for potential differences in perceptions among trainees. Because medical student participants were self-selected volunteers, results may be subject to voluntary response bias. Comparisons of images to living patient images and tissue to living tissue are anecdotal. Trainees were not asked about image quality and there was no review by experts (sonographers/IR physicians). Similarly, no data about “the feel” was collected from experts who could compare the
TagedPcadaver tissue to living tissue. These comparisons could be included in future studies. TagedPSeveral factors impact the ability of a physician to successfully execute clinical IR procedures, including knowledge of the anatomy related to the procedure, understanding procedural details, technical skill and ability, familiarity with instruments and devices, and experience. Traditional training may leave gaps in the acquisition of any or all of these aspects. Cadaver training can be used successfully to close many, if not all, of these performance gaps. When practicing in a realistic environment, trainees can problem solve and refine techniques without putting patients at risk. They can attempt needle passes multiple times, improving or failing without negative consequences. Cadaver training can expose common mistakes and prevent inappropriately learned techniques
TABLE 1. First-Year Medical Student (M1) Evaluation of USGuided Central Venous Line Placement on Lightly Embalmed Cadavers (2014) Mean § Standard error of the mean (n = 16) 1. The session was well organized and material presented in a logical sequence 2. The lightly embalmed cadaver was a great learning tool 3. The information presented was clinically relevant 4 The presenter was knowledgeable in the topic 5. The overall quality of this session was outstanding 6. I would recommend this session to M1 students next year
Figure 5. Renal US showing a transverse view of the interpolar region of the kidney with the caudal aspect of the right lobe of the liver in a lightly embalmed cadaver.
4.47 § 0.14
5.00 § 0.00 4.89 § 0.07 4.84 § 0.09 4.58 § 0.14 4.79 § 0.12
Rating scale: 5—Strongly agree; 4—Agree; 3—Neither Agree or Disagree; 2—Disagree; 1—Strongly Disagree.
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MEEK ET AL
TABLE 2. First-Year Medical Student (M1) Evaluation of US Guided Liver and Kidney Biopsy on Lightly Embalmed Cadavers (2018) Mean § Standard error of the mean (n = 29) 1. The session was well organized and material presented in a logical sequence 2. The lightly embalmed cadaver was a great learning tool 3. The information presented was clinically relevant 4. The presenter was knowledgeable in the topic 5. The overall quality of this session was outstanding 6. I would recommend this session to M1 students next year 7. As a result of this session, I feel more confident in my ability to perform US-guided procedures.
4.76 § 0.44
4.93 § 0.26 4.86 § 0.44 4.90 § 0.31 4.76 § 0.44 4.90 § 0.31 4.59 § 0.57
Rating scale: 5 —Strongly agree; 4—Agree; 3—Neither Agree or Disagree; 2—Disagree; 1—Strongly Disagree.
TagedPfrom making their way into the angiography suite. Common mistakes can be used as teaching points for other trainees. TagedPAll IR physicians must be aware of the limits of their practice and the circumstances under which they act independently (19). Cadaver training programs can help IR physicians keep up with their rapidly evolving specialty (8,19). Physicians can be given the opportunity to learn and perform state-of-the-art procedures they had not previously been exposed to, giving them a greater variety of treatment options for their patients. Attempting new procedures on a nonliving subject would likely improve outcomes and reduce complications associated with first attempts in patients. Lightly embalmed cadavers can be a cost-effective method to achieve such high-fidelity training, while maximizing the time spent in deliberate practice. TagedPThe greatest benefit of this training method may be decreased adverse events caused by medical or technical error. Medical students and residents—and even fellows and practitioners—can improve their technical ability and procedural knowledge, potentially leading to improved performance, and decreased complications. Hands-on educational experiences, fundamental to the IR curriculum, stimulate learner engagement, and enhance the development of clinical skills. Hands-on training with a lightly embalmed cadaver reduces the risks associated with learning on patients. Further study is
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TagedPneeded to determine optimal uses for the lightly embalmed cadaver as a training tool in medical education.
TAGEDH1REFERENCESTAGEDN TagedP 1. Miller R, Ho H, Ng V, et al. Introducing a fresh cadaver model for ultrasound-guided central venous access training in undergraduate medical education. West J Emerg Med 2016; 17:362–366. TagedP 2. Hoffman L, Wadman MC, Erickson T, et al. Self-reported EM residency applicant attitudes towards a procedural cadaver laboratory curriculum. West J Emerg Med 2008; 9:141–145. TagedP 3. Gould D. Using simulation for interventional radiology training. Br J Radiol 2010; 83:546–553. TagedP 4. Ericsson KA. Deliberate practice and acquisition of expert performance: a general overview. Acad Emerg Med 2008; 15:988–994. TagedP 5. Kneebone R. Evaluating clinical simulations for learning procedural skills: a theory-based approach. Acad Med 2005; 23(5):549–553. TagedP 6. Levine RL, Kives S, Cathey G, et al. The use of lightly embalmed (fresh tissue) cadavers for resideny laproscopic training. J Minim Invasive Gynecol 2006; 13:451–456. TagedP 7. Fulton N, Buethe J, Gollamudi J, et al. Simulation-based training may improve resident skill in ultrasound-guided biopsy. AJR 2016; 207:1329– 1333. TagedP 8. Passiment M, Sacks H, Huang G. Medical simulation in medical education: results of an AAMC survey. Assoc Am Med Coll Rep 2011 . Available at: https://www.aamc.org/download/259760/data. Accessed February 7, 2017. TagedP 9. Baadh A, Fadl A, Georgiou N, et al. A pilot program for use of a homemade phantom for CT biopsy simulation training. JVIR 2015; 26:S167. TagedP10. Ball R, Scouras N, Orebaugh S, et al. Randomized, prospective, observational simulation study comparing residents’ needle-guided vs freehand ultrasound technique for central venous catheter access. Br J Anaesth 2012; 108:72–79. TagedP11. Cook DA, Hatala R, Brydges R, et al. Technology-enhanced simulation for health professions education: a systematic review and meta-analysis. JAMA 2011; 306:978–988. TagedP12. Lewandowski W, Gould D. A summary of the subjective opinions of interventional radiologist regarding selected medical simulations. Available from: http://www.whichinterventionaldevice.com/product-categories/ simulators.aspx. Accessed February 13, 2017. TagedP13. Anderson SD. Practical light embalming technique for use in the surgical fresh tissue dissection laboratory. Clin Anat 2006; 19:8–11. TagedP14. Cork K. UNMC's 'lightly embalmed' cadaver program provides innovative learning tool. UNMC Depart Pharmacol/Exp\ Neurosci 2015. Available at https://www.unmc.edu/news.cfm?match=16295. Accessed April 12, 2018. TagedP15. Wadman MC, Lomneth CS, Hoffman LH, et al. Assessment of a new model for femoral ultrasound-guided central venous access procedural training: a pilot study. Acad Emerg Med 2010; 17:88–92. TagedP16. Wadman M, Nicholas TA, Bernhagen MA, et al. A comparison of an integrated suction blade versus a traditional videolaryngoscope blade in the endotracheal intubation of a hemorrhagic cadaver model: a pilot study. Stud Health Technol Inform 2012; 173:534–536. TagedP17. Keim Janssen SA, VanderMeulen SP, Shostrom VK, et al. Enhancement of anatomical learning and developing clinical competence of first-year medical and allied health profession students. Anat Sci Educ 2014; 7:181–190. TagedP18. Adhikari S, Zeger W, Wadman M, et al. Assessment of a human cadaver model for training emergency medicine residents in the ultrasound diagnosis of pneumothorax. Biomed Res Int 2014 :724050. TagedP19. Siragusa DA, Cardella JF, Hieb RA, et al. Requirements for training in interventional radiology. JVIR 2013; 24:1609–1612.
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TAGEDH1APPENDIX A. MEDICAL STUDENT COMMENTS AND SUGGESTIONSTAGEDN TagedPComments: TagedPI'd rate the session an 11 out of 10 any day. TagedPIt was pretty useful and very interesting to get to try. TagedPI really feel the lightly embalmed cadaver sessions help me to understand and connect information that we learn in class. TagedPThe explanations were very good. TagedPI really appreciate having more time using the US. TagedPReally cool to get hands-on time.
TRAINING WITH LIGHTLY EMBALMED CADAVERS
TagedPThis was well organized and an appropriate length of time. It was a lot of fun too. TagedPSuggestions: TagedPI would of course love longer session times to maybe take another biopsy on each cadaver, but I understand that for time purposes that may not be allowable. TagedPI think time restraint was the only issue. TagedPIt might be possible to put more students into each session, however the smaller groups allow for more hands on interaction.
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Radiologic Resident Education
Lightly Embalmed Cadavers as a Training Tool for Ultrasound-Guided Procedures Commonly Used in Interventional Radiology TagedPMary E. (Mollie) Meek, MD, James C. Meek, DO, Blake Hollowoa, BS, Ruizong Li, MD, Linda A. Deloney, EdD, Kevin D. Phelan, PhD
TagedPAbbreviations US Ultrasound IR Interventional Radiology WA Washington USA United States of America
Rationale and Objectives: TagedPCompetency in ultrasound (US) imaging and US-guided procedures is often difficult for medical students and residents to master. The use of simulation training has been strongly encouraged but the quality of phantom models available for US-guided procedures is limited. As a feasible alternative, we describe the innovative use of a lightly embalmed cadaver for realistic practice of common interventional radiology (IR) procedures prior to direct patient care. Materials and Methods: L TagedP ightly embalmed cadavers were positioned as patients would be in the IR suite: supine, prone, and erect seated position. Lidocaine was injected and visualized under standard percutaneous techniques and sonographic guidance was used to simulate common US-guided procedures performed in IR including liver biopsy, kidney biopsy, thoracentesis, and vascular access. Results: TagedPThe ability to position cadavers was a key factor that allowed entire procedures to be simulated. Medical students with very limited exposure to US imaging and diagnostic radiology residents with minimal exposure to US imaging successfully completed common US-guided procedures. Arterial and venous vascular access was obtained. Wires were passed and catheters easily placed via both access sites. The texture of the tissue layers provided realistic feedback for the trainees as they advanced the needle or dilated the tissues. Images from each simulated procedure resembled images expected in a living patient. Conclusion: L TagedP ightly embalmed cadavers are an innovative and feasible tool to simulate common IR USguided procedures in a realistic fashion for deliberate practice in advance of first-attempt encounters with patients. TagedPKey Words: Radiology; Image-guided procedures; Interventional radiology; Lightly embalmed cadaver; Medical education; Simulation; Ultrasound-guided procedures. © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
Acad Radiol 2018; &:1 7 Grant Funding: None. Preliminary findings were presented as Educational Exhibit Abstract No. 521 at the Society of Interventional Radiology Annual Meeting in Vancouver British Columbia, Canada, April 2-7, 2016 by Sam McMurry, DO, Diagnostic Radiology Class of 2016. From the University of Arkansas for Medical Sciences, Little Rock, Arkansas (M.E.(M.)M.); Interventional Radiology Division, University of Arkansas for Medical Sciences, Little Rock, Arkansas (J.C.M., R.L.); College of Medicine, MS4, University of Arkansas for Medical Sciences, Little Rock, Arkansas (B.H.); Department of Radiology, University of Arkansas for Medical Sciences, 4301 W. Markham, #556, Little Rock, AR 72205 (L.A.D.); Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas (K.D.P.). Received February 15, 2018; revised May 23, 2018; accepted May 24, 2018. Address correspondence to: L.D. e-mail: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected] © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.acra.2018.05.019
TAGEDH1INTRODUCTIONTAGEDN
C
ompetency in ultrasound (US) imaging and USguided procedures is a fundamental skill required for interventional radiology (IR) physicians but often difficult for trainees to master. Although the use of USguided procedures in the field of medicine has drastically increased in recent years, students are minimally exposed to US during medical school (1,2). IR procedures are classically taught via literature, simulations, and demonstration before trainees attempt procedures under direct observation. Attempting IR procedures when patients are awake or minimally sedated creates apprehension in patients which in turn increases the resident’s anxiety and can lead to mistakes in technique, medical errors, and less effective teaching. As a 1
ARTICLE IN PRESS MEEK ET AL
learning experience, this approach limits open communication, instruction, and experimentation the resident needs to develop the appropriate skill set. TagedPThe use of simulation to achieve excellence and safety in IR patient care has been strongly encouraged (3). Hours spent in deliberate practice, intentionally repeating an activity in order to improve performance or master a task, have correlated with the development of expertise. Simulation allows deliberate practice in a safe environment, as often as needed for mastery learning, without jeopardizing patient safety (4,5). Combined with immediate feedback and self-evaluation, deliberate practice requires effort, and, though not innately enjoyable, can reduce training time and be more effective than nonfocused training (4). With permission to fail and correct mistakes remote from patients, novice operators can practice common percutaneous procedures that range in complexity from superficial skin punctures to biopsies, aspirations, and central venous access. Likewise, experts can refresh old skills and learn new ones. TagedPAs time for training and practice becomes increasingly limited, simulation can maximize the productivity of educational time. Obstetric/gynecology residents significantly improved laparoscopic surgical techniques in a relatively short amount of time in a cadaver training program (6). Radiology residents who had a 30-minute training session with an abdominal imaging phantom reported improved overall procedure time, number of skin punctures, and needle adjustments, and subjective performance compared to residents who did not have the training session (7). Simulation allows trainees to master basic skills through deliberate practice and then use their time with patients to learn complex skills. For example, a trainee might perform 10 procedures in 1 hour of simulation while the same number of procedures on live patients could take 10 hours or more. TagedPSuccessful adoption of a simulation strategy requires understanding the strengths and limitations of simulators, determining and improving their effectiveness, and establishing standards for documentation (3). In medical education, simulation uses lifelike mannequins, physical models, standardized patients, or computers to replicate real health encounters (8). A variety of US simulators have been used in IR with differing degrees of sophistication. Primitive simulators, such as home-made or manufactured gelatin molds, have been used to replicate image guided biopsy and USguided vascular access training has been achieved with phantom models (CAE Blue Phantom, Redmond, Washington) (3,7,9,10). Computer-based simulators are the most sophisticated, providing a virtual reality where trainees must complete complex tasks. The Vascular Interventional Surgical Trainer (VIST-VR, Mentice, Gothenburg, Sweden) and ANGIO Mentor (Simbionix Ltd, Lod, Israel) allow catheterbased endovascular simulation. Benefits of computer simulators include: use of virtual fluoroscopy, physical manipulation of guidewires, ability to replicate complex vasculature, and providing objective measures (ie time) useful in evaluating trainees. Compared to no intervention, simulation training 2
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TagedPhas shown improvements in knowledge, skill, and patientrelated outcomes (11). While these endovascular simulators are suitable to train cognitive steps, evidence supporting their validity in training fine motor actions is insufficient (12). Phantom models bear little resemblance to live patients and the replication of real human tissue is subpar (1). Despite advancements in simulation, the human body remains the best tool for mastering a skill (12). TagedPCadaveric dissection has been used in medical education for centuries and is an essential tool for understanding the human body, but applications are limited. Fresh cadavers are most realistic but, because they only last about two weeks, they cannot feasibly be used for multiple training sessions (13). Unembalmed bodies deteriorate rapidly, and possible associated health hazards are usually considered unacceptable. Although unembalmed cadavers can be frozen for later use, freezing spoils their texture and deterioration is suspended only as long as they remain frozen (13). TagedPTraditional embalming techniques are also unable to produce high-fidelity training models. They leave the body stiff and fail to preserve the tissue in a life-like manner. Their inflexibility prevents appropriately positioning the cadavers as needed in IR training (14). In traditionally embalmed cadavers preserved with formaldehyde, tissues become rigid and organs and structures are difficult to distinguish, and this leads to poor image quality (14). TagedPThe light embalming technique preserves the cadaver in a life-like manner and provides the most realistic training model available. Tissue of lightly embalmed cadavers is much more like living tissue and provides a better model for simulating surgical procedures and techniques, allowing entire procedures to be replicated (13). In particular, the light embalming technique maintains the US anatomy and the ability to manipulate the cadaver into a variety of positions, simulating patient mobility (1). These cadavers can be kept in a refrigeration unit with negligible loss of tissue quality and color. Lightly embalmed cadavers typically last 8 10 weeks before deterioration begins to make them unsuitable for training purposes (13). TagedPThe technique, as first described by Anderson, consists of three major components: a preinjection chemical, embalming fluid, and a dye (13). The technique differs from traditional embalming in three ways: weaker embalming fluid is used, lower volumes are used, and the fluid is not allowed to accumulate (13). This allows for the cadaver to be positioned as needed,. The method is cost-effective, comparable to the traditional embalming method. The lightly embalmed cadavers must be refrigerated between uses. TagedPThe literature on lightly embalmed cadavers in medical education is sparse. Reports of lightly embalmed cadavers as patient simulators include realistic simulation of central venous access (15) and orotracheal intubation (16). First-year medical, physician assistant, and physical therapy students reported increased confidence and clinical competence after hands-on cadaver training (17). Surgical residents consistently rated an open surgical skills program using lightly embalmed
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TagedPcadavers the highest among their training activities (14). Lightly embalmed cadavers created an excellent model for mimicking the sonographic appearance of pneumothorax (18). The use of lightly embalmed cadavers in IR training has not been previously described. TagedPFor this pilot study, we investigated the feasibility of using lightly embalmed cadavers in a controlled environment as a training model to improve the knowledge, technical ability, and confidence of novice trainees performing common IR procedures. This single-center study, conducted at an academic medical center, was conducted in a gross anatomy laboratory using normal educational practices. The study was classified exempt by the university’s Institutional Review Board. TAGEDH1MATERIALS AND METHODSTAGEDN TagedPTraining workshops using lightly embalmed cadavers were conducted. First-year medical students were recruited via email to participate in training using US-guided placement of central venous lines (2014) and for US-guided kidney and liver biopsy (2018). The medical students had some familiarity with positioning techniques since radiologists in our department facilitate an introductory US-guidance session in their first-year Gross Anatomy Human Structures Course. Diagnostic radiology residents with minimal exposure to US imaging and IR procedures were recruited to perform simulated biopsies, thoracentesis, and vascular access (2016). TagedPLightly embalmed cadavers were prepared as previously reported (13) from anatomical gift donors acquired within 3 days of death. Blood work was obtained on each cadaver to exclude any cadaver with evidence of HIV or hepatitis A, B, or C. All cadavers were stored in the refrigeration unit between uses.
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TagedPFor each workshop, cadavers were positioned on a dissection table as they would be in the IR department including supine, prone, and erect seated positions. Due to the flexibility of the tissue, lidocaine was injected and visualized under US. Standard percutaneous techniques and US-guidance were used to simulate liver biopsy (supine) and kidney biopsy (prone). The cadaver was placed in a seated position for USguided thoracentesis. The Seldinger wire technique to obtain access to blood vessels and other hollow organs was reviewed before vascular access was attempted. Hands-on performance was supervised by IR faculty, fellows, and senior residents. Trainees controlled the US probe with the assistance of experienced IR practitioners. Attempts for medical students were time limited due to the size of the class, but the learning objective was to introduce them to US-guided techniques, not to master procedures. In general, participants simulated each procedure one time. TagedPAt the conclusion of each medical student workshop, participants were asked to evaluate the learning experience by rating their perception of the session’s organization and structure, satisfaction with the lightly embalmed cadaver as a learning tool, the clinical relevance of the training, the presenter’s knowledge of the topic, and the overall quality of the session. TAGEDH1RESULTSTAGEDN TagedPUS images from each simulated procedure resembled images expected from a living patient (Figs 1 5). Some were not as clear and detailed of those of live patients, but were comparable overall. The ability to position the cadavers in various positions was a key factor that allowed entire procedures to be simulated. Arterial vascular access was obtained in the
Figure 1. (a) Common carotid artery (green arrow) and partially compressed internal jugular vein (red arrow). (b) Common carotid artery (green arrow) and echogenic needle in the internal jugular vein (red arrow) of a lightly embalmed cadaver. (Color version of figure is available online.)
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Figure 2. (a) Common femoral artery (red arrow). (b) Echogenic needle in the common femoral artery (red arrow) of a lightly embalmed cadaver. (Color version of figure is available online.)
TagedPcommon femoral artery. Wires were passed and catheters easily placed via both access sites. The texture of the tissue layers provided realistic feedback for the learners as they advanced the needle or dilated the tissues. Pleural fluid was easily identified and needle passage was visualized under US guidance with the cadaver in a seated position. Images of the kidneys showed remarkable US anatomy preservation that allowed for training in US-guided renal procedures. TagedPIn our first workshop, 31 first-year medical students successfully completed US-guided placement of a central venous line. Of these students, 16 (61% response rate) provided information regarding their experience (Table 1) Notably, 100% “strongly agreed” the lightly embalmed cadaver was a “great” learning tool (5.00 § 0.00). In our second workshop, 8 diagnostic radiology residents successfully completed US-guided biopsy of the liver. They
TagedPprovided anecdotal information about their experience, agreeing with medical students that the lightly embalmed cadaver was a “great” learning tool. Our third workshop attracted 55 first-year medical students to perform USguided liver and kidney biopsies. Satisfaction with the training was again high. Of the 55 participants, 29 completed the evaluation (53% response rate) and “strongly agreed (93%) or “agreed (7%) the lightly embalmed cadaver was a “great” learning tool. (Table 2). One self-efficacy question was added to their evaluation and, with the exception of one medical student, participants “strongly agreed” (62%) or “agreed” (35%) they were more confident of their ability to perform US-guided procedures after the session. We also asked the medical students to offer comments and suggestions for improvement. Representative comments are displayed in Appendix A.
Figure 3. (a) US of a liver in a lightly embalmed cadaver. (b) Echogenic needle in the liver of a lightly embalmed cadaver (red arrow). (Color version of figure is available online.)
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Figure 4. (a) US showing the right pleural space in a lightly embalmed cadaver. (b) Echogenic needle in the right pleural space (red arrow) of a lightly embalmed cadaver. (Color version of figure is available online.)
TAGEDH1DISCUSSIONTAGEDN TagedPOur experience confirms that lightly embalmed cadavers are realistic simulators for practicing common US-guided procedures prior to direct patient care. The ability to position the cadavers was a key factor that allowed entire procedures to be simulated. For medical students, the combination of cadaveric and radiographic anatomy makes these preclinical lessons particularly relevant to future clinical training. TagedPLimitations of this pilot study are its small size and the single site. No demographic information was collected and it is impossible to account for potential differences in perceptions among trainees. Because medical student participants were self-selected volunteers, results may be subject to voluntary response bias. Comparisons of images to living patient images and tissue to living tissue are anecdotal. Trainees were not asked about image quality and there was no review by experts (sonographers/IR physicians). Similarly, no data about “the feel” was collected from experts who could compare the
TagedPcadaver tissue to living tissue. These comparisons could be included in future studies. TagedPSeveral factors impact the ability of a physician to successfully execute clinical IR procedures, including knowledge of the anatomy related to the procedure, understanding procedural details, technical skill and ability, familiarity with instruments and devices, and experience. Traditional training may leave gaps in the acquisition of any or all of these aspects. Cadaver training can be used successfully to close many, if not all, of these performance gaps. When practicing in a realistic environment, trainees can problem solve and refine techniques without putting patients at risk. They can attempt needle passes multiple times, improving or failing without negative consequences. Cadaver training can expose common mistakes and prevent inappropriately learned techniques
TABLE 1. First-Year Medical Student (M1) Evaluation of USGuided Central Venous Line Placement on Lightly Embalmed Cadavers (2014) Mean § Standard error of the mean (n = 16) 1. The session was well organized and material presented in a logical sequence 2. The lightly embalmed cadaver was a great learning tool 3. The information presented was clinically relevant 4 The presenter was knowledgeable in the topic 5. The overall quality of this session was outstanding 6. I would recommend this session to M1 students next year
Figure 5. Renal US showing a transverse view of the interpolar region of the kidney with the caudal aspect of the right lobe of the liver in a lightly embalmed cadaver.
4.47 § 0.14
5.00 § 0.00 4.89 § 0.07 4.84 § 0.09 4.58 § 0.14 4.79 § 0.12
Rating scale: 5—Strongly agree; 4—Agree; 3—Neither Agree or Disagree; 2—Disagree; 1—Strongly Disagree.
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TABLE 2. First-Year Medical Student (M1) Evaluation of US Guided Liver and Kidney Biopsy on Lightly Embalmed Cadavers (2018) Mean § Standard error of the mean (n = 29) 1. The session was well organized and material presented in a logical sequence 2. The lightly embalmed cadaver was a great learning tool 3. The information presented was clinically relevant 4. The presenter was knowledgeable in the topic 5. The overall quality of this session was outstanding 6. I would recommend this session to M1 students next year 7. As a result of this session, I feel more confident in my ability to perform US-guided procedures.
4.76 § 0.44
4.93 § 0.26 4.86 § 0.44 4.90 § 0.31 4.76 § 0.44 4.90 § 0.31 4.59 § 0.57
Rating scale: 5 —Strongly agree; 4—Agree; 3—Neither Agree or Disagree; 2—Disagree; 1—Strongly Disagree.
TagedPfrom making their way into the angiography suite. Common mistakes can be used as teaching points for other trainees. TagedPAll IR physicians must be aware of the limits of their practice and the circumstances under which they act independently (19). Cadaver training programs can help IR physicians keep up with their rapidly evolving specialty (8,19). Physicians can be given the opportunity to learn and perform state-of-the-art procedures they had not previously been exposed to, giving them a greater variety of treatment options for their patients. Attempting new procedures on a nonliving subject would likely improve outcomes and reduce complications associated with first attempts in patients. Lightly embalmed cadavers can be a cost-effective method to achieve such high-fidelity training, while maximizing the time spent in deliberate practice. TagedPThe greatest benefit of this training method may be decreased adverse events caused by medical or technical error. Medical students and residents—and even fellows and practitioners—can improve their technical ability and procedural knowledge, potentially leading to improved performance, and decreased complications. Hands-on educational experiences, fundamental to the IR curriculum, stimulate learner engagement, and enhance the development of clinical skills. Hands-on training with a lightly embalmed cadaver reduces the risks associated with learning on patients. Further study is
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TagedPneeded to determine optimal uses for the lightly embalmed cadaver as a training tool in medical education.
TAGEDH1REFERENCESTAGEDN TagedP 1. Miller R, Ho H, Ng V, et al. Introducing a fresh cadaver model for ultrasound-guided central venous access training in undergraduate medical education. West J Emerg Med 2016; 17:362–366. TagedP 2. Hoffman L, Wadman MC, Erickson T, et al. Self-reported EM residency applicant attitudes towards a procedural cadaver laboratory curriculum. West J Emerg Med 2008; 9:141–145. TagedP 3. Gould D. Using simulation for interventional radiology training. Br J Radiol 2010; 83:546–553. TagedP 4. Ericsson KA. Deliberate practice and acquisition of expert performance: a general overview. Acad Emerg Med 2008; 15:988–994. TagedP 5. Kneebone R. Evaluating clinical simulations for learning procedural skills: a theory-based approach. Acad Med 2005; 23(5):549–553. TagedP 6. Levine RL, Kives S, Cathey G, et al. The use of lightly embalmed (fresh tissue) cadavers for resideny laproscopic training. J Minim Invasive Gynecol 2006; 13:451–456. TagedP 7. Fulton N, Buethe J, Gollamudi J, et al. Simulation-based training may improve resident skill in ultrasound-guided biopsy. AJR 2016; 207:1329– 1333. TagedP 8. Passiment M, Sacks H, Huang G. Medical simulation in medical education: results of an AAMC survey. Assoc Am Med Coll Rep 2011 . Available at: https://www.aamc.org/download/259760/data. Accessed February 7, 2017. TagedP 9. Baadh A, Fadl A, Georgiou N, et al. A pilot program for use of a homemade phantom for CT biopsy simulation training. JVIR 2015; 26:S167. TagedP10. Ball R, Scouras N, Orebaugh S, et al. Randomized, prospective, observational simulation study comparing residents’ needle-guided vs freehand ultrasound technique for central venous catheter access. Br J Anaesth 2012; 108:72–79. TagedP11. Cook DA, Hatala R, Brydges R, et al. Technology-enhanced simulation for health professions education: a systematic review and meta-analysis. JAMA 2011; 306:978–988. TagedP12. Lewandowski W, Gould D. A summary of the subjective opinions of interventional radiologist regarding selected medical simulations. Available from: http://www.whichinterventionaldevice.com/product-categories/ simulators.aspx. Accessed February 13, 2017. TagedP13. Anderson SD. Practical light embalming technique for use in the surgical fresh tissue dissection laboratory. Clin Anat 2006; 19:8–11. TagedP14. Cork K. UNMC's 'lightly embalmed' cadaver program provides innovative learning tool. UNMC Depart Pharmacol/Exp\ Neurosci 2015. Available at https://www.unmc.edu/news.cfm?match=16295. Accessed April 12, 2018. TagedP15. Wadman MC, Lomneth CS, Hoffman LH, et al. Assessment of a new model for femoral ultrasound-guided central venous access procedural training: a pilot study. Acad Emerg Med 2010; 17:88–92. TagedP16. Wadman M, Nicholas TA, Bernhagen MA, et al. A comparison of an integrated suction blade versus a traditional videolaryngoscope blade in the endotracheal intubation of a hemorrhagic cadaver model: a pilot study. Stud Health Technol Inform 2012; 173:534–536. TagedP17. Keim Janssen SA, VanderMeulen SP, Shostrom VK, et al. Enhancement of anatomical learning and developing clinical competence of first-year medical and allied health profession students. Anat Sci Educ 2014; 7:181–190. TagedP18. Adhikari S, Zeger W, Wadman M, et al. Assessment of a human cadaver model for training emergency medicine residents in the ultrasound diagnosis of pneumothorax. Biomed Res Int 2014 :724050. TagedP19. Siragusa DA, Cardella JF, Hieb RA, et al. Requirements for training in interventional radiology. JVIR 2013; 24:1609–1612.
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TAGEDH1APPENDIX A. MEDICAL STUDENT COMMENTS AND SUGGESTIONSTAGEDN TagedPComments: TagedPI'd rate the session an 11 out of 10 any day. TagedPIt was pretty useful and very interesting to get to try. TagedPI really feel the lightly embalmed cadaver sessions help me to understand and connect information that we learn in class. TagedPThe explanations were very good. TagedPI really appreciate having more time using the US. TagedPReally cool to get hands-on time.
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TagedPThis was well organized and an appropriate length of time. It was a lot of fun too. TagedPSuggestions: TagedPI would of course love longer session times to maybe take another biopsy on each cadaver, but I understand that for time purposes that may not be allowable. TagedPI think time restraint was the only issue. TagedPIt might be possible to put more students into each session, however the smaller groups allow for more hands on interaction.
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