A Low-Cost Venturi Ambient Air-Oxygen Blender for Neonatal Oxygen Therapy

The concentration of oxygen delivered to neonates in respiratory distress should be controlled to prevent hyperoxia. Current available oxygen blending devices have limited use in resource-limited settings due to their reliance on electricity, compressed air, skilled maintenance, and high cost. This study evaluated the ability of a novel blending device that addresses these limitations to deliver inspired concentrations of oxygen over a range of 30-100%. Our blending device was designed based on the Venturi principle. The blender consists of a nozzle, air entrainment window, and orifice. Oxygen exits the nozzle at high velocity into an air-entrainment chamber, where the low pressure surrounding the jet draws in ambient air. The mixture of air and oxygen is then transported into the orifice and thereafter further downstream via tubing. We investigated the effect of geometric factors and process variables on the delivered oxygen concentrations. The diameter of the Venturi nozzle and outlet orifice, the cross-sectional area of the air-entrainment window, the distance between the Venturi nozzle and the outlet orifice, flow rate, and temperature were each analyzed as independent variables. Understanding the geometric relationships between Venturi nozzle diameters, air-entrainment window cross-sectional areas, and Venturi nozzle to outlet orifice distances provided guidance on the design of an ultra-low-cost Venturi ambient air-oxygen blender. This study demonstrates the feasibility of manufacturing an air-oxygen blender that is low cost, does not require electricity or compressed air, and can provide accurate concentrations of oxygen for optimal delivery to neonates with respiratory distress.