The COVID-19 pandemic situation has called for an urgent need for the development of low cost respiratory ventilators across the globe. Such ventilators must include functionalities to cater to the patients experiencing severe respiratory illnesses, such as ARDS, where lung compliance and patient breathing cycles are dynamic, and require an accurate and controllable ventilator design. A low cost ventilator design is presented here which offers essential pressure and volume control ventilator modes for critical patients while being cost-effective as compared to all other presently available commercial alternatives which provide similar functions. The presented design is currently in the conceptual stage, and is presented here to elicit feedback for further refinement, prototyping, medical approval and large scale manufacturing.
The system consists of two gas inlets for hospital supplied O2 and ambient air supplied through a blower assembly respectively, a mixing tank with safety valves, sets of solenoid valves and pressure sensors, humidity exchanger, filters and standard inhalation/exhalation tubes with a Y-connector. A low cost processor (Raspberry Pi) monitors the pressures at six stations in the circuit and operates on four proportional solenoid valves using standard control mechanisms, such as pulse width modulation (PWM) and proportional-integral-derivative control (PID). This enables the ventilator to operate both pressure and volume controlled modes with a variety of breath sequence modes such as Assist Control (AC), Synchronized Intermittent Mandatory Ventilation (SIMV), Spontaneous/Timed (S/T) ventilation mode combined with patient inspiration triggers, as well as the Continuous Positive Airway Pressure (CPAP) mode.
More details are provided in our article on the open source platform: https://engrxiv.org/mwekx/
It is worth noting that the design has received appreciation from notable respiratory physicians as well as engineers in US and Canada.