Jet ventilation dynamics in rigid bronchoscope: insights from a simulated experimental model

Abstract

Background: Jet ventilation has emerged as a critical technique in airway management during airway interventions involving rigid bronchoscopy. Given the open airway and the lack of objective data on jet ventilation flow dynamics, intraoperative airway management is currently guided primarily by SpO₂ monitoring and arterial blood gas analysis.

Objective: To analyze the effects of jet ventilation modes (normal frequency jet ventilation (NFJV), high frequency jet ventilation (HFJV), and superimposed high frequency jet ventilation (SHFJV)), driving pressure, and frequency on airflow dynamics using a simulated airway model.

Methods: A 3D-printed rigid bronchoscope and artificial airway were integrated with a jet ventilator, airflow analyzer, and test lung. Peak airway pressure (P_peak), positive end-expiratory pressure (PEEP) and tidal volume, were measured under various conditions.

Results: The major trend observed was that as the frequency increases, both P_peak and tidal volume decrease, while PEEP increases; with higher driving pressure, there is an increase in P_peak, PEEP and tidal volume. During NFJV, maxim P_peak 26.0 (0.7) cmH₂O and tidal volume1399 (3) ml were observed at 1.5 bar and12 bpm, while minimum values 11.8 (0.4) cmH₂O and 488 (3) ml occurred at 0.7 bar and 24 bpm. During HFJV, P_peak, PEEP and tidal volume reached their lowest values at 4.7 (0.3) cmH₂O, 0.8 (0.2) cmH₂O and 24 (3) ml (set at 0.3 bar and 300 bpm). When driving pressure was set at 1.1 bar, both P_peak and tidal volume reached their highest values at 22.3 (0.4) cmH₂O and 280 (2) ml when jet frequency was100 bpm; while, the maximum PEEP reaches highest value of 6.1 (0.3) cmH₂O when jet frequency increased to 300 bpm. SHFJV demonstrated dynamic interactions, with tidal volume ranging from 614 (3) ml to 1105 (1) ml as driving pressure increased from 0.3 to 1.1 bar. At 1.1 bar and 100 bpm, P_peak achieved a value of 41.1 (0.3) cmH₂O and PEEP levels increase to 8.4 (0.3) cmH₂O set at 1.1 bar and 1500 bpm.

Conclusions: NFJV provides a larger tidal volume and maintains stable peak pressure, whereas HFJV results in lower tidal volumes at high frequencies and low pressures, which may clinically result in CO₂ retention. SHFJV combines the benefits of both modes, showing potential for complex airway conditions. These findings emphasize the importance of protocolized parameter selection based on individualized airway mechanics.

Keywords: Airway interventions; jet ventilation; Flow dynamic; Rigid bronchoscope; Simulated experimental model.