Design Rationale

At the start of the COVID-19 pandemic, New York Governor Andrew Cuomo requested 30,000 ventilators to serve those afflicted with the respiratory disease. Initially, NY state guidelines for the allocation of ventilators projected peak shortages of 16,000 ventilators in the state and the US projected that 25,000 additional ventilators would be needed during peak dates, with rural hospitals being severely under-resourced (Source:

https://covid19.healthdata.org/projections⁠

). VentCU was envisioned to serve as an interim manual ventilation device while more sophisticated devices were being produced. Though the projected shortage did not meaningfully arise, we believe VentCU is still a valuable area of research for communities without access to ventilators or should there be another surge in ventilator demand.

Clinicians we consulted with during the height of the ventilator panic suggested that they would use such a device for patients waiting for a ventilator, those waiting to be matched with another patient to share a ventilator, or for patients in less critical condition. In essence, the device would act as a temporary, life-saving alternative for when traditional ventilators were unavailable.

To meet this goal, the device would need to be rapidly and safely constructed en masse. In researching the multitude of existing Ambu-bag ventilator designs, we found that every single interim manual ventilation assistive device relied on custom manufactured parts (3D printed, laser cut, waterjet, CNC milled, etc). Although functional in allowing more complex or custom mechanical components, this greatly limits the possible speed of production. Our conversations with doctors, medical experts, and engineers confirmed this as a critical flaw.

Our consultations, including the Director of Medical Technology for New York Presbyterian Hospital, suggested that hospitals have ample personnel to assemble simple devices, and that they would likely be more comfortable constructing them in house rather than accepting donations. For these reasons, we determined our ventilator design had to be built as simply as possible and with 100% commercial-off-the-shelf (COTS) components readily available from numerous sources. Additionally, we aimed to minimize construction time and required assembly tools.

However, such a design constraint is useless if the ventilator is not clinically viable. We identified that beyond meeting manufacturing requirements, we needed to address the fears, expectations, and desires of the medical professionals destined to use our device.

Our analysis of existing designs, consideration of intended use case, and consultations with medical and engineering experts have led to the following guiding principles of design:

Robustness, Safety and Clinical Viability

To withstand the rigors of hospital environments, VentCU must have a sturdy frame which protects its fragile internal electrical and mechanical components. It should sit firmly on a table and not slip or be jostled easily. To achieve this, VentCU is constructed from an 80/20 frame with a rubber tread bottom cover to prevent slipping and absorb shock from dropping. Furthermore, VentCU must be a portable and versatile product; to avoid exposing clinical workers to COVID-19, hospitals strive to keep patients on ventilators at all times, even during transportation. Thus, the ventilator should be able to hang securely from a hook or wall and be easily transported by a single adult, hence the two adjustable handles on the sides of VentCU.

VentCU must meet the minimum clinical standards set by attending anesthesiologists and respiratory therapists. To this end our control system must have sufficient sensing capabilities and provide adequately modifiable and precise ventilation cycles. We will detail these specifications under the

Control System⁠

section.

Mass Producibility

To meet the growing demand for ventilators, VentCU must be able to be sourced and produced by someone with little to no engineering experience. Almost all of the mechanical and electrical parts can be purchased in large quantities from McMaster-Carr and Digi-Key respectively. Many parts are commonly found in physical shops and can be purchased from numerous other vendors. We have chosen only standard parts which are stocked and available to ship in the hundreds or thousands. Furthermore, we have worked to create a design which can easily be modified for whatever materials are available on hand. This is detailed more explicitly under the

Mechanical Specifications⁠

and

Electrical Specifications⁠

sections.

Speed of Construction

Seeking the possibility of widespread construction of our ventilator, we worked to make the construction process as accessible to as many groups as possible. While many DIY ventilator designs rely on access to a shop of some kind, our design only assumes access to a set of Allen keys, scissors, and a soldering iron. A greater variety of parts selection is possible if more tools are available on hand, but our minimum specifications guarantee that a package can be sent to a hospital and they can have a fully constructed device in a matter of hours with no prior knowledge or access to specific machinery. VentCU was designed to be highly customizable to the needs and capabilities of whoever might make or use it.

Next:
`Mechanical Specifications`⁠
|
`Overview`⁠
⁠

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Design Rationale

Robustness, Safety and Clinical Viability

Mass Producibility

Speed of Construction

Next: Mechanical Specifications⁠ | Overview⁠⁠

Next:
`Mechanical Specifications`⁠
|
`Overview`⁠
⁠