GOAL :   To investigate the feasibility of producing low-cost mechanical ventilators using widely available materials in Cambodia

    According to worldometers, the number of new cases of COVID-19 worldwide is linearly increasing, and developing countries like Brazil, India, Iran, Pakistan, Mexico, and Bangladesh are facing thousands of new cases in one day. A ventilator designed by a group of researchers from MIT has published open-source specification and design in e-vent. This team has interviewed several doctors and ventilator operators about the situation of the patients suffered by Covid-19. They gathered the best information in terms of clinical specification and operation of a ventilator for such patients and published on the website. They have analyzed and come up with the best Ventilator design with a low cost that could help Covid-19 patients. Our design is mainly based on this design. In addition, we have successfully made our own pressure sensor for use with our ventilator. Our ultimate goal is to get our ventilators in use for those who will need it. Because the ventilator is produced with local materials mostly available in Cambodia, the same one can be produced almost anywhere in the world as long as we provide automatic control system design and program code that guarantees the safety of operation.

    The ventilator being proposed by our ITC team is an automated Ambu bag. A conventional Ambu bag or a bag resuscitator works with a person (a doctor, nurse, technician, or another health worker) squeezing the Ambu bag by hand to inflate the patient lungs until a mechanical ventilator becomes available. This is done by intubating a patient (inserting a tube into the patient’s airway) and then pumping air into the lungs by squeezing and releasing the Ambu bag. Our automated Ambu bag (based on the MIT model) would essentially add an automated process that will replace the person squeezing the Ambu bag. The health-related risks of conventional Ambu bag include air inflating the stomach, lung injuries from over-stretching, lung injuries from over pressurization, and hyperventilation (too many breaths per minute). To avoid these problems, our ventilator is equipped with components and that can adjust breaths per minute (BPM), tidal volume, Inhale/Exhale time ratio. Our control program operates according to the adjustable parameters input by the operator. A pressure sensor is also used to detect over-pressurization. Our ventilator can operate in two modes, Volume Control and Assist Control (see our latest update ventilator from this link).

    For Volume Control mode, the amount of tidal volume is adjusted according to the percentage of squeezing Ambu bag. For a particular BPM, the amount of air entering and getting out of the lung may not be the same. The Plateau Pressure may increase or decrease over a period of time since the lung compliance of each patient is different from one another. So, the pressure sensor detects the Plateau Pressure for monitoring and alarming (sound, and message) in accordance with the safety condition provided in the list of alarms. If the pressure is higher than PIP, the ventilator stops operation and raises an alarm sound as well as an alarm message. The alarm notification will allow the operator to learn and make adjustments to the relevant parameter before restarting the ventilator.

    For Assist Control mode, the inhale phase is triggered by depressurization below PEEP pressure. The Plateau Pressure and PEEP pressure are monitored. If any of the pressure is out of operation range, alarm sound and message are raised. Since the lung compliance of each patient is different from one another, the amount of air volume entering may be too low or too high. A flow meter (design based on different pressure at an orifice) is used to measure the amount of air volume. The amount of air volume is monitored and alarm conditions are set accordingly.

    We will develop a second version prototype of a ventilator integrated with all necessary sensing devices to have as high safety as possible. It has features of producing using local material, high safety control programs, and high durability.