Led by Ryan Diesem, research manager of Valley Inspired Products, a study aimed to explore the output of PVDF airflow sensors as compared to traditional nasal pressure sensors.

Ryan Diesem, research manager of Valley Inspired Products, led a recent study examining the efficiency of PVDF airflow sensors and how different variables affected the outcome produced. The resulting white paper “Comparison of Polyvinylidene Fluoride (PVDF) Airflow Sensor and Nasal Cannula Pressure Sensor Output During Simulated Breathing With and Without Temperature Change,” compares the output of a traditional nasal pressure sensor to that of a PVDF airflow sensor in simulated breathing conditions with and without temperature change. The research team wanted to see how temperature and heat might affect each method of measurement. The resulting nasal pressure and PVDF traces retrieved from the PSG software were compared.

Methods and Resources

The research was conducted with breathing simulators, which enabled the researchers to better control the testing environment as well as eliminate potential variables. Todd Eiken, RPSGT, coordinator of the study and director of product development at Dymedix Diagnostics Inc, says the simulator was able to eliminate possible variables in several ways, including being able to provide unequivocal sleep-disordered breathing patterns and events that meet all standardized waveform characteristics.

In addition, with the use of the simulator, the breathing patterns are digitized and researchers are able to demonstrate a reproducible response to the same sleep-disordered breathing pattern during multiple trials. Also, the researchers were able to introduce or eliminate temperature changes, which is “particularly important when comparing PVDF to nasal pressure,” Eiken says.

PVDF or polyvinylidene fluoride is a unique material that responds to changes in temperature and air pressure. The research team sought to test PVDF sensors with and without temperature change. Eiken says, “In the interest of showing that PVDF is just as sensitive as nasal pressure in identifying hypopnea events, a breathing simulator allowed us to eliminate temperature change (resembling human breathing) from the equation, and perform a more ‘apples to apples’ comparison of pressure changes only.”

Study Results

The results showed that PVDF airflow sensors respond to both changes in pressure alone as well as simultaneous changes in pressure and temperature. The bench test also indicated that a PVDF airflow sensor signal output is increased as compared to nasal pressure when both changes in temperature and pressure are being monitored and that is a practical option for measuring hypopnea and apnea events during PSG.

Significance for Sleep Centers

The results of this investigational study may impact the options available for sleep centers and patients, Eiken says. “As of the publishing of the 2007 AASM Scoring Manual, nasal pressure monitoring is the only method recommended for identification of hypopnea events,” Eiken says. “As a result, patients have been required to wear two airflow sensors for apnea and hypopnea detection (thermal and pressure), PSG montages require two separate airflow channels for apnea and hypopnea scoring, disposable nasal pressure cannulas create nasal resistance and increase testing costs.”

According to Eiken, sleep centers are now able to consider options with PVDF airflow sensors, which have the benefits of reducing potential patient discomfort, eliminating costs for the nasal cannula, and displaying and scoring apnea and hypopnea events in one PSG channel.

PVDF Sensors for Hypopnea Identification

The Scoring Manual of the American Academy of Sleep Medicine (AASM) presently lists PVDF sensors as being accepted for apnea detection but are not listed as accepted for hypopnea detection. Dymedix, however, has met with the AASM’s Scoring Manual Committee in hopes of having this revised. Eiken says this white paper, in addition to other peer-reviewed and published research supporting the use of PVDF airflow sensors for hypopnea identification, has been submitted and is currently being reviewed by the committee.

Eiken says, “Based on current discussions and feedback from the committee, Dymedix is optimistic that PVDF airflow will be categorized as ‘accepted’ for hypopnea identification in the AASM Scoring Manual at some point this year.”

Cassandra Perez is associate editor for Sleep Review. CONTACT cperez@allied360.com