- Email: [email protected]
Central Venous Catheterization Using a Perfused Human Cadaveric Model: Application to Surgical Education
ORIGINAL REPORTS
Central Venous Catheterization Using a Perfused Human Cadaveric Model: Application to Surgical Education Stephen Varga, MD,* Jennifer Smith, MD,† Michael Minneti, BA,† Joseph Carey, MD,† Scott Zakaluzny, MD,† Thomas Noguchi, MD,† Demetrios Demetriades, PhD,† and Peep Talving, PhD† *
Trauma and Acute Care Surgery, Surgical Critical Care, Department of Surgery, San Antonio Military Medical Center, San Antonio, Texas; and †Los Angeles County and University of Southern California Medical Center Fresh Tissue Dissection Laboratory, Los Angeles, California OBJECTIVE: The purpose of this article is to present a unique training model using a perfused human cadaver for central line placement training with the ultimate goal of reducing central venous catheter mechanical complications. DESIGN: The applicability of the fresh tissue cadaver model
for central line placement was assessed using a 10-item questionnaire with a 5-point Likert-type scale. Respondents were asked to rate their opinions as strongly agree, agree, neutral, disagree, or strongly disagree. SETTING: All participants received a didactic lecture followed by supervised practice on a commercially available simulator. The students were then relocated to the Fresh Tissue Dissection Laboratory where they practiced central vein catheterization on a fresh perfused human cadaver. PARTICIPANTS: Course participants included 87 physicians from various medical specialties at different stages of training. RESULTS: Results of the survey demonstrated that 91% of
the participating physicians found the perfused cadaveric model to be a true simulation of conditions that exist in live patients, and 98% reported that the use of this model promoted acquisition of technical skills. CONCLUSION: The integration of central line placement
training on perfused cadavers into residency and fellowship training provides an unparalleled realistic simulation to participants. Further study is needed to assess whether realistic simulation translates into objective end points such as decreased mechanical complications. ( J Surg 72:28-32. Correspondence: Inquiries to Stephen Varga, MD, Department of Surgery, San Antonio Military Medical Center, 3551 Roger Brooke Drive, Ft. Sam Houston, TX 78234; fax: (210) 916-9148; E-mail: [email protected], [email protected]
28
Published by Elsevier Inc on behalf of the Association of Program Directors in Surgery) KEY WORDS: central line education, surgical education,
cadaver model, resident training COMPETENCIES: Patient Care, Medical Knowledge, Practice-Based Learning and Improvement
BACKGROUND Complications following medical procedures are a significant cause of morbidity and mortality.1 The Halstedian “see one, do one, teach one” model of procedural education is no longer acceptable. This type of training is unstructured and allows for great variation among learners. To counter these concerns, the use of simulation for procedural education has recently been increasing. Simulators allow residents to practice procedures in a controlled environment before performing them on patients. The placement of central venous catheters is a common procedure performed in hospitalized patients. Central line simulators have been developed to aid in the education of trainees. These simulators have been shown to improve selfreported confidence and decrease the rates of procedurerelated complications.2-5 However, commercially available central line simulators are limited in functionality. Although they allow residents to learn the technical steps necessary to perform the task, they lack the ability to demonstrate normal anatomic variations found in clinical practice and have poor tissue haptics.6 With the addition of perfused human cadavers into central line training, tissue texture and elasticity are preserved. To fully use all available techniques, we developed a
Journal of Surgical Education Published by Elsevier Inc on behalf of the Association of Program Directors in Surgery
1931-7204/$30.00 http://dx.doi.org/10.1016/j.jsurg.2014.07.005
central line training model that involves the use of didactic lectures followed by practice on simulation models. Once procedural competence on a model is demonstrated, the procedure is performed on a perfused fresh human cadaver to further simulate clinical practice. The purpose of this article is to present a unique training model using a perfused human cadaver in a functional simulation, providing a lifelike environment for more realistic and practical central line training. By adding this experience to the current curriculum, we hope to broaden the educational experience of participants with the ultimate goal of reducing central line procedure–related complications and improving patient care.
minute. During the central line instruction sessions, the arterial pressure is minimally adjusted while the venous pressure is maintained at approximately 15 mm Hg with serial clamping and unclamping of the venous circuit. The applicability of the fresh tissue cadaver model for simulation of real-life central line placement was assessed using a short questionnaire completed by all course participants. The survey was designed to determine the participant’s opinions regarding the utility of the model as a true simulation of the procedure on live patients and its value compared with the simulation model training. This questionnaire was adapted from other cadaver simulation studies and used a 5-point Likert-type scale in which respondents were asked to rate their opinions on 10 items as strongly agree, agree, neutral, disagree, or strongly disagree.8
METHODS The 87 course participants represented different medical specialties including surgery, emergency medicine, internal medicine, anesthesia, and pulmonary critical care. The students comprised interns, residents, and fellows. All participants began the course with a didactic lecture on central line placement including a review of anatomy, discussion of indications and contraindications for central venous access, site selection, technical performance instruction with both ultrasound guidance and anatomic landmarks, how to avoid common pitfalls, and how to trouble shoot encountered problems. Following the lecture, students assembled into small groups and attempted catheterization on a commercially available simulation model with direct supervision from instructors. Students practiced placing catheters using anatomic landmarks for internal jugular, subclavian, and femoral vessels as well as using ultrasound guidance techniques for the internal jugular and femoral vessels. After students demonstrated proficiency on the commercial model, they were relocated to the Fresh Tissue Dissection Laboratory where they performed the same skills on fresh, perfused human cadavers. All bodies were donated by the Los Angeles County Coroner’s Office. Cadavers admitted to the Fresh Tissue Dissection Laboratory at the Los Angeles County and University of Southern California Keck School of Medicine are acquired and maintained in compliance with hospital policy and California law. Preparation of the cadavers for educational use is performed by our laboratory technician and manager. The complete step-by-step methodologic preparation is available for review in Appendix A and the Figure. Briefly, the femoral artery and vein are cannulated and conditioned in a method adapted from other published perfusion models.7 Arterial and venous perfusate consists of tap water and nontoxic red- and blue-pigmented concentrate. The arterial cannula tubing is attached to a centrifugal pump. The cadaver vasculature is then pressurized to a mean venous pressure of 15 mm Hg and a mean arterial pressure of 80 mm Hg by increasing the revolutions per
RESULTS A total of 87 physicians participated in this simulation program and completed the questionnaire (Table). Of these participants, 91% agreed or strongly agreed that the perfused cadaver was a true simulation of the conditions they would encounter in live patients, 98% agreed or strongly agreed that the human perfused cadaver promoted acquisition of technical skills, and 94% believed that the model offered benefits not available in existing central line training models. Interestingly, 44% disagreed that a disadvantage of the cadaver model is that the tissue characteristics are different compared with living tissue; most thought that the tissue characteristics were either not different or that the difference was not a disadvantage. Moreover, 98% of the participants agreed or strongly agreed that the perfused human cadaver model is a valuable addition to current models in central line placement, and 95% agreed or strongly agreed that the cadaver model could improve current training. In addition, 67% of learners disagreed or strongly disagreed that the model did not add to central line training in general; roughly one-fourth of learners thought that the perfused model did not add to central line training. Furthermore, 83% thought the perfused cadaver could completely replace the use of mannequins in central line education. Overall, 99% of learners would recommend this training method to a colleague, and 98% would integrate this model into their training program.
DISCUSSION With the evolution of surgical education, stricter regulation regarding supervision, and limitations on work hours, a dilemma arises as to how to teach the next generation of physicians in a safe and efficient manner.9,10 Simulationbased training has been shown to provide benefits to the learner and patient outcomes. It is well known and
Journal of Surgical Education Volume 72/Number 1 January/February 2015
29
FIGURE. Venous Perfusion Model.
TABLE. Survey Questions With Number of Responses (%) Question This model was a true simulation of the conditions of live patients This model promotes the acquisition of technical skills This model offers benefits not available in existing central line training models A disadvantage to this model is that the tissue characteristics are very different than that of living tissue This model is a valuable addition to current methods in central line education This model could significantly improve current training in central line placement This model does not add significantly to central line training in general This model could replace the use of mannequins in central line education I would recommend this training method to my colleagues If it were available, I would integrate this model into my training program 30
Strongly Disagree
Disagree
1 (1.1)
1 (1.1)
6 (7)
47 (54)
32 (36.8)
0 0
0 1 (1.1)
2 (2.3) 4 (4.6)
28 (32.2) 23 (26.4)
57 (65.5) 59 (67.9)
21 (24.1)
23 (26.4)
10 (11.5)
6 (7)
27 (31)
Neutral
Agree
Strongly Agree
0
1 (1.1)
1 (1.1)
25 (28.7)
60 (69)
0
0
4 (4.6)
24 (27.6)
59 (67.8)
30 (34.5)
36 (41.4)
2 (2.3)
6 (6.9)
13 (14.9)
0
11 (12.6)
4 (4.6)
29 (33.3)
43 (49.4)
0 0
0 0
1 (1.1) 2 (2.3)
21 (24.1) 21 (24.1)
65 (74.8) 64 (73.6)
Journal of Surgical Education Volume 72/Number 1 January/February 2015
previously published that the more experienced the operator, the fewer the number of complications and the greater the number of early successful central venous cannulations.2-5,11 Simulator-trained residents have fewer needle passes, pneumothoraces, and catheter adjustments and higher success rates.4,5,11 In a study done by Barsuk et al., residents underwent simulation-based training for central line insertion. Before the simulation training, they were given a pretest, which demonstrated that only 14% of residents met minimum passing score for subclavian insertion. After simulation training, they were given a posttest demonstrating that all of the participants met or exceeded the minimum passing score.11 Although the simulator allowed residents to learn the technical steps necessary to perform the task, it lacked the ability to demonstrate normal anatomic variations found in clinical practice and had poor tissue haptics.6 Therefore, the development of a model more representative of real patient conditions using fresh, perfused cadavers should arguably be superior. Use of fresh cadavers to train medical personnel has been used for centuries, and interest in this methodology for surgical education has returned with the implementation of the work-hour restrictions placed on trainees. The use of animal models can be beneficial in that the tissue closely resembles human tissue; however, more often than not, the anatomic comparison to humans falls short. Commercially available simulators provide a means to practice basic surgical skills and are reproducible but tend to be costly and inaccurate with respect to anatomic variation or replication of tissue consistency. For these reasons, there has been a resurgence of interest in using fresh cadavers for surgical education. The benefits are clear with respect to tactile feedback and anatomic accuracy. The addition of perfusion to the model allows the trainee to receive immediate feedback regarding their success at cannulation. If the aspirated fluid is bright red, they have been unsuccessful, and feedback is given to the learner to correct potential errors in their technical competency. If the aspirated fluid is dark blue, the trainee has been successful, and they gain further confidence in their ability to perform the procedure. By using the perfused cadaver model, the students gain the added benefit of anatomic variability. This is an added challenge in the cadavers, so students can learn how to place lines with varied anatomy and body habitus. Once a learner has placed a central line on a commercially available model, it is very easy to reproduce that success because all the models are structurally identical. However, by using the cadaveric model, the learner is forced to make adjustments in both thinking and technique as they would in real life to achieve successful cannulation. These data suggest that introducing a perfused, fresh cadaver simulator to current central line simulation training adds a more realistic and reproducible model to the learners education. The addition of this model will hopefully lead to decreased complication in the future. Although it is difficult
to demonstrate at this stage whether individual physicians have fewer procedure-related complications based on the number of procedures performed in the laboratory, it is clear that learner’s interest and confidence has improved significantly. Future research would do well to follow individual physicians over the course of their training to demonstrate that more practice on perfused cadavers translates to improved patient outcomes. The greatest limitation to this model is the access to fresh cadavers. The cost of the other materials used for the cannulation and perfusion of the cadavers is modest, but the cost of whole-body human cadavers may be prohibitive to some training institutions.12 Another limitation is the fact that a high-fidelity perfusion simulation would, ideally, have the look and feel of a true living patient; cadaveric tissue may have a similar feel to human tissue but it cannot replace true live tissue. Moreover, the solution used for perfusion is colored tap water, making the consistency much less than that of real blood. In addition, cadavers are nonembalmed and therefore fully pathogenic, so there is always the possibility of disease transmission with needle sticks when using the cadavers. The risk of disease transmission is limited by not selecting cadavers with a known history of communicable disease for use in the study and by using the standard personal protective equipment and safeguards for all sharps. Safety policies and risks are verbalized to all students before participation, and their consent to participate according to laboratory safety policies is documented. Finally, the perfusion model is relatively simple to set up as described in Appendix A and seen in the Figure, but there can be some technical challenges in maintaining the model. The main challenge is the need for intermittent clamping and unclamping of the infusion lines to maintain venous pressure of 10 to 15 mmHg to allow for adequate visualization and successful cannulation of the vessels; allowing continuous unregulated flow causes the bowels to become engorged and may limit the use of cadavers for other educational activities. The cadaver simulator is not meant to replace current model teaching but should be applied as the next step in central line training. The literature on simulator use demonstrates that the effectiveness of any simulator-based curriculum is dependent mainly on the curriculum rather than the simulator used.9,13 Didactic education followed by model training will help the learner to gain the basic techniques in performing the skill. The addition of the perfused fresh cadaver allows the learner to apply those basic skills in a more realistic environment with anatomic variability and in a model that more closely represents the learner’s patient before they perform central lines on live patients.
CONCLUSION The perfused fresh cadaver model adds a new dimension to central line training and creates a laboratory experience that
Journal of Surgical Education Volume 72/Number 1 January/February 2015
31
simulates placing central lines in live patients. The addition of a perfused cadaver model to central line training in this study increased the trainees’ experience and comfort level, allowed them to learn variable anatomy, demonstrated improved tactile sensation over standard model simulation, and may potentially lead to fewer central line complications in the future. The integration of central line placement training on perfused cadavers into residency and fellowship training provides an unparalleled realistic simulation to participants. Further study is needed to assess objective end points to determine translation into improved patient outcomes.
catheterization: a systematic review and meta-analysis. Acad Med. 2011;86(9):1137-1147. 6. Wadman MC, Lomneth CS, Hoffman LH, Zeger WG,
Lander LL, Walker RA. Assessment of a new model for femoral ultrasound-guided central venous access procedural training: a pilot study. Acad Emerg Med. 2010;17 (1):88-92. 7. Anderson SD. Practical light embalming technique for
use in the surgical fresh tissue dissection laboratory. Clin Anat. 2006;19(1):8-11. 8. Aboud ET, O’Keeffe T, Nader R, et al. Novel
simulation for training trauma surgeons. J Trauma. 2011;71(6):1484-1490.
REFERENCES 1. Leape LL, Brennan TA, Laird N, et al. The nature of
9. Kolozsvari
adverse events in hospitalized patients. Results of the Harvard Medical Practice Study II. N Eng J Med. 1991;324(6):377-384.
NO, Feldman LS, Vassiliou MC, Demyttenaere S, Hoover ML. Sim one, do one, teach one: considerations in designing training curricula for surgical simulation. J Surg Educ. 2011;68(5):421-427.
2. Barsuk JH, McGaghie WC, Cohen ER, Balachandran JS,
10. Resnick RK, MacRae H. Teaching surgical skills—
Wayne DB. Use of simulation-based mastery learning to improve the quality of central venous catheter placement in a medical intensive care unit. J Hosp Med. 2009;4 (7):397-403.
changes in the wind. N Engl J Med. 2006;355(25): 2664-2669.
3. Barsuk JH, Cohen ER, Feinglass J, McGaghie WC,
Wayne DB. Use of simulation-based education to reduce catheter-related bloodstream infections. Arch Intern Med. 2009;169(15):1420-1423. 4. Evans LV, Dodge KL, Shah TD, et al. Simulation
11. Barsuk JH, McGaghie WC, Cohen ER, O’Leary KJ,
Wayne DB. Simulation-based mastery learning reduces complications during central venous catheter insertion in medical intensive care unit. Crit Care Med. 2009;37(10):2697-2701. 12. Henry B, Clark P, Sudan R. Cost and logistics of
training in central venous catheter insertion: improved performance in clinical practice. Acad Med. 2010;85 (9):1462-1469.
implementing a tissue-based American College of Surgeons/Association of Program Directors in Surgery surgical skills curriculum for general surgery residents of all clinical years. Am J Surg. 2014;207(2):201-208.
5. Ma IW, Brindle ME, Ronksley PE, Lorenzetti DL,
13. Stefanidis D. Optimal acquisition and assessment of
Sauve RS, Ghali WA. Use of simulation-based education to improve outcomes of central venous
proficiency on simulators in surgery. Surg Clin North Am. 2010;90(3):475-489.
SUPPLEMENTARY DATA Supplementary data cited in this article is available online at doi:10.1016/j.jsurg.2014.07.005.
32
Journal of Surgical Education Volume 72/Number 1 January/February 2015
Central Venous Catheterization Using a Perfused Human Cadaveric Model: Application to Surgical Education Stephen Varga, MD,* Jennifer Smith, MD,† Michael Minneti, BA,† Joseph Carey, MD,† Scott Zakaluzny, MD,† Thomas Noguchi, MD,† Demetrios Demetriades, PhD,† and Peep Talving, PhD† *
Trauma and Acute Care Surgery, Surgical Critical Care, Department of Surgery, San Antonio Military Medical Center, San Antonio, Texas; and †Los Angeles County and University of Southern California Medical Center Fresh Tissue Dissection Laboratory, Los Angeles, California OBJECTIVE: The purpose of this article is to present a unique training model using a perfused human cadaver for central line placement training with the ultimate goal of reducing central venous catheter mechanical complications. DESIGN: The applicability of the fresh tissue cadaver model
for central line placement was assessed using a 10-item questionnaire with a 5-point Likert-type scale. Respondents were asked to rate their opinions as strongly agree, agree, neutral, disagree, or strongly disagree. SETTING: All participants received a didactic lecture followed by supervised practice on a commercially available simulator. The students were then relocated to the Fresh Tissue Dissection Laboratory where they practiced central vein catheterization on a fresh perfused human cadaver. PARTICIPANTS: Course participants included 87 physicians from various medical specialties at different stages of training. RESULTS: Results of the survey demonstrated that 91% of
the participating physicians found the perfused cadaveric model to be a true simulation of conditions that exist in live patients, and 98% reported that the use of this model promoted acquisition of technical skills. CONCLUSION: The integration of central line placement
training on perfused cadavers into residency and fellowship training provides an unparalleled realistic simulation to participants. Further study is needed to assess whether realistic simulation translates into objective end points such as decreased mechanical complications. ( J Surg 72:28-32. Correspondence: Inquiries to Stephen Varga, MD, Department of Surgery, San Antonio Military Medical Center, 3551 Roger Brooke Drive, Ft. Sam Houston, TX 78234; fax: (210) 916-9148; E-mail: [email protected], [email protected]
28
Published by Elsevier Inc on behalf of the Association of Program Directors in Surgery) KEY WORDS: central line education, surgical education,
cadaver model, resident training COMPETENCIES: Patient Care, Medical Knowledge, Practice-Based Learning and Improvement
BACKGROUND Complications following medical procedures are a significant cause of morbidity and mortality.1 The Halstedian “see one, do one, teach one” model of procedural education is no longer acceptable. This type of training is unstructured and allows for great variation among learners. To counter these concerns, the use of simulation for procedural education has recently been increasing. Simulators allow residents to practice procedures in a controlled environment before performing them on patients. The placement of central venous catheters is a common procedure performed in hospitalized patients. Central line simulators have been developed to aid in the education of trainees. These simulators have been shown to improve selfreported confidence and decrease the rates of procedurerelated complications.2-5 However, commercially available central line simulators are limited in functionality. Although they allow residents to learn the technical steps necessary to perform the task, they lack the ability to demonstrate normal anatomic variations found in clinical practice and have poor tissue haptics.6 With the addition of perfused human cadavers into central line training, tissue texture and elasticity are preserved. To fully use all available techniques, we developed a
Journal of Surgical Education Published by Elsevier Inc on behalf of the Association of Program Directors in Surgery
1931-7204/$30.00 http://dx.doi.org/10.1016/j.jsurg.2014.07.005
central line training model that involves the use of didactic lectures followed by practice on simulation models. Once procedural competence on a model is demonstrated, the procedure is performed on a perfused fresh human cadaver to further simulate clinical practice. The purpose of this article is to present a unique training model using a perfused human cadaver in a functional simulation, providing a lifelike environment for more realistic and practical central line training. By adding this experience to the current curriculum, we hope to broaden the educational experience of participants with the ultimate goal of reducing central line procedure–related complications and improving patient care.
minute. During the central line instruction sessions, the arterial pressure is minimally adjusted while the venous pressure is maintained at approximately 15 mm Hg with serial clamping and unclamping of the venous circuit. The applicability of the fresh tissue cadaver model for simulation of real-life central line placement was assessed using a short questionnaire completed by all course participants. The survey was designed to determine the participant’s opinions regarding the utility of the model as a true simulation of the procedure on live patients and its value compared with the simulation model training. This questionnaire was adapted from other cadaver simulation studies and used a 5-point Likert-type scale in which respondents were asked to rate their opinions on 10 items as strongly agree, agree, neutral, disagree, or strongly disagree.8
METHODS The 87 course participants represented different medical specialties including surgery, emergency medicine, internal medicine, anesthesia, and pulmonary critical care. The students comprised interns, residents, and fellows. All participants began the course with a didactic lecture on central line placement including a review of anatomy, discussion of indications and contraindications for central venous access, site selection, technical performance instruction with both ultrasound guidance and anatomic landmarks, how to avoid common pitfalls, and how to trouble shoot encountered problems. Following the lecture, students assembled into small groups and attempted catheterization on a commercially available simulation model with direct supervision from instructors. Students practiced placing catheters using anatomic landmarks for internal jugular, subclavian, and femoral vessels as well as using ultrasound guidance techniques for the internal jugular and femoral vessels. After students demonstrated proficiency on the commercial model, they were relocated to the Fresh Tissue Dissection Laboratory where they performed the same skills on fresh, perfused human cadavers. All bodies were donated by the Los Angeles County Coroner’s Office. Cadavers admitted to the Fresh Tissue Dissection Laboratory at the Los Angeles County and University of Southern California Keck School of Medicine are acquired and maintained in compliance with hospital policy and California law. Preparation of the cadavers for educational use is performed by our laboratory technician and manager. The complete step-by-step methodologic preparation is available for review in Appendix A and the Figure. Briefly, the femoral artery and vein are cannulated and conditioned in a method adapted from other published perfusion models.7 Arterial and venous perfusate consists of tap water and nontoxic red- and blue-pigmented concentrate. The arterial cannula tubing is attached to a centrifugal pump. The cadaver vasculature is then pressurized to a mean venous pressure of 15 mm Hg and a mean arterial pressure of 80 mm Hg by increasing the revolutions per
RESULTS A total of 87 physicians participated in this simulation program and completed the questionnaire (Table). Of these participants, 91% agreed or strongly agreed that the perfused cadaver was a true simulation of the conditions they would encounter in live patients, 98% agreed or strongly agreed that the human perfused cadaver promoted acquisition of technical skills, and 94% believed that the model offered benefits not available in existing central line training models. Interestingly, 44% disagreed that a disadvantage of the cadaver model is that the tissue characteristics are different compared with living tissue; most thought that the tissue characteristics were either not different or that the difference was not a disadvantage. Moreover, 98% of the participants agreed or strongly agreed that the perfused human cadaver model is a valuable addition to current models in central line placement, and 95% agreed or strongly agreed that the cadaver model could improve current training. In addition, 67% of learners disagreed or strongly disagreed that the model did not add to central line training in general; roughly one-fourth of learners thought that the perfused model did not add to central line training. Furthermore, 83% thought the perfused cadaver could completely replace the use of mannequins in central line education. Overall, 99% of learners would recommend this training method to a colleague, and 98% would integrate this model into their training program.
DISCUSSION With the evolution of surgical education, stricter regulation regarding supervision, and limitations on work hours, a dilemma arises as to how to teach the next generation of physicians in a safe and efficient manner.9,10 Simulationbased training has been shown to provide benefits to the learner and patient outcomes. It is well known and
Journal of Surgical Education Volume 72/Number 1 January/February 2015
29
FIGURE. Venous Perfusion Model.
TABLE. Survey Questions With Number of Responses (%) Question This model was a true simulation of the conditions of live patients This model promotes the acquisition of technical skills This model offers benefits not available in existing central line training models A disadvantage to this model is that the tissue characteristics are very different than that of living tissue This model is a valuable addition to current methods in central line education This model could significantly improve current training in central line placement This model does not add significantly to central line training in general This model could replace the use of mannequins in central line education I would recommend this training method to my colleagues If it were available, I would integrate this model into my training program 30
Strongly Disagree
Disagree
1 (1.1)
1 (1.1)
6 (7)
47 (54)
32 (36.8)
0 0
0 1 (1.1)
2 (2.3) 4 (4.6)
28 (32.2) 23 (26.4)
57 (65.5) 59 (67.9)
21 (24.1)
23 (26.4)
10 (11.5)
6 (7)
27 (31)
Neutral
Agree
Strongly Agree
0
1 (1.1)
1 (1.1)
25 (28.7)
60 (69)
0
0
4 (4.6)
24 (27.6)
59 (67.8)
30 (34.5)
36 (41.4)
2 (2.3)
6 (6.9)
13 (14.9)
0
11 (12.6)
4 (4.6)
29 (33.3)
43 (49.4)
0 0
0 0
1 (1.1) 2 (2.3)
21 (24.1) 21 (24.1)
65 (74.8) 64 (73.6)
Journal of Surgical Education Volume 72/Number 1 January/February 2015
previously published that the more experienced the operator, the fewer the number of complications and the greater the number of early successful central venous cannulations.2-5,11 Simulator-trained residents have fewer needle passes, pneumothoraces, and catheter adjustments and higher success rates.4,5,11 In a study done by Barsuk et al., residents underwent simulation-based training for central line insertion. Before the simulation training, they were given a pretest, which demonstrated that only 14% of residents met minimum passing score for subclavian insertion. After simulation training, they were given a posttest demonstrating that all of the participants met or exceeded the minimum passing score.11 Although the simulator allowed residents to learn the technical steps necessary to perform the task, it lacked the ability to demonstrate normal anatomic variations found in clinical practice and had poor tissue haptics.6 Therefore, the development of a model more representative of real patient conditions using fresh, perfused cadavers should arguably be superior. Use of fresh cadavers to train medical personnel has been used for centuries, and interest in this methodology for surgical education has returned with the implementation of the work-hour restrictions placed on trainees. The use of animal models can be beneficial in that the tissue closely resembles human tissue; however, more often than not, the anatomic comparison to humans falls short. Commercially available simulators provide a means to practice basic surgical skills and are reproducible but tend to be costly and inaccurate with respect to anatomic variation or replication of tissue consistency. For these reasons, there has been a resurgence of interest in using fresh cadavers for surgical education. The benefits are clear with respect to tactile feedback and anatomic accuracy. The addition of perfusion to the model allows the trainee to receive immediate feedback regarding their success at cannulation. If the aspirated fluid is bright red, they have been unsuccessful, and feedback is given to the learner to correct potential errors in their technical competency. If the aspirated fluid is dark blue, the trainee has been successful, and they gain further confidence in their ability to perform the procedure. By using the perfused cadaver model, the students gain the added benefit of anatomic variability. This is an added challenge in the cadavers, so students can learn how to place lines with varied anatomy and body habitus. Once a learner has placed a central line on a commercially available model, it is very easy to reproduce that success because all the models are structurally identical. However, by using the cadaveric model, the learner is forced to make adjustments in both thinking and technique as they would in real life to achieve successful cannulation. These data suggest that introducing a perfused, fresh cadaver simulator to current central line simulation training adds a more realistic and reproducible model to the learners education. The addition of this model will hopefully lead to decreased complication in the future. Although it is difficult
to demonstrate at this stage whether individual physicians have fewer procedure-related complications based on the number of procedures performed in the laboratory, it is clear that learner’s interest and confidence has improved significantly. Future research would do well to follow individual physicians over the course of their training to demonstrate that more practice on perfused cadavers translates to improved patient outcomes. The greatest limitation to this model is the access to fresh cadavers. The cost of the other materials used for the cannulation and perfusion of the cadavers is modest, but the cost of whole-body human cadavers may be prohibitive to some training institutions.12 Another limitation is the fact that a high-fidelity perfusion simulation would, ideally, have the look and feel of a true living patient; cadaveric tissue may have a similar feel to human tissue but it cannot replace true live tissue. Moreover, the solution used for perfusion is colored tap water, making the consistency much less than that of real blood. In addition, cadavers are nonembalmed and therefore fully pathogenic, so there is always the possibility of disease transmission with needle sticks when using the cadavers. The risk of disease transmission is limited by not selecting cadavers with a known history of communicable disease for use in the study and by using the standard personal protective equipment and safeguards for all sharps. Safety policies and risks are verbalized to all students before participation, and their consent to participate according to laboratory safety policies is documented. Finally, the perfusion model is relatively simple to set up as described in Appendix A and seen in the Figure, but there can be some technical challenges in maintaining the model. The main challenge is the need for intermittent clamping and unclamping of the infusion lines to maintain venous pressure of 10 to 15 mmHg to allow for adequate visualization and successful cannulation of the vessels; allowing continuous unregulated flow causes the bowels to become engorged and may limit the use of cadavers for other educational activities. The cadaver simulator is not meant to replace current model teaching but should be applied as the next step in central line training. The literature on simulator use demonstrates that the effectiveness of any simulator-based curriculum is dependent mainly on the curriculum rather than the simulator used.9,13 Didactic education followed by model training will help the learner to gain the basic techniques in performing the skill. The addition of the perfused fresh cadaver allows the learner to apply those basic skills in a more realistic environment with anatomic variability and in a model that more closely represents the learner’s patient before they perform central lines on live patients.
CONCLUSION The perfused fresh cadaver model adds a new dimension to central line training and creates a laboratory experience that
Journal of Surgical Education Volume 72/Number 1 January/February 2015
31
simulates placing central lines in live patients. The addition of a perfused cadaver model to central line training in this study increased the trainees’ experience and comfort level, allowed them to learn variable anatomy, demonstrated improved tactile sensation over standard model simulation, and may potentially lead to fewer central line complications in the future. The integration of central line placement training on perfused cadavers into residency and fellowship training provides an unparalleled realistic simulation to participants. Further study is needed to assess objective end points to determine translation into improved patient outcomes.
catheterization: a systematic review and meta-analysis. Acad Med. 2011;86(9):1137-1147. 6. Wadman MC, Lomneth CS, Hoffman LH, Zeger WG,
Lander LL, Walker RA. Assessment of a new model for femoral ultrasound-guided central venous access procedural training: a pilot study. Acad Emerg Med. 2010;17 (1):88-92. 7. Anderson SD. Practical light embalming technique for
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SUPPLEMENTARY DATA Supplementary data cited in this article is available online at doi:10.1016/j.jsurg.2014.07.005.
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Journal of Surgical Education Volume 72/Number 1 January/February 2015