Jet Ventilation vs Thrive: Which Is a Greater Risk as an AGP?

Introduction: In the past two decades, three global airborne viral infectious diseases: severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and coronavirus disease (COVID-19), have impacted healthcare systems worldwide. Early studies demonstrated that SARS-CoV-1 transmission rate to healthcare workers was significantly higher among emergency room providers, nurses, and specific physicians. Aerosol generating procedures (AGPs) may increase those risks.

Methods: We designed a Background Oriented Schlieren (BOS) system capable of discerning invisible airflows within an operating room that predicts AGP risk. Jet ventilation and Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) was implemented using a Dedo laryngoscope and a manikin with simulated lungs (Laerdal Airway Management Trainer). Images were acquired at 1000 frames per second and analyzed with a technique previously described by our team.

Results: Video documentation of airflows during both THRIVE and Jet Ventilation will be presented with both qualitative and quantitative measurements utilizing a line integral convolution (LIC) technique. This technique conveys information not only about the potential concentration of the aerosol in the plume by the magnitude of the displacement, but also reveals turbulent structures along the isocontours of the refractive index gradient. The speed of the plume head created by a jet ventilation pulse was found to be 2.4 m/s: 80% faster than those from normal breathing, 40% faster than coughing, and about the same flow rate produced by a sneeze. The THRIVE plume is continuous with flow rates ranging from 50-70 L/min.

Conclusions: Otolaryngologists managing complex airway disease with advanced techniques such as jet ventilation or THRIVE may be at greater risk with high flow rates of gas required. However, with novel technique such as BOS available, we can now plan mitigation efforts and more appropriately classify which otolaryngology procedures are actually AGPs.