OxyJet CPAP: an electricity-free low-cost emergency respiratory support device

<h4>Background</h4>Respiratory support devices in resource-limited settings should be inexpensive, portable, effective, and easy to use. Non-invasive respiratory support devices can reduce expensive ICU admissions, but these facilities are severely lacking in low-resource settings. Here, we describe the design and validation of a low-cost, portable, electricity-free, and 3D-printed continuous positive airway pressure (CPAP) device named 'OxyJet' that can provide non-invasive respiratory support outside the ICU. The OxyJet is uniquely built using off-the-shelf components and 3D printing technology, making it both inexpensive and easy to produce. OxyJet costs less than 10% of the price of a similar CPAP system. Inspired by the fundamental mechanics of gas ejectors and harnessing the potential energy of a high-pressure oxygen jet, the device can deliver a high flow of oxygenated air up to 65 L/min (approx.), a positive end-expiratory pressure (PEEP) within 5-15 cmH₂O, and a fraction of inspired oxygen (FiO₂) of up to 100%.<h4>Results</h4>The device was bench-tested following UK-MHRA RMCPAP guidelines and tested on healthy volunteers (n = 5) and hypoxemic patients (n = 5). A comparative pilot study involving 23 hypoxemic adult patients conducted in Dhaka, Bangladesh, showed a significant improvement (p < 0.05) in the peripheral oxygen saturation (SpO₂) of patients following the administration of OxyJet CPAP. The mean SpO₂ increase was 12.0% (95% CI 10.8-13.2) with OxyJet versus 11.5% (95% CI 9.3-13.8) for standard CPAP (p = 0.695). The findings indicate the device's feasibility and short-term physiological effects comparable to those of standard CPAP systems. Further studies are required to confirm its clinical efficacy and broader utility in resource-limited settings.<h4>Conclusion</h4>Our findings suggest that OxyJet CPAP has the potential to serve as an emergency respiratory support device outside the ICU, strengthening health systems in resource-limited settings.<h4>Methods</h4>OxyJet's performance was first assessed through benchtop testing following the UK-MHRA RMCPAP protocol. This was followed by preliminary human testing in healthy volunteers and hypoxemic patients to evaluate safety and usability. A pilot feasibility study involving hypoxemic adult patients in Dhaka, Bangladesh, was then conducted to compare the device's physiological effects with those of standard CPAP therapy.