A Volume and Assist Controlled Mechanical Emergency Ventilator for Respiratory Support

Even before the COVID-19 pandemic, most hospitals in the Philippines, especially the rural and small hospitals, lacked respirators such as medical ventilators. With only a few thousand of these devices, the lack of emergency ventilators is a crucial problem in battling the COVID-19 pandemic in the Philippines. Hence, the study aimed to design an economical and portable mechanical emergency ventilator for respiratory support. It was achieved by effectively calibrating, automating, and controlling the working principle of BVM. Particularly, a CAM arm was designed to allow constant, smooth, and repeatable compression on the bag. Subsequently, driving the arm is a motor that was selected carefully according to the necessary motor torque and power calculations. Consequently, an effective close loop control system using a PID controller was implemented to control the motor position and speed. Although, the controller contains small inaccuracies that generate discrepancies in the volume measurement, and the pressure sensor records unusual readings due to breathing connection issues. The overall prototype confirms the minimum clinical specifications for a mechanical ventilator. As a result, the prototype has two ventilator modes, volume and assist control. It weighs 6.75 kg and has adimension of 385 × 270 × 235 mm.