A Quick Comparison of the AmboVent and Apollo BVM pandemic Ventilators

Drive Mechanism

Ambovent

Microcontroller

Most non-pneumatic ventilators designs have a microcontroller. Both of these use the ubiquitous, open source hardware Arduino family. The Apollo BVM uses two Arduino Unos, available all over the world in high quantities and scroungable from maker spaces. The AmboVent uses the Arduino Nano. The AmboVent mounts the Nano on a printed circuit board that is simple; it could be etched in a maker space or mass-produced with normal PCB production. I’ve been told you could wire it by hand easily if you had two. The Apollo BVM uses two Arduinos and at this writing connects them with jumper wires to a breadboard. This is great because it can be easily duplicated by almost anyone with any experience. That approach is too fragile for clinical use, IMHO.

Apollo BVM uses two Arduino Unos and a breadboard for connections

User Interface

The AmboVent is controlled by knobs you turn. It is similar to older ventilators that clinicians will be familiar with. It is a robust and simple system. The ApolloBVM uses tiny buttons that would be hard to use when stressed and wearing gloves. The AmboVent display seems very small. I would like to see a standard user interface emerge, that is used by all teams or most teams to minimize training effort. I encourage the Rice team and other teams to copy the AmboVent design in this regard.

AmboVent Basic Controls
A diagram of the Rice Displays, control interface uncertain

Alarms and Monitoring

The AmboVent has them; at this writing I see no evidence that the Apollo BVM does. I believe the AmboVent has an internal airway pressure sensor, and I don’t think the ApolloBVM does at present. Public Invention has created an early-stage open project, VentMon, to modularize alarms and monitoring so that teams can reusing similar monitoring solutions. Alarms and monitoring are integral to testing and clinical use and absolutely mandatory according to the RMVS spec.

Enclosure

The Apollo BVM uses laser-cut plywood which will be easily made in small units. (As I was writing this, Amy Kavalewitz showed me a photo of an acrylic case — these teams are moving fast!)

Testing

I believe the Rice team is doing pressure/volume testing as I type; the Israeli team has done a great job of this already. Testing is essential in last-resort ventilators because they are life-critical equipment in which a bug or mechanical failure can mean a fatality. Likewise, not all AmbuBags are the same. Supply chain disruption means open-source pandemic ventilators have to be more robust and accept more variation in their components than any modern manufacturer ever had to consider. There is an urgent need right now for an independent team to build and test the AmboVent to independently verify its performance, the clarity of its documentation, and its reliability.

Clinical Suitability

Both systems fail to meet the RMVS without additional equipment, because they cannot take pressurized air from a clinic wall at 50 psi (American Standard) or 4.5 bar (65 psi) (British standard). They each would require a free-standing air-oxygen mixer of some kind. The recently released Medtronic ventilator also fails to meet this spec and does not support 100% oxygen.

Documentation

In order to be reproducible and testable by a third party and to help the community, a design must be well-documented. This is a primary concern, but I have saved it because both teams have done a great job!

Gratitude for the Teams

Everyone in the world is doing their part; engineers and makers are doing their part. I would especially like to thank the Rice and Israeli teams for making their designs fully open so that we can learn from them. If I have said something inaccurate or that soon-will-be-wrong I apologize.

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Robert L. Read

Robert L. Read

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Public Inventor. Founder of Public Invention. Co-founder of @18F. Presidential Innovation Fellow. Agilist. PhD Comp. Sci. Amateur mathematician.