Development and assessment of the performance of a shared ventilatory system that uses clinically available components to individualize tidal volumes

ObjectivesTo develop and assess the performance of a system for shared ventilation that uses clinically available components to individualize tidal volumes under a variety of clinically relevant conditions. DesignEvaluation and in vitro validation study. SettingVentilator shortage during the SARS-CoV-2 global pandemic. ParticipantsThe design and validation team consisted of intensive care physicians, bioengineers, computer programmers, and representatives from the medtech sector. MethodsUsing standard clinical components, a system of shared ventilation consisting of two ventilatory limbs was assembled and connected to a single ventilator. Individual monitors for each circuit were developed using widely available equipment and open source software. System performance was determined under 2 sets of conditions. First, the effect of altering ventilator settings (Inspiratory Pressure, Respiratory rate, I:E ratio) on the tidal volumes delivered to each lung circuit was determined. Second, the impact of altering the compliance and resistance in one simulated lung circuit on the tidal volumes delivered to that lung and the second lung circuit was determined. All measurements at each setting were repeated three times to determine the variability in the system. ResultsThe system permitted accurate and reproducible titration of tidal volumes to each lung circuit over a wide range of ventilator settings and simulated lung conditions. Alteration of ventilator inspiratory pressures stepwise from 4-20cm H2O, of respiratory rates from 6-20 breaths/minute and I:E ratio from 1:1 to 1:4 resulted in near identical tidal volumes delivered under each set of conditions to each simulated lung. Stepwise alteration of compliance and resistance in one test lung circuit resulted in reproducible alterations in tidal volume to the test lung, with little change to tidal volumes in the control lung (a change of only 6% is noted). All tidal volumes delivered were highly reproducible upon repetition. ConclusionsWe demonstrate the reliability of a simple shared ventilation system assembled using commonly available clinical components that allows individual titration of tidal volumes. This system may be useful as a temporary strategy of last resort where the numbers of patients requiring invasive mechanical ventilation exceeds supply of ventilators. Article Summary Strengths and limitations of this studyO_LIThis solution provides the ability to safely and robustly ventilate two patients simultaneously while allowing differing tidal volumes in each limb. C_LIO_LIThe designed solution uses equipment readily available in most hospitals. C_LIO_LIAccurate and reproducible titration of tidal volumes to each lung was possible over a wide range of ventilator settings. C_LIO_LIAlteration of one simulated lung conditions had minimal impact on the tidal volumes delivered to the unaffected lung C_LIO_LIThe system relies on patients being sedated and paralysed. C_LIO_LIWe have not yet tested this solution in vivo, on COVID-19 patients. C_LI