The Idea

In February 2020, amidst the CoVid-19 pandemic, concerns about a global shortage of ventilators began to surface and these worries rapidly became a reality. We sought to find a local solution to the rapidly evolving crisis, working alongside the hundreds of open-source projects worldwide, aimed at tackling the same problem.

We believe that we add a novel solution to an evolving landscape of low cost ventilators. Built using readily-available materials, our aim was to produce a device capable of being produced at a sub-$100 price point for low-resource settings, as well as a more robust model, both founded using the same principles.

Modern commercial ventilators are complex machines with specialized components. According to the Department of Health and Social Care guidance statement on Rapidly Manufactured Ventilator System Specification (20/03/2020), ventilators must meet certain criteria to be considered “clinically acceptable”.

RMVS-compatible ventilators must be capable of providing one of two modes of ventilation. The first is mandatory ventilation, wherein the patient is completely sedated, and all work of breathing must be done by the ventilator, according to preset criteria (e.g. tidal volume, respiratory rate, E/I ratio). Supportive ventilation, on the other hand, is used when the patient can do some work on their own. The machine must be able to sense when the patient is attempting to inhale (and provide inspiratory support), and when the patient is exhaling. We aim to accomplish both.

The Design

How it works

The basis of the gVent system is gravity, water, and two cylindrical vessels fitted together to create a pressurized system. This pressure can then be used to ventilate a sick patient. The two vessels are each sealed at one end. The larger vessel is filled with water; the smaller vessel is placed inside the larger vessel.

Air is then introduced into the system from the hospital's gas outlets. A clinician can thus control the FiO2 by titrating the amount of hospital air to the amount of delivered oxygen. As this pressurized gas builds up in the system, the top cylinder is displaced upwards from its resting position, commensurate to the weight of the top cylinder (which can have weight added to adjust the pressure).

To deliver air, a valve is opened, releasing the pressurized air/O2 mixture through to the intubated patient. With the valve controlled on an electronic circuit, the operator has the ability to control important respiratory parameters, including respiratory rate, I:E ratio, and the volume of air delivered to the patient.

Maintenance and cleaning are relatively simple. The majority of the main ventilator components are assembled with un-plasticized PVC, an inert, chemically resistant substance. Insertion of parts can be accomplished through plastic welding, PVC glue or friction fitting with Teflon tape. All of these are suitable for drinking water purposes. The only interface between air going to the patient and the outside environment is through the water in the system. As this leads to the small potential for contamination in the system, this water is constantly cleaned and sanitized throughout the use of the ventilator, by using UV sterilization or a concentrated saline solution .

What features make the gVent unique?

One of this system’s greatest strengths is its ability to give constant inspiratory pressures, which greatly reduces the risk of barotrauma which is inherent in many low cost ventilator designs. This constant plateau pressure, which mimics a commercial ventilator’s air delivery, has been a popular feature among the end users who have evaluated our device, including respiratory therapists, anesthesiologists, and intensivists. We feel that this unique and reliable method of delivery sets this ventilator apart from many other designs.

Find out more at gvent.ca