Comparison of Labial and Mechanical Interruption for Measurement of Aerodynamic Parameters

Summary 

Objectives/Hypothesis

To directly compare the mechanical and labial interruption techniques of measuring subglottal pressure (P_s), mean flow rate (MFR), and laryngeal resistance (R_L).

Methods

Thirty-four subjects performed 10 trials with both mechanical and labial interruption. P_s and MFR were recorded, whereas R_L was calculated by dividing P_s by MFR. Coefficients of variation were calculated to compare intrasubject precision. A subset of 10 subjects performed the tasks twice with 30 minutes between sessions. Bland-Altman plots were used to determine intrasubject repeatability for each of the methods.

Results

Mechanical interruption produced coefficients of variation for P_s, MFR, and R_L of 0.0995, 0.127, and 0.129, respectively. Labial interruption produced coefficients of variation of 0.102, 0.147, and 0.169, respectively. P values were 0.824 for P_s, 0.159 for MFR, and 0.043 for R_L. The Bland-Altman plots revealed comparable repeatability between the two methods. The 95% confidence intervals of the Bland-Altman plots for mechanical interruption were (−0.050, 0.072), (−0.543, 1.832), and (−2.498, 10.528) for MFR, P_s, and R_L. Confidence intervals for labial interruption were (−0.018, 0.031), (0.057, 2.442), and (−3.267, 10.595) for MFR, P_s, and R_L.

Conclusions

Mechanical interruption produced higher precision when measuring R_L because of more reliable airflow measurements. Mechanical and labial interruption showed comparable repeatability. Further research into using mechanical interruption clinically is warranted.

Key Words: Labial interruption, Mechanical interruption, Subglottal pressure, Laryngeal airflow, Laryngeal resistance