The prehospital phase of emergency medical care plays a critical role in patient survival and clinical outcomes [1]. Emergency medical services (EMS) clinicians provide on-site assessment, triage, and treatment and are therefore essential to public health [2,3]. Previous studies have consistently shown that patients treated by well-trained EMS clinicians have better clinical outcomes, particularly in critical conditions such as severe trauma and cardiac arrest [4,5]. Advanced prehospital procedures, including advanced airway management and intravenous (IV) drug administration, have also been associated with improved outcomes in emergency patients [6,7]. Studies of other healthcare professionals, including physicians and nurses, have shown that confidence is related to procedural performance [8-10]. Even in hospital settings, clinicians with greater case experience tend to report higher procedural confidence [11,12]. These findings suggest that ongoing clinical experience may help build both technical skills and self-confidence. Assessing procedural confidence among EMS clinicians and identifying its determinants may therefore help improve the success of advanced interventions in prehospital care.

Although the determinants of procedural confidence among EMS clinicians have not been clearly established, we hypothesized that field deployment frequency might be associated with hesitation to perform advanced procedures. Supraglottic airways (SGAs) have increasingly been adopted as alternatives to endotracheal intubation (ETI) because they are easier to insert, require shorter training, and have comparable effectiveness in prehospital settings [13-18]. This study evaluated the association between case volume and hesitation to perform SGA insertion among EMS clinicians using a nationwide survey.

This study found no significant relationship between case volume and hesitation to perform SGA insertion among EMS clinicians. In contrast, IV drug administration showed a significant inverse association, with higher case volume associated with lower hesitation. These findings suggest that field exposure alone may not improve confidence in airway management, particularly for invasive procedures such as ETI and intermediate-level skills such as SGA insertion. For other procedures, including mass-casualty triage, ECG interpretation, and end-tidal carbon dioxide monitoring, no significant association with case volume was observed. Overall, repeated on-scene exposure may help build confidence in some frequently encountered procedures, whereas rarely performed skills may require additional educational interventions. Several mechanisms may explain these findings. First, case volume reflects the quantity of field exposure but does not necessarily reflect opportunities to perform specific procedures. EMS units with high transport volumes may prioritize a “scoop and run” approach, which can limit thorough assessment and the use of advanced procedures. In addition, the role of each EMS clinician at the scene may not be clearly defined; consequently, clinicians with lower confidence may have few opportunities to perform a given procedure despite higher case volume. This discrepancy is particularly relevant for infrequent interventions such as SGA insertion, for which increased deployment does not guarantee procedural exposure. General field experience alone may therefore be insufficient to reduce hesitation, underscoring the need for procedure-specific training strategies. Table 1 shows that even in the very high-volume group, the proportion of clinicians who performed ETI ≤2 times per month (96.2%) was similar to that in the low-volume group (99.8%). In contrast, procedures such as IV drug administration and prehospital stroke assessment varied substantially across case-volume groups, suggesting that frequent deployments do not necessarily provide adequate opportunities to perform rare, high-complexity procedures such as ETI. Second, complex invasive procedures require deliberate practice rather than passive exposure. Prior studies of laryngoscopic intubation training suggest that approximately 47 attempts may be required to achieve a 90% probability of competent performance [23]. This threshold is unlikely to be achieved through routine field exposure alone, which may explain why hesitation toward ETI remained high (approximately 90%) across all groups. Persistent hesitation may also reflect the invasive nature, technical complexity, and low prehospital frequency of ETI. In South Korea, ETI and SGA are currently recommended at a similar level in prehospital performance evaluations. This evaluation framework is based on evidence from a recent clinical trial [24]; as a result, EMS clinicians may have fewer incentives to choose more technically demanding procedures. Third, confidence development may depend on qualitative reinforcement rather than repetition alone. For example, IV drug administration may provide immediate positive feedback, such as rapid improvement in consciousness after glucose administration for hypoglycemia, which may reinforce clinician confidence. In contrast, SGA insertion provides limited direct feedback and is often performed under stressful, high-risk conditions, which may perpetuate hesitation even among experienced providers. Collectively, these observations suggest that procedure-specific experience, rather than the sheer number of deployments, may be the main determinant of confidence in advanced procedural skills.

The current findings both align with and diverge from prior research. They differ from some previous studies because total case volume, rather than procedure-specific exposure, was not associated with SGA hesitation in the present analysis. Hill et al. [25] found that Australian EMS clinicians had low confidence in out-of-hospital childbirth, even among experienced providers, suggesting that rare, high-risk interventions may elicit hesitation regardless of general experience. Similarly, Furin et al. [26] reported that more than half of Pennsylvania EMS clinicians lacked confidence in performing surgical airways, further emphasizing the gap between rare procedures and clinician confidence. In contrast, Yang et al. [12] found that greater procedural frequency was correlated with higher confidence in routine core skills among hospital nurses, which is consistent with our finding that hesitation regarding IV drug administration decreased as case volume increased.

Increasing deployment frequency alone is unlikely to reduce EMS clinicians’ hesitation to perform advanced procedures. Instead, structured educational programs and expanded procedural opportunities are needed. Simulation-based refresher training, hospital-based airway rotations, and standardized retraining protocols, as recommended by Ono et al. [27], could help address the experience gap for rarely performed skills. Our findings regarding IV drug administration further highlight the value of deliberate practice opportunities and feedback-rich learning environments. Future studies should evaluate whether these interventions improve clinician confidence and, ultimately, patient outcomes.

This study has several limitations. First, because of its cross-sectional design, causal inferences between case volume and procedural hesitation cannot be made; only associations at a single time point were examined. Second, hesitation was assessed using a self-administered questionnaire, which may be affected by respondent subjectivity and social desirability bias. In addition, although the survey instrument underwent pilot testing, formal psychometric validation was not performed, which may limit the reliability and interpretability of the responses. Third, only approximately 12% of EMS personnel nationwide voluntarily participated in the survey, raising the possibility of selection bias if respondents with greater interest or confidence in clinical procedures were more likely to participate. Fourth, case volume was categorized according to 24-hour duty shifts, which may not adequately represent cumulative long-term exposure or varied work conditions, and the measure did not account for qualitative aspects of exposure, such as the frequency of critically ill patients. Finally, residual confounding from unmeasured variables may have influenced the findings. Future studies should use validated instruments and more detailed measures of procedure-specific exposure to address these methodological limitations.

In conclusion, case volume was not significantly associated with hesitation to perform most advanced procedures, including SGA insertion, the primary outcome. These findings suggest that enhancing procedural confidence among EMS clinicians requires structured education and continuous practice rather than field experience alone.