OxyJet: Design and Evaluation of A Low-Cost Precision Venturi Based Continuous Positive Airway Pressure (CPAP) System

Abstract

The Covid-19 pandemic has strained the hospital systems in many countries in the world, especially in developing countries. In many low-resource hospitals, severely ill hypoxemic Covid-19 patients are treated with various forms of low-flow oxygen therapy (0-15 L/min), including interfaces such as a nasal cannula, Hudson mask, venturi-mask, and non-rebreather masks. When 15L/min of pure oxygen flow is not sufficient for the patient, treatment guidelines suggest non-invasive positive pressure ventilation (NIPPV) or high-flow nasal oxygenation (HFNO) as the next stage of treatment. However, administering HFNO in the general wards of a low-resource hospital is difficult due to several factors, including difficulty in operation, unavailability of electric power outlets, and frequent maintenance. Therefore, in many cases, the highest level of care a patient receives in the general ward is 15L/min of oxygen on a Non-Rebreather Mask. With a shortage of Intensive Care Unit (ICU) beds, this is a major problem since intermediate forms of treatments are simply not available at an affordable cost. To address this gap, we have developed a low-cost CPAP system specifically designed for low-resource hospitals. The device is a precision venturi-based flow-generator capable of providing up to 60L/min of flow. The device utilizes the mechanics of a jet pump driven by high-pressure oxygen to increase the volumetric flow rate by entraining atmospheric air. The fraction of inspired oxygen (FiO2) can be attained between 40 - 100% using a dual-flowmeter. Consisting of a traditional 22mm breathing circuit, a non-vented CPAP mask, and a Positive End-Expiratory Pressure (PEEP) valve, the CPAP can provide positive pressures between 5-20 cm H2O. The device is manufactured using local 3D printing and workshop facilities.