Percutaneous dilatational tracheostomy (PDT) is a frequent invasive procedure performed by critical care physicians at the bedside of the patient.1 Reported advantages over surgical tracheostomy include less bleeding, less operative time, less infection rate, and lower overall cost.2–7 Nonetheless, severe complications can occur in up to 5%,8,9 especially at the beginning of the learning curve.10,11
Compared with other common intensive care unit (ICU) procedures, like orotracheal intubation12 and central venous catheter (CVC) installation,13 there are scarce data regarding PDT training protocols,14 learning curves,10,11 and consensus on procedural expertise.4,6,15 To further add complexity, there is a myriad of PDT techniques described16 and both ultrasound (UG-PDT)17 and bronchoscopic (BG-PDT)18 guidance have been proposed to enhance safety. This procedural variety adds potential barriers to the optimal competence acquisition by trainees.5,19
Simulation-based training has allowed healthcare professionals to acquire procedural skills in a safe learning environment without harming patients.20 The implementation of the mastery learning framework21,22 in simulation-based educational programs has delivered better outcomes in competency acquisition than other training methodologies, as well as a positive impact on clinical results.22–24 Among its distinctive characteristics, the mastery learning paradigm intends to ensure that all trainees achieve predefined minimum passing standards, although individual learning time might be variable.21,22 Recent expert recommendations4,6,25 have advocated for simulation-based PDT training, but to the best of our knowledge, no PDT training programs have been published.
The objectives of this study are as follows: (1) to assess acquisition of BG-PDT procedural competency with a simulation-based mastery learning training program in a prospective cohort of novices and (2) to validate the training program by assessing the transfer of acquired skills into cadaveric models.
The institutional review board approved this project (Approval Number 180704005, Comité de Ética en Investigación, Facultad de Medicina, Pontificia Universidad Católica de Chile) and waived the need for written informed consent.
Training Program Design
This study was designed following recent expert recommendations for mastery educational research.26 This study consisted of a prospective interventional study in a cohort of trainees from January 2019 to July 2019, divided in 2 parts: the BG-PDT training program and the cadaveric transfer of skills. The study protocol is shown in Figure 1. The training protocol was conducted in the simulation center and the cadaveric laboratory of Pontificia Universidad Católica de Chile.
Inclusion criteria for participant selection included the following: senior (postgraduate year 3) residents from anesthesiology, emergency medicine, internal medicine, or first-year intensive care fellows. Exclusion criteria included prior clinical or simulation experience in BG-PDT. Participation in the study protocol was voluntary, and trainees could desist from continuing at any time point.
Before starting the training, participants were handed BG-PDT step-by-step instructions, selected bibliography, and a video recording of an expert execution both in the simulator and in a real patient. Because of local preferences, the BG-PDT technique used was the modified Ciaglia single-tapered dilator technique8,27 and performed with Ciaglia's Blue Rhino kit (Cook Medical LLC, Bloomington, IN). Before the first execution, both the simulator and PDT kit were presented to participants, and relevant questions were resolved.
We have previously described the design of a low-cost BG-PDT simulator,28 which was used for the simulation training in this study. This model presented high fidelity, user satisfaction, and effectively discriminated novice versus expert skills, allowing to assess trainee's skill progression through training.
Before each session, participants overviewed the complete procedure with the expert. Each execution was video recorded in a way in which no identification of the participant was possible. After each execution, an expert debriefed the participant, according to the deliberate practice approach.29 Feedback was given with the aid of a procedural flowchart,30,31 to better identify execution errors, and the most important aspects were highlighted before starting the subsequent session. Training sessions were scheduled less than 7 days apart to prevent potential skill decay.32 According to previously published simulation-based training from cricothyroidotomy,33 each trainee would perform at least 6 training sessions in the simulator. If the minimum passing score (MPS) was not achieved, remedial sessions were offered until accomplished.
Bronchoscopy-guided percutaneous dilatational tracheostomy executions were assessed using a multimodal approach. Based on previous learning curve reports11 and assessable intraprocedural complications in the simulator, we defined proficient tracheostomy as a composite outcome that included all the following criteria to be considered positive: finalization of procedure, less than 3 puncture attempts, midline puncture, no cartilage fracture, and no posterior tracheal wall lesion.
The video recordings were assessed using the global rating score (GRS) section of the Objective Structured Assessment of Technical Skills Scale. We chose this instrument because GRS have been regarded as superior instruments to checklists in assessing technical proficiency,34 and no checklists have been developed to assess BG-PDT execution. Furthermore, we have previously used this instrument to assess BG-PDT performance in the same simulator and in other training protocols.13,28,34,35 The GRS assesses 5 technical aspects (respect for tissues, time and movements, use of instruments, procedural flow, and procedural knowledge), and scores from 5 to 25 points. Videos were assessed blindly by 2 independent expert observers with previous experience in the use of the instrument. When significant differences were observed between expert assessments, a third expert was consulted. Total procedural time (from skin asepsis to mechanical ventilator connection) was recorded.
The Imperial College Surgical Assessment Device (ICSAD) is a hand-motion tracking device. It uses an electromagnetic system (Isotrak Il; Polhemus, Inc, Colchester, VT), composed by a field generator and 2 sensors, which were installed in the dorsum of the participants hands during each execution.36 There are 2 main ICSAD-derived parameters: total path length (TPL), which refers to the sum of the length of movements of both hands in the 3-dimensional Cartesian plane, and the total number of movements (NM) performed. These objective parameters have been used to assess procedural proficiency and have been correlated with expertise, movement economy, and procedural flow in a wide variety of clinical settings.13,35
Benchmarking and Standard Setting Definition
Benchmark data were obtained from a previous study of our group, in which experts performed BG-PDT execution in the same simulator.28 To determine the GRS MPS, we used the Angoff approach.32 Cutoff value was considered at the 85% of expert's GRS score.35 Bronchoscopy-guided percutaneous dilatational tracheostomy mastery was defined as a proficient execution with a GRS score of higher than 21 points.
Cadaveric Model Skills Transfer
Among training models, cadavers have been regarded as the highest fidelity alternative37 and have been extensively used for procedural training, both in surgical and medical interventions. Different studies have shown that procedural proficiency in cadaveric models is transferable to the clinical scenario.38,39
To further assess competency acquisition, once students completed the simulation training, they performed a BG-PDT in a full-body cadaveric model. Cadavers were injected by femoral artery with a mixture of alcohol, water, glycerol, and phenol; this preservation procedure maintains the characteristics of flexibility and coloration of tissue in a better way than a formalin-fixed corpse.40 Cadavers were donated to the Departamento de Anatomía Normal, Facultad de Medicina, under its surgical simulation project in cadaveric material, program approved by the Ethics Committee Pontificia Universidad Católica de Chile (ID 190115002). These procedures were video recorded, and the same multimodal assessment approach was used. After each procedure, feedback was given to trainees, and cadavers were dissected to assess major procedural complications such as vascular and tracheal injuries.
Once the training protocol was finished, an electronic and anonymous satisfaction survey was sent to participants addressing the following topics: importance of simulation training in BG-PDT, quality of the training program, resemblance of the simulator with the cadaveric model, self-perception of skills on BG-PDT after finishing training, and strengths and weaknesses of the training protocol.
Primary outcome was acquisition of BG-PDT mastery in the simulator, defined as a proficient execution with a GRS score of higher than 21 points. Secondary outcomes included other variables of the multimodal proficiency assessment (procedural time, overall success rate, and ICSAD-derived parameters), transfer of skills to the cadaveric model, participant satisfaction, and costs.
To calculate sample size, we considered our previous study's novice execution28 (which presented a GRS score of 8 ± 6) and our predefined BG-PDT mastery (GRS score of 21). As a result, with an 80% power and 5% α values, we needed to recruit at least 7 participants.
Data are presented as median (interquartile range) or percentage. Because of nonnormal distribution of variables, we used nonparametric testing, including a Mann-Whitney U test, Wilcoxon matched-pairs signed rank test, Fisher exact test, and intraclass correlation coefficient (2-way mixed effects) when appropriate. Data were analyzed with Minitab v17 (Minitab, Inc, State College, PA) and Graphpad Prism (Graphpad Softwares, La Joya, CA) softwares. A 2-tailed P value of less than 0.05 was considered statistically significant.
Eight residents were invited to participate, and all successfully completed the training protocol. Relevant characteristics of the study population are shown in Table 1. Evolution of selected proficiency parameters through the training sessions are shown in Figure 2 (GRS score, procedural time, and ICSAD-derived parameters). Table 2 shows multimodal measurements during the initial and final BG-PDT execution in the simulator.
TABLE 1 -
Demographic Characteristics of Study Participants
|Anesthesiology resident, %
|Emergency medicine resident, %
|ICU fellow, %
|Previous simulation-based procedural training (CVC or OI), %
|BG-PDT performed in patients, %
|Cricothyroidotomy performed in patients, %
OI, orotracheal intubation.
TABLE 2 -
Trainees' Initial and Final Performance in the Simulator
|GRS score (5–25)
|Proficient BG-PDT, %
Wilcoxon matched-pairs signed rank test was used.
At the sixth session, all trainees achieved both BG-PDT mastery criteria: they scored higher than the predefined minimum GRS passing score and performed a proficient BG-PDT. There was no need for remedial sessions. Interrater agreement for GRS score was of 0.91.
All trainees assisted to cadaveric tracheostomy sessions before 2 weeks of finishing the training protocol. No cadaver presented anatomical predictors for difficult tracheostomy.16Table 3 shows the comparison between the final training session and the cadaveric BG-PDT execution. Only 1 trainee did not achieve the “proficient tracheostomy” end point in the cadaver, because of a posterior tracheal wall puncture.
TABLE 3 -
Transfer of Trainees' Skills From the Simulator to the Cadaveric Model
||Final Simulator Assessment
|GRS score (5–25)
|Proficient BG-PDT, %
Wilcoxon matched-pairs signed rank test was used.
Trainees were highly satisfied with the training program, including areas like program design, resemblance of the simulator with the cadaveric model, and feedback briefs. Among weaknesses and strengths identified, participants mentioned the lack of bleeding of both the simulator and cadaveric model, the importance of structured feedback, and the use of a flowchart to guide procedural learning and identification of errors (see Document, Supplemental Digital Content 1, available at https://links.lww.com/SIH/A551, detailing results of the satisfaction surveys).
The total cost of the training program per student, including the construction and use of the simulator, cost of consumables, renting of training rooms, and expert's opportunity cost, was of US $234 (see Table, Supplemental Digital Content 2, available at https://links.lww.com/SIH/A552, detailing the programs' cost breakdown). Cadaveric models and the ICSAD machine were not considered in the cost analysis because they were used for research and program validation purposes.
The main results of this study can be summarized as the following: we have described the design of a successful mastery learning simulation-based BG-PDT training program. Skills acquired are effectively transferred to a cadaveric model, further validating the training protocol. The program presented a high user satisfaction and low cost of implementation.
To the best of our knowledge, this is the first study reporting a simulation-based training protocol for BG-PDT. Previous experiences only focused on PDT simulator design and user satisfaction,41–43 but no comprehensive skill assessment and protocolized training had been performed. Many procedural similarities between PDT and CVC installation can be drawn. For instance, real-patient learning curves have been estimated to be similar.11,44 Central venous catheter insertion has been a hallmark example of successful simulation training protocols in the ICU setting, allowing trainees to improve skills,13 increase compliance to protocols,45 and have a positive impact on clinical outcomes.23 Thus, it is desirable that similar efforts are made to further develop PDT training.
In the first part of our study, we assessed procedural competence acquisition of BG-PDT in the simulator. Although we did not include a control group, we analyzed the progression of the trained cohort along the training sessions, as seen in Figure 2 and Table 2, and observed significant differences between initial and final iterations, and more importantly, completion of the predefined MPS. Because there are no previous training protocols described in the literature, we could not compare our training program with another predefined training benchmark or criterion standard.
On the second part of the study, we assessed competence transfer from the simulator to cadavers. Cadavers have been stated as the highest fidelity alternative, but they do not replace the clinical scenario. There are many differences between both, from physical properties (ie, lack of bleeding and relative stiffness of tissues), to the absence of clinical components (ie, potential hemodynamic or respiratory complications). We acknowledge this potential criticism, but our training protocol was not meant to assess clinical outcomes, rather to evaluate transfer of the technical aspects of BG-PDT from the proposed simulator to a more complex model. In our opinion, the importance of the transfer assessment to the cadaver model is a crucial aspect of this research, because it reinforces that competence is acquired in more complex scenarios as well. With this information, future students can be trained only in simulator (first part of this protocol) and then switch safely to supervised patient performance without the need of cadavers, which are expensive and not readily available.
The use of a mastery learning framework is among the methodological strengths of this program, as it provides a flexible structure that aims to ensure accomplishment of intended learning outcomes by all students.21,46 Participants regarded feedback as a central aspect of the training and stated the benefits of using a procedural flowchart as a feedback aid.30 This allows both the student and teacher to focus on the procedural flow and promptly identify errors, reducing extrinsic cognitive load,47 thus enabling effective learning.
The use of a low-cost and easy to construct simulator in the program design allows it to be easily replicated. This aspect is particularly important for low- and middle-income countries ICU's, where high costs and lack of availability of commercial simulators have been described as potential barriers for simulation training implementation.48,49
A recent survey in France suggests that critical care physicians perform between 2 and 4 PDT per month.50 In this sense, in infrequent procedures, like BG-PDT, simulation training has even a more important role,32 because the limited clinical cases residents are exposed to are not invested in learning basic procedural aspects, but rather in capitalizing the specific details before autonomous execution, and in preventing skills decay through continuous training.32
Despite acquired competency in simulated and cadaveric models, trainees' patient performance should be adequately supervised, and structured feedback for continuous improvement should be given until trainees become proficient and can perform autonomously. Simulation training does not intend to replace clinical training, but it allows trainees to advance faster through the learning curve (ie, from novice to advance beginner),46 promote learning in a safe environment,20 and reduce harm to patients.23
This study has several limitations. First, we performed training of one technique (modified Ciaglia's single-tapered dilator technique with bronchoscopic guidance), so external validity to other methods of percutaneous tracheostomy could be limited. In addition, it could be argued that the sample size was small, but it was based on the results of our previous study, and significant differences were found in the primary outcome. Neither the simulator nor the cadaveric models bleed, so hemorrhagic complications could not be assessed. Nonetheless, multiple complications can be accurately identified, like nonmidline puncture, cartilage fracture, and posterior tracheal wall lesion. Finally, other factors that are present in the clinical scenario like situational awareness,51 potential harm to a patient, or summative assessment stakes could impact on trainee performance and were not present in this controlled scenario.
Future studies focused on PDT training should aim at answering clinically relevant questions, like defining the best training methodology, the optimal number of training sessions before real-patient execution, use of simulators to avoid expert skill decay, and impact of simulation training on BG-PDT learning curves and clinical results.
In conclusion, we have successfully demonstrated the acquisition of BG-PDT procedural skills with a simulation-based mastery learning program and skills transfer to a cadaveric model. This low-cost training protocol can be easily replicated in any ICU, to develop simulation-based training programs and work toward safer patient care.
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