Pufferfish
ABSTRACT
We describe a minimum, rapidly scalable ventilator designed for COVID-19 patients with ARDS. Our design philosophy is not only to try to address potential ventilator shortages, but also to account for uncertainties in the supply chains of parts commonly used in traditional ventilators. To do so we employ a modular design approach and broadly explore taking advantage of parts from non-traditional supply chains. In our current prototype, we demonstrate volume control with assist control on a test lung and present a linear actuator-driven pinch valve-based implementation for both pressure control and volume control with decelerating inspiratory flow. We estimate the component cost of the system to be around $500. We publish our draft design documents and current implementation which is open and accessible in the hope that broadening the community globally will accelerate arriving at a solution and that peer review will improve the final design.
Many commercial ICU ventilators cost tens of thousands of dollars per unit. While that may be affordable for high-profile hospitals, the surge in COVID-19 cases along and shortage of ventilators in LMIC settings begged for a different production and distribution model that could significantly reduce per-unit cost, while maintaining high-standard performance.
BIG QUESTION
“Could we understand and make the production of ICU ventilators open-source and allow local manufacturers to rapidly produce them at much lower costs?”
What is Pufferfish?
This goal led to a global collaboration across institutions and manufacturing partners, to produce a low-cost open-source full-featured ICU ventilator that can be rapidly manufactured and is clinically relevant for COVID-19 patients. With peak flow rate above 300 l/min, Pufferfish can be used to provide both invasive and noninvasive ventilation as well as high-flow oxygen therapy. Pufferfish in its current implementation uses compressed air and oxygen from the wall or cylinders. Flow of air and oxygen are controlled by two proportional valves to deliver the set flow or pressure at selected FiO2. The proportional valve can be either an off-the-shelf high flow proportional solenoid valve, or when supply is limited, a linear actuator driven pinch valve that we have developed, which can deliver over 180 l/min of flow with 60 ms rise time at supply pressure of 15 psi (currently tested for continuous operation of 2.6 M cycles without degradation in performance). Multiple flow and pressure sensors are used and read at > 500 Hz to allow precise feedback control and adequate monitoring. Pufferfish is designed to support VC-AC, PC-AC, VC-SIMV, PC-SIMV and PSV/CPAP modes. The goal of the project was to develop a product that can function and be replicated in multiple manufacturing facilities at lower costs (~$1000).
Project supported by Bharat Forge (manufacturing + materials)
