Critical updates for COVID-19 unit (Rev 2)
Rev 2 requires more experience with electronics, but can still be built with parts you can acquire online.
April 8, 2020
Today we began building the second unit, aided by an outstanding team of engineers, flow mechanics specialists and supply chain professionals at RK Mission Critical in Aurora, Colorado. Special thanks to President and CEO of RK Mission Critical, John Marinnucci for his leadership, flexibility, people and resources to make this happen. RC Mission Critical is providing the resources to build five units for the Colorado healthcare community and the people it serves. As with other areas, Colorado may be facing a critical shortage of ventilators in the coming days. Thanks as well to Plant Manager, Scott Dickerson; Pre-Construction Manager Phillip Powers; and Floor Manager, Sam Soares. Thanks to SVP and Chief Customer Officer, RK Corporate, Marc Paolicelli for putting together this team and making it happen. Finally, special thanks to Chancellor Don Elliman, Excecutive Vice Chancellor For Biotechnology, Steve VanNurden for catalyzing, supporting, and participating in this project.
Today we critically evaluated the potential failure modes of the ventilator as designed and prototyped. We identified better solenoid valves (20 Million Cycle anticipated life vs. 1 Million on the existing valves); and better digital relay timers with 100% solid state electronics to replace the existing DRT’s, which have mechanical relays and may also have limited life. We will provide specs on the new valves shortly. They are made by Spartan Scientific. Use of a new solid state programmable logic controller offers the possibility of simplifying the design. We will have a spec ASAP.
April 9, 2020
Today we revised the prototype to improve anticipated service life in the digital valve timers, solenoid valves and switching relays. Thanks to Dwayne Kessinger for spec’g a drop-in power module, complete with new programmable logic controller (PLC); 24V DC Power Rail, and solid state relays for each patient ventilator manifold. Thanks to Jim Koller at Spartan Scientific (Canfield) for spec’g new 20 million cycle solenoid valves. These will be custom O2 cleaned valves. Thanks as well to Jesse Davern and Zdenka Mueller at RK for the flexibility with design modifications, extraordinary patience and their incredible supply chain connections/efficiency.
April 10-14, 2020
We’ve been busy building the Rev 2 vents. Working on training the RK team; building manifolds, enclosure modifications; vibration and sound damping; enclosure cooling; trying to find parts; substituting parts on the fly; training the RK Mission Critical assembly teams and Floor Manager (shout out to Sam, Danny, Leon and Cesar. You guys learn quickly and are making things happen. Thanks to Veronica and the custodial staff for clearing and cleaning the assembly area.
Between yesterday and today, also introduced a room air bypass feature to the vent. This will avoid dead heading the pump and will expand the range of FiO2 the unit can deliver. Not deadheading the pump allows the unit to run CPAP on one manifold; BiPAP on the second manifold; and 1:2 or 1:1.6 on the third manifold, where four intubated patients can potentially be supported (both requested I:E ratios by the ER physicians and respiratory therapists). The 1:2 I:E mode provides pure square wave inspiration/exhalation; whereas the 1:1.6 mode provides some clipping to the wave forms. These will be posted as soon as available. It is also important to note that running simultaneous CPAP, BiPAP and asymmetrical I:E ratios does produce fluctuations in CPAP flows, though air is always moving. 1:1.8 would also be possible, with peak flows lying between the 1:1.6 and 1:2 we have analyzed. There would also be clipping to the inhale waveforms as with 1:1.6 I:E mode.
April 15-17, 2020
Acquired parts to complete six Rev2 field ventilator units. Passed the one month anniversary date of the project on April 16. Continued to model system performance, inhale/exhale wave forms when each manifold is running different respiratory modes (e.g. CPAP, BIPAP and 1:X Inhale:Exhale). These are posted here. Developed concept of peak shifting (synchronizing the inhale of 1:X and BIPAP modes to minimize manifold flow fluctuations). RK Electronics assembly personnel Ricardo, Matt and Mike joined Dwayne in assembling and testing the new power and control modules. They did a great job and even provided some video footage to help others with the build. Completed unit number 2 on 17APR2020. Posted more build photos and videos for Rev2 in the Rev2 Build section of this site. Planning to complete assembly and bench testing of all six units on 20APR2020 and begin deploying the units.
April 18-24, 2020
Received a few components that were needed to complete the build of Rev2 units 2 through 7. Delivered unit 2 to UC Health Pulmonology Research Laboratory (Dr. Jeff Sippel) for evaluation and testing. Units 3-7 should be completed this week. Unit 3 will go to UCSF for testing. Although the role of ventilators in helping to manage patients with COVID-19 has continued to evolve very quickly, the Field Ventilator’s viability in multiple respiratory modes as an emergency solution; and as a possible solution with appropriate modifications for developing nations with no ventilators appears sound at this point.
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