I. Introduction
1. Need for the study
Endotracheal intubation is an essential emergency medical procedure performed to secure a patient’s airway in prehospital settings, particularly for patients requiring artificial ventilation[1]. Among various techniques, oral intubation is one of the most frequently performed skills by paramedics due to its relative speed and ease of application in urgent situations. However, in real-world field environments, stable conditions such as a hospital bed are often unavailable, and providers are frequently required to perform intubation on the ground[2].
These prehospital scenarios vary widely depending on the mechanism of injury, patient positioning, and environmental constraints, necessitating that paramedics be capable of selecting and executing the most appropriate procedural position in real time[3].
Previous studies on endotracheal intubation have actively focused on improving the success rate of intubation during ambulance transportation[4], and there have also been comparative studies on difficult intubation performed by 119 emergency medical teams[5]. In particular, various studies have been conducted to improve the success rate, such as research on the ease of using a single-lumen endotracheal tube[6] and comparisons of video laryngoscopes, fiberoptic bronchoscopes, and stylets[7,8].
However, there is a relative lack of research on performing endotracheal intubation on the floor. While some studies have addressed the use of video laryngoscopes or bougies in performing endotracheal intubation on the floor[1,9], research on the performance characteristics based on different positions in real-world settings is limited.
Therefore, this study aims to compare and analyze the performance characteristics of endotracheal intubation according to different procedural positions, in order to enhance real-world response capabilities and provide direction for practical training based on intubation environments. A simulation-based repeated measures design was adopted. Participants performed intubation in four different positions: on a bed, kneeling, prone, and lateral positions. Objective measurements such as intubation time and depth were recorded, while subjective evaluations regarding perceived difficulty, immersion, physical discomfort, positional flexibility, procedural preference, and educational value were collected through a structured questionnaire administered immediately after each procedure
II. Methods
1. Study design and methods
This study was conducted with 30 students enrolled in the bachelor’s degree advancement program in Emergency Medical Technology at J University. Participants were selected based on voluntary agreement after receiving a full explanation of the study’s purpose, methodology, and procedures. Informed consent was obtained from all participants prior to the start of the study.
This study adopted a simulation-based repeated measures experimental design to investigate the characteristics of endotracheal intubation performance across various procedural positions. Four distinct positions were evaluated: (1) the conventional bed position, (2) a kneeling position on the floor, (3) a prone position on the floor, and (4) a lateral position on the floor. Each participant performed intubation procedures in all four positions, allowing for within-subject comparisons of procedural difficulty, physical discomfort, intubation depth, and user preference under simulated prehospital conditions<Fig. 1>.
Participants performed endotracheal intubation once in each of the four positions in a fixed sequence. Immediately after each procedure, they completed a self-administered questionnaire to subjectively evaluate the position, which included perceived difficulty, task immersion, and physical discomfort.
All participants were fourth-year students enrolled in a bachelor’s degree program following the completion of a three-year Emergency Medical Technology curriculum. They were already well-acquainted with the structure and operation of the endotracheal intubation simulator(manikin). To minimize learning effects from repeated procedures, the interval between each position was set to one week.
2. Materials
This study simulated real-life prehospital endotracheal intubation scenarios using a training manikin(Laerdal Airway Management Trainer, Laerdal Medical, Norway) placed on a patient transport stretcher. The intubation procedure was performed using a standard endotracheal tube(Hi-Lo, Mallinckrodt Medical, Ireland) with an internal diameter of 7.5 mm(7.5 mm ID), which is commonly used in actual emergency medical settings. The procedural protocol strictly followed the national practical skills examination guidelines provided by the Korea Health Personnel Licensing Examination Institute for paramedic certification<Table 1>.
Table 1
Endotracheal Intubation Procedure
Intubation was performed using a Fiber Optic laryngoscope set(HEINE, Germany), and the time required to complete the procedure was measured from the initial handling of the laryngoscope to the first ventilation using a bag-valve-mask(Laerdal Silicone Resuscitator, Laerdal Medical, Norway). The benchmark for successful intubation was set at 30 seconds or less. All procedures were conducted under controlled simulation conditions that closely resembled real field environments..
An assistant was present to support each simulation by ventilating with the BVM, recording the intubation time, and measuring the insertion depth of the tube. For each participant, performance was evaluated based on three key metrics: the time required to complete endotracheal intubation(seconds), the depth of tube insertion(cm), and the overall success rate of intubation(%).
3. Questionnaire
The self-administered questionnaire used in this study was specifically developed to align with the research objectives. It consisted of three domains: perceived difficulty of performance(e.g., “It was difficult to maintain the required posture”), task immersion(e.g., “I was able to immerse myself as if it were a real-life situation”), and physical discomfort(e.g., “I experienced physical discomfort while performing the posture”).
Each item was rated on a 5-point Likert scale, ranging from 1(strongly disagree) to 5(strongly agree). The content validity of the questionnaire was ensured through a review process conducted by two professors of Emergency Medical Technology and one expert with clinical field experience.
4. Analysis method
All statistical analyses were performed using SPSS Statistics version 27.0(IBM Corp., Armonk, NY, USA). Descriptive statistics, including frequencies, percentages, means, and standard deviations, were used to summarize the general characteristics of the participants.
To examine differences in endotracheal intubation time and insertion depth across the four procedural positions, repeated measures analysis of variance(Repeated Measures ANOVA) was conducted. If the assumption of normality was not satisfied, the Friedman test was used as a non-parametric alternative.
Subjective evaluations of procedural difficulty, task immersion, and physical discomfort according to position were analyzed using the Friedman test, in line with the repeated measures design. Preferences for procedural positions were assessed through frequency analysis. Perceived educational value of the simulation training was presented using mean and standard deviation for each survey item.
In addition, correlations between participants’ perceived physical flexibility and subjective outcomes(difficulty, immersion, and discomfort) were analyzed using Pearson’s correlation coefficients or Spearman’s rank correlation coefficients, depending on the distribution characteristics of the variables.
For all analyses, the significance level(α) was set at 0.05. Bonferroni correction was applied in post-hoc analyses to adjust for multiple comparisons.
III. Research results
1. General characteristics of participants
The general characteristics of participants are presented in <Table 2>.
Table 2
General characteristics of participants (N=30)
Among the participants, 46.7%(n=14) were male and 53.3%(n=16) were female. In terms of age, 83.3%(n=25) were aged 25 years or younger, while 16.7%(n=5) were older than 26 years, indicating that the majority of participants were in their mid-twenties or younger. Regarding participants’ occupations, 46.7%(14 individuals) were students currently enrolled in an advanced bachelor’s degree program, 23.3%(7 individuals) were hospital employees, 16.7%(5 individuals) were firefighters, and 13.3%(4 individuals) were employed in private industries. In terms of practical experience, 40.0%(12 participants) had no prior field experience, 36.7%(11 participants) had less than one year of experience, 13.3%(4 participants) had between one and three years, 3.3%(1 participant) had between three and five years, and 6.7%(2 participants) had more than five years of experience.
Regarding self-perceived flexibility, 43.3%(13 individuals) reported being “average”, followed by “somewhat flexible” at 23.3%(7 individuals), and “not flexible” at 20.0%(6 individuals).
2. Endotracheal intubation time and insertion depth by procedural position
The endotracheal intubation time and insertion depth according to the procedure position are presented in <Table 3>.
Table 3
Endotracheal Intubation time and depth by procedure position (N=30)
| Procedure position | Intubation time (seconds, M±SD) | Intubation depth (cm, M±SD) | |
|---|---|---|---|
| On bed | 19.93±3.95 | 21.33±1.29a | |
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| On the floor | Kneeling | 20.10±4.56 | 21.17±1.91 |
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| Prone | 21.44±4.25 | 20.33±1.49 | |
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| Lateral | 20.49±3.46 | 20.23±1.30b | |
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| F(p) | 1.056(.372) | 5.080(.003)** | |
The shortest average intubation time was observed in the bed position at 19.93 seconds(±3.95), while the longest was in the prone position at 21.44 seconds(±4.25). However, repeated measures ANOVA revealed no statistically significant difference among the positions (F=1.056, p=.372).
In terms of intubation depth, the bed position showed the greatest average depth at 21.33 cm(±1.29), whereas the lateral position showed the shortest at 20.23 cm(±1.30). A statistically significant difference in insertion depth was found depending on the procedure position (F=5.080, p=.003).
Post hoc analysis using the Bonferroni method indicated that the only significant difference in depth was between the bed position and the lateral position(p<.05).
In this study, the main experimental variables—intubation time and insertion depth by posture—were all within acceptable reference ranges for all participants. Therefore, the average values of the four postures for each participant were used to test homogeneity based on clinical experience using an independent samples t-test. The results indicated no significant differences in mean intubation time(t=.028, p=.978) or mean insertion depth(t=.293, p=.772), suggesting a low risk of bias in interpreting the experimental results based on prior experience(data not shown).
3. Perceived difficulty, immersion, and physical discomfort by procedural position
The perceived difficulty, immersion, and physical discomfort according to the procedural position are presented in <Table 4>.
Table 4
Perceived difficulty, immersion, and physical discomfort by intubation position (N=30)
| Procedure position | Perceived difficulty (M±SD) | Immersion (M±SD) | |
|---|---|---|---|
| On bed | 1.53±.93a | 3.83±1.17 | |
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| On the floor | Kneeling | 2.56±1.00b | 3.93±.86a |
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| Prone | 3.16±.91c | 3.80±.96a | |
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| Lateral | 3.16±1.14c | 3.43±1.10b | |
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| Friedman χ2(p) | 36.906(.000)*** | 6.070(.108) | |
According to the results of the Friedman test, there was a statistically significant difference in perceived difficulty among the different positions(χ2=36.906, p<.001). Post hoc analysis revealed that the bed position showed the lowest level of difficulty(1.53±.93), followed by the kneeling position(2.56±1.00), prone position (3.16±.91), and lateral position(3.16±1.14).
Similarly, physical discomfort also showed a statistically significant difference by position(χ2 =44.349, p<.001). The bed position had the lowest discomfort score(1.30±.74), followed by the kneeling(2.73±1.01), prone(3.26±1.01), and lateral(3.43±.93) positions.
On the other hand, immersion did not show a statistically significant difference across positions(χ2=6.070, p=.108). However, according to the Bonferroni-adjusted criterion, the lateral position(3.43±1.10) demonstrated a significantly lower immersion score compared to kneeling 3.93±.86) and prone (3.80±.96) positon.
4. Distribution of preferred procedural positions
<Table 5> presents the distribution of participants’ most preferred procedural positions overall<Fig. 2> and specifically among floor-level positions<Fig. 3>.
Table 5
Preferred position for all intubation positions and preferred position for intubation on the floor
| Procedure position | All n(%) | Floor intubation position n(%) | |
|---|---|---|---|
| On bed | 23(76.7) | - | |
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| On the floor | Kneeling | 5(16.7) | 13(43.3) |
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| Prone | 0(0.0) | 7(23.3) | |
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| Lateral | 2(6.7) | 10(33.3) | |
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| Total | 30(100.0) | 30(100.0) | |
Among the 30 participants, 76.7%(n=23) reported a preference for the bed position, while the remaining 23.3%(n=7) preferred floor-level positions, with the kneeling position most frequently selected(16.7%, n=5), followed by the lateral position(6.7%, n=2). Notably, no participants selected the prone position as their most preferred overall.
<Table 5> and <Fig. 3> also display preferences under the hypothetical scenario in which the bed position is excluded, focusing solely on the distribution of preferences among floor-level positions. Under this condition, 43.3%(n=13) of participants preferred the kneeling position, followed by the lateral position(33.3%, n=10), and the prone position(23.3%, n=7).
5. Correlation between self-perceived flexibility and intubation time by procedural position
<Table 6> present the correlation between self-perceived flexibility and endotracheal intubation time across different procedural positions.
Table 6
Correlation matrix between self-perceived physical flexibility and intubation time by intubation position
| Variables | 1 | 2 | 3 | 4 | 5 | |
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| Self-perceived physical flexibility | 1 | |||||
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| On bed | .196 | 1 | ||||
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| On the floor | Kneeling | -.233 | .199 | 1 | ||
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| Prone | -.212 | -.118 | .526** | 1 | ||
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| Lateral | -.139 | .303 | .242 | .168 | 1 | |
The correlation analysis revealed no statistically significant relationships between perceived flexibility and intubation time in any of the positions. However, a correlation trend was observed in the kneeling position(r=-.233) and the prone position(r=-.212), suggesting that participants who perceived themselves as more flexible tended to achieve faster intubation in these positions.
Meanwhile, a statistically significant positive correlation was found between intubation times in the kneeling and prone positions(r=.526, p<.01).
IV. Discussion
Endotracheal intubation is a critical procedure for airway maintenance in prehospital emergency settings, requiring the practitioner to adapt to various patient positions and environmental conditions. Previous studies have largely focused on the effectiveness of intubation tools, visualization devices, or the impact of provider experience on success rates and procedure time. For instance, Youn and Han[7] compared the use of a flexible bronchoscope and a video stylet to evaluate intubation efficiency in settings with limited visibility, while Song et al. examined the effectiveness of bougies and video laryngoscopes when performing intubation in floor-level positions[1].
However, many of these studies have been conducted using specific equipment or a single procedural posture, offering limited insight into how intubation performance varies across diverse patient positions and surface conditions that resemble real-life emergency scenarios[2,9]. Therefore, this study employed a repeated measures design to compare intubation characteristics across a range of procedural postures—namely, the bed position, and three floor-level positions: kneeling, prone, and lateral. The goal was to generate empirical data applicable to realistic and educationally meaningful simulation training environments.
However, many of these studies have been conducted using specific equipment or a single procedural posture, offering limited insight into how intubation performance varies across diverse patient positions and surface conditions that resemble real-life emergency scenarios. Therefore, this study employed a repeated measures design to compare intubation characteristics across a range of procedural postures—namely, the bed position, and three floor-level positions: kneeling, prone, and lateral. The goal was to generate empirical data applicable to realistic and educationally meaningful simulation training environments.
Furthermore, perceived task difficulty and physical discomfort were notably higher in the kneeling and lateral positions. The prone position, in particular, appeared to limit wrist maneuverability and overall hand positioning, potentially contributing to increased physical fatigue[10]. Although immersion levels did not differ significantly across positions, the lateral position showed a trend toward reduced immersion, suggesting potential psychological or ergonomic barriers associated with that posture.
According to the preference survey, most participants favored the bed position, while the kneeling position was selected as an alternative when floor-level procedures were unavoidable. These results suggest that training should not be biased toward table-based procedures alone, but should also include diverse positional training that closely reflects real-world field conditions[5,6].
The finding that the bed position showed the lowest levels of perceived difficulty and physical discomfort is likely attributable to the participants’ familiarity with this posture, which is commonly used in standard training environments. In this context, the result is considered predictable. Notably, the average perceived difficulty scores for the prone and lateral positions were both 3.16 on a 5-point Likert scale—suggesting a level of difficulty that exceeds mere discomfort and may warrant pedagogical consideration. Therefore, rather than interpreting these scores in isolation, future research should consider establishing meaningful benchmarks or incorporating qualitative evaluations to contextualize these results more accurately[10].
Meanwhile, a weak negative correlation trend between self-perceived flexibility and intubation time was observed in certain floor-level positions. This implies that physical flexibility may influence intubation efficiency in more complex postures. Therefore, when designing future simulation-based training, it is necessary to incorporate personalized feedback and strategies based on individual physical characteristics.
Furthermore, in alignment with this study’s stated goal of contributing to a more realistic and educationally meaningful simulation environment, it is essential to move beyond the simple act of changing procedural positions. Concrete strategies for applying these findings to educational settings should be proposed. For example, training modules could be structured progressively based on the levels of perceived difficulty and discomfort: starting with the bed position, followed by kneeling, lateral, and finally prone positions. Additionally, scenario-based simulations that reflect real-world field limitations—such as restricted visibility, non-ideal patient access angles, or spatial constraints—should be actively incorporated into the curriculum. Through such approaches, simulation training can evolve from mere posture adaptation to a more comprehensive educational design that fosters both cognitive preparedness and problem-solving capabilities.
In conclusion, this study underscores the necessity of incorporating repeated simulation training that reflects various on-scene patient positions into paramedic education. Rather than focusing solely on equipment-based practice, the curriculum should emphasize adaptability to diverse procedural postures. In particular, repeated practice in kneeling and lateral positions is proposed as a key strategy to enhance postural adaptability, which is essential for improving real-world emergency response capabilities.
However, this study has certain limitations. First, the sample size was relatively small and consisted solely of students from a single institution, which may limit the generalizability of the findings. Second, the simulation environment cannot fully replicate the complexities of real-world emergency settings, such as patient variability, environmental obstacles, and emotional stressors. Third, performance difficulty and discomfort were measured through self-reported questionnaires, which are subject to individual bias. Future studies should incorporate more diverse participants—including practicing Paramedics—and consider objective performance metrics and real-world scenario testing to enhance ecological validity.
V. Conclusion
This study aimed to analyze the characteristics of endotracheal intubation performance according to various procedural positions in prehospital emergency settings, with the goal of developing more realistic and effective simulation-based training materials for paramedic education.
A statistically significant difference in intubation depth was found across positions, with the bed(supine) position tending to result in deeper insertion compared to the lateral position. In terms of perceived task difficulty and physical discomfort, the bed position was rated the lowest, whereas the prone and lateral positions were rated the highest, indicating greater physical burden for the provider in those positions.
Participants showed the highest preference for the bed position. However, when the table was unavailable, the kneeling position was relatively more preferred among the floor-level positions. These findings suggest that paramedics need to develop proficiency in performing procedures across a variety of patient positions and environments. Therefore, repeated simulation training that incorporates realistic ground-level positions—such as kneeling or lateral orientations—should be emphasized in emergency care education.
Traditionally, endotracheal intubation training and assessments have been conducted with the assumption of a bed-based environment. However, recent shifts toward floor-based testing settings reflect a growing emphasis on real-world clinical conditions. This study holds educational significance in that it empirically demonstrated that such environmental changes do not negatively impact physical burden or procedural success for the performer. Rather, with adequate training, these challenges can be sufficiently overcome.
Therefore, there is a need to move beyond bed-centered instruction and implement repetitive, field-oriented simulation training that includes a variety of floor-based postures. In particular, the development of structured programs aimed at enhancing clinical confidence and performance in realistic positions—such as kneeling or lateral approaches—is essential.
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