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

Abstract

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 enhance optimization of patient safety and clinical applicability. We performed bench testing to test our hypothesis and identify limitations. We performed a bench testing in two test 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 and d) determine PEEP as a function of flow restriction, (5) individualization of FiO 2. 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 and 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. Tidal volumes, PEEP and FiO 2 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.

Simultaneous ventilation in the Covid-19 pandemic. A bench study

“…Technical innovations have been proposed to individualize ventilator settings in each test-lung/patient, such as set inspiratory pressure, PEEP, and F I O 2 . These innovations include a one-way flow control valve at inspiratory and expiratory limbs in each test-lung/patient [ 13 ], a fixed pressure resistor regulator added at the inspiratory limb [ 32 ], a variable flow restrictor at the inspiratory limb, and a one-way valve at the expiratory limb [ 33 ], a flow restrictor on-way valve at the outlet of the ventilator [ 10 ], and bag-in-the box [ 23 ]. It should be noted that even though some of the interventions described above have been tested in a few patients [ 13 ], the experience is limited, they are complex to use and may generate further severe problems, as in case of an acute change in respiratory mechanics or gas exchange in one or two patients if the staff is not well trained.…”

“…In this case, in volume control ventilation and pressure control ventilation mode, each patient is expected to receive half of the set V T . Any decrease in compliance and/or increase in resistance in one patient will decrease V T in each mode [ 9 , 10 ]. For the other patient with unchanged compliance and resistance, V T will depend, at least in part, on mechanical ventilation mode.…”

Sharing ventilators in the Covid-19 pandemics. A bench study

“…Therefore, technical innovations have been proposed to individualize ventilator settings in each patient, such as set inspiratory pressure, PEEP, and F I O 2 . These innovations include a one-way flow control valve at inspiratory and expiratory limbs in each patient [12], a fixed pressure resistor regulator added at the inspiratory limb [31], a variable flow restrictor at the inspiratory limb, and a one-way valve at the expiratory limb [32], a flow restrictor on-way valve at the outlet of the ventilator [9], and bag-in-the box [29]. It should be noted that even though some of the interventions described above have been tested in a few patients [12], the experience is limited, they are complex to use and may generate further severe problems, as in case of an acute change in respiratory mechanics or gas exchange in one or two patients if the staff is not well trained.…”

“…In this case, in volume control ventilation and pressure control ventilation mode, each patient is expected to receive half of the set V T . Any decrease in compliance and/or increase in resistance in one patient will decrease V T in each mode [8, 9]. For the other patient with unchanged compliance and resistance, V T will depend on a part on mechanical ventilation mode.…”

The eSpiro Ventilator: An Open-Source Response to a Worldwide Pandemic

“…This situation compounded the urgent need to develop ventilator systems that can be rapidly deployed [ 2 ]. In situations like a global pandemic [ 1 ] and regional emergencies [ 3 ], or in low-resource ICUs, a ventilator-sharing strategy that maximizes the number of patients able to receive life-saving treatment has been used [ 4 , 5 ]. To address the issue of ventilator shortages, our group (eSpiro Network) developed a freely replicable, open-source hardware ventilator, which should provide better care for critically ill patients while requiring fewer resources [ 6 ].…”