SPECIAL ARTICLE
Simulation of Cardiopulmonary Bypass Management: An Approach to Resident Training Rex J. Morais, FFARCSI,* Balakrishnan Ashokka, FANZCA,† Chiang Siau, MMed,† and Lian Kah Ti, MMed†
S
IMULATION-BASED TRAINING is used in anesthesia in a variety of ways, such as task trainers for intubation and major vascular access, crisis resource management, transesophageal echocardiography (TEE), and screen-based simulation. The use of high-fidelity mannequin simulators in cardiac anesthesia training is somewhat limited by their inability to simulate the cardiopulmonary bypass (CPB) state. The programmed physiology of the Human Patient Simulator (HPS, Anesthesia Model CAE Healthcare, Sarasota, FL) does not allow the combination of an adequate perfusion pressure in the presence of asystole or serious arrhythmias such as ventricular fibrillation, which may exist during CPB. In a previously described HPSbased simulation scenario for cardiac anesthesia, which included patient management during CPB, the authors report keeping the actual scenario in “pause” mode for the period of CPB during the scenario. An external pressure input from a pressurized bag was fed in to demonstrate the perfusion pressure of CPB. During this period, common learning points related to management of the patient on CPB were discussed.1 The present article reports the design of a mannequin-based cardiac anesthesia simulation training (CAST) module to teach patient management during CPB and discontinuation of CPB and the authors’ experience of using it in anesthesia resident training. The adaptations enabled the scenario to be mannequin-based throughout without any break in the progression of the case, maintaining a degree of realism and allowing for clinical interventions. The modifications applied, the construction of the scenario, and its successful implementation are described. METHODS Halfway into their 1 month rotation in cardiac anesthesia, firstyear anesthesia residents underwent the CAST module. The training objectives were (1) to understand the impact of CPB on the underlying patho-physiology of coronary artery disease; (2) to recognize complications that may arise during the progression of CPB; (3) to be able to clarify individual roles of the operating team, specifically the anesthesiologist, surgeon, and perfusionist; and (4) to communicate clearly with the team to have a coordinated response in patient care. Four residents at a time underwent the training, and three sessions were conducted for a total of 12 residents. They were given pre-reading material outlining the principles of managing patients on CPB. On the day of CAST, written consent was obtained for audiovisual recording during the scenario and confidentiality of peer performance and module content. They were then given a set of 10 multiple choice questions (MCQ) to answer as a pretest. A short teaching session on the principles of CPB followed. The residents then were orientated to the simulation environment. A cardiac surgical operating room layout was set (Figs 1 and 2). A HPS was intubated and draped, with standard cardiac anesthetic monitoring in progress according to institutional practice. Participants in the scenario included a surgeon, a perfusionist,
and a scrub nurse, all playing their real-life roles. A separate screen displayed bispectral index (BIS), blood results, and TEE images or video clips at various stages, so that the resident anesthesiologist and the participants could interact to decide on management. The scenario was conducted in 2 parts. During the first part, 2 of the residents managed the anesthesia together, while the other 2 were observers. These roles were reversed for the second part of the scenario. The residents were instructed to take over the anesthetic management of a middle aged patient undergoing elective coronary artery revascularization, on cardiopulmonary bypass with the distal graft anastomoses in progress. The monitors at this time displayed asystole with MAP 70 mmHg, CVP 5 and nasal and rectal temperatures close to 34oC, with BIS around 44. As the case progressed, the following abnormalities were introduced in sequence: (1) respiratory alkalosis with severe hypokalemia, (2) BIS rising to 59 with rewarming, and (3) repeated ventricular fibrillation (VF) after aortic cross clamp release (Fig 3). They were expected to recognize and respond appropriately. With the VF, they were handed internal defibrillator paddle leads to connect and use in coordination with the surgeon. After rhythm stabilization and completion of the proximal anastomoses, the surgeon handed pacing leads to the residents to connect to and set up the pacemaker. At this point, the first part of the scenario ended and a short debriefing was done. For the second part of the scenario, the managing anesthesia residents were swapped with the observing residents. The scenario continued with the aortic cross clamp removed and pacing established. In preparing to wean from CPB, inotropic support was prepared as considered necessary and a check list of parameters (Table 1) before weaning was verified. The patient then was weaned gradually off CPB with coordinated actions from the team. Hemodynamic stability was expected to be achieved, by titrating preload and inotropes as required. TEE images were available to show volume status and contractility. Heparin reversal followed and protamine was administered according to institution protocol. Halfway through protamine administration, the scenario was programmed to show a drop in blood pressure, with a TEE clip of an under-filled ventricle being displayed. The trainees were expected to manage a possible type I protamine reaction and thereafter complete protamine administration. A short interval for hemostasis followed and the aorta was decannulated. Subsequently, the hemodynamics deteriorated, with a distending right heart on TEE image and the ECG remaining
From the *Department of Anesthesia; and †Yong Loo Lin School of Medicine, National University Healthcare System, Singapore, Singapore. Address reprint requests to Rex J. Morais, Department of Anesthesia, National University Healthcare System, 5 Lower Kent Ridge Road, Singapore 119074, Singapore. E-mail: [email protected] © 2014 Elsevier Inc. All rights reserved. 1053-0770/2601-0001$36.00/0 http://dx.doi.org/10.1053/j.jvca.2014.05.026 Key Words: training, simulators, human patient simulator, resident education, cardiopulmonary bypass
Journal of Cardiothoracic and Vascular Anesthesia, Vol 28, No 5 (October), 2014: pp 1387–1392
1387
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OBSERVERS
5 6
1. Anesthesia workstation 2. Managing anesthesiologists
10
3. Patient / Mannequin 2
1
11
3
4. Surgeon 5. Perfusionist 6. CPB machine
4
7. TEE machine 8. Defibrillator
9 8
9. Drugs trolley 10. ECG simulator ONE WAY MIRROR
11. LCD display
CONTROL STATION
Fig 1.
Diagram of layout of CAST operating room.
unchanged. A short discussion prompted by the surgeon followed and possible type III protamine reaction was considered among the differentials. Supportive CPB was reinstituted after heparinization. With hemodynamics reestablished, the scenario came to an end. Alternative response options such as introduction of an intra-aortic balloon pump for circulatory support also may be considered. After each part of the case scenario, the participants were brought through a facilitated debriefing session. The debriefing session also included a short instructional interactive teaching component on the basics of TEE supported management. At the end, a post test consisting of another set of 10 MCQs was administered. Residents completed a module evaluation and feedback form at the end of the session.
RESULTS
All residents returned completed feedback forms, which sought opinion on the module organization and format, usefulness of the module to reinforce knowledge and understanding, stimulate learning, improve confidence in patient management, and to promote better communication with the rest of the cardiac surgical team. Feedback mostly was assessed as good or excellent (Fig 4). Course organization and format was evaluated as good or excellent by 88.1% and as average or fair by 11.9%. The average pretest score was 96% and the posttest score 99%. DISCUSSION
In this pilot study, the authors tested the feasibility of adapting the HPS to simulate hemodynamics of CPB and, its
application in teaching anesthesia residents the elements of patient management on CPB in a simulated cardiac operating room (OR) environment with improved realism. Enabling CPB Simulation with Improved Realism Simulating CPB requires the ability to maintain normal perfusion pressure and oxygenation in the presence of asystole or serious arrhythmias. To achieve this, the ECG electrodes were disconnected from the HPS mannequin while it was running at a baseline state with MAP 60 mmHg, and ECG input was added from an external simulator (HeartSim 200, Laerdal Medical AS, Stavanger, Norway). With this, the patient monitor was able to display any rhythm or even asystole, with normal perfusion impulses shown, simulating on-going extracorporeal circulation, without the need to pause the scenario. The anesthesia workstation was set up to show CPB mode on the ventilator with no bellows movements or end-tidal CO2 tracings. The simulator was programmed not to deteriorate to a cardiac arrest in the absence of ventilation by enabling the ischemic index sensitivity option. Keeping the level of ischemia sensitivity of the mannequin to a very low level, such as o0.05, keeps the mannequin crash-proof. Enabling the intrinsic ventilation rate of the mannequin to 4 breaths per minute with a low tidal volume of 200 mL enabled the mannequin to hold saturation, with minimal chest rise to be noticed through the surgical drapes. Temperatures were displayed with the thermistor tips placed in water at suitable temperatures. During the aortic cross clamp release stage, the rhythm was still generated by the external ECG simulator.
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Fig 2.
Actual layout of the CAST operating room. (Color version of figure is available online.)
This enabled the simulation of various arrhythmias (e.g. VF), while the HPS maintained a satisfactory MAP and pulse oximetry reading, as would be experienced on CPB in clinical practice. A planned debriefing break was introduced into the scenario at this stage. The break at this stage allowed the trainees to switch places, thus increasing the number of trainees who could participate at one time. During the break, the mannequin’s
Fig 3.
intrinsic ECG output was reconnected to ECG electrodes from the patient monitor, so that all further ECG signals were set by the operator from the control room, outside the view of the scenario participants. It should be possible to wire the ECG inputs to a selector switch placed in the control room, providing the ability to choose signals from either the ECG simulator or the mannequin. The anesthesia workstation was adjusted to provide ventilation and the end-tidal CO2 tracing back on the screen.
Screen shot of monitor during CAST. (Color version of figure is available online.)
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Table 1. The TRAVVEL Checklist for Termination of Cardiopulmonary Bypass2 T R
Temperature Rate
A
Air
V V
Venting Ventilation
E
Electrolytes
L
Level
Nasopharyngeal 36 oC-37oC Stable cardiac rate and rhythm Epicardial pacing may be required Techniques to remove intracardiac air TEE may be used to confirm adequacy Venting lines either clamped or removed before coming off bypass. Mechanical ventilation restarted Left lower lobe expansion visually confirmed if left pleura opened Normal metabolic indices Base excess o-5 mmol/L, Po2 4 10 kPa, Pco2 5 kPa, Hematocrit 420%, Kþ 4 4.5 mmol/L Operating table
When simulating clinical situations, the degree of realism introduced is important in increasing the likelihood that the response reflects actual behavior in clinical settings.3 Different elements such as the staff, the setting and the simulator itself contribute to the authenticity of the experience by the learners, and each one may be varied again according to the training objectives. Two important characteristics of simulator fidelity are, the notion of physical fidelity and, functional fidelity.4 Enhancement of realism in simulation-based training with technological advancement may not necessarily translate to increased effectiveness of training. Increased efficiency and transfer of training may in fact occur through the careful process of instructional systems design, in particular the design of the simulation-based scenarios that are responsive to the real operational needs of the organization.5 In previously reported mannequin-based simulation scenarios that included CPB, the need to interrupt the scenario progression during CPB and revert to instructor-led discussion-based teaching,1 deviated significantly from the actual management of a case in progress. The present simulated scenario was presented as a case in progress with inputs
requiring learner response without instructor-led discussion and was entirely mannequin-based, helping to maintain realism. Particular care was taken to ensure no external instructor or “voice of God” was used through microphones, as this could reduce realism. The participants playing this role were real-life cardiac surgeons and perfusionists and were well oriented to facilitate the scenario by interjecting callouts to engage residents and to prompt attention to inputs such as blood gas results, in case the trainees did not recognize the event or act in time. A big part of anesthesia practice involves interacting with other physicians, staff, and patients. The skill to do this may be innate, learned with experience, or remain a struggle throughout.6 The cardiac surgical OR environment is uniquely complex in its components, which include the patient, monitors, surgeon, nurses, perfusionist, and the additional technology such as the CPB machine and TEE machine. Functioning effectively in this demands a high degree of teamwork. There is strong consensus that good communication in the operating room is essential to patient safety and quality of care.7–9 Situation awareness is recognized to be an essential nontechnical skill for effective and safe practice in high-risk
12
Number of Respondents
10
8
6
4
Help Understand Physiology Pharmac Reinforce Knowledge Patient Management Stimulus to Learn
2
Improve Communiction Improve Confidence
0 Strongly Disagree
Disagree
Neutral
Fig 4.
Agree
Strongly Agree
Evaluation of course content by trainees.
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situations such as the operating room. Unlike the conventional model of situation awareness, in which the anesthesiologist processes information from the monitors and makes therapeutic decisions, the distributive situation awareness approach emphasizes the continuous interaction between the environment and the anesthesiologist.10 The complex environment of the cardiac OR necessitates a high degree of distributive situation awareness. Functioning as a team then becomes much more important in patient management. High-fidelity simulation through the CAST requires processing inputs from multiple sources, such as the monitored parameters, displayed screen variables such as TEE, blood gas, and electrolytes, and active solicitation and deliberation by the participants, calling for a degree of distributive system awareness. The enhanced realism and minimal inscenario external faculty input aids in the learning of multidisciplinary team building and anesthesia nontechnical or “soft” skills.11 Debriefing To achieve a more structured process of debriefing for postgraduate learners, the present approach included obtaining data from the scenario, analyzing the experience, and summarizing the learning. The focus of the debriefing was toward encouraging the trainees and the team to share their own experiences of the scenario in terms of what went well, what went wrong, and why that may have been so. Aspects of the scenario, such as adherence to the checklist protocol for weaning CPB, were of necessity dealt with in an instructional approach. The last occurrence in the scenario, with the steadily deteriorating hemodynamics of the patient, is an example of a situation for which there might be more than one correct option for management. This gave an opportunity for team interaction in deciding on a course of management. A formal explanation of the pre- and post-test quiz helped to emphasize the core concepts in the management. These points give credence to the idea that debriefing in the more complex clinical scenario has to be a judicial mix of a facilitatory nature as well as an instructional approach. It is true that the trainees managing the second part of the scenario have the benefit of the first debriefing, which might have influenced their behavior during the second part. However, the aim of the simulation was to teach and not to assess, and it was considered that learning occurring at any stage is useful. For the same reasons, the performance in the MCQs and the checklisting was discussed and knowledge reinforced during debriefing rather than feeding back scores. Trainees scoring high in both the pre- and post-test MCQs could reflect on the degree of difficulty of the test and its relevance to testing the knowledge component of the module. The module, incorporating the core competencies of experiential learning and of patient care, medical knowledge, communication, practice-based learning, professionalism, and systems-based practice, has successfully dovetailed into the anesthesia residency training program at the authors’
institution. Assessing the effectiveness of such an innovation can be challenging. Task training can be assessed quantitatively by checklist-based measures of proficiency. The CAST module, which includes elements of distributive situation awareness, teamwork in the cardiac operating room, and possible alternative management pathways, is expected to influence behavior in a multidisciplinary clinical setting. This is likely to span toward lifelong learning12 and may not lend itself easily to quantitative assessment. Future Development The absence of the input from direct observation of the operating field to the trainees, as in real life, does somewhat limit realism in the simulation. In current cardiac anesthetic practice, TEE plays an ever increasing role in the intraoperative management. The ability to make the TEE input more interactive also may facilitate a more realistic involvement of the trainees in the case management. Currently, the authors are exploring ways to address these points. In the present model, the participants in the scenario were enacting functions consistent with their normal clinical role and not merely role playing. Looking ahead, these roles may be undertaken by surgical and perfusion trainees, with the view to establish team training in the cardiac OR setting. The scenario itself was run without any break in the actual progression of the case. The adaptations made enabled the scenario to be mannequin-based throughout, maintaining a degree of realism and allowing for clinical interventions. CONCLUSION
High-fidelity mannequins such as HPS can be adapted to simulate CPB hemodynamics, and the modification was incorporated successfully in the CAST scenario. Having established this core capability, the authors believe it has the potential to be used in a variety of more complex clinical scenarios involving CPB and also in team training of anesthetic, surgical, and perfusion trainees. The benefit of simulation and its effectiveness in improving knowledge, judgment, and performance is not established easily. In spite of this, simulation in medicine, particularly anesthesia training, is now established widely and gaining momentum. The module was well received by the trainees undergoing the session, as evident in the feedback. Future studies may potentially include increasing the range of clinical situations for which the CAST adaptation may be applied, examining ways to enhance the realism, and adapting the scenarios for multidisciplinary training. ACKNOWLEDGMENTS The authors acknowledge the Operations Team of the Center for Healthcare Simulation, National University of Singapore, especially Ms. Karen Ho and Mr. Tan Kok Ann, for their contributions and support, and the faculty for the CAST course which included cardiac anesthesia, cardiothoracic surgery, and perfusion staff.
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REFERENCES 1. Hassan ZU, Sloan P: Using a mannequin-based simulator for anesthesia resident training in cardiac anesthesia. Simul Healthc 1: 44-48, 2006 2. Gray SJ, Gifford G: Conduct of cardiopulmonary bypass, in Mackay J, Arrowsmith JE (eds). Core Topics in Cardiac Anaesthesia. Greenwich Medical Media Limited, Cambridge University Press, 2004, pp. 153-156 3. Cumin D, Weller JM, Henderson K, et al: Standards for simulation in anaesthesia: Creating confidence. Br. J. Anaesth 105:45-51, 2010 4. Hays RT, Singer MJ: Simulation fidelity in training systems design: Bridging the gap between reality and training. New York: Springer-Verlag, 1989 5. Thomas M JW: Operational fidelity in simulation-based training: The use of data from threat and error management analysis in instructional systems design. In Proceedings of SimTecT2003: Simulation Conference, Adelaide, Australia, Simulation Industry Association of Australia, 2003, pp: 91-95 6. Sinz E: Simulation-based education for cardiac, thoracic, and vascular anaesthesiology. Semin Cardiothorac Vasc Anesth 9:291-307, 2005
7. Makary MA, Sexton JB, Freischlag JA, et al: Operating room teamwork among physicians and nurses: Teamwork in the eye of the beholder. J Am Coll Surg 202:746-752, 2006 8. Lingard L, Espin S, Whyte S, et al: Communication failure in the operating room: An observational classification of recurrent types and effects. Qual Saf Health Care 13:330-334, 2004 9. Parush A, Kramer C, Foster-Hunt T, et al: Communication and team situation awareness in the OR: Implications for augmentative information display. J Biomed Inform 44:477-485, 2011 10. Fioratou E, Flin R, Glavin R, et al: Beyond monitoring: Distributed situation awareness in anaesthesia. Br J Anaesth 105:83-90, 2010 11. Fletcher GC, McGeorge P, Flin RH, et al: The role of nontechnical skills in anesthesia: A review of current literature. Br J Anaesth 88:418-429, 2002 12. Sadler R: The era of assessment engineering: Changing perspectives on teaching and learning and the role of new modes of assessment, in Segers M, Dochy F, Cascallar E (eds). Optimizing new modes of assessment: In search of qualities and standards. Dordrecht, The Netherlands, Kluwer Academic Publishers, 2003, pp. 1-12
Simulation of Cardiopulmonary Bypass Management: An Approach to Resident Training Rex J. Morais, FFARCSI,* Balakrishnan Ashokka, FANZCA,† Chiang Siau, MMed,† and Lian Kah Ti, MMed†
S
IMULATION-BASED TRAINING is used in anesthesia in a variety of ways, such as task trainers for intubation and major vascular access, crisis resource management, transesophageal echocardiography (TEE), and screen-based simulation. The use of high-fidelity mannequin simulators in cardiac anesthesia training is somewhat limited by their inability to simulate the cardiopulmonary bypass (CPB) state. The programmed physiology of the Human Patient Simulator (HPS, Anesthesia Model CAE Healthcare, Sarasota, FL) does not allow the combination of an adequate perfusion pressure in the presence of asystole or serious arrhythmias such as ventricular fibrillation, which may exist during CPB. In a previously described HPSbased simulation scenario for cardiac anesthesia, which included patient management during CPB, the authors report keeping the actual scenario in “pause” mode for the period of CPB during the scenario. An external pressure input from a pressurized bag was fed in to demonstrate the perfusion pressure of CPB. During this period, common learning points related to management of the patient on CPB were discussed.1 The present article reports the design of a mannequin-based cardiac anesthesia simulation training (CAST) module to teach patient management during CPB and discontinuation of CPB and the authors’ experience of using it in anesthesia resident training. The adaptations enabled the scenario to be mannequin-based throughout without any break in the progression of the case, maintaining a degree of realism and allowing for clinical interventions. The modifications applied, the construction of the scenario, and its successful implementation are described. METHODS Halfway into their 1 month rotation in cardiac anesthesia, firstyear anesthesia residents underwent the CAST module. The training objectives were (1) to understand the impact of CPB on the underlying patho-physiology of coronary artery disease; (2) to recognize complications that may arise during the progression of CPB; (3) to be able to clarify individual roles of the operating team, specifically the anesthesiologist, surgeon, and perfusionist; and (4) to communicate clearly with the team to have a coordinated response in patient care. Four residents at a time underwent the training, and three sessions were conducted for a total of 12 residents. They were given pre-reading material outlining the principles of managing patients on CPB. On the day of CAST, written consent was obtained for audiovisual recording during the scenario and confidentiality of peer performance and module content. They were then given a set of 10 multiple choice questions (MCQ) to answer as a pretest. A short teaching session on the principles of CPB followed. The residents then were orientated to the simulation environment. A cardiac surgical operating room layout was set (Figs 1 and 2). A HPS was intubated and draped, with standard cardiac anesthetic monitoring in progress according to institutional practice. Participants in the scenario included a surgeon, a perfusionist,
and a scrub nurse, all playing their real-life roles. A separate screen displayed bispectral index (BIS), blood results, and TEE images or video clips at various stages, so that the resident anesthesiologist and the participants could interact to decide on management. The scenario was conducted in 2 parts. During the first part, 2 of the residents managed the anesthesia together, while the other 2 were observers. These roles were reversed for the second part of the scenario. The residents were instructed to take over the anesthetic management of a middle aged patient undergoing elective coronary artery revascularization, on cardiopulmonary bypass with the distal graft anastomoses in progress. The monitors at this time displayed asystole with MAP 70 mmHg, CVP 5 and nasal and rectal temperatures close to 34oC, with BIS around 44. As the case progressed, the following abnormalities were introduced in sequence: (1) respiratory alkalosis with severe hypokalemia, (2) BIS rising to 59 with rewarming, and (3) repeated ventricular fibrillation (VF) after aortic cross clamp release (Fig 3). They were expected to recognize and respond appropriately. With the VF, they were handed internal defibrillator paddle leads to connect and use in coordination with the surgeon. After rhythm stabilization and completion of the proximal anastomoses, the surgeon handed pacing leads to the residents to connect to and set up the pacemaker. At this point, the first part of the scenario ended and a short debriefing was done. For the second part of the scenario, the managing anesthesia residents were swapped with the observing residents. The scenario continued with the aortic cross clamp removed and pacing established. In preparing to wean from CPB, inotropic support was prepared as considered necessary and a check list of parameters (Table 1) before weaning was verified. The patient then was weaned gradually off CPB with coordinated actions from the team. Hemodynamic stability was expected to be achieved, by titrating preload and inotropes as required. TEE images were available to show volume status and contractility. Heparin reversal followed and protamine was administered according to institution protocol. Halfway through protamine administration, the scenario was programmed to show a drop in blood pressure, with a TEE clip of an under-filled ventricle being displayed. The trainees were expected to manage a possible type I protamine reaction and thereafter complete protamine administration. A short interval for hemostasis followed and the aorta was decannulated. Subsequently, the hemodynamics deteriorated, with a distending right heart on TEE image and the ECG remaining
From the *Department of Anesthesia; and †Yong Loo Lin School of Medicine, National University Healthcare System, Singapore, Singapore. Address reprint requests to Rex J. Morais, Department of Anesthesia, National University Healthcare System, 5 Lower Kent Ridge Road, Singapore 119074, Singapore. E-mail: [email protected] © 2014 Elsevier Inc. All rights reserved. 1053-0770/2601-0001$36.00/0 http://dx.doi.org/10.1053/j.jvca.2014.05.026 Key Words: training, simulators, human patient simulator, resident education, cardiopulmonary bypass
Journal of Cardiothoracic and Vascular Anesthesia, Vol 28, No 5 (October), 2014: pp 1387–1392
1387
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MORAIS ET AL
OBSERVERS
5 6
1. Anesthesia workstation 2. Managing anesthesiologists
10
3. Patient / Mannequin 2
1
11
3
4. Surgeon 5. Perfusionist 6. CPB machine
4
7. TEE machine 8. Defibrillator
9 8
9. Drugs trolley 10. ECG simulator ONE WAY MIRROR
11. LCD display
CONTROL STATION
Fig 1.
Diagram of layout of CAST operating room.
unchanged. A short discussion prompted by the surgeon followed and possible type III protamine reaction was considered among the differentials. Supportive CPB was reinstituted after heparinization. With hemodynamics reestablished, the scenario came to an end. Alternative response options such as introduction of an intra-aortic balloon pump for circulatory support also may be considered. After each part of the case scenario, the participants were brought through a facilitated debriefing session. The debriefing session also included a short instructional interactive teaching component on the basics of TEE supported management. At the end, a post test consisting of another set of 10 MCQs was administered. Residents completed a module evaluation and feedback form at the end of the session.
RESULTS
All residents returned completed feedback forms, which sought opinion on the module organization and format, usefulness of the module to reinforce knowledge and understanding, stimulate learning, improve confidence in patient management, and to promote better communication with the rest of the cardiac surgical team. Feedback mostly was assessed as good or excellent (Fig 4). Course organization and format was evaluated as good or excellent by 88.1% and as average or fair by 11.9%. The average pretest score was 96% and the posttest score 99%. DISCUSSION
In this pilot study, the authors tested the feasibility of adapting the HPS to simulate hemodynamics of CPB and, its
application in teaching anesthesia residents the elements of patient management on CPB in a simulated cardiac operating room (OR) environment with improved realism. Enabling CPB Simulation with Improved Realism Simulating CPB requires the ability to maintain normal perfusion pressure and oxygenation in the presence of asystole or serious arrhythmias. To achieve this, the ECG electrodes were disconnected from the HPS mannequin while it was running at a baseline state with MAP 60 mmHg, and ECG input was added from an external simulator (HeartSim 200, Laerdal Medical AS, Stavanger, Norway). With this, the patient monitor was able to display any rhythm or even asystole, with normal perfusion impulses shown, simulating on-going extracorporeal circulation, without the need to pause the scenario. The anesthesia workstation was set up to show CPB mode on the ventilator with no bellows movements or end-tidal CO2 tracings. The simulator was programmed not to deteriorate to a cardiac arrest in the absence of ventilation by enabling the ischemic index sensitivity option. Keeping the level of ischemia sensitivity of the mannequin to a very low level, such as o0.05, keeps the mannequin crash-proof. Enabling the intrinsic ventilation rate of the mannequin to 4 breaths per minute with a low tidal volume of 200 mL enabled the mannequin to hold saturation, with minimal chest rise to be noticed through the surgical drapes. Temperatures were displayed with the thermistor tips placed in water at suitable temperatures. During the aortic cross clamp release stage, the rhythm was still generated by the external ECG simulator.
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Fig 2.
Actual layout of the CAST operating room. (Color version of figure is available online.)
This enabled the simulation of various arrhythmias (e.g. VF), while the HPS maintained a satisfactory MAP and pulse oximetry reading, as would be experienced on CPB in clinical practice. A planned debriefing break was introduced into the scenario at this stage. The break at this stage allowed the trainees to switch places, thus increasing the number of trainees who could participate at one time. During the break, the mannequin’s
Fig 3.
intrinsic ECG output was reconnected to ECG electrodes from the patient monitor, so that all further ECG signals were set by the operator from the control room, outside the view of the scenario participants. It should be possible to wire the ECG inputs to a selector switch placed in the control room, providing the ability to choose signals from either the ECG simulator or the mannequin. The anesthesia workstation was adjusted to provide ventilation and the end-tidal CO2 tracing back on the screen.
Screen shot of monitor during CAST. (Color version of figure is available online.)
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Table 1. The TRAVVEL Checklist for Termination of Cardiopulmonary Bypass2 T R
Temperature Rate
A
Air
V V
Venting Ventilation
E
Electrolytes
L
Level
Nasopharyngeal 36 oC-37oC Stable cardiac rate and rhythm Epicardial pacing may be required Techniques to remove intracardiac air TEE may be used to confirm adequacy Venting lines either clamped or removed before coming off bypass. Mechanical ventilation restarted Left lower lobe expansion visually confirmed if left pleura opened Normal metabolic indices Base excess o-5 mmol/L, Po2 4 10 kPa, Pco2 5 kPa, Hematocrit 420%, Kþ 4 4.5 mmol/L Operating table
When simulating clinical situations, the degree of realism introduced is important in increasing the likelihood that the response reflects actual behavior in clinical settings.3 Different elements such as the staff, the setting and the simulator itself contribute to the authenticity of the experience by the learners, and each one may be varied again according to the training objectives. Two important characteristics of simulator fidelity are, the notion of physical fidelity and, functional fidelity.4 Enhancement of realism in simulation-based training with technological advancement may not necessarily translate to increased effectiveness of training. Increased efficiency and transfer of training may in fact occur through the careful process of instructional systems design, in particular the design of the simulation-based scenarios that are responsive to the real operational needs of the organization.5 In previously reported mannequin-based simulation scenarios that included CPB, the need to interrupt the scenario progression during CPB and revert to instructor-led discussion-based teaching,1 deviated significantly from the actual management of a case in progress. The present simulated scenario was presented as a case in progress with inputs
requiring learner response without instructor-led discussion and was entirely mannequin-based, helping to maintain realism. Particular care was taken to ensure no external instructor or “voice of God” was used through microphones, as this could reduce realism. The participants playing this role were real-life cardiac surgeons and perfusionists and were well oriented to facilitate the scenario by interjecting callouts to engage residents and to prompt attention to inputs such as blood gas results, in case the trainees did not recognize the event or act in time. A big part of anesthesia practice involves interacting with other physicians, staff, and patients. The skill to do this may be innate, learned with experience, or remain a struggle throughout.6 The cardiac surgical OR environment is uniquely complex in its components, which include the patient, monitors, surgeon, nurses, perfusionist, and the additional technology such as the CPB machine and TEE machine. Functioning effectively in this demands a high degree of teamwork. There is strong consensus that good communication in the operating room is essential to patient safety and quality of care.7–9 Situation awareness is recognized to be an essential nontechnical skill for effective and safe practice in high-risk
12
Number of Respondents
10
8
6
4
Help Understand Physiology Pharmac Reinforce Knowledge Patient Management Stimulus to Learn
2
Improve Communiction Improve Confidence
0 Strongly Disagree
Disagree
Neutral
Fig 4.
Agree
Strongly Agree
Evaluation of course content by trainees.
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situations such as the operating room. Unlike the conventional model of situation awareness, in which the anesthesiologist processes information from the monitors and makes therapeutic decisions, the distributive situation awareness approach emphasizes the continuous interaction between the environment and the anesthesiologist.10 The complex environment of the cardiac OR necessitates a high degree of distributive situation awareness. Functioning as a team then becomes much more important in patient management. High-fidelity simulation through the CAST requires processing inputs from multiple sources, such as the monitored parameters, displayed screen variables such as TEE, blood gas, and electrolytes, and active solicitation and deliberation by the participants, calling for a degree of distributive system awareness. The enhanced realism and minimal inscenario external faculty input aids in the learning of multidisciplinary team building and anesthesia nontechnical or “soft” skills.11 Debriefing To achieve a more structured process of debriefing for postgraduate learners, the present approach included obtaining data from the scenario, analyzing the experience, and summarizing the learning. The focus of the debriefing was toward encouraging the trainees and the team to share their own experiences of the scenario in terms of what went well, what went wrong, and why that may have been so. Aspects of the scenario, such as adherence to the checklist protocol for weaning CPB, were of necessity dealt with in an instructional approach. The last occurrence in the scenario, with the steadily deteriorating hemodynamics of the patient, is an example of a situation for which there might be more than one correct option for management. This gave an opportunity for team interaction in deciding on a course of management. A formal explanation of the pre- and post-test quiz helped to emphasize the core concepts in the management. These points give credence to the idea that debriefing in the more complex clinical scenario has to be a judicial mix of a facilitatory nature as well as an instructional approach. It is true that the trainees managing the second part of the scenario have the benefit of the first debriefing, which might have influenced their behavior during the second part. However, the aim of the simulation was to teach and not to assess, and it was considered that learning occurring at any stage is useful. For the same reasons, the performance in the MCQs and the checklisting was discussed and knowledge reinforced during debriefing rather than feeding back scores. Trainees scoring high in both the pre- and post-test MCQs could reflect on the degree of difficulty of the test and its relevance to testing the knowledge component of the module. The module, incorporating the core competencies of experiential learning and of patient care, medical knowledge, communication, practice-based learning, professionalism, and systems-based practice, has successfully dovetailed into the anesthesia residency training program at the authors’
institution. Assessing the effectiveness of such an innovation can be challenging. Task training can be assessed quantitatively by checklist-based measures of proficiency. The CAST module, which includes elements of distributive situation awareness, teamwork in the cardiac operating room, and possible alternative management pathways, is expected to influence behavior in a multidisciplinary clinical setting. This is likely to span toward lifelong learning12 and may not lend itself easily to quantitative assessment. Future Development The absence of the input from direct observation of the operating field to the trainees, as in real life, does somewhat limit realism in the simulation. In current cardiac anesthetic practice, TEE plays an ever increasing role in the intraoperative management. The ability to make the TEE input more interactive also may facilitate a more realistic involvement of the trainees in the case management. Currently, the authors are exploring ways to address these points. In the present model, the participants in the scenario were enacting functions consistent with their normal clinical role and not merely role playing. Looking ahead, these roles may be undertaken by surgical and perfusion trainees, with the view to establish team training in the cardiac OR setting. The scenario itself was run without any break in the actual progression of the case. The adaptations made enabled the scenario to be mannequin-based throughout, maintaining a degree of realism and allowing for clinical interventions. CONCLUSION
High-fidelity mannequins such as HPS can be adapted to simulate CPB hemodynamics, and the modification was incorporated successfully in the CAST scenario. Having established this core capability, the authors believe it has the potential to be used in a variety of more complex clinical scenarios involving CPB and also in team training of anesthetic, surgical, and perfusion trainees. The benefit of simulation and its effectiveness in improving knowledge, judgment, and performance is not established easily. In spite of this, simulation in medicine, particularly anesthesia training, is now established widely and gaining momentum. The module was well received by the trainees undergoing the session, as evident in the feedback. Future studies may potentially include increasing the range of clinical situations for which the CAST adaptation may be applied, examining ways to enhance the realism, and adapting the scenarios for multidisciplinary training. ACKNOWLEDGMENTS The authors acknowledge the Operations Team of the Center for Healthcare Simulation, National University of Singapore, especially Ms. Karen Ho and Mr. Tan Kok Ann, for their contributions and support, and the faculty for the CAST course which included cardiac anesthesia, cardiothoracic surgery, and perfusion staff.
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7. Makary MA, Sexton JB, Freischlag JA, et al: Operating room teamwork among physicians and nurses: Teamwork in the eye of the beholder. J Am Coll Surg 202:746-752, 2006 8. Lingard L, Espin S, Whyte S, et al: Communication failure in the operating room: An observational classification of recurrent types and effects. Qual Saf Health Care 13:330-334, 2004 9. Parush A, Kramer C, Foster-Hunt T, et al: Communication and team situation awareness in the OR: Implications for augmentative information display. J Biomed Inform 44:477-485, 2011 10. Fioratou E, Flin R, Glavin R, et al: Beyond monitoring: Distributed situation awareness in anaesthesia. Br J Anaesth 105:83-90, 2010 11. Fletcher GC, McGeorge P, Flin RH, et al: The role of nontechnical skills in anesthesia: A review of current literature. Br J Anaesth 88:418-429, 2002 12. Sadler R: The era of assessment engineering: Changing perspectives on teaching and learning and the role of new modes of assessment, in Segers M, Dochy F, Cascallar E (eds). Optimizing new modes of assessment: In search of qualities and standards. Dordrecht, The Netherlands, Kluwer Academic Publishers, 2003, pp. 1-12
