ExoventQ: A Novel Low-Cost Portable Negative Pressure Ventilator Design and Implementation

Abstract

The onset of Coronavirus Disease 2019 (COVID-19) led to significant shortages in mechanical ventilators worldwide. This situation prompted investigations to discover new methods for producing lowcost, safe ventilators. Among the popular types of ventilators are positive pressure ventilators (PPVs), conventional negative pressure ventilators (NPVs), and biphasic cuirass ventilators (BCVs). Unfortunately, PPVs were found to cause serious health complications for patients, not to mention their high manufacturing costs. Therefore, in this study, we introduce ExoventQ, an innovative, cost-effective respiratory support device derived from historical NPV designs. The system was meticulously designed, simulated, implemented, and tested in two modes: continuous negative extrathoracic pressure (CNEP) and cyclic negative pressure ventilation (CNPV). ExoventQ comprises a pressure vessel, a pumping system, and a control panel. Each of these three major subsystems was designed with considerations of pressure distribution, material, safety, cost, and portability. The ANSYS stress analysis of the polycarbonate pressure vessels indicates that a semicylindrical vessel can withstand more pressure than a prismatic vessel without experiencing permanent deformations or fractures. Subsequently, the structure was modified to adopt a squircle-shaped vessel to prevent the airway from tilting when assembled on the side, providing the patient with more space to lie comfortably. The pressure inside the vessel is regulated via a bypass butterfly valve actuated by a servo motor. The user interface was implemented on a Raspberry Pi touchscreen, allowing inputs to be entered by rotating the knobs on the screen, with the output displayed for monitoring. To ensure patient safety, a range of safety measures were implemented, including audio and visual alarms and a power switch that halts ventilation if the vacuum in the vessel drops below 40 mbar. The successful design and implementation of this system have the potential to pave the way for the mass production of safe and affordable NPVs to address pulmonary complications.