The Reliability and Influence of Body Position on Acoustic Pharyngometry and Rhinometry Outcomes.

Objectives: The aim of this cross sectional study was to analyze the method error and reliability in acoustic pharyngometry and rhinometry and to analyze the difference between standing and sitting position in acoustic pharyngometry and rhinometry.

Material and methods: The sample comprised 38 healthy subjects (11 men and 27 women) as part of a control group in another study. The subjects underwent repeated measures of acoustic pharyngometry and rhinometry in standing and sitting position. Upper airway dimensions in terms of volume, minimum cross-sectional areas (MCA) and distances were evaluated using the Eccovision^® Acoustic Pharyngometer and Rhinometer. Method error and reliability were analyzed using paired t-test, Dahlberg's formula and the Houston reliability coefficient, and differences between body positions were analyzed using paired t-test.

Results: There was no systematic error in the repeated measures except for the distance to MCA in the left nostril in sitting position (P = 0.041). The method error for the pharyngometry ranged between 0.001 to 0.164 cm/cm²/cm³ and the reliabity was 0.99. The method error for rhinometry ranged between 0.001 to 0.37 cm/cm²/cm³ and the reliability between 0.99 to 1. Difference between standing and sitting position was found only in the pharyngeal airway in terms of volume (P = 0.025) and mean area (P = 0.009) with smaller airway in sitting position.

Conclusions: The results indicate that acoustic pharyngometry and rhinometry are reliable methods to perform repeated measures of the upper airway dimensions especially in the standing mirror position. It may be essential to perform the measures with the patient positioned in the same body position each time.