Bench Evaluation of a Digitally Controlled Venturi Adapter PAP System With Integrated Respiratory Monitoring

Brigham Young University Engineering Building, Provo, UT

Purpose: Research has demonstrated that Continuous Positive Airway Pressure (CPAP) during procedural sedation reduces apnea and oxygen desaturation. However, the cost, size, and complexity of non-invasive ventilators hinder its wider adoption. We designed a small and low-cost Venturi Positive Airway Pressure (PAP) system that provides pressure-controlled PAP therapy, tidal volume estimates, respiratory rate reporting, improved end-tidal carbon dioxide (EtCO₂) monitoring, and audible noise suppression. This study evaluated the system's accuracy and effectiveness in a bench setting.

Methods: The system was evaluated on a simulator comprised of a test lung, face model, and mask. The mask was interfaced with a Venturi adapter that connected to our PAP system. Respiratory rate accuracy was evaluated against a respiratory flow monitor. Pressure control and tidal volume accuracies were assessed against the tolerances of a common non-invasive ventilator. The accuracy of EtCO₂ measurements was also measured.

Results: Pressure control errors were less than 1 cmH₂O, and lower than tolerances of the non-invasive ventilator (±2 cmH₂O). Tidal volume measurements were made with errors less than 15% of the reading. EtCO₂ measurements were within two mmHg of the reference.

Conclusion: Our system provides accurate pressure control and tidal volume and respiratory rate monitoring, comparable to a non-invasive ventilator. EtCO₂ monitoring is accurate, thus providing useful capnometry to clinicians. Our system may be a simple and cost-effective alternative to a non-invasive ventilator for administering PAP therapy to reduce apnea and oxygen desaturation during sedation.