In Vitro Comparison of a Low-Cost Bubble-NIV and Ventilator-Driven NIV

Background: Almost 2.5 million neonatal deaths occur annually, disproportionately affecting low- and middle-income countries. Respiratory support devices remain largely inaccessible in these regions because of prohibitive costs and infrastructure requirements. The WHO-style bubble CPAP provides accessible continuous positive pressure but cannot deliver bi-level support when CPAP alone is insufficient. We hypothesized that a low-cost bubble noninvasive ventilatory (Bubble-NIV) system, meant to augment the WHO-style bubble CPAP, would perform non-inferiorly to the ventilator-driven RAM-NIV in delivering positive pressure across variable nasal interface conditions in bench testing. Methods: We developed a low-cost Bubble-NIV system (∼$50) with a servo motor-driven lever to drive bi-level pressures via variable distal tubing water submersion depths. Performance was compared with ventilator-driven RAM-NIV in a static in vitro model across 3 nasal cannula fits (80%, 70%, 60% nostril occlusion). Primary outcome was mean airway pressure Paw (should be a line over P) measured in the nasopharynx. Results: Bubble-NIV maintained bi-level pressures and delivered pressures closer to target (mean airway pressure, mean goal: 15 cm H 2 O) than ventilator-driven RAM-NIV across all nasal interface scenarios: 15.1 versus 13.4 cm H 2 O at 80% occlusion ( P < .001), 12.6 versus 7.4 cm H 2 O at 70% occlusion ( P < .001), and 5.6 versus 1.8 cm H 2 O at 60% occlusion ( P < .001). The performance advantage increased with worsening leak (1.1-fold to 3.1-fold). Optimal Bubble-NIV pressures occurred with flows set within 2 L/min of minimal bubbling. Oscillatory waveforms of Bubble-NIV were greater than RAM-NIV. Conclusions: A low cost Bubble-NIV system demonstrated superior nasal leak tolerance compared with ventilator-driven RAM-NIV in bench testing. The low-cost, nonproprietary design addresses accessibility barriers to delivering bi-level noninvasive respiratory support for neonates in resource-limited settings.