Agreement and Reliability of a Newly Developed Tidal Volume Monitoring Device in Bag-Valve Ventilation and Intubation Scenarios: A Simulation-Based Study.

Background

Manual bag-valve ventilation is a fundamental intervention in prehospital and emergency care but remains highly operator-related and frequently associated with inappropriate tidal volume delivery. Excessive or insufficient ventilation may adversely affect hemodynamics and clinical outcomes. Although real-time tidal volume monitoring has the potential to improve ventilation quality, its measurement performance across different airway conditions has not been sufficiently evaluated.

Methods

This simulation-based repeated-measures study evaluated the measurement agreement and reliability of a newly developed tidal volume monitoring device during manual ventilation using an adult airway management manikin. Twenty emergency medical technicians performed bag-valve ventilation across three airway scenarios: face mask ventilation, endotracheal tube (ETT) intubation, and supraglottic airway (I-gel) insertion. For each scenario, 10 repeated breaths were recorded. Tidal volumes measured by the test device were compared with simulator-derived reference values. Measurement agreement was assessed using paired t-tests, Pearson correlation coefficients, effect sizes, and Bland-Altman analysis, while measurement reliability was evaluated using intraclass correlation coefficients (ICC). Mixed repeated-measures ANOVA was performed to examine interaction effects between airway scenario and operator characteristics.

Results

The test device consistently overestimated tidal volume compared with the simulator reference across all airway scenarios (p < 0.001). Correlation between measurements was weak during mask ventilation (r = 0.174) but strong during ETT (r = 0.854) and I-gel (r = 0.709) ventilation, whereas Bland-Altman analysis demonstrated wider limits of agreement in mask ventilation and narrower limits under intubated conditions. ICC analysis revealed airway-dependent reliability, with minimal agreement in normal BVM ventilation but substantially higher agreement during ET-tube and I-gel intubation. Significant effects of airway scenario and operator characteristics (gender, age group, and clinical experience level) were observed, with notable interaction effects between airway scenario and clinical experience.

Conclusions

Despite systematic overestimation, the tidal volume monitoring device demonstrated consistent and repeatable performance, particularly under secured airway conditions. Its primary clinical value may lie in reducing operator-related variability and supporting safer manual ventilation through real-time feedback, rather than replacing gold-standard measurement systems. Further algorithm refinement and clinical validation are warranted.