Design and validation of a low-cost emergency mechanical ventilator in response to the pandemic caused by COVID-19

In this paper, the redesign and construction of a low- cost, open-source, emergency mechanical ventilator prototype is presented, in response to the shortage of mechanical ventilators caused by the COVID-19 pandemic in low- and middle-income countries. This redesign took as its starting point an open-source mechanical ventilator already validated through preclinical testing in a porcine animal model. The objective ofthis work was to improve the previous device, with changes in hardware and software, which resulted in a lower-cost device with greater replicability, maintaining the functional characteristics previously obtained with the base ventilator, verified by means of a mechanical ventilator calibrator. Results show a stable and precise behavior, and with an adequate operating range in accordance with the WHO and MHRA requirements, with a maximum error of 4.97% for pressure and 8.23% for tidal volume measurements. © 2022 Latin American and Caribbean Consortium of Engineering Institutions. All rights reserved.

Real-Time Estimation of Alternative Stress Index for Low-Cost, Mechanical Ventilators for Emergency Use

Stress index is a useful indicator in mechanical ventilation to assess improper ventilation settings. It can indicate tidal overdistension or tidal recruitment, which are two major mechanisms of ventilator-induced lung injury. However, it's implementation require dedicated hardware and software and is not a widespread parameter used in commercial ventilators. In this work, an alternative, simple way to visually inspect the concavity of the pressure-time curve during mechanical ventilation is presented, by calculating the pressure difference of the pressure-time curve. This proves useful when implemented in low-cost emergency devices, such as those designed to cope with the COVID-19 pandemic, because of the reduced computational load required to perform its calculation. The method was implemented in a low-cost emergency mechanical ventilator and tested with an artificial lung for a proof-of-concept. Results show that this alternative method can be effectively used to qualitatively assess the concavity of the pressure-time curve.