Nasal airflow resistance measurement: forced oscillation technique versus posterior rhinomanometry

Abstract

This study was designed to determine whether nasal airflow resistance (Rn) which is nonlinear during tidal breathing, can be assessed by the forced oscillation (FO) technique. Rn values obtained by the FO technique and extrapolated to 0 Hz (Rn,FO) were compared to those assessed by posterior rhinomanometry at maximal tidal inspiratory flow (Rn,m), at a 0.5 L x s(-1) flow (Rn,F), and at a 1 hPa transnasal pressure (Rn,P). All Rn estimates were derived from the same inspiratory and expiratory nasal flow and transnasal pressure signals obtained during tidal nasal breathing whilst a forced flow was applied at the nose via a rigid nasal mask in 23 healthy volunteers, of whom 14 had additional measurements after vasoconstrictor treatment. In the basal state, no significant difference, and significant correlations (p<0.0001) were found between Rn,FO and the other Rn estimates. Only the regression line of Rn,FO versus Rn,m was not significantly different from the identity line. After nasal decongestion, Rn,P became significantly higher than the other Rn estimates (p<0.005). The regression line of Rn,FO versus Rn,m remained nonsignificantly different from the identity line. Similar results were observed regarding the percentage values of the different Rn estimates after decongestant treatment. This study shows that, despite its nonlinearity, Rn can be assessed by the FO technique, and that Rn,FO and Rn,m could be indifferently used as physiological indices of nasal patency. As the FO technique is more difficult to implement than the conventional rhinomanometry, its interest in rhinology appears not to be obvious.

Ventilation Mechanics

“…However, it could be possible that nonlinearities become apparent even within a single V T maneuver, particularly at high PEEP values since the elastic properties are more nonlinear at high lung volumes. [48][49][50][51] In this case, the elastic nonlinearity is revealed by an upward curvature of the P ao at the final phase of inspiration with constant flow.…”

“…However, this hypothesis is questioned in some important ventilatory conditions in healthy subjects and particularly in patients. [48][49][50][51][52][53][54][55][56][57][58][59][60] A clear example in healthy subjects is exercise given the considerable flow values associated with high-amplitude and high-rate breathing.…”