336 - Benchtop validation of remote pressure sensing- scope for airway pressure monitoring by nasogastric tube

Publication Number: 336.3846

Iman Salafian, The University of Texas at Austin, Austin, TX, United States; Joseane E. Tejada, University of Texas at Austin, Austin, TX, United States; Angie Englert, Dell Children's Medical Center of Central Texas, Austin, TX, United States; Chris Rylander, The University of Texas at Austin, Austin, TX, United States; Alan Groves, University of Texas at Austin Dell Medical School, Austin, TX, United States

Background: Respiratory support remains the core pillar of care for premature infants. CPAP is currently the primary modality but it requires frequent nursing interventions, and can cause skin damage and nasal injury. High-flow nasal cannula (HFNC) offers increased comfort and reduced injury risk but lacks consistent airway pressure feedback. A hybrid approach, Pressure Targeted High Flow (PTHF) therapy, could maintain the airway pressure required to prevent lung collapse while being more comfortable and requiring less intensive nursing intervention. A cost-effective, non-invasive way to continuously measure airway pressure would facilitate PTHF therapy.

Objective: This study aims to validate the equipment and sensing hardware needed to perform remote airway pressure sensing using a nasogastric tube to measure esophageal airway pressure with a sensor located outside the patient’s body.

Design/Methods: Six pressure sensors were individually tested for noise, accuracy, and drift under sinusoidal pressure changes (0–5 cm H₂O) over 24 hours. The optimal sensor was then used to assess pressure transmission across 34 tubes of varying internal diameters (0.149 mm–2.692 mm) and two lengths (610 mm, 305 mm). Each tube connected the sensor at the proximal end to an adjustable air pressure source, measuring distal pressure remotely.

Results: Results indicated that the Honeywell TruStability® High Accuracy Board Mount Pressure Sensor, an amplified, temperature-compensated sensor, was optimal for low, rapidly fluctuating air pressures. Tubes with internal diameters under 0.3 mm (1F) exhibited pressure change delays of up to 10 seconds before reaching the target pressure, with longer delays in 610 mm tubes than in 305 mm. Tubes with diameters over 0.3 mm showed minimal delay, reaching the target pressure in under 1 second, regardless of length.

Conclusion(s): This study demonstrated that remote sensing can reliably measure pressure through small-diameter tubing, validating it as an effective benchtop method for accurate pressure measurements when the sensor is positioned away from the pressure source. These findings support the future application of remote sensing in clinical settings, particularly for obtaining esophageal pressure measurements via a secondary lumen of a nasogastric tube, and eliminating the need for an electronically powered transducer inside the patient. This approach could enable PTHF therapy, combining the comfort of HFNC with the accuracy of CPAP. Further studies should investigate its clinical efficacy and potential benefits for patient outcomes.

First 60 seconds of data aquired from the optimal sensor
The sensor is connected to a periodic pressure change source. The obtained data shows almost no noise highlighting its suitable performance for remote pressure monitoring.

24h hour of drift test
The sensor is connected to a pressure chamber where the pressure is kept constant for 24 hours. The obtained data shows a drift of less than 0.5cmH2O over 24 hours which is significantly better than other sensors tested in the cohort of 6 sensors.

Tube diameter effect in mesuring remote air pressure
Pressure is raised 0 to 10 cmH2O in about 1 second. For the tube with an ID of 0.149 mm, it resulted in a 10-second delay until the sensor's reading reached the target pressure of 10 cmH2O. This delay is shorter for tubes at or larger than ID 0.297 mm