Study design and setting
This cohort study was conducted at the Centre d’apprentissage des attitudes et habiletés cliniques (CAAHC), Université de Montréal’s medical simulation centre, in Canada, in July 2015 and July 2016. It was approved by the local Institutional Review Board for research in healthcare (15-051-CERES-D).
Every July, the CAAHC offers a mandatory 2-day ACLS provider course to over 200 first-year residents beginning their postgraduate training. The course complies with all rules and requirements of the Heart and Stroke Foundation and follows the most recent AHA guidelines [12]. Its first day consists of lectures, and its second day of six hands-on learning stations organized around the ACLS algorithms. Each station lasts 50 min, with one certified instructor supervising no more than six participants. Bradycardia management is covered in a lecture on day 1 and a hands-on station on day 2.
Study population and participant selection
Two consecutive cohorts of junior residents during their first month of postgraduate medical training were used as a study population (July 2015 and July 2016). First-year residents from both cohorts with no prior residency experience were approached on day 1 of the course. The study was presented as evaluating a teaching method without providing any specific information about which method was being investigated. All recruited volunteers signed informed consent waivers and a confidentiality agreement prior to inclusion in the study. The first cohort was the control cohort and the second cohort the intervention cohort.
ALS simulator® mannequin (Laerdal Medical, Stavanger, Norway)
The ALS simulator mannequin (Laerdal Medical, Stavanger, Norway) was used during the bradycardia workshops of the first cohort (Control—July 2015) to demonstrate and practice TCP. This mannequin reproduces some aspects of TCP, with the following notable exceptions:
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It does not allow the use of multifunction pads, requiring instead special connectors not used in clinical practice (which cannot be misplaced)
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It does not present muscular twitching with increasing TCP output as a real patient would
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It does not reproduce electrical artifacts that can appear on the ECG tracing during TCP, and that can be misinterpreted as ventricular capture because they have the same frequency as the rate set on the TCP [5, 6].
Modified high-fidelity TMM
The modified high-fidelity TMM was used during the bradycardia workshops of the second cohort (Intervention—July 2016) to demonstrate and practice TCP. This custom-made mannequin combines a modified Human Patient Simulator mannequin (HPS®, CAE Healthcare, Montreal, Canada) with whom the participants interact in the simulation suite and a SimMan 3G® (Laerdal Medical, Stavanger, Norway) located in an adjacent room and used solely to generate the electrocardiogram (ECG) tracings seen by the participants (the participants never interact with the SimMan 3G®, they only see its ECG tracing which comes out of the HPS mannequin and is displayed on the monitor). Compared to the ALS simulator®, the TMM’s response to TCP more closely resembles that of a real patient [8]. The TMM:
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Allows the use of the same multifunction pads used clinically (which can be misplaced on the chest)
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Replicates the muscular twitching of the patient with increasing TCP output, which can mislead users into inferring that pacing is effective
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Reproduces the artifacts that often appear on the ECG with TCP, as the electric current traveling through the chest with each stimulation is picked up by the monitor; the presence of these artifacts, which are synchronous with pacing, may be mistaken for pacemaker-generated wide complex QRS, giving a false impression of ventricular capture; users must therefore distinguish these artifacts from true ventricular capture just as they would clinically on a real patient, by palpating a pulse and checking if it corresponds to the rate set on the TCP
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Allows simultaneous ECG monitoring on the TCP and on a clinical monitor
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Can mimic many other characteristics of real patients (i.e., talks, closes its eyes) [13]
Supplemental videos further illustrate differences between the two mannequins (see video, Additional file 1, for the ALS simulator®) (see video, Additional file 2, for the TMM).
TCP simulation with the ALS simulator® mannequin. (WMV 45130 kb)
TCP simulation with the Two Mannequin Model (TMM). (WMV 61318 kb)
Intervention
Both cohorts received a similar bradycardia workshop: the objectives were the same and were standardized following ACLS guidelines. Furthermore, the workshops were given by the same six ACLS instructors, under the supervision of the same course director. No change in ACLS guidelines occurred between the two years of the study for the bradycardia algorithm.
The bradycardia workshop focused on the management of unstable bradycardia as described by the ACLS guidelines [12]. A HeartStart XL® monitor/defibrillator (Philips, Andover, MA) was used to demonstrate and then practice TCP. The lower-fidelity ALS simulator® mannequin (Laerdal Medical, Stavanger, Norway), the one customarily used for ACLS courses at the Université de Montréal simulation center, was used for the bradycardia workshops for the first cohort. The modified high-fidelity TMM was used for the bradycardia workshops for the second cohort. Because they were not required by the workshop objectives, some features of the TMM were not used during the training sessions (e.g., talking, eyes closing and opening). For both cohorts, the participants’ learning of TCP was assessed through their ability to complete six critical tasks during a high-fidelity simulation scenario involving a case of unstable bradycardia with complete atrioventricular block (see Appendix 1). This test was administered after the morning stations on day 2 of the course, which always included the bradycardia station. In order for the mannequin to replicate as closely as possible a real patient, the modified high-fidelity TMM was used, exploiting not only its TCP capability, but also its full potential for integration in a scenario reproducing a real clinical context. Indeed, the simulation technician controlling the TMM could answer participants’ questions as well as control the TMM to interact with the participants by reacting to their actions (telling the participants that the TCP was painful, for example). Since the participants from the control cohort may not have had prior exposure to such a mannequin, a short video of a simulation scenario demonstrating its features was presented to all participants during the first day of ACLS training. The exact same simulation scenario was repeated with every participant, regardless of their cohort. Great care was taken to ensure that participants and workshop instructors were not aware of the content of the scenario.
Before the simulation, each participant completed a survey about demographics and prior clinical and simulation experience. An individual briefing was then given about the context of the simulated case. During the briefing, participants were explicitly told to act as they would during a real patient encounter (e.g., talk to the patient and expect an answer, appropriately examine the patient). The participant was then invited into the simulation suite to begin the scenario, during which a facilitator acted as a nurse. Participants could interact with the patient (TMM), order any test, and start any treatment deemed necessary.
All simulations were video-recorded. Based on the work of Ahn et al. [4], the following six tasks were used to determine clinical competency in TCP (see Appendix 2):
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1.
Turning on pacer function within 4 min
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2.
Applying multifunction pads correctly
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Recognizing that TCP is ineffective initially
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4.
Achieving ventricular capture
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5.
Verifying capture by taking the pulse
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6.
Prescribing sedation or analgesia
The time to completion of each task was also noted.
The scenario was allowed to run until all tasks had been completed, or up to a maximum of 9 min. For the first task only, a time limit of 4 min was used, after which the facilitator recommended TCP use. In this case, this task was considered as not having been done, but the scenario was allowed to continue. Scripted debriefing systematically followed simulation, after which participants completed a survey on their previous experience with bradycardia management and TCP.
Two investigators (CR, MRP) graded each participant’s performance using the video recording of the simulation. In case of discrepancy, a third investigator (AR) was involved and the results were determined by consensus. The time to completion of each task was evaluated using the same technique.
Study outcomes
The primary outcome measure was the completion of all six previously mentioned tasks during the course of the simulation scenario. The secondary outcomes were the completion of each of the six tasks on an individual basis and the time to completion of each of the six tasks on an individual basis.
Sample size calculation and statistical analyses
Based on previous experience running a simulation scenario similar to the one used in this study with 20 cohorts of ACLS-trained internal medicine residents, it was estimated that the success rate in our control cohort would be 20%. Including 50 participants per cohort would allow the detection of a 30% absolute difference regarding the success rate, accepting alpha and beta errors of 0.05 and 0.1 respectively. It was planned to exclude and replace candidates with a breach of protocol.
Continuous variables are presented as means with standard deviations and categorical variables are presented as frequencies with percentages. Cohort differences for demographic, prior clinical, and simulation experience were assessed using Student’s t test and Pearson’s chi-squared test, as appropriate.
For the primary outcome, the proportion of each cohort who completed all six tasks were compared using a Pearson’s chi-squared test. For the secondary outcomes, the proportion of each cohort who completed each individual task were described as the time to completion of each of these individual tasks. Statistical analyses were performed using SPSS Statistics 23.0 (IBM, Chicago, USA) and PRISM 7 (GraphPad, La Jolla, USA). Alpha levels were fixed at 0.05.