Design, manufacturing, and testing of 3D-printed fittings for ergonomic helmet CPAP devices: a case study

This study presents the design, optimisation, and experimental evaluation of additively manufactured fittings for a custom helmet continuous positive airway pressure (hCPAP) system. The project was initiated as a rapid response to the shortage of respiratory support equipment during the COVID-19 pandemic. The inlet and outlet connectors of the helmet were redesigned to comply with the EN ISO 5356-1:2015 standard, reduce mass, and simplify assembly, while ensuring functional reliability and patient comfort. Components were fabricated using fused filament fabrication (FFF) and selective laser sintering (SLS) with medical-grade ABS, TPU-95A, and PA 2200 materials. A comprehensive assessment of material safety was performed, including tests for potential particle detachment under high-flow air conditions. Results confirmed that ABS Medical printed without active cooling exhibited no measurable release of microplastic particles, making it the preferred material for oxygen pathway components. Computational fluid dynamics (CFD) analyses guided the optimisation of the internal diffuser geometry, leading to improved air distribution and reduced perceived noise. The redesigned helmet system was evaluated in clinical trials involving 120 participants, demonstrating good ergonomic performance, low noise levels, and high user comfort. The findings validate additive manufacturing as a practical and reliable method for the small-batch production of medical fittings, particularly under emergency or resource-limited conditions. The proposed design approach highlights the potential of 3D printing to enable flexible, localised, and rapid development of medical devices adapted to current clinical needs.