Respiratory bi-directional pressure and flow data collection device with auxiliary thoracic and abdominal circumferential monitoring.

The venturi flow meter is adapted from a basic 3D printed design [1], to monitor differential pressure in both directions, which can be combined to generate complete breath profiles. The venturi is designed to be integrated in series with respiratory circuitry, combined 22m cone and 15 mm socket (22 M/15F) connections. In its current application one end is connected to a CPAP device using its accompanying circuitry, and the other end is connected to Heat and Moisture Exchanger Pleated Mechanical (HEPA) Filter (002874, Smiths Medical, MN, USA), subsequently leading to a Bi-level CPAP System Hospital Mask (RT041S, Fisher and Paykel Healthcare, Auckland, New Zealand). Auxiliary measurements of thoracic and abdominal circumferences provide external non-invasive data, which can be correlated to change in lung volume. Thus, measurement of change in circumference can be used to validate models of patient specific lung mechanics applied to the venturi pressure and flow dataset. Circumference is measured by a flexible fiberglass dressmakers tape spooled onto spring loaded barrel which is connected to a rotary encoder. The rotary encoder counts are subsequently translated into change in unspooled tape length in data processing. Ultimately the device is designed for respiratory research, specifically the application and validation of models designed to ascertain patient-specific respiratory condition using simple non-invasive measurements. The outlined device provides researchers with: - A low-cost alternative to commercial sensor systems - Non-invasive data collection - Built in validation for respiratory models - High customisability