Continuous assessment of nasal airflow resistance by adaptive modeling

Abstract

A method to assess nasal airflow resistance is presented that provides a continuous resistance value and applies a novel minimally obtrusive measurement technique. Instead of calculating the resistance once for each breathing cycle conventionally, it is calculated for each signal sample at any sampling frequency. The continuous pressure recording is produced with a nasopharyngeal catheter inserted 8 cm deep along the floor of the other nasal cavity and the flow recording is produced with respiratory effort bands. A least-mean-square (LMS) extension for the resistance model of Broms is developed that dynamically adapts to the time-varying characteristics of the nasal functioning and produces the continuous resistance values. Experimental results are shown that demonstrate the uniqueness and applicability of the new technique in assessing quickly changing resistance in a histamine/xylometatsolin challenges, the differences between normal and symptomatic patients, and the effect of nasal treatment of patients.

Continuous Nasal Airflow Resistance during Birch Pollen Provocation Test

“…A novel method to estimate continuous resistance of the nasal airways using signals from the respiratory effort belts and pressure signal from nasopharyngeal catheter inserted transnasally into the nasopharynx was recently presented by Seppänen et al (2009;. A least-mean-square (LMS) extension for the model of Broms was developed that adapts to the time-varying characteristics of the nasal functioning.…”

“…Before applying the resistance calculation method, the respiratory belts are calibrated, as described in Section 2.3 above. For further details, refer to the original publication (Seppänen et al, 2009). Instantaneous resistance values are calculated over the measurement data and shown as dynamic plots over time.…”

“…Recently, a novel method was presented to assess nasal airflow resistance in a way that provides a continuous resistance values and applies a minimally obtrusive measurement method (Seppänen et al, 2009;. The pressure recording is produced with a nasopharyngeal catheter and the flow recording is produced with calibrated respiratory belts.…”

Addendum to ‘Continuous assessment of nasal airflow resistance by adaptive modeling’

“…The present measurement system (patent SE 530 004 C2 Sweden, patent FI 120132 B Finland) acquires the pressure signal by using a small catheter inserted transnasally into the nasopharynx, and the flow signal predicted from the respiratory effort signals after calibration with the regression method described in detail in our previous paper (Seppänen et al 2009).…”

“…In a recent study (Seppänen et al 2009) we presented a novel method to assess nasal airflow resistance in a way that provided a continuous resistance value and applied a minimally obtrusive measurement technique. Instead of calculating the resistance once for each breathing cycle conventionally, it was calculated for each signal sample at any sampling frequency.…”