New Nasal Interface to Improve Breath Detection From Pulsed Oxygen Sources: Healthy Participant Study

Abstract

Background:

Pulsed oxygen sources rely on pressure triggering to detect inhalation: during inhalation, room air entrainment creates a small drop in pressure monitored through the cannula tubing, referred to herein as the signal pressure. When the signal pressure exceeds the triggering threshold of a pulsed-flow oxygen device, a pulse of oxygen is released. Patients may struggle to trigger oxygen delivery during sleep, oral breathing, or other circumstances characterized by low nasal inhalation flows. To address this issue, a new nasal interface that can provide higher and more consistent signal pressures is being developed.

Methods:

Eight volunteers ranging from 22-47 years old participated in the study. Each volunteer was asked to breathe at different flows through their nose while connected to an oxygen tank with a Philips SimplyGo Mini POC, an OxyGo Next POC via standard nasal cannula, or the new nasal interface. A Precision Medical Easy Pulse 5+6 oxygen conserving device was used with the tank. To monitor flows, a respiratory belt (Respiration Sensor, TTLP2HRVSYS, Bio-medical Instruments, MI) was strapped around each participant’s chest. The respiratory belt was calibrated using spirometer data (MicroLoop Spirometer, #ML3535-S, Micro Medical, ME). Tests were repeated while participants breathed through their mouths. Video recordings with a close-up view of the oxygen sources were used to detect pulse triggering. Each participant breath was retroactively matched with a pulse/no pulse response, and the number of pulses was divided by the number of breaths to calculate triggering success rates. A two-tailed t-test (P <.05) was conducted with triggering success rate as the dependent variable and cannula type as the independent variable. Ethics approval was granted by the NAIT Research Ethics Board.

Results:

Pooled across all study conditions, triggering success rates were significantly higher (P = .03) when using the new nasal interface (78.9%) compared to the standard nasal cannula (65.2%). When using a standard nasal cannula during oral breathing, mean triggering success rates were below 40% for all oxygen sources. Using the new nasal interface approximately doubled oral breathing triggering success rates.

Conclusions:

Reliable breath detection is an issue when using pulsed-flow oxygen sources, especially during oral breathing. Significantly improved breath detection was observed when healthy participants used the new nasal interface versus a standard nasal cannula.

Figure 1: Average triggering success rates (%) when using a Standard Cannula and the New Nasal Interface. Error bars represent standard deviations. Data is pooled across all breathing patterns and oxygen sources.

Figure 2: Triggering Success Rates during Oral Breathing sorted based on Cannula Type and Oxygen Source. Error bars represent standard errors.