A Novel Ventilator Design for COVID-19 and Resource-Limited Settings

Michael Madekurozwa,Axel C Moore,James Moore,Molly M Stevens,Daniel J Watson,Jennifer Frattolin,Willy V Bonneuil,Joseph Van Batenburg-Sherwood,Jakob Mathiszig-Lee

doi:10.3389/fmedt.2021.707826

Abstract

There has existed a severe ventilator deficit in much of the world for many years, due in part to the high cost and complexity of traditional ICU ventilators. This was highlighted and exacerbated by the emergence of the COVID-19 pandemic, during which the increase in ventilator production rapidly overran the global supply chains for components. In response, we propose a new approach to ventilator design that meets the performance requirements for COVID-19 patients, while using components that minimise interference with the existing ventilator supply chains. The majority of current ventilator designs use proportional valves and flow sensors, which remain in short supply over a year into the pandemic. In the proposed design, the core components are on-off valves. Unlike proportional valves, on-off valves are widely available, but accurate control of ventilation using on-off valves is not straightforward. Our proposed solution combines four on-off valves, a two-litre reservoir, an oxygen sensor and two pressure sensors. Benchtop testing of a prototype was performed with a commercially available flow analyser and test lungs. We investigated the accuracy and precision of the prototype using both compressed gas supplies and a portable oxygen concentrator, and demonstrated the long-term durability over 15 days. The precision and accuracy of ventilation parameters were within the ranges specified in international guidelines in all tests. A numerical model of the system was developed and validated against experimental data. The model was used to determine usable ranges of valve flow coefficients to increase supply chain flexibility. This new design provides the performance necessary for the majority of patients that require ventilation. Applications include COVID-19 as well as pneumonia, influenza, and tuberculosis, which remain major causes of mortality in low and middle income countries. The robustness, energy efficiency, ease of maintenance, price and availability of on-off valves are all advantageous over proportional valves. As a result, the proposed ventilator design will cost significantly less to manufacture and maintain than current market designs and has the potential to increase global ventilator availability.

Highlights

During the COVID-19 pandemic, one of the first challenges to healthcare systems worldwide was the supply of intensive care unit (ICU) ventilators
The results demonstrated no negative effects on the performance, indicating the system is robust to a range of gas supply options
We described a novel ventilator design, intended to address the global shortage of ventilators that was exacerbated by the COVID-19 pandemic

Summary

Introduction

During the COVID-19 pandemic, one of the first challenges to healthcare systems worldwide was the supply of intensive care unit (ICU) ventilators. In the early days of the pandemic, ∼30% of hospitalised patients required invasive ventilation [1]. This stressed existing ventilator stocks in countries hit with early waves of the disease, prompting calls for increased production of existing designs. In the UK, the Medicines and Healthcare Products Regulatory Agency (MHRA) provided special performance criteria that could alternatively be met for “emergency use” designs. The USA’s Food and Drug Administration (FDA) began approving emergency use ventilators under reduced criteria

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