LRTee: Last Resort 22mm Ventilator Tubing Splitter

thingiverse

Patients with COVID-19 in serious or critical condition often require assisted breathing via ventilator. As the number of patients in need of ventilators grows (exponentially in many densely populated regions), there are not adequate numbers of ventilators to support the high number of patients. **Update April 14, 2020**: [LRTee is now in a GitHub repository](https://github.com/makefastworkshop/LRTee) -- all future updates will be hosted there, so make sure you use the latest files and info in the repo! **- - - - - - - - - - - - - - - - - - - -** This is an EXPERIMENTAL splitter for 22m tubing to allow two patients to share a single ventilator. After printing/testing multiple versions of other splitter designs (see below) we decided to build a new splitter that: * Has uniformly thicker walls. * Has shorter branches (less likely to break). * Is much faster to print. * Doesn't require supports or rafts. * Can be scaled to (ideally) handle basic low-temp sterilization. * Released as Public Domain with all design file for further modifications. As with other similar efforts, **THIS IS UNCERTIFIED, HIGHLY EXPERIMENTAL, and UNTESTED ON HUMANS**. As such, any potential use scenario would also require **legal waivers to use uncertified/untested non-medical devices** and **significant additional patient monitoring by medical professionals and certified diagnostic equipment** to reduce the risk of serious consequences in the event that the device fails to operate as intended by doctors. Use at your own risk. We take no responsibility for the safety of this device/design. These parts have been test-fit on anesthesia machines with ventilator capabilities and standard 22mm ventilator tubing/circuit connectors. After a few rounds of iterative tests, the parts should be able to pass the system's automated "leak test" directly off the printer with no post-processing. The general theory of using a splitter to ventilate multiple patients is nicely spelled out in [COVID-19 How to Use One Ventilator to Save Multiple Lives](https://www.youtube.com/watch?v=uClq978oohY) and [A Single Ventilator for Multiple Simulated Patients to Meet Disaster Surge](https://onlinelibrary.wiley.com/doi/epdf/10.1197/j.aem.2006.05.009). Thanks to these projects for informing/sharing/catalyzing design and discussion to yield a usable printable splitter. * [3D Printed Circuit Splitter and Flow Restriction Devices for Multiple Patient Lung Ventilation](https://www.prusaprinters.org/prints/25808-3d-printed-circuit-splitter-and-flow-restriction-d) * [Ventilator Circuit Splitters - reinforced & thicker walls](https://www.prusaprinters.org/prints/27803-ventilator-circuit-splitters-reinforced-thicker-wa) **Update April 5, 2020**: More testing with annealing (via hot water bath) to simulate sterilization temperatures was performed and added as a graph (see image). Added a small rise to the lower/female lip to soften the sharp corner, and now including a PETG printer config that seems to produce good results. **Update April 7, 2020**: We've found that PLA seems to print a bit more air-tight than PETG, but that can be greatly improved by setting the "extrusion multiplier" to 1.2x and using the modified STL file that compensates for the slightly larger dimensions when printed. **Update April 8, 2020**: Produced 4 pairs in PETG with 1.2x extrusion multiplier and ran through the full process (from intake of printed parts at a medical facility, thorough cleaning/decontamination/sanitization, and finally testing on ventilators to verify it passes the leak test). Parts show no sign of deformation or failure and pass all primary initial tests. Next, we'll put together more concise documentation to help other medical facilities replicate the intake/cleaning/testing process.