Maximizing the full potential of a single ventilator to be split amongst multiple patients.
Written by: Linda Yan
Bench testing of the Tetra prototype with medical simulation mannequins and pulmonary function tests.
The Challenge
COVID-19 causes severe respiratory problems for some patients. To help these patients survive the illness, ventilators are critical in some clinical circumstances However, creating new ventilators can pose challenges, as these machines use parts from throughout the global supply chain. This has resulted in a global shortage of these life-saving devices.
In Critical Care units, conventional ventilators are not designed to treat more than one patient at a time, as proper ventilation requires the use of individualized settings including the concentration of oxygen flowing to the lungs, the volume of air administered, the pressure rate, and flow at which air is administered. Furthermore, even if these patients sharing a single ventilator have the same initial clinical requirements, the patients may recover or deteriorate at different rates.
In Critical Care units, conventional ventilators are not designed to treat more than one patient at a time…
Deteriorating patients will have varied levels of lung compliance, meaning that the lung will differ in their abilities to stretch and expand. As a result, all the air flow will redirect to the lungs of the patient with stronger lung compliance. This imbalance poses a risk to the patient with more compliant lungs, as their lungs may become overwhelmed with too much air. This can subsequently damage healthier lungs, while also under-ventilating the patient with weaker lung compliance. Therefore, the resulting pressure shift is less than therapeutically optimal.
Monitoring of flow rates and volume exchanges is essential in minimizing ventilator-induced lung injury, especially with ventilator splitting, as conditions may change rapidly. The use of flow meters is ideal, as the amount of air delivered to the patient can be monitored and be titrated to an appropriate level as needed. Monitors and flow meters are key tools for doctors to manage the distribution of airflow and ensure that each patient is receiving the correct amount of air needed at an appropriate flow rate. Management of these ventilator parameters is essential for the ventilator to perform its intended function, particularly when multiple patients are attached, Thus, flow monitors and meters are necessary for splitting to be a viable option.
Tetra’s logo.
The Solution
The objective of Project Tetra is to create a ventilator splitting ecosystem that allows one machine to support two to four people. Ventilator splitting would be used as a last resort solution, for hospitals needing emergency increased ventilator support. Four-way attachments are being designed and printed to fit onto ventilators in order to increase the capacity. These are low cost and easy to manufacture, but do not yet provide sufficient control or usage information to improve patient outcomes.
The Project Tetra team has been working to produce a manufactured prototype that combines air flow splitting with both monitoring and flow control systems. The prototype is intended to be a single unit and easily maintainable on-site, to which a patient can be attached or detached without disturbing defined airflow to other patients attached to their own individual circuits.
Clinicians and respiratory therapists will then be able to set both the peak inspiratory pressure (PIP) and the positive end-expiratory pressure (PEEP) through mechanical valves and monitor each patient’s expiratory pressure on monitors attached to the device. As the splitter allows for individual patient adjustment of tidal volume, clinicians, respiratory therapists, and other caregivers can tailor at least one aspect of the therapy to accommodate the changing nature of our understanding of the disease.
The project team’s primary goal is to achieve FDA/EUA authorization to distribute the device to all hospitals facing ventilator shortages throughout the United States, via a partnership with a medical device manufacturer. They are also looking to gain approval in the EU to enable the distribution of the device there as well.
Their additional goal is to make the design and building process, as well as rough printing guidance, open-source and accessible to everyone around the world. Although the quality of the device does not yet have a determined quality assurance process in this second approach, anyone with a 3D printer, some mass airflow sensors, and a Raspberry Pi would be able to create a working version of Tetra.
Tetra makes all of their work and resources publicly available.
Deteriorating patients will have varied levels of lung compliance, meaning that the lung will differ in their abilities to stretch and expand. As a result, all the air flow will redirect to the lungs of the patient with stronger lung compliance. This imbalance poses a risk to the patient with more compliant lungs, as their lungs may become overwhelmed with too much air. This can subsequently damage healthier lungs, while also under-ventilating the patient with weaker lung compliance. Therefore, the resulting pressure shift is less than therapeutically optimal.
Monitoring of flow rates and volume exchanges is essential in minimizing ventilator-induced lung injury, especially with ventilator splitting, as conditions may change rapidly. The use of flow meters is ideal, as the amount of air delivered to the patient can be monitored and be titrated to an appropriate level as needed. Monitors and flow meters are key tools for doctors to manage the distribution of airflow and ensure that each patient is receiving the correct amount of air needed at an appropriate flow rate. Management of these ventilator parameters is essential for the ventilator to perform its intended function, particularly when multiple patients are attached, Thus, flow monitors and meters are necessary for splitting to be a viable option.
The Tetra Vent Splitter extends a single ventilator’s capacity to treat up to four patients.
How You Can Help
The project is currently in the testing phase. The team is collaborating with engineers, clinicians, and respiratory therapists at USC and UCLA to further develop and improve their design. They are also working to provide the device in both the United States and the rest of the world.
Want to volunteer?
At the moment, the project is in need of:
- A QA/RA Lead that would provide advice and guidance to make sure that Tetra complies with all best practices with respect to both quality and regulatory requirements, including FDA expectations and for an EUA application.
- Individuals with past fundraising experience to help Tetra bring in money from investors and donors to support their nonprofit mission of creating and distributing medical devices, and the plans for creating medical devices, throughout the world.
- PR and communications professionals to help generate an overall strategy for spreading the word and gathering donations. Creating this strategy would involve developing promotional content and working to promote the project through various channels, including online media.
If you are someone you know can potentially help in any capacity, please contact project lead Jamie Waters.
Want to learn more?
Learn more about this project through their Github repository, on the UCLA website, their website, on their media documentation site, and on Instagram @tetrabio.
References
- Ranney, Megan L., et al. “Critical Supply Shortages – The Need for Ventilators and Personal Protective Equipment during the Covid-19 Pandemic: NEJM.” New England Journal of Medicine, 21 May 2020, www.nejm.org/doi/full/10.1056/NEJMp2006141.
- Staff. “Vent Splitting Breakthrough Shows Promise During Global Ventilator Shortage.” Global Biodefense, 24 May 2020, globalbiodefense.com/2020/05/23/vent-splitting-breakthrough-shows-promise-during-global-ventilator-shortage/.
- Woods, Anne Dabrow. “COVID-19 – Not Your.” COVID-19 – Not Your “Typical” ARDS | Lippincott NursingCenter, NursingCenter, 10 Apr. 2020, www.nursingcenter.com/ncblog/april-2020/covid-19-not-your-typical-ards.
The designs for Tetra are presented As-Is. Tetra is an exploratory proof of concept prototype which is not intended for clinical use. It has not been authorized by the FDA or any other regulatory agency. You accept responsibility and release Helpful Engineering from liability for the manufacture or use of this product. This design was created in response to the announcement on March 10, 2020, from the HHS. Secretary of the Department of Health and Human Services (HHS) who issued a declaration pursuant to the Public Readiness and Emergency Preparedness (PREP) Act.
Link to Prep act. :https://www.phe.gov/Preparedness/legal/prepact/Pages/default.aspx
ALL WARRANTIES OF ANY KIND WHATSOEVER, EXPRESS, IMPLIED AND STATUTORY, ARE HEREBY DISCLAIMED. ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. THIS APPARATUS (INCLUDING ANY ACCESSORIES AND COMPONENTS) IS PRESENTED ‘AS IS.’
