Efficacy and Safety Testing of a COVID-19 Era Emergency Ventilator in a Healthy Rabbit Lung Model

Background: The COVID-19 pandemic revealed a substantial and unmet need for low-cost, easily accessible mechanical ventilation strategies for use in medical resource-challenged areas. Internationally, several groups developed non-conventional COVID-19 era emergency ventilator strategies as a stopgap measure when conventional ventilators were unavailable. Here, we compared our FALCON emergency ventilator in a rabbit model and compared its safety and functionality to conventional mechanical ventilation. Methods: New Zealand white rabbits (n = 5) received mechanical ventilation from either the FALCON or a conventional mechanical ventilator (Engström Carestation TM ) for 1 hour each. Airflow and pressure, blood O 2 saturation, end tidal CO 2 , and arterial blood gas measurements were measured. Additionally, gross and histological lung samples were compared to spontaneously breathing rabbits (n = 3) to assess signs of ventilator induced lung injury. Results: All rabbits were successfully ventilated with the FALCON. At identical ventilator settings, tidal volumes, pressures, and respiratory rates were similar between both ventilators, but the inspiratory to expiratory ratio was lower using the FALCON. End tidal CO 2 was significantly higher on the FALCON, and arterial blood gas measurements demonstrated lower arterial partial pressure of O 2 at 30 minutes and higher arterial partial pressure of CO 2 at 30 and 60 minutes using the FALCON. However, when ventilated at higher respiratory rates, we observed a stepwise decrease in end tidal CO 2 . Poincaré plot analysis demonstrated small but significant increases in short-term and long-term variation of peak inspiratory pressure generation from the FALCON. Wet to dry lung weight and lung injury scoring between the mechanically ventilated and spontaneously breathing rabbits were similar. Conclusions: Although conventional ventilators are always preferable outside of emergency use, the FALCON ventilator safely and effectively ventilated healthy rabbits without lung injury. Emergency ventilation using accessible and inexpensive strategies like the FALCON may be useful for communities with low access to medical resources and as a backup form of emergency ventilation.