Audiovisual Feedback from a Handheld Monitoring Device Improves Manual Ventilation

Abstract

Background Manual ventilation with a self-inflating bag is a difficult clinical skill to perform safely and effectively. Hyperventilation is a common and harmful adverse effect, potentially causing deleterious hemodynamic changes, gastric insufflation, and/or direct volutrauma to the lungs. To improve manual ventilation safety and efficacy, we developed the Bag valve mask Emergency Narration Guided Instrument (BENGI), a handheld tidal volume feedback device that provides simple and intuitive audio-visual feedback in real-time on the correctness of the user’s ventilations. To test whether the BENGI improves manual ventilation, a randomized crossover manikin simulation study was performed. Methods Participants (n = 20) were recruited from LSUHS-Shreveport medical school to manually ventilate both with and without the BENGI. Participants were asked to manually ventilate a manikin for 5 min under four different scenarios at different target tidal volumes (500, 750, 300, and 20 mL) and respiratory rates (10 min−1 for Scenarios 1 through 3 and 60 min−1 for Scenario 4). Air pressure and flow waveforms were measured to calculate tidal volume, respiratory rate, inspiratory time, peak inspiratory pressure, and the work and power imparted to the test lungs by the manual ventilation. Intra-participant (standard deviations throughout a given test) and inter-participant variations (standard deviation among all participants for a given scenario) in respiratory parameters were assessed, and Poincaré plots were constructed to further reveal alterations in short-term (SD1) and long-term (SD2) variations in tidal volume and respiratory rate delivery. Results BENGI use during manual ventilation significantly reduced deviations in tidal volume and respiratory rates from the target values. Both intra- and inter-participant variations in tidal volumes and respiratory rates were reduced. Poincaré plot analysis suggested that long-term (SD2) variations in tidal volume and respiratory rate were decreased in all scenarios, and short-term (SD1), or cycle-to-cycle, variations in tidal volume (Scenario 4) and respiratory rate (Scenarios 1 through 3) were also diminished. Conclusion Use of the BENGI improved both tidal volume and respiratory rate accuracy and consistency during manual ventilation in a manikin simulation study. The BENGI may have utility as a medical device for improving manual ventilation and reducing manual hyperventilation.