Individualized mechanical ventilation in a shared ventilator setting: limits, safety and technical details.

Abstract Background- The COVID-19 pandemic has resulted in an increased need for ventilators. The potential to ventilate more than one patient with a single ventilator, a so-called split ventilator setup, provides an emergency solution. Our hypothesis is that ventilation can be individualized by adding a flow restrictor to limit tidal volumes, add PEEP, titrate FiO 2 and monitor ventilation. This way we could ensure optimization of patient safety and clinical applicability. We performed bench testing to test our hypothesis and identify limitations. Methods- We performed a bench testing in two lungs: 1) determine lung compliance 2) determine volume, plateau pressure and PEEP, 3) illustrate individualization of airway pressures and tidal volume with a flow restrictor, 4a) illustrate that PEEP can be applied and individualized 4b) create and measure intrinsic PEEP 4c-d) determine PEEP as a function of flow restriction, 5) individualization of FiO 2 . Results- The lung compliance varied between 13 and 27 mL/cmH 2 O. Set ventilator settings could be applied and measured. Extrinsic PEEP can be applied except for settings with a large expiratory time. Volume and pressure regulation is possible between 70-39% flow restrictor valve closure. Flow restriction in the tested circuit had no effect on the other circuit or on intrinsic PEEP. FiO 2 could be modulated individually between 0.21 and 0.8 by gradually adjusting the additional flow, and minimal affecting FiO 2 in the other circuit. Conclusions- Tidal volumes, PEEP and FiO2 can be individualized and monitored in a bench testing of a split ventilator. In vivo research is needed to further explore the clinical limitations and outcomes, making implementation possible as a last resort ventilation strategy.